TY  - JOUR
AU  - Lazarov, Nenad Đ.
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Jovanović, Predrag
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11234
AB  - In our work we presented the modified field equations generated by action with unspecified function f (R). Assuming spherical symmetry, we used the corresponding static Schwarzschild-like metric in the weak field limit. Also we considered geodesic equations of motion describing orbits and orbital speeds which can be measured in galactic environment. We solved geodesic equations in the case of a power-law f (R) theories, that is we set f (R) = f0nRn.
T2  - Filomat
T1  - Geodesic equations in the weak field limit of general f (R) gravity theory
VL  - 37
IS  - 25
SP  - 8575
EP  - 8581
DO  - 10.2298/FIL2325575L
ER  - 

@article{
author = "Lazarov, Nenad Đ. and Borka Jovanović, Vesna and Borka, Duško and Jovanović, Predrag",
year = "2023",
abstract = "In our work we presented the modified field equations generated by action with unspecified function f (R). Assuming spherical symmetry, we used the corresponding static Schwarzschild-like metric in the weak field limit. Also we considered geodesic equations of motion describing orbits and orbital speeds which can be measured in galactic environment. We solved geodesic equations in the case of a power-law f (R) theories, that is we set f (R) = f0nRn.",
journal = "Filomat",
title = "Geodesic equations in the weak field limit of general f (R) gravity theory",
volume = "37",
number = "25",
pages = "8575-8581",
doi = "10.2298/FIL2325575L"
}

Lazarov, N. Đ., Borka Jovanović, V., Borka, D.,& Jovanović, P.. (2023). Geodesic equations in the weak field limit of general f (R) gravity theory. in Filomat, 37(25), 8575-8581.
https://doi.org/10.2298/FIL2325575L

Lazarov NĐ, Borka Jovanović V, Borka D, Jovanović P. Geodesic equations in the weak field limit of general f (R) gravity theory. in Filomat. 2023;37(25):8575-8581.
doi:10.2298/FIL2325575L .

Lazarov, Nenad Đ., Borka Jovanović, Vesna, Borka, Duško, Jovanović, Predrag, "Geodesic equations in the weak field limit of general f (R) gravity theory" in Filomat, 37, no. 25 (2023):8575-8581,
https://doi.org/10.2298/FIL2325575L . .

TY  - JOUR
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
AU  - Nikolić, Violeta N.
AU  - Lazarov, Nenad Đ.
AU  - Jovanović, Predrag
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10151
AB  - We estimate the parameters of the Hybrid Palatini gravity model with the Schwarzschild precession of S-stars, specifically of the S2, S38 and S55 stars. We also take into account the case of bulk mass distribution near the Galactic Center. We assume that the Schwarzschild orbital precession of mentioned S-stars is the same as in General Relativity (GR) in all studied cases. In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the GR prediction. The astronomical data analysis of S38 and S55 orbits showed that, also in these cases, the orbital precession is close to the GR prediction. Based on this observational fact, we evaluated the parameters of the Hybrid Palatini Gravity model with the Schwarzschild precession of the S2, S38 and S55 stars, and we estimated the range of parameters of the Hybrid Palatini gravity model for which the orbital precession is as in GR for all three stars. We also evaluated the parameters of the Hybrid Palatini Gravity model in the case of different values of bulk mass density distribution of extended matter. We believe that proposed method is a useful tool to evaluate parameters of the gravitational potential at the Galactic Center. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
T2  - Universe
T1  - Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution
VL  - 8
IS  - 2
SP  - 70
DO  - 10.3390/universe8020070
ER  - 

@article{
author = "Borka, Duško and Borka Jovanović, Vesna and Nikolić, Violeta N. and Lazarov, Nenad Đ. and Jovanović, Predrag",
year = "2022",
abstract = "We estimate the parameters of the Hybrid Palatini gravity model with the Schwarzschild precession of S-stars, specifically of the S2, S38 and S55 stars. We also take into account the case of bulk mass distribution near the Galactic Center. We assume that the Schwarzschild orbital precession of mentioned S-stars is the same as in General Relativity (GR) in all studied cases. In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the GR prediction. The astronomical data analysis of S38 and S55 orbits showed that, also in these cases, the orbital precession is close to the GR prediction. Based on this observational fact, we evaluated the parameters of the Hybrid Palatini Gravity model with the Schwarzschild precession of the S2, S38 and S55 stars, and we estimated the range of parameters of the Hybrid Palatini gravity model for which the orbital precession is as in GR for all three stars. We also evaluated the parameters of the Hybrid Palatini Gravity model in the case of different values of bulk mass density distribution of extended matter. We believe that proposed method is a useful tool to evaluate parameters of the gravitational potential at the Galactic Center. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.",
journal = "Universe",
title = "Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution",
volume = "8",
number = "2",
pages = "70",
doi = "10.3390/universe8020070"
}

Borka, D., Borka Jovanović, V., Nikolić, V. N., Lazarov, N. Đ.,& Jovanović, P.. (2022). Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution. in Universe, 8(2), 70.
https://doi.org/10.3390/universe8020070

Borka D, Borka Jovanović V, Nikolić VN, Lazarov NĐ, Jovanović P. Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution. in Universe. 2022;8(2):70.
doi:10.3390/universe8020070 .

Borka, Duško, Borka Jovanović, Vesna, Nikolić, Violeta N., Lazarov, Nenad Đ., Jovanović, Predrag, "Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution" in Universe, 8, no. 2 (2022):70,
https://doi.org/10.3390/universe8020070 . .

TY  - JOUR
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
AU  - Capozziello, Salvatore
AU  - Jovanović, Predrag
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10420
AB  - We investigate the velocity distribution of elliptical galaxies in the framework of Non-local Gravity. According to this approach, it is possible to recover the fundamental plane of elliptical galaxies without the dark matter hypothesis. Specifically, we compare theoretical predictions for circular velocity in Non-local Gravity context with the corresponding values coming from a large sample of observed elliptical galaxies. We adopt the surface brightness, effective radius and velocity dispersion as structural parameters for the fundamental plane. As final result, it is possible to show that non-local gravity effects can reproduce the stellar dynamics in elliptical galaxies and fit consistently observational data.
T2  - Advances in Space Research
T1  - Velocity distribution of elliptical galaxies in the framework of Non-local Gravity model
VL  - 71
IS  - 2
SP  - 1235
EP  - 1244
DO  - 10.1016/j.asr.2022.08.060
ER  - 

@article{
author = "Borka, Duško and Borka Jovanović, Vesna and Capozziello, Salvatore and Jovanović, Predrag",
year = "2022",
abstract = "We investigate the velocity distribution of elliptical galaxies in the framework of Non-local Gravity. According to this approach, it is possible to recover the fundamental plane of elliptical galaxies without the dark matter hypothesis. Specifically, we compare theoretical predictions for circular velocity in Non-local Gravity context with the corresponding values coming from a large sample of observed elliptical galaxies. We adopt the surface brightness, effective radius and velocity dispersion as structural parameters for the fundamental plane. As final result, it is possible to show that non-local gravity effects can reproduce the stellar dynamics in elliptical galaxies and fit consistently observational data.",
journal = "Advances in Space Research",
title = "Velocity distribution of elliptical galaxies in the framework of Non-local Gravity model",
volume = "71",
number = "2",
pages = "1235-1244",
doi = "10.1016/j.asr.2022.08.060"
}

Borka, D., Borka Jovanović, V., Capozziello, S.,& Jovanović, P.. (2022). Velocity distribution of elliptical galaxies in the framework of Non-local Gravity model. in Advances in Space Research, 71(2), 1235-1244.
https://doi.org/10.1016/j.asr.2022.08.060

Borka D, Borka Jovanović V, Capozziello S, Jovanović P. Velocity distribution of elliptical galaxies in the framework of Non-local Gravity model. in Advances in Space Research. 2022;71(2):1235-1244.
doi:10.1016/j.asr.2022.08.060 .

Borka, Duško, Borka Jovanović, Vesna, Capozziello, Salvatore, Jovanović, Predrag, "Velocity distribution of elliptical galaxies in the framework of Non-local Gravity model" in Advances in Space Research, 71, no. 2 (2022):1235-1244,
https://doi.org/10.1016/j.asr.2022.08.060 . .

TY  - JOUR
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Arsenić, Arsenije
AU  - Jovanović, Predrag
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10341
AB  - The goal of this paper is to investigate the flux and spectral index distribution of FR II radio galaxy 4C 14.11. We focused on the distribution of flux and spectral indices over the lobes, as well as in their hot spots. For that purpose, we used publicly available observations of this radio galaxy given at 1450 and 8440 MHz. Particularly, we used Leahy’s Atlas of radio-emitting double radio sources, Jodrell Bank Centre for Astrophysics in Manchester, as well as NASA/IPAC Extragalactic Database. We found that the non-thermal (synchrotron) radiation dominates over the areas of the lobes. Distinction between hot spots and rest of the lobes are much smaller in the spectral index than in the flux. We also found that over the inner parts of both lobes, spectral index α is flat in average and significantly higher than 1.2, indicating that 4C 14.11 is old AGN.
T2  - Advances in Space Research
T1  - Spectral index distribution over radio lobes of 4C 14.11 using astrophysical data in FITS format
DO  - 10.1016/j.asr.2022.05.062
ER  - 

@article{
author = "Borka Jovanović, Vesna and Borka, Duško and Arsenić, Arsenije and Jovanović, Predrag",
year = "2022",
abstract = "The goal of this paper is to investigate the flux and spectral index distribution of FR II radio galaxy 4C 14.11. We focused on the distribution of flux and spectral indices over the lobes, as well as in their hot spots. For that purpose, we used publicly available observations of this radio galaxy given at 1450 and 8440 MHz. Particularly, we used Leahy’s Atlas of radio-emitting double radio sources, Jodrell Bank Centre for Astrophysics in Manchester, as well as NASA/IPAC Extragalactic Database. We found that the non-thermal (synchrotron) radiation dominates over the areas of the lobes. Distinction between hot spots and rest of the lobes are much smaller in the spectral index than in the flux. We also found that over the inner parts of both lobes, spectral index α is flat in average and significantly higher than 1.2, indicating that 4C 14.11 is old AGN.",
journal = "Advances in Space Research",
title = "Spectral index distribution over radio lobes of 4C 14.11 using astrophysical data in FITS format",
doi = "10.1016/j.asr.2022.05.062"
}

Borka Jovanović, V., Borka, D., Arsenić, A.,& Jovanović, P.. (2022). Spectral index distribution over radio lobes of 4C 14.11 using astrophysical data in FITS format. in Advances in Space Research.
https://doi.org/10.1016/j.asr.2022.05.062

Borka Jovanović V, Borka D, Arsenić A, Jovanović P. Spectral index distribution over radio lobes of 4C 14.11 using astrophysical data in FITS format. in Advances in Space Research. 2022;.
doi:10.1016/j.asr.2022.05.062 .

Borka Jovanović, Vesna, Borka, Duško, Arsenić, Arsenije, Jovanović, Predrag, "Spectral index distribution over radio lobes of 4C 14.11 using astrophysical data in FITS format" in Advances in Space Research (2022),
https://doi.org/10.1016/j.asr.2022.05.062 . .

TY  - JOUR
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
AU  - Capozziello, Salvatore
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9981
AB  - After giving a short overview of previous results on constraining of Extended Gravity by stellar orbits, we discuss the Schwarzschild orbital precession of S2 star assuming the congruence with predictions of General Relativity (GR). At the moment, the S2 star trajectory is remarkably fitted with the first post-Newtonian approximation of GR. In particular, both Keck and VLT (GRAVITY) teams declared that the gravitational redshift near its pericenter passage for the S2 star orbit corresponds to theoretical estimates found with the first post-Newtonian (pN) approximation. In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the GR prediction. Based on this observational fact, we evaluated parameters of the Extended Gravity theories with the Schwarzschild precession of the S2 star. Using the mentioned method, we estimate the orbital precession angles for some Extended Gravity models including power-law f(R), general Yukawa-like corrections, scalar–tensor gravity, and non-local gravity theories formulated in both metric and Palatini formalism. In this consideration, we assume that a gravitational field is spherically symmetric, therefore, alternative theories of gravity could be described only with a few parameters. Specifically, considering the orbital precession, we estimate the range of parameters of these Extended Gravity models for which the orbital precession is like in GR. Then we compare these results with our previous results, which were obtained by fitting the simulated orbits of S2 star to its observed astrometric positions. In case of power-law f(R), generic Yukawa-like correction, scalar–tensor gravity and non-local gravity theories, we were able to obtain a prograde orbital precession, like in GR. According to these results, the method is a useful tool to evaluate parameters of the gravitational potential at the Galactic Center.
T2  - Universe
T1  - Estimating the Parameters of Extended Gravity Theories with the Schwarzschild Precession of S2 Star
VL  - 7
IS  - 11
SP  - 407
DO  - 10.3390/universe7110407
ER  - 

@article{
author = "Borka, Duško and Borka Jovanović, Vesna and Capozziello, Salvatore and Zakharov, Alexander F. and Jovanović, Predrag",
year = "2021",
abstract = "After giving a short overview of previous results on constraining of Extended Gravity by stellar orbits, we discuss the Schwarzschild orbital precession of S2 star assuming the congruence with predictions of General Relativity (GR). At the moment, the S2 star trajectory is remarkably fitted with the first post-Newtonian approximation of GR. In particular, both Keck and VLT (GRAVITY) teams declared that the gravitational redshift near its pericenter passage for the S2 star orbit corresponds to theoretical estimates found with the first post-Newtonian (pN) approximation. In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the GR prediction. Based on this observational fact, we evaluated parameters of the Extended Gravity theories with the Schwarzschild precession of the S2 star. Using the mentioned method, we estimate the orbital precession angles for some Extended Gravity models including power-law f(R), general Yukawa-like corrections, scalar–tensor gravity, and non-local gravity theories formulated in both metric and Palatini formalism. In this consideration, we assume that a gravitational field is spherically symmetric, therefore, alternative theories of gravity could be described only with a few parameters. Specifically, considering the orbital precession, we estimate the range of parameters of these Extended Gravity models for which the orbital precession is like in GR. Then we compare these results with our previous results, which were obtained by fitting the simulated orbits of S2 star to its observed astrometric positions. In case of power-law f(R), generic Yukawa-like correction, scalar–tensor gravity and non-local gravity theories, we were able to obtain a prograde orbital precession, like in GR. According to these results, the method is a useful tool to evaluate parameters of the gravitational potential at the Galactic Center.",
journal = "Universe",
title = "Estimating the Parameters of Extended Gravity Theories with the Schwarzschild Precession of S2 Star",
volume = "7",
number = "11",
pages = "407",
doi = "10.3390/universe7110407"
}

Borka, D., Borka Jovanović, V., Capozziello, S., Zakharov, A. F.,& Jovanović, P.. (2021). Estimating the Parameters of Extended Gravity Theories with the Schwarzschild Precession of S2 Star. in Universe, 7(11), 407.
https://doi.org/10.3390/universe7110407

Borka D, Borka Jovanović V, Capozziello S, Zakharov AF, Jovanović P. Estimating the Parameters of Extended Gravity Theories with the Schwarzschild Precession of S2 Star. in Universe. 2021;7(11):407.
doi:10.3390/universe7110407 .

Borka, Duško, Borka Jovanović, Vesna, Capozziello, Salvatore, Zakharov, Alexander F., Jovanović, Predrag, "Estimating the Parameters of Extended Gravity Theories with the Schwarzschild Precession of S2 Star" in Universe, 7, no. 11 (2021):407,
https://doi.org/10.3390/universe7110407 . .

TY  - JOUR
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Jovanović, Predrag
AU  - Capozziello, Salvatore
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9802
AB  - We use the Fundamental Plane of Elliptical Galaxies to constrain the so-called Hybrid Gravity, a modified theory of gravity where General Relativity is improved by further degrees of freedom of metric-affine Palatini formalism of f(R) gravity. Because the Fundamental Plane is connected to the global properties of elliptical galaxies, it is possible to obtain observational constraints on the parameters of Hybrid Gravity in the weak field limit. We analyze also the velocity distribution of elliptical galaxies comparing our theoretical results in the case of Hybrid Gravity with astronomical data for elliptical galaxies. In this way, we are able to constrain the Hybrid Gravity parameters mϕ and ϕ. We show that the Fundamental Plane, i.e., vc/ σ relations, can be used as a standard tool to probe different theories of gravity in the weak field limit. We conclude that Hybrid Gravity is able to explain elliptical galaxies with different stellar kinematics without the dark matter hypothesis. © 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.
T2  - European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics
T1  - Possible effects of hybrid gravity on stellar kinematics in elliptical galaxies
VL  - 75
IS  - 5
DO  - 10.1140/epjd/s10053-021-00163-y
ER  - 

@article{
author = "Borka Jovanović, Vesna and Borka, Duško and Jovanović, Predrag and Capozziello, Salvatore",
year = "2021",
abstract = "We use the Fundamental Plane of Elliptical Galaxies to constrain the so-called Hybrid Gravity, a modified theory of gravity where General Relativity is improved by further degrees of freedom of metric-affine Palatini formalism of f(R) gravity. Because the Fundamental Plane is connected to the global properties of elliptical galaxies, it is possible to obtain observational constraints on the parameters of Hybrid Gravity in the weak field limit. We analyze also the velocity distribution of elliptical galaxies comparing our theoretical results in the case of Hybrid Gravity with astronomical data for elliptical galaxies. In this way, we are able to constrain the Hybrid Gravity parameters mϕ and ϕ. We show that the Fundamental Plane, i.e., vc/ σ relations, can be used as a standard tool to probe different theories of gravity in the weak field limit. We conclude that Hybrid Gravity is able to explain elliptical galaxies with different stellar kinematics without the dark matter hypothesis. © 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.",
journal = "European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics",
title = "Possible effects of hybrid gravity on stellar kinematics in elliptical galaxies",
volume = "75",
number = "5",
doi = "10.1140/epjd/s10053-021-00163-y"
}

Borka Jovanović, V., Borka, D., Jovanović, P.,& Capozziello, S.. (2021). Possible effects of hybrid gravity on stellar kinematics in elliptical galaxies. in European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics, 75(5).
https://doi.org/10.1140/epjd/s10053-021-00163-y

Borka Jovanović V, Borka D, Jovanović P, Capozziello S. Possible effects of hybrid gravity on stellar kinematics in elliptical galaxies. in European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics. 2021;75(5).
doi:10.1140/epjd/s10053-021-00163-y .

Borka Jovanović, Vesna, Borka, Duško, Jovanović, Predrag, Capozziello, Salvatore, "Possible effects of hybrid gravity on stellar kinematics in elliptical galaxies" in European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics, 75, no. 5 (2021),
https://doi.org/10.1140/epjd/s10053-021-00163-y . .

TY  - JOUR
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
AU  - Zakharov, Alexander F.
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9803
AB  - In this study we investigate possible applications of observed S2 orbit around Galactic Center for constraining the Yukawa gravity at scales in the range between several tens and several thousands astronomical units (AU) to obtain graviton mass constraints. In our model we suppose that bulk distribution of matter (includes stellar cluster, interstellar gas distribution and dark matter) exists near Supermassive Black Hole (SMBH) in our Galactic Center. We obtain the values of orbital precession angle for different values of mass density of matter, and we require that the value of orbital precession is the same like in general relativity (GR). From that request we determine gravity parameter λ and the upper value for graviton mass. We found that in the cases where the density of extended mass is higher, the maximum allowed value for parameter λ is smaller and the upper limit for graviton mass is higher. It is due to the fact that the extended mass causes the retrograde orbital precession. We believe that this study is a very efficient tool to evaluate a gravitational potential at the Galactic Center, parameter λ of the Yukawa gravity model, and to constrain the graviton mass. Graphic Abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.
T2  - European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics
T2  - European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics
T1  - Influence of bulk mass distribution on orbital precession of S2 star in Yukawa gravity
VL  - 75
IS  - 5
DO  - 10.1140/epjd/s10053-021-00154-z
ER  - 

@article{
author = "Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna and Zakharov, Alexander F.",
year = "2021",
abstract = "In this study we investigate possible applications of observed S2 orbit around Galactic Center for constraining the Yukawa gravity at scales in the range between several tens and several thousands astronomical units (AU) to obtain graviton mass constraints. In our model we suppose that bulk distribution of matter (includes stellar cluster, interstellar gas distribution and dark matter) exists near Supermassive Black Hole (SMBH) in our Galactic Center. We obtain the values of orbital precession angle for different values of mass density of matter, and we require that the value of orbital precession is the same like in general relativity (GR). From that request we determine gravity parameter λ and the upper value for graviton mass. We found that in the cases where the density of extended mass is higher, the maximum allowed value for parameter λ is smaller and the upper limit for graviton mass is higher. It is due to the fact that the extended mass causes the retrograde orbital precession. We believe that this study is a very efficient tool to evaluate a gravitational potential at the Galactic Center, parameter λ of the Yukawa gravity model, and to constrain the graviton mass. Graphic Abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.",
journal = "European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics, European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics",
title = "Influence of bulk mass distribution on orbital precession of S2 star in Yukawa gravity",
volume = "75",
number = "5",
doi = "10.1140/epjd/s10053-021-00154-z"
}

Jovanović, P., Borka, D., Borka Jovanović, V.,& Zakharov, A. F.. (2021). Influence of bulk mass distribution on orbital precession of S2 star in Yukawa gravity. in European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics, 75(5).
https://doi.org/10.1140/epjd/s10053-021-00154-z

Jovanović P, Borka D, Borka Jovanović V, Zakharov AF. Influence of bulk mass distribution on orbital precession of S2 star in Yukawa gravity. in European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics. 2021;75(5).
doi:10.1140/epjd/s10053-021-00154-z .

Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, Zakharov, Alexander F., "Influence of bulk mass distribution on orbital precession of S2 star in Yukawa gravity" in European Physical Journal D. Atoms, Molecules, Clusters and Optical Physics, 75, no. 5 (2021),
https://doi.org/10.1140/epjd/s10053-021-00154-z . .

TY  - JOUR
AU  - Jovanović, Predrag
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Popović, Luka Č.
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8827
AB  - Here we study the potential observational signatures of supermassive black hole binaries (SMBHBs) in the Fe Kα line profiles emitted from the accretion disks around their components. We simulated the Fe Kα line emission from the relativistic accretion disks using ray tracing method in Kerr metric. The obtained profiles from the SMBHBs are then compared with those in the case of the single supermassive black holes (SMBHs). We considered two models of the SMBHBs: a model when the secondary SMBH is embedded in the accretion disk around the primary, causing an empty gap in the disk, and a model with clearly separated components, where the accretion disks around both primary and secondary give a significant contribution to the composite Fe Kα line emission of a such SMBHB. The obtained results showed that both models of SMBHBs can leave imprints in the form of ripples in the cores of the emitted Fe Kα line profiles, which may look like an absorption component in the line profile. However, in the case of the composite line profiles emitted from two accretion disks, these ripples could have much higher amplitudes and strongly depend on orbital phase of the system, while for those emitted from a disk with an empty gap, the corresponding ripples mostly have lower amplitudes and do not vary significantly with orbital phase. The present day X-ray telescopes are not able to detect such signatures in the observed X-ray spectra of SMBHBs. However this will be possible with the next generation of X-ray observatories, which will also enable application of such effects as a tool for studying the properties of these objects. © 2020, Astronomical Institute, Slovak Academy of Sciences.
T2  - Contributions of the Astronomical Observatory Skalnaté Pleso
T1  - Possible observational signatures of supermassive black hole binaries in their Fe Kα line profiles
VL  - 50
IS  - 1
SP  - 219
EP  - 234
DO  - 10.31577/caosp.2020.50.1.219
ER  - 

@article{
author = "Jovanović, Predrag and Borka Jovanović, Vesna and Borka, Duško and Popović, Luka Č.",
year = "2020",
abstract = "Here we study the potential observational signatures of supermassive black hole binaries (SMBHBs) in the Fe Kα line profiles emitted from the accretion disks around their components. We simulated the Fe Kα line emission from the relativistic accretion disks using ray tracing method in Kerr metric. The obtained profiles from the SMBHBs are then compared with those in the case of the single supermassive black holes (SMBHs). We considered two models of the SMBHBs: a model when the secondary SMBH is embedded in the accretion disk around the primary, causing an empty gap in the disk, and a model with clearly separated components, where the accretion disks around both primary and secondary give a significant contribution to the composite Fe Kα line emission of a such SMBHB. The obtained results showed that both models of SMBHBs can leave imprints in the form of ripples in the cores of the emitted Fe Kα line profiles, which may look like an absorption component in the line profile. However, in the case of the composite line profiles emitted from two accretion disks, these ripples could have much higher amplitudes and strongly depend on orbital phase of the system, while for those emitted from a disk with an empty gap, the corresponding ripples mostly have lower amplitudes and do not vary significantly with orbital phase. The present day X-ray telescopes are not able to detect such signatures in the observed X-ray spectra of SMBHBs. However this will be possible with the next generation of X-ray observatories, which will also enable application of such effects as a tool for studying the properties of these objects. © 2020, Astronomical Institute, Slovak Academy of Sciences.",
journal = "Contributions of the Astronomical Observatory Skalnaté Pleso",
title = "Possible observational signatures of supermassive black hole binaries in their Fe Kα line profiles",
volume = "50",
number = "1",
pages = "219-234",
doi = "10.31577/caosp.2020.50.1.219"
}

Jovanović, P., Borka Jovanović, V., Borka, D.,& Popović, L. Č.. (2020). Possible observational signatures of supermassive black hole binaries in their Fe Kα line profiles. in Contributions of the Astronomical Observatory Skalnaté Pleso, 50(1), 219-234.
https://doi.org/10.31577/caosp.2020.50.1.219

Jovanović P, Borka Jovanović V, Borka D, Popović LČ. Possible observational signatures of supermassive black hole binaries in their Fe Kα line profiles. in Contributions of the Astronomical Observatory Skalnaté Pleso. 2020;50(1):219-234.
doi:10.31577/caosp.2020.50.1.219 .

Jovanović, Predrag, Borka Jovanović, Vesna, Borka, Duško, Popović, Luka Č., "Possible observational signatures of supermassive black hole binaries in their Fe Kα line profiles" in Contributions of the Astronomical Observatory Skalnaté Pleso, 50, no. 1 (2020):219-234,
https://doi.org/10.31577/caosp.2020.50.1.219 . .

TY  - JOUR
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8826
AB  - It is established that there are supermassive black holes in centers of galaxies. A supermassive black hole with mass around 4 × 106 M⊙ is located at the Galactic Center. Such an approach for the Galactic Center looks rather natural, in spite of that consequences of model must be checked with observa- tions. We discuss opportunities to check this with forthcoming observations of shadows in mm band for the Galactic Center as it was done recently for M87*. Observations of bright stars moving near the Galactic Center gives another op-portunity to evaluate gravitational potential. We discuss opportunities to use these observations to constrain alternative theories of gravity. © 2020, Astronomical Institute, Slovak Academy of Sciences.
T2  - Contributions of the Astronomical Observatory Skalnaté Pleso
T1  - Observational tests of general relativity and alternative theories of gravity with Galactic Center observations using current and future large observational facilities
VL  - 50
IS  - 1
SP  - 203
EP  - 218
DO  - 10.31577/caosp.2020.50.1.203
ER  - 

@article{
author = "Zakharov, Alexander F. and Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2020",
abstract = "It is established that there are supermassive black holes in centers of galaxies. A supermassive black hole with mass around 4 × 106 M⊙ is located at the Galactic Center. Such an approach for the Galactic Center looks rather natural, in spite of that consequences of model must be checked with observa- tions. We discuss opportunities to check this with forthcoming observations of shadows in mm band for the Galactic Center as it was done recently for M87*. Observations of bright stars moving near the Galactic Center gives another op-portunity to evaluate gravitational potential. We discuss opportunities to use these observations to constrain alternative theories of gravity. © 2020, Astronomical Institute, Slovak Academy of Sciences.",
journal = "Contributions of the Astronomical Observatory Skalnaté Pleso",
title = "Observational tests of general relativity and alternative theories of gravity with Galactic Center observations using current and future large observational facilities",
volume = "50",
number = "1",
pages = "203-218",
doi = "10.31577/caosp.2020.50.1.203"
}

Zakharov, A. F., Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2020). Observational tests of general relativity and alternative theories of gravity with Galactic Center observations using current and future large observational facilities. in Contributions of the Astronomical Observatory Skalnaté Pleso, 50(1), 203-218.
https://doi.org/10.31577/caosp.2020.50.1.203

Zakharov AF, Jovanović P, Borka D, Borka Jovanović V. Observational tests of general relativity and alternative theories of gravity with Galactic Center observations using current and future large observational facilities. in Contributions of the Astronomical Observatory Skalnaté Pleso. 2020;50(1):203-218.
doi:10.31577/caosp.2020.50.1.203 .

Zakharov, Alexander F., Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Observational tests of general relativity and alternative theories of gravity with Galactic Center observations using current and future large observational facilities" in Contributions of the Astronomical Observatory Skalnaté Pleso, 50, no. 1 (2020):203-218,
https://doi.org/10.31577/caosp.2020.50.1.203 . .

TY  - JOUR
AU  - Capozziello, Salvatore
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Jovanović, Predrag
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8951
AB  - We show that fundamental plane of elliptical galaxies can be used to obtain observational constraints on metric theories of gravity. Being it connected to global properties of ellipticals, it can fix parameters of modified gravity. Specifically, we use fundamental plane to constrain modified theories of gravity with Yukawa-like corrections which commonly emerge in the post-Newtonian limit. After giving examples on how these corrections are derived, we first analyze the velocity distribution of elliptical galaxies comparing theoretical results of modified gravity with Yukawa-like corrections with astronomical data. According to these results, it is possible to constrain the parameters of the corrections discriminating among classes of models compatible with astronomical observations. We conclude that fundamental plane can be used as a standard tool to probe different theories of gravity in the weak field limit.
T2  - Physics of the Dark Universe
T1  - Constraining theories of gravity by fundamental plane of elliptical galaxies
VL  - 29
SP  - 100573
DO  - 10.1016/j.dark.2020.100573
ER  - 

@article{
author = "Capozziello, Salvatore and Borka Jovanović, Vesna and Borka, Duško and Jovanović, Predrag",
year = "2020",
abstract = "We show that fundamental plane of elliptical galaxies can be used to obtain observational constraints on metric theories of gravity. Being it connected to global properties of ellipticals, it can fix parameters of modified gravity. Specifically, we use fundamental plane to constrain modified theories of gravity with Yukawa-like corrections which commonly emerge in the post-Newtonian limit. After giving examples on how these corrections are derived, we first analyze the velocity distribution of elliptical galaxies comparing theoretical results of modified gravity with Yukawa-like corrections with astronomical data. According to these results, it is possible to constrain the parameters of the corrections discriminating among classes of models compatible with astronomical observations. We conclude that fundamental plane can be used as a standard tool to probe different theories of gravity in the weak field limit.",
journal = "Physics of the Dark Universe",
title = "Constraining theories of gravity by fundamental plane of elliptical galaxies",
volume = "29",
pages = "100573",
doi = "10.1016/j.dark.2020.100573"
}

Capozziello, S., Borka Jovanović, V., Borka, D.,& Jovanović, P.. (2020). Constraining theories of gravity by fundamental plane of elliptical galaxies. in Physics of the Dark Universe, 29, 100573.
https://doi.org/10.1016/j.dark.2020.100573

Capozziello S, Borka Jovanović V, Borka D, Jovanović P. Constraining theories of gravity by fundamental plane of elliptical galaxies. in Physics of the Dark Universe. 2020;29:100573.
doi:10.1016/j.dark.2020.100573 .

Capozziello, Salvatore, Borka Jovanović, Vesna, Borka, Duško, Jovanović, Predrag, "Constraining theories of gravity by fundamental plane of elliptical galaxies" in Physics of the Dark Universe, 29 (2020):100573,
https://doi.org/10.1016/j.dark.2020.100573 . .

TY  - JOUR
AU  - Dialektopoulos, Konstantinos F.
AU  - Borka, Duško
AU  - Capozziello, Salvatore
AU  - Borka Jovanović, Vesna
AU  - Jovanović, Predrag
PY  - 2019
UR  - https://link.aps.org/doi/10.1103/PhysRevD.99.044053
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8084
AB  - Nonlocal theories of gravity have recently drawn a lot of attention because they can suitably represent the behavior of gravitational interaction in the ultraviolet regime. Furthermore, at infrared scales, they give rise to notable cosmological effects which could be important to describe the dark energy behavior. In particular, exponential forms of the distortion function seem particularly useful for this purpose. Using Noether symmetries, it can be shown that the only nontrivial form of the distortion function is the exponential one, which is working not only for cosmological minisuperspaces, but also in a spherically symmetric spacetime. Taking this result into account, we study the weak-field approximation of this type of nonlocal gravity, and comparing with the orbits of the S2 star around the Galactic center (NTT/VLT data), we set constraints on the parameters of the theory. Nonlocal effects do not play a significant role on the orbits of S2 stars around Sgr A∗ but give richer phenomenology at cosmological scales than the ΛCDM model. Also, we show that the nonlocal gravity model gives better agreement between theory and astronomical observations than Keplerian orbits. © 2019 American Physical Society.
T2  - Physical Review D
T1  - Constraining nonlocal gravity by S2 star orbits
VL  - 99
IS  - 4
SP  - 044053
DO  - 10.1103/PhysRevD.99.044053
ER  - 

@article{
author = "Dialektopoulos, Konstantinos F. and Borka, Duško and Capozziello, Salvatore and Borka Jovanović, Vesna and Jovanović, Predrag",
year = "2019",
abstract = "Nonlocal theories of gravity have recently drawn a lot of attention because they can suitably represent the behavior of gravitational interaction in the ultraviolet regime. Furthermore, at infrared scales, they give rise to notable cosmological effects which could be important to describe the dark energy behavior. In particular, exponential forms of the distortion function seem particularly useful for this purpose. Using Noether symmetries, it can be shown that the only nontrivial form of the distortion function is the exponential one, which is working not only for cosmological minisuperspaces, but also in a spherically symmetric spacetime. Taking this result into account, we study the weak-field approximation of this type of nonlocal gravity, and comparing with the orbits of the S2 star around the Galactic center (NTT/VLT data), we set constraints on the parameters of the theory. Nonlocal effects do not play a significant role on the orbits of S2 stars around Sgr A∗ but give richer phenomenology at cosmological scales than the ΛCDM model. Also, we show that the nonlocal gravity model gives better agreement between theory and astronomical observations than Keplerian orbits. © 2019 American Physical Society.",
journal = "Physical Review D",
title = "Constraining nonlocal gravity by S2 star orbits",
volume = "99",
number = "4",
pages = "044053",
doi = "10.1103/PhysRevD.99.044053"
}

Dialektopoulos, K. F., Borka, D., Capozziello, S., Borka Jovanović, V.,& Jovanović, P.. (2019). Constraining nonlocal gravity by S2 star orbits. in Physical Review D, 99(4), 044053.
https://doi.org/10.1103/PhysRevD.99.044053

Dialektopoulos KF, Borka D, Capozziello S, Borka Jovanović V, Jovanović P. Constraining nonlocal gravity by S2 star orbits. in Physical Review D. 2019;99(4):044053.
doi:10.1103/PhysRevD.99.044053 .

Dialektopoulos, Konstantinos F., Borka, Duško, Capozziello, Salvatore, Borka Jovanović, Vesna, Jovanović, Predrag, "Constraining nonlocal gravity by S2 star orbits" in Physical Review D, 99, no. 4 (2019):044053,
https://doi.org/10.1103/PhysRevD.99.044053 . .

TY  - JOUR
AU  - Dialektopoulos, Konstantinos F.
AU  - Borka, Duško
AU  - Capozziello, Salvatore
AU  - Borka Jovanović, Vesna
AU  - Jovanović, Predrag
PY  - 2019
UR  - https://link.aps.org/doi/10.1103/PhysRevD.99.044053
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8090
AB  - Nonlocal theories of gravity have recently drawn a lot of attention because they can suitably represent the behavior of gravitational interaction in the ultraviolet regime. Furthermore, at infrared scales, they give rise to notable cosmological effects which could be important to describe the dark energy behavior. In particular, exponential forms of the distortion function seem particularly useful for this purpose. Using Noether symmetries, it can be shown that the only nontrivial form of the distortion function is the exponential one, which is working not only for cosmological minisuperspaces, but also in a spherically symmetric spacetime. Taking this result into account, we study the weak-field approximation of this type of nonlocal gravity, and comparing with the orbits of the S2 star around the Galactic center (NTT/VLT data), we set constraints on the parameters of the theory. Nonlocal effects do not play a significant role on the orbits of S2 stars around Sgr A∗ but give richer phenomenology at cosmological scales than the ΛCDM model. Also, we show that the nonlocal gravity model gives better agreement between theory and astronomical observations than Keplerian orbits.
T2  - Physical Review D
T1  - Constraining nonlocal gravity by S2 star orbits
VL  - 99
IS  - 4
SP  - 044053
DO  - 10.1103/PhysRevD.99.044053
ER  - 

@article{
author = "Dialektopoulos, Konstantinos F. and Borka, Duško and Capozziello, Salvatore and Borka Jovanović, Vesna and Jovanović, Predrag",
year = "2019",
abstract = "Nonlocal theories of gravity have recently drawn a lot of attention because they can suitably represent the behavior of gravitational interaction in the ultraviolet regime. Furthermore, at infrared scales, they give rise to notable cosmological effects which could be important to describe the dark energy behavior. In particular, exponential forms of the distortion function seem particularly useful for this purpose. Using Noether symmetries, it can be shown that the only nontrivial form of the distortion function is the exponential one, which is working not only for cosmological minisuperspaces, but also in a spherically symmetric spacetime. Taking this result into account, we study the weak-field approximation of this type of nonlocal gravity, and comparing with the orbits of the S2 star around the Galactic center (NTT/VLT data), we set constraints on the parameters of the theory. Nonlocal effects do not play a significant role on the orbits of S2 stars around Sgr A∗ but give richer phenomenology at cosmological scales than the ΛCDM model. Also, we show that the nonlocal gravity model gives better agreement between theory and astronomical observations than Keplerian orbits.",
journal = "Physical Review D",
title = "Constraining nonlocal gravity by S2 star orbits",
volume = "99",
number = "4",
pages = "044053",
doi = "10.1103/PhysRevD.99.044053"
}

Dialektopoulos, K. F., Borka, D., Capozziello, S., Borka Jovanović, V.,& Jovanović, P.. (2019). Constraining nonlocal gravity by S2 star orbits. in Physical Review D, 99(4), 044053.
https://doi.org/10.1103/PhysRevD.99.044053

Dialektopoulos KF, Borka D, Capozziello S, Borka Jovanović V, Jovanović P. Constraining nonlocal gravity by S2 star orbits. in Physical Review D. 2019;99(4):044053.
doi:10.1103/PhysRevD.99.044053 .

Dialektopoulos, Konstantinos F., Borka, Duško, Capozziello, Salvatore, Borka Jovanović, Vesna, Jovanović, Predrag, "Constraining nonlocal gravity by S2 star orbits" in Physical Review D, 99, no. 4 (2019):044053,
https://doi.org/10.1103/PhysRevD.99.044053 . .

TY  - CONF
AU  - Ignjatović, Siniša R.
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Jovanović, Predrag
PY  - 2019
UR  - http://aip.scitation.org/doi/abs/10.1063/1.5091205
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8093
AB  - The simplest form of the Hyperfine Interaction (HFI) of quarks is a color-spin interaction, sometimes called Fermi-Breit (FB) HFI. For conventional hadrons, this HFI for quark-antiquark (qq) pairs is twice as strong as the same HFI for quark-quark (qq or qq) pairs, but this difference is absorbed into the different HFI constants for mesons and baryons, which are free parameters of the fits. For tetraquarks, however, qqHFI is only half as strong as the qq/qqHFI and both kinds of pairs coexist within the same state. Hence it is worth investigating a model with different fit constants for qq and qq/q pairs. We have investigated 3 models of spin-color HFI for light scalar tetraquarks: 2 models with single constants for both kinds of pairs and one model with different fit constants. The light scalar nonet is chosen because of a lack of other experimentally observed multiplets interpretable as pure exotic states. Since even the nonet contains only 3 particles with distinct masses (i. e. 3 fit points), the constituent quark masses had to be taken from conventional hadron fits obtained in our previous work. The two-constant model did not prove to be a viable alternative to the one-constant models. © 2019 Author(s).
C3  - AIP Conference Proceedings
T1  - Hyperfine interactions of constituent quarks and the mass spectrum of tetraquark states
VL  - 2075
SP  - 080004
DO  - 10.1063/1.5091205
ER  - 

@conference{
author = "Ignjatović, Siniša R. and Borka Jovanović, Vesna and Borka, Duško and Jovanović, Predrag",
year = "2019",
abstract = "The simplest form of the Hyperfine Interaction (HFI) of quarks is a color-spin interaction, sometimes called Fermi-Breit (FB) HFI. For conventional hadrons, this HFI for quark-antiquark (qq) pairs is twice as strong as the same HFI for quark-quark (qq or qq) pairs, but this difference is absorbed into the different HFI constants for mesons and baryons, which are free parameters of the fits. For tetraquarks, however, qqHFI is only half as strong as the qq/qqHFI and both kinds of pairs coexist within the same state. Hence it is worth investigating a model with different fit constants for qq and qq/q pairs. We have investigated 3 models of spin-color HFI for light scalar tetraquarks: 2 models with single constants for both kinds of pairs and one model with different fit constants. The light scalar nonet is chosen because of a lack of other experimentally observed multiplets interpretable as pure exotic states. Since even the nonet contains only 3 particles with distinct masses (i. e. 3 fit points), the constituent quark masses had to be taken from conventional hadron fits obtained in our previous work. The two-constant model did not prove to be a viable alternative to the one-constant models. © 2019 Author(s).",
journal = "AIP Conference Proceedings",
title = "Hyperfine interactions of constituent quarks and the mass spectrum of tetraquark states",
volume = "2075",
pages = "080004",
doi = "10.1063/1.5091205"
}

Ignjatović, S. R., Borka Jovanović, V., Borka, D.,& Jovanović, P.. (2019). Hyperfine interactions of constituent quarks and the mass spectrum of tetraquark states. in AIP Conference Proceedings, 2075, 080004.
https://doi.org/10.1063/1.5091205

Ignjatović SR, Borka Jovanović V, Borka D, Jovanović P. Hyperfine interactions of constituent quarks and the mass spectrum of tetraquark states. in AIP Conference Proceedings. 2019;2075:080004.
doi:10.1063/1.5091205 .

Ignjatović, Siniša R., Borka Jovanović, Vesna, Borka, Duško, Jovanović, Predrag, "Hyperfine interactions of constituent quarks and the mass spectrum of tetraquark states" in AIP Conference Proceedings, 2075 (2019):080004,
https://doi.org/10.1063/1.5091205 . .

TY  - JOUR
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8788
AB  - In this work we used the observed additional perihelion precession in the Solar System, obtained from the observations of planets and spacecrafts, to study the possible existence of Yukawa correction term to the Newtonian gravitational potential. Our study was motivated by previous analyses which indicated the possible discrepancies from Newtonian gravity in this form and at wide range of astrophysical scales. Yukawa gravity was introduced to cure some shortcomings of General Relativity (GR) at galactic and extragalactic scales. We demonstrated that this form of gravity can give the values for orbital precession which are comparable or even in better agreement with observations than the corresponding predictions of GR. The obtained results can be used for setting stronger constraints on variation of the gravitational constant G, as well as on the fundamental constant δ of Yukawa gravity. Moreover, Yukawa gravity could be used to improve the results for the motion of planets, other Solar System bodies, as well as spacecrafts, and as a consequence, it can help us to get more reliable predictions for natural hazards in the Solar System, such as potential impacts by near-Earth objects. © 2019, Geographical Institute "Jovan Cviji" of the Serbian Academy of Sciences and Arts. All rights reserved.
T2  - Journal of the Geographical Institute Jovan Cvijic, SASA
T1  - Constraining Yukawa gravity from planetary motion in the solar system
VL  - 69
IS  - 3
SP  - 265
EP  - 269
DO  - 10.2298/IJGI1903265J
ER  - 

@article{
author = "Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2019",
abstract = "In this work we used the observed additional perihelion precession in the Solar System, obtained from the observations of planets and spacecrafts, to study the possible existence of Yukawa correction term to the Newtonian gravitational potential. Our study was motivated by previous analyses which indicated the possible discrepancies from Newtonian gravity in this form and at wide range of astrophysical scales. Yukawa gravity was introduced to cure some shortcomings of General Relativity (GR) at galactic and extragalactic scales. We demonstrated that this form of gravity can give the values for orbital precession which are comparable or even in better agreement with observations than the corresponding predictions of GR. The obtained results can be used for setting stronger constraints on variation of the gravitational constant G, as well as on the fundamental constant δ of Yukawa gravity. Moreover, Yukawa gravity could be used to improve the results for the motion of planets, other Solar System bodies, as well as spacecrafts, and as a consequence, it can help us to get more reliable predictions for natural hazards in the Solar System, such as potential impacts by near-Earth objects. © 2019, Geographical Institute "Jovan Cviji" of the Serbian Academy of Sciences and Arts. All rights reserved.",
journal = "Journal of the Geographical Institute Jovan Cvijic, SASA",
title = "Constraining Yukawa gravity from planetary motion in the solar system",
volume = "69",
number = "3",
pages = "265-269",
doi = "10.2298/IJGI1903265J"
}

Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2019). Constraining Yukawa gravity from planetary motion in the solar system. in Journal of the Geographical Institute Jovan Cvijic, SASA, 69(3), 265-269.
https://doi.org/10.2298/IJGI1903265J

Jovanović P, Borka D, Borka Jovanović V. Constraining Yukawa gravity from planetary motion in the solar system. in Journal of the Geographical Institute Jovan Cvijic, SASA. 2019;69(3):265-269.
doi:10.2298/IJGI1903265J .

Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Constraining Yukawa gravity from planetary motion in the solar system" in Journal of the Geographical Institute Jovan Cvijic, SASA, 69, no. 3 (2019):265-269,
https://doi.org/10.2298/IJGI1903265J . .

TY  - JOUR
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2018
UR  - http://stacks.iop.org/1475-7516/2018/i=04/a=050?key=crossref.a23e3c8d44b40fe0c07114ff29f9d9ae
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7668
AB  - Recently, the LIGO-Virgo collaboration discovered gravitational waves and in their first publication on the subject the authors also presented a graviton mass constraint as m(g) < 1.2 x 10(-22) eV {[}1] (see also more details in a complimentary paper {[}2]). In our previous papers we considered constraints on Yukawa gravity parameters {[}3] and on graviton mass from analysis of the trajectory of S2 star near the Galactic Center {[}4]. In the paper we analyze a potential to reduce upper bounds for graviton mass with future observational data on trajectories of bright stars near the Galactic Center. Since gravitational potentials are different for these two cases, expressions for relativistic advance for general relativity and Yukawa potential are different functions on eccentricity and semimajor axis, it gives an opportunity to improve current estimates of graviton mass with future observational facilities. In our considerations of an improvement potential for a graviton mass estimate we adopt a conservative strategy and assume that trajectories of bright stars and their apocenter advance will be described with general relativity expressions and it gives opportunities to improve graviton mass constraints. In contrast with our previous studies, where we present current constraints on parameters of Yukawa gravity {[}3] and graviton mass {[}4] from observations of S2 star, in the paper we express expectations to improve current constraints for graviton mass, assuming the GR predictions about apocenter shifts will be confirmed with future observations. We concluded that if future observations of bright star orbits during around fifty years will confirm GR predictions about apocenter shifts of bright star orbits it give an opportunity to constrain a graviton mass at a level around 5 x 10(-23) eV or slightly better than current estimates obtained with LIGO observations.
T2  - Journal of Cosmology and Astroparticle Physics
T1  - Constraining the range of Yukawa gravity interaction from S2 star orbits III: improvement expectations for graviton mass bounds
VL  - 2018
IS  - 04
SP  - 050
EP  - 050
DO  - 10.1088/1475-7516/2018/04/050
ER  - 

@article{
author = "Zakharov, Alexander F. and Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2018",
abstract = "Recently, the LIGO-Virgo collaboration discovered gravitational waves and in their first publication on the subject the authors also presented a graviton mass constraint as m(g) < 1.2 x 10(-22) eV {[}1] (see also more details in a complimentary paper {[}2]). In our previous papers we considered constraints on Yukawa gravity parameters {[}3] and on graviton mass from analysis of the trajectory of S2 star near the Galactic Center {[}4]. In the paper we analyze a potential to reduce upper bounds for graviton mass with future observational data on trajectories of bright stars near the Galactic Center. Since gravitational potentials are different for these two cases, expressions for relativistic advance for general relativity and Yukawa potential are different functions on eccentricity and semimajor axis, it gives an opportunity to improve current estimates of graviton mass with future observational facilities. In our considerations of an improvement potential for a graviton mass estimate we adopt a conservative strategy and assume that trajectories of bright stars and their apocenter advance will be described with general relativity expressions and it gives opportunities to improve graviton mass constraints. In contrast with our previous studies, where we present current constraints on parameters of Yukawa gravity {[}3] and graviton mass {[}4] from observations of S2 star, in the paper we express expectations to improve current constraints for graviton mass, assuming the GR predictions about apocenter shifts will be confirmed with future observations. We concluded that if future observations of bright star orbits during around fifty years will confirm GR predictions about apocenter shifts of bright star orbits it give an opportunity to constrain a graviton mass at a level around 5 x 10(-23) eV or slightly better than current estimates obtained with LIGO observations.",
journal = "Journal of Cosmology and Astroparticle Physics",
title = "Constraining the range of Yukawa gravity interaction from S2 star orbits III: improvement expectations for graviton mass bounds",
volume = "2018",
number = "04",
pages = "050-050",
doi = "10.1088/1475-7516/2018/04/050"
}

Zakharov, A. F., Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2018). Constraining the range of Yukawa gravity interaction from S2 star orbits III: improvement expectations for graviton mass bounds. in Journal of Cosmology and Astroparticle Physics, 2018(04), 050-050.
https://doi.org/10.1088/1475-7516/2018/04/050

Zakharov AF, Jovanović P, Borka D, Borka Jovanović V. Constraining the range of Yukawa gravity interaction from S2 star orbits III: improvement expectations for graviton mass bounds. in Journal of Cosmology and Astroparticle Physics. 2018;2018(04):050-050.
doi:10.1088/1475-7516/2018/04/050 .

Zakharov, Alexander F., Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Constraining the range of Yukawa gravity interaction from S2 star orbits III: improvement expectations for graviton mass bounds" in Journal of Cosmology and Astroparticle Physics, 2018, no. 04 (2018):050-050,
https://doi.org/10.1088/1475-7516/2018/04/050 . .

TY  - CONF
AU  - Capozziello, Salvatore
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
AU  - Jovanović, Predrag
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7748
AB  - We demonstrate that the existence of a Noether symmetry in f (R) theories of gravity gives rise to an additional gravitational radius, besides the standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Tully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis. Furthermore, under the same standard, the Fundamental Plane of elliptical galaxies can be addressed.
C3  - Galaxies
T1  - Galactic Structures from Gravitational Radii
VL  - 6
IS  - 1
SP  - 22
DO  - 10.3390/galaxies6010022
ER  - 

@conference{
author = "Capozziello, Salvatore and Borka, Duško and Borka Jovanović, Vesna and Jovanović, Predrag",
year = "2018",
abstract = "We demonstrate that the existence of a Noether symmetry in f (R) theories of gravity gives rise to an additional gravitational radius, besides the standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Tully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis. Furthermore, under the same standard, the Fundamental Plane of elliptical galaxies can be addressed.",
journal = "Galaxies",
title = "Galactic Structures from Gravitational Radii",
volume = "6",
number = "1",
pages = "22",
doi = "10.3390/galaxies6010022"
}

Capozziello, S., Borka, D., Borka Jovanović, V.,& Jovanović, P.. (2018). Galactic Structures from Gravitational Radii. in Galaxies, 6(1), 22.
https://doi.org/10.3390/galaxies6010022

Capozziello S, Borka D, Borka Jovanović V, Jovanović P. Galactic Structures from Gravitational Radii. in Galaxies. 2018;6(1):22.
doi:10.3390/galaxies6010022 .

Capozziello, Salvatore, Borka, Duško, Borka Jovanović, Vesna, Jovanović, Predrag, "Galactic Structures from Gravitational Radii" in Galaxies, 6, no. 1 (2018):22,
https://doi.org/10.3390/galaxies6010022 . .

TY  - JOUR
AU  - Borka Jovanović, Vesna
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Capozziello, Salvatore
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7781
AB  - The role of f(R) gravity, as well as the other modifications of standard Einstein’s gravity, is to explain the accelerated expansion, structure formation of the Universe, and some other phenomena at extragalactic scales (such as e.g. flat rotation curves of spiral galaxies) without adding unknown forms of dark energy or dark matter. In f(R) model, the Ricci scalar in the Einstein–Hilbert action is replaced by a general function of it. Its power-law form Rn is analyzed here using observed orbits of S-stars around the Galactic Center and also their computer simulations. We review the various consequences of the Rn gravity parameters (rc, the characteristic radius, i.e. the scalelength depending on the gravitating system properties; and β, the universal constant) on stellar dynamics and investigate their constraints from the observed S-star orbits. The presented results show that these observations could put reliable constraints on the parameters of Rn gravity.
T2  - Astronomical and Astrophysical Transactions
T1  - Rn gravity as a viable alternative to dark matter: Application to stellar dynamics
VL  - 30
IS  - 3
SP  - 351
EP  - 358
UR  - https://hdl.handle.net/21.15107/rcub_vinar_7781
ER  - 

@article{
author = "Borka Jovanović, Vesna and Jovanović, Predrag and Borka, Duško and Capozziello, Salvatore",
year = "2018",
abstract = "The role of f(R) gravity, as well as the other modifications of standard Einstein’s gravity, is to explain the accelerated expansion, structure formation of the Universe, and some other phenomena at extragalactic scales (such as e.g. flat rotation curves of spiral galaxies) without adding unknown forms of dark energy or dark matter. In f(R) model, the Ricci scalar in the Einstein–Hilbert action is replaced by a general function of it. Its power-law form Rn is analyzed here using observed orbits of S-stars around the Galactic Center and also their computer simulations. We review the various consequences of the Rn gravity parameters (rc, the characteristic radius, i.e. the scalelength depending on the gravitating system properties; and β, the universal constant) on stellar dynamics and investigate their constraints from the observed S-star orbits. The presented results show that these observations could put reliable constraints on the parameters of Rn gravity.",
journal = "Astronomical and Astrophysical Transactions",
title = "Rn gravity as a viable alternative to dark matter: Application to stellar dynamics",
volume = "30",
number = "3",
pages = "351-358",
url = "https://hdl.handle.net/21.15107/rcub_vinar_7781"
}

Borka Jovanović, V., Jovanović, P., Borka, D.,& Capozziello, S.. (2018). Rn gravity as a viable alternative to dark matter: Application to stellar dynamics. in Astronomical and Astrophysical Transactions, 30(3), 351-358.
https://hdl.handle.net/21.15107/rcub_vinar_7781

Borka Jovanović V, Jovanović P, Borka D, Capozziello S. Rn gravity as a viable alternative to dark matter: Application to stellar dynamics. in Astronomical and Astrophysical Transactions. 2018;30(3):351-358.
https://hdl.handle.net/21.15107/rcub_vinar_7781 .

Borka Jovanović, Vesna, Jovanović, Predrag, Borka, Duško, Capozziello, Salvatore, "Rn gravity as a viable alternative to dark matter: Application to stellar dynamics" in Astronomical and Astrophysical Transactions, 30, no. 3 (2018):351-358,
https://hdl.handle.net/21.15107/rcub_vinar_7781 .

TY  - JOUR
AU  - Borka Jovanović, Vesna
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Capozziello, Salvatore
PY  - 2018
UR  - http://www.mdpi.com/2218-2004/7/1/4
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8218
AB  - The global properties of elliptical galaxies are connected through the so-called fundamental plane of ellipticals, which is an empirical relation between their parameters: effective radius, central velocity dispersion and mean surface brightness within the effective radius. We investigated the relation between the parameters of the fundamental plane equation and the parameters of modified gravity potential f ( R ) . With that aim, we compared theoretical predictions for circular velocity in f ( R ) gravity with the corresponding values from a large sample of observed elliptical galaxies. Besides, we consistently reproduced the values of coefficients of the fundamental plane equation as deduced from observations, showing that the photometric quantities like mean surface brightness are related to gravitational parameters. We show that this type of modified gravity, especially its power-law version— R n , is able to reproduce the stellar dynamics in elliptical galaxies. In addition, it is shown that R n gravity fits the observations very well, without the need for a dark matter.
T2  - Atoms
T1  - Fundamental Plane of Elliptical Galaxies in f(R) Gravity: The Role of Luminosity
VL  - 7
IS  - 1
SP  - 4
DO  - 10.3390/atoms7010004
ER  - 

@article{
author = "Borka Jovanović, Vesna and Jovanović, Predrag and Borka, Duško and Capozziello, Salvatore",
year = "2018",
abstract = "The global properties of elliptical galaxies are connected through the so-called fundamental plane of ellipticals, which is an empirical relation between their parameters: effective radius, central velocity dispersion and mean surface brightness within the effective radius. We investigated the relation between the parameters of the fundamental plane equation and the parameters of modified gravity potential f ( R ) . With that aim, we compared theoretical predictions for circular velocity in f ( R ) gravity with the corresponding values from a large sample of observed elliptical galaxies. Besides, we consistently reproduced the values of coefficients of the fundamental plane equation as deduced from observations, showing that the photometric quantities like mean surface brightness are related to gravitational parameters. We show that this type of modified gravity, especially its power-law version— R n , is able to reproduce the stellar dynamics in elliptical galaxies. In addition, it is shown that R n gravity fits the observations very well, without the need for a dark matter.",
journal = "Atoms",
title = "Fundamental Plane of Elliptical Galaxies in f(R) Gravity: The Role of Luminosity",
volume = "7",
number = "1",
pages = "4",
doi = "10.3390/atoms7010004"
}

Borka Jovanović, V., Jovanović, P., Borka, D.,& Capozziello, S.. (2018). Fundamental Plane of Elliptical Galaxies in f(R) Gravity: The Role of Luminosity. in Atoms, 7(1), 4.
https://doi.org/10.3390/atoms7010004

Borka Jovanović V, Jovanović P, Borka D, Capozziello S. Fundamental Plane of Elliptical Galaxies in f(R) Gravity: The Role of Luminosity. in Atoms. 2018;7(1):4.
doi:10.3390/atoms7010004 .

Borka Jovanović, Vesna, Jovanović, Predrag, Borka, Duško, Capozziello, Salvatore, "Fundamental Plane of Elliptical Galaxies in f(R) Gravity: The Role of Luminosity" in Atoms, 7, no. 1 (2018):4,
https://doi.org/10.3390/atoms7010004 . .

TY  - CONF
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7166
AB  - One could use trajectories of test particles to evaluate a gravitational potential. In particular, in the case of the Galactic Center one could use photon trajectories to analyze a shadow structure. Another way is to use bright stars near the Galactic Center to evaluate a gravitational potential and constrain parameters of a model for the Galactic Center. In particular, one could obtain constraints on parameters of black hole, stellar cluster and dark matter concentration. Earlier, we constrained parameters of Fr and a Yukawa potential from observational data for the S2 star trajectory. Now gravity theories with a massive graviton are a subject of intensive studies. People proposed different experimental ways to evaluate a graviton mass. Recently, the joint LIGO and VIRGO collaboration reported not only a discovery of gravitational waves and binary black holes, but the team claimed also that found a constraint on a graviton mass as 1.2 x 10(-22) eV. We show that an analysis of the S2 star trajectory could constrain a graviton mass with a comparable accuracy and this constraint is consistent with LIGOs one.
C3  - Journal of Physics: Conference Series
T1  - Graviton mass evaluation with trajectories of bright stars at the Galactic Center
VL  - 798
DO  - 10.1088/1742-6596/798/1/012081
ER  - 

@conference{
author = "Zakharov, Alexander F. and Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2017",
abstract = "One could use trajectories of test particles to evaluate a gravitational potential. In particular, in the case of the Galactic Center one could use photon trajectories to analyze a shadow structure. Another way is to use bright stars near the Galactic Center to evaluate a gravitational potential and constrain parameters of a model for the Galactic Center. In particular, one could obtain constraints on parameters of black hole, stellar cluster and dark matter concentration. Earlier, we constrained parameters of Fr and a Yukawa potential from observational data for the S2 star trajectory. Now gravity theories with a massive graviton are a subject of intensive studies. People proposed different experimental ways to evaluate a graviton mass. Recently, the joint LIGO and VIRGO collaboration reported not only a discovery of gravitational waves and binary black holes, but the team claimed also that found a constraint on a graviton mass as 1.2 x 10(-22) eV. We show that an analysis of the S2 star trajectory could constrain a graviton mass with a comparable accuracy and this constraint is consistent with LIGOs one.",
journal = "Journal of Physics: Conference Series",
title = "Graviton mass evaluation with trajectories of bright stars at the Galactic Center",
volume = "798",
doi = "10.1088/1742-6596/798/1/012081"
}

Zakharov, A. F., Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2017). Graviton mass evaluation with trajectories of bright stars at the Galactic Center. in Journal of Physics: Conference Series, 798.
https://doi.org/10.1088/1742-6596/798/1/012081

Zakharov AF, Jovanović P, Borka D, Borka Jovanović V. Graviton mass evaluation with trajectories of bright stars at the Galactic Center. in Journal of Physics: Conference Series. 2017;798.
doi:10.1088/1742-6596/798/1/012081 .

Zakharov, Alexander F., Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Graviton mass evaluation with trajectories of bright stars at the Galactic Center" in Journal of Physics: Conference Series, 798 (2017),
https://doi.org/10.1088/1742-6596/798/1/012081 . .

TY  - CONF
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7172
AB  - In February 2016 the LIGO and VIRGO collaboration reported the discovery of gravitational waves in merging black holes, therefore, the team confirmed GR predictions about an existence of black holes and gravitational waves in the strong gravitational field limit. Moreover, in their papers the joint LIGO and VIRGO team presented an upper limit on graviton mass such as m(g) LT 1.2 x 10(-22) eV (Abbott et al. 2016). So, the authors concluded that their observational data do not show any violation of classical general relativity. We show that an analysis of bright star trajectories could constrain graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and the estimate is consistent with the one obtained by the LIGO and VIRGO collaboration. This analysis gives an opportunity to treat observations of bright stars near the Galactic Center as a useful tool to obtain constraints on the fundamental gravity law such as modifications of the Newton gravity law in a weak field approximation. In that way, based on a potential reconstruction at the Galactic Center we obtain bounds on a graviton mass.
C3  - EPJ Web of Conferences
T1  - Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center
VL  - 138
SP  - UNSP 01010
DO  - 10.1051/epjconf/201713801010
ER  - 

@conference{
author = "Zakharov, Alexander F. and Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2017",
abstract = "In February 2016 the LIGO and VIRGO collaboration reported the discovery of gravitational waves in merging black holes, therefore, the team confirmed GR predictions about an existence of black holes and gravitational waves in the strong gravitational field limit. Moreover, in their papers the joint LIGO and VIRGO team presented an upper limit on graviton mass such as m(g) LT 1.2 x 10(-22) eV (Abbott et al. 2016). So, the authors concluded that their observational data do not show any violation of classical general relativity. We show that an analysis of bright star trajectories could constrain graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and the estimate is consistent with the one obtained by the LIGO and VIRGO collaboration. This analysis gives an opportunity to treat observations of bright stars near the Galactic Center as a useful tool to obtain constraints on the fundamental gravity law such as modifications of the Newton gravity law in a weak field approximation. In that way, based on a potential reconstruction at the Galactic Center we obtain bounds on a graviton mass.",
journal = "EPJ Web of Conferences",
title = "Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center",
volume = "138",
pages = "UNSP 01010",
doi = "10.1051/epjconf/201713801010"
}

Zakharov, A. F., Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2017). Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center. in EPJ Web of Conferences, 138, UNSP 01010.
https://doi.org/10.1051/epjconf/201713801010

Zakharov AF, Jovanović P, Borka D, Borka Jovanović V. Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center. in EPJ Web of Conferences. 2017;138:UNSP 01010.
doi:10.1051/epjconf/201713801010 .

Zakharov, Alexander F., Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Graviton mass bounds from an analysis of bright star trajectories at the Galactic Center" in EPJ Web of Conferences, 138 (2017):UNSP 01010,
https://doi.org/10.1051/epjconf/201713801010 . .

TY  - JOUR
AU  - Capozziello, Salvatore
AU  - Jovanović, Predrag
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1696
AB  - We demonstrate that the existence of a Noether symmetry in f theories of gravity gives rise to a further gravitational radius, besides tile standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Fully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis.
T2  - Journal of Cosmology and Astroparticle Physics
T1  - Addressing the missing matter problem in galaxies through a new fundamental gravitational radius
IS  - 6
DO  - 10.1088/1475-7516/2017/06/044
ER  - 

@article{
author = "Capozziello, Salvatore and Jovanović, Predrag and Borka Jovanović, Vesna and Borka, Duško",
year = "2017",
abstract = "We demonstrate that the existence of a Noether symmetry in f theories of gravity gives rise to a further gravitational radius, besides tile standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Fully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis.",
journal = "Journal of Cosmology and Astroparticle Physics",
title = "Addressing the missing matter problem in galaxies through a new fundamental gravitational radius",
number = "6",
doi = "10.1088/1475-7516/2017/06/044"
}

Capozziello, S., Jovanović, P., Borka Jovanović, V.,& Borka, D.. (2017). Addressing the missing matter problem in galaxies through a new fundamental gravitational radius. in Journal of Cosmology and Astroparticle Physics(6).
https://doi.org/10.1088/1475-7516/2017/06/044

Capozziello S, Jovanović P, Borka Jovanović V, Borka D. Addressing the missing matter problem in galaxies through a new fundamental gravitational radius. in Journal of Cosmology and Astroparticle Physics. 2017;(6).
doi:10.1088/1475-7516/2017/06/044 .

Capozziello, Salvatore, Jovanović, Predrag, Borka Jovanović, Vesna, Borka, Duško, "Addressing the missing matter problem in galaxies through a new fundamental gravitational radius" in Journal of Cosmology and Astroparticle Physics, no. 6 (2017),
https://doi.org/10.1088/1475-7516/2017/06/044 . .

TY  - JOUR
AU  - Borka Jovanović, Vesna
AU  - Jovanović, Predrag
AU  - Borka, Duško
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1496
AB  - We use radio-continuum all-sky surveys at 1420 and 408 MHz with the aim to investigate properties of the Galactic radio source Lupus Loop. The survey data at 1435 MHz, with the linear polarization of the southern sky, are also used. We calculate properties of this supernova remnant: the brightness temperature, surface brightness and radio spectral index. To determine its borders and to calculate its properties, we use the method we have developed. The non-thermal nature of its radiation is confirmed. The distribution of spectral index over its area is also given. A significant correlation between the radio spectral index distribution and the corresponding polarized intensity distribution inside the loop borders is found, indicating that the polarization maps could provide us information about the distribution of the interstellar medium, and thus could represent one additional way to search for new Galactic loops.
T2  - Revista Mexicana de Astronomia y Astrofisica
T1  - Snr Radio Spectral Index Distribution and Its Correlation with Polarization. a Case Study: the Lupus Loop
VL  - 53
IS  - 1
SP  - 37
EP  - 44
UR  - https://hdl.handle.net/21.15107/rcub_vinar_1496
ER  - 

@article{
author = "Borka Jovanović, Vesna and Jovanović, Predrag and Borka, Duško",
year = "2017",
abstract = "We use radio-continuum all-sky surveys at 1420 and 408 MHz with the aim to investigate properties of the Galactic radio source Lupus Loop. The survey data at 1435 MHz, with the linear polarization of the southern sky, are also used. We calculate properties of this supernova remnant: the brightness temperature, surface brightness and radio spectral index. To determine its borders and to calculate its properties, we use the method we have developed. The non-thermal nature of its radiation is confirmed. The distribution of spectral index over its area is also given. A significant correlation between the radio spectral index distribution and the corresponding polarized intensity distribution inside the loop borders is found, indicating that the polarization maps could provide us information about the distribution of the interstellar medium, and thus could represent one additional way to search for new Galactic loops.",
journal = "Revista Mexicana de Astronomia y Astrofisica",
title = "Snr Radio Spectral Index Distribution and Its Correlation with Polarization. a Case Study: the Lupus Loop",
volume = "53",
number = "1",
pages = "37-44",
url = "https://hdl.handle.net/21.15107/rcub_vinar_1496"
}

Borka Jovanović, V., Jovanović, P.,& Borka, D.. (2017). Snr Radio Spectral Index Distribution and Its Correlation with Polarization. a Case Study: the Lupus Loop. in Revista Mexicana de Astronomia y Astrofisica, 53(1), 37-44.
https://hdl.handle.net/21.15107/rcub_vinar_1496

Borka Jovanović V, Jovanović P, Borka D. Snr Radio Spectral Index Distribution and Its Correlation with Polarization. a Case Study: the Lupus Loop. in Revista Mexicana de Astronomia y Astrofisica. 2017;53(1):37-44.
https://hdl.handle.net/21.15107/rcub_vinar_1496 .

Borka Jovanović, Vesna, Jovanović, Predrag, Borka, Duško, "Snr Radio Spectral Index Distribution and Its Correlation with Polarization. a Case Study: the Lupus Loop" in Revista Mexicana de Astronomia y Astrofisica, 53, no. 1 (2017):37-44,
https://hdl.handle.net/21.15107/rcub_vinar_1496 .

TY  - CONF
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7119
AB  - Scientists worked in Saint-Petersburg (Petrograd, Leningrad) played the extremely important role in creation of scientific school and development of general relativity in Russia. Very recently LIGO collaboration discovered gravitational waves [1] predicted 100 years ago by A. Einstein. In the papers reporting about this discovery, the joint LIGO and VIRGO team presented an upper limit on graviton mass such as m(g) LT 1.2 x 10(-22) eV [1, 2]. The authors concluded that their observational data do not show violations of classical general relativity because the graviton mass limit is very small. We show that an analysis of bright star trajectories could bound graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and expected with forthcoming pulsar timing observations for gravitational wave detection. This analysis gives an opportunity to treat observations of bright stars near the Galactic Center as a tool for an evaluation specific parameters of the black hole and also to obtain constraints on the fundamental gravity law such as a modifications of Newton gravity law in a weak field approximation. In that way, based on a potential reconstruction at the Galactic Center we give a bounds on a graviton mass.
C3  - EPJ Web of Conferences
T1  - Trajectories of bright stars at the Galactic Center as a tool to evaluate a graviton mass
VL  - 125
DO  - 10.1051/epjconf/201612501011
ER  - 

@conference{
author = "Zakharov, Alexander F. and Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2016",
abstract = "Scientists worked in Saint-Petersburg (Petrograd, Leningrad) played the extremely important role in creation of scientific school and development of general relativity in Russia. Very recently LIGO collaboration discovered gravitational waves [1] predicted 100 years ago by A. Einstein. In the papers reporting about this discovery, the joint LIGO and VIRGO team presented an upper limit on graviton mass such as m(g) LT 1.2 x 10(-22) eV [1, 2]. The authors concluded that their observational data do not show violations of classical general relativity because the graviton mass limit is very small. We show that an analysis of bright star trajectories could bound graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and expected with forthcoming pulsar timing observations for gravitational wave detection. This analysis gives an opportunity to treat observations of bright stars near the Galactic Center as a tool for an evaluation specific parameters of the black hole and also to obtain constraints on the fundamental gravity law such as a modifications of Newton gravity law in a weak field approximation. In that way, based on a potential reconstruction at the Galactic Center we give a bounds on a graviton mass.",
journal = "EPJ Web of Conferences",
title = "Trajectories of bright stars at the Galactic Center as a tool to evaluate a graviton mass",
volume = "125",
doi = "10.1051/epjconf/201612501011"
}

Zakharov, A. F., Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2016). Trajectories of bright stars at the Galactic Center as a tool to evaluate a graviton mass. in EPJ Web of Conferences, 125.
https://doi.org/10.1051/epjconf/201612501011

Zakharov AF, Jovanović P, Borka D, Borka Jovanović V. Trajectories of bright stars at the Galactic Center as a tool to evaluate a graviton mass. in EPJ Web of Conferences. 2016;125.
doi:10.1051/epjconf/201612501011 .

Zakharov, Alexander F., Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Trajectories of bright stars at the Galactic Center as a tool to evaluate a graviton mass" in EPJ Web of Conferences, 125 (2016),
https://doi.org/10.1051/epjconf/201612501011 . .

TY  - JOUR
AU  - Borka Jovanović, Vesna
AU  - Capozziello, Salvatore
AU  - Jovanović, Predrag
AU  - Borka, Duško
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1408
AB  - The fundamental plane (FP) of galaxies can be recovered in the framework of f (R) gravity avoiding the issues related to dark matter to fit the observations. In particular, the power-law version f (R) proportional to R-n, resulting from the existence of Noether symmetries for f (R), is sufficient to implement the approach. In fact, relations between the FP parameters and the corrected Newtonian potential, coming from Rn, can be found and justified from a physical point of view. Specifically, we analyze the velocity distribution of elliptical galaxies and obtain that r(c), the scale-length depending on the gravitational system properties, is proportional to re, the galaxy effective radius. This fact points out that the gravitational corrections induced by f (R) can lead photometry and dynamics of the system. Furthermore, the main byproduct of such an approach is that gravity could work in different ways depending on the scales of self-gravitating systems. (C) 2016 Elsevier B.V. All rights reserved.
T2  - Physics of the Dark Universe
T1  - Recovering the fundamental plane of galaxies by f (R) gravity
VL  - 14
SP  - 73
EP  - 83
DO  - 10.1016/j.dark.2016.10.003
ER  - 

@article{
author = "Borka Jovanović, Vesna and Capozziello, Salvatore and Jovanović, Predrag and Borka, Duško",
year = "2016",
abstract = "The fundamental plane (FP) of galaxies can be recovered in the framework of f (R) gravity avoiding the issues related to dark matter to fit the observations. In particular, the power-law version f (R) proportional to R-n, resulting from the existence of Noether symmetries for f (R), is sufficient to implement the approach. In fact, relations between the FP parameters and the corrected Newtonian potential, coming from Rn, can be found and justified from a physical point of view. Specifically, we analyze the velocity distribution of elliptical galaxies and obtain that r(c), the scale-length depending on the gravitational system properties, is proportional to re, the galaxy effective radius. This fact points out that the gravitational corrections induced by f (R) can lead photometry and dynamics of the system. Furthermore, the main byproduct of such an approach is that gravity could work in different ways depending on the scales of self-gravitating systems. (C) 2016 Elsevier B.V. All rights reserved.",
journal = "Physics of the Dark Universe",
title = "Recovering the fundamental plane of galaxies by f (R) gravity",
volume = "14",
pages = "73-83",
doi = "10.1016/j.dark.2016.10.003"
}

Borka Jovanović, V., Capozziello, S., Jovanović, P.,& Borka, D.. (2016). Recovering the fundamental plane of galaxies by f (R) gravity. in Physics of the Dark Universe, 14, 73-83.
https://doi.org/10.1016/j.dark.2016.10.003

Borka Jovanović V, Capozziello S, Jovanović P, Borka D. Recovering the fundamental plane of galaxies by f (R) gravity. in Physics of the Dark Universe. 2016;14:73-83.
doi:10.1016/j.dark.2016.10.003 .

Borka Jovanović, Vesna, Capozziello, Salvatore, Jovanović, Predrag, Borka, Duško, "Recovering the fundamental plane of galaxies by f (R) gravity" in Physics of the Dark Universe, 14 (2016):73-83,
https://doi.org/10.1016/j.dark.2016.10.003 . .

TY  - JOUR
AU  - Zakharov, Alexander F.
AU  - Jovanović, Predrag
AU  - Borka, Duško
AU  - Borka Jovanović, Vesna
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1125
AB  - Recently LIGO collaboration discovered gravitational waves [1] predicted 100 years ago by A. Einstein. Moreover, in the key paper reporting about the discovery, the joint LIGO and VIRGO team presented an upper limit on graviton mass such as m(g) LT 1.2 x 10(-22)eV [1] (see also more details in another LIGO paper [2] dedicated to a data analysis to obtain such a small constraint on a graviton mass). Since the graviton mass limit is so small the authors concluded that their observational data do not show violations of classical general relativity. We consider another opportunity to evaluate a graviton mass from phenomenological consequences of massive gravity and show that an analysis of bright star trajectories could bound graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and expected with forthcoming pulsar timing observations for gravitational wave detection. It gives an opportunity to treat observations of bright stars near the Galactic Center as a wonderful tool not only for an evaluation specific parameters of the black hole but also to obtain constraints on the fundamental gravity law such as a modifications of Newton gravity law in a weak field approximation. In particular, we obtain bounds on a graviton mass based on a potential reconstruction at the Galactic Center.
T2  - Journal of Cosmology and Astroparticle Physics
T1  - Constraining the range of Yukawa gravity interaction from S2 star orbits II: bounds on graviton mass
IS  - 5
DO  - 10.1088/1475-7516/2016/05/045
ER  - 

@article{
author = "Zakharov, Alexander F. and Jovanović, Predrag and Borka, Duško and Borka Jovanović, Vesna",
year = "2016",
abstract = "Recently LIGO collaboration discovered gravitational waves [1] predicted 100 years ago by A. Einstein. Moreover, in the key paper reporting about the discovery, the joint LIGO and VIRGO team presented an upper limit on graviton mass such as m(g) LT 1.2 x 10(-22)eV [1] (see also more details in another LIGO paper [2] dedicated to a data analysis to obtain such a small constraint on a graviton mass). Since the graviton mass limit is so small the authors concluded that their observational data do not show violations of classical general relativity. We consider another opportunity to evaluate a graviton mass from phenomenological consequences of massive gravity and show that an analysis of bright star trajectories could bound graviton mass with a comparable accuracy with accuracies reached with gravitational wave interferometers and expected with forthcoming pulsar timing observations for gravitational wave detection. It gives an opportunity to treat observations of bright stars near the Galactic Center as a wonderful tool not only for an evaluation specific parameters of the black hole but also to obtain constraints on the fundamental gravity law such as a modifications of Newton gravity law in a weak field approximation. In particular, we obtain bounds on a graviton mass based on a potential reconstruction at the Galactic Center.",
journal = "Journal of Cosmology and Astroparticle Physics",
title = "Constraining the range of Yukawa gravity interaction from S2 star orbits II: bounds on graviton mass",
number = "5",
doi = "10.1088/1475-7516/2016/05/045"
}

Zakharov, A. F., Jovanović, P., Borka, D.,& Borka Jovanović, V.. (2016). Constraining the range of Yukawa gravity interaction from S2 star orbits II: bounds on graviton mass. in Journal of Cosmology and Astroparticle Physics(5).
https://doi.org/10.1088/1475-7516/2016/05/045

Zakharov AF, Jovanović P, Borka D, Borka Jovanović V. Constraining the range of Yukawa gravity interaction from S2 star orbits II: bounds on graviton mass. in Journal of Cosmology and Astroparticle Physics. 2016;(5).
doi:10.1088/1475-7516/2016/05/045 .

Zakharov, Alexander F., Jovanović, Predrag, Borka, Duško, Borka Jovanović, Vesna, "Constraining the range of Yukawa gravity interaction from S2 star orbits II: bounds on graviton mass" in Journal of Cosmology and Astroparticle Physics, no. 5 (2016),
https://doi.org/10.1088/1475-7516/2016/05/045 . .