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  - Jovanović, Predrag
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Popović, Luka C. 
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/952
AB  - Here we present a short overview and main results of our investigations of several effects which can induce shifts in the broad Fe K alpha line emitted from relativistic accretion disks around single and binary supermassive black holes. We used numerical simulations based on ray-tracing method in the Kerr metric to study the role of classical Doppler shift, special relativistic transverse Doppler shift and Doppler beaming, general relativistic gravitational red-shift, and perturbations of the disk emissivity in the formation of the observed Fe K alpha line profiles. Besides, we also investigated whether the observed line profiles from the binary systems of supermassive black holes could be affected by the Doppler shifts due to dynamics of such systems. The presented results demonstrate that all these effects could have a significant influence on the observed profiles of the broad Fe K alpha line emitted from relativistic accretion disks around single and binary supermassive black holes.
PB  - Springer
T2  - Astrophysics and Space Science
T1  - Line shifts in accretion disks-the case of Fe K alpha
VL  - 361
IS  - 2
DO  - 10.1007/s10509-016-2653-z
ER  - 

@article{
author = "Jovanović, Predrag and Borka Jovanović, Vesna and Borka, Duško and Popović, Luka C. ",
year = "2016",
abstract = "Here we present a short overview and main results of our investigations of several effects which can induce shifts in the broad Fe K alpha line emitted from relativistic accretion disks around single and binary supermassive black holes. We used numerical simulations based on ray-tracing method in the Kerr metric to study the role of classical Doppler shift, special relativistic transverse Doppler shift and Doppler beaming, general relativistic gravitational red-shift, and perturbations of the disk emissivity in the formation of the observed Fe K alpha line profiles. Besides, we also investigated whether the observed line profiles from the binary systems of supermassive black holes could be affected by the Doppler shifts due to dynamics of such systems. The presented results demonstrate that all these effects could have a significant influence on the observed profiles of the broad Fe K alpha line emitted from relativistic accretion disks around single and binary supermassive black holes.",
publisher = "Springer",
journal = "Astrophysics and Space Science",
title = "Line shifts in accretion disks-the case of Fe K alpha",
volume = "361",
number = "2",
doi = "10.1007/s10509-016-2653-z"
}

Jovanović, P., Borka Jovanović, V., Borka, D.,& Popović, L. C.. (2016). Line shifts in accretion disks-the case of Fe K alpha. in Astrophysics and Space Science
Springer., 361(2).
https://doi.org/10.1007/s10509-016-2653-z

Jovanović P, Borka Jovanović V, Borka D, Popović LC. Line shifts in accretion disks-the case of Fe K alpha. in Astrophysics and Space Science. 2016;361(2).
doi:10.1007/s10509-016-2653-z .

Jovanović, Predrag, Borka Jovanović, Vesna, Borka, Duško, Popović, Luka C. , "Line shifts in accretion disks-the case of Fe K alpha" in Astrophysics and Space Science, 361, no. 2 (2016),
https://doi.org/10.1007/s10509-016-2653-z . .

TY  - JOUR
AU  - Bon, E.
AU  - Jovanović, Predrag
AU  - Marziani, P.
AU  - Shapovalova, A. I.
AU  - Bon, N.
AU  - Borka Jovanović, Vesna
AU  - Borka, Duško
AU  - Sulentic, J.
AU  - Popović, Luka C. 
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5154
AB  - One of the most intriguing scenarios proposed to explain how active galactic nuclei are triggered involves the existence of a supermassive binary black hole (BH) system in their cores. Here, we present an observational evidence for the first spectroscopically resolved sub-parsec orbit of a such system in the core of Seyfert galaxy NGC 4151. Using a method similar to those typically used for spectroscopic binary stars, we obtained radial velocity curves of the supermassive binary system, from which we calculated orbital elements and made estimates about the masses of the components. Our analysis shows that periodic variations in the light and radial velocity curves can be accounted for by an eccentric, sub-parsec Keplerian orbit with a 15.9 year period. The flux maximum in the light curve corresponds to the approaching phase of the secondary component toward the observer. According to the obtained results, we speculate that the periodic variations in the observed Ha line shape and flux are due to shock waves generated by the supersonic motion of the components through the surrounding medium. Given the large observational effort needed to reveal this spectroscopically resolved binary orbital motion, we suggest that many such systems may exist in similar objects even if they are hard to find. Detecting more of them will provide us with insight into the BH mass growth process.
T2  - Astrophysical Journal
T1  - The First Spectroscopically Resolved Sub-Parsec Orbit of a Supermassive Binary Black Hole
VL  - 759
IS  - 2
DO  - 10.1088/0004-637X/759/2/118
ER  - 

@article{
author = "Bon, E. and Jovanović, Predrag and Marziani, P. and Shapovalova, A. I. and Bon, N. and Borka Jovanović, Vesna and Borka, Duško and Sulentic, J. and Popović, Luka C. ",
year = "2012",
abstract = "One of the most intriguing scenarios proposed to explain how active galactic nuclei are triggered involves the existence of a supermassive binary black hole (BH) system in their cores. Here, we present an observational evidence for the first spectroscopically resolved sub-parsec orbit of a such system in the core of Seyfert galaxy NGC 4151. Using a method similar to those typically used for spectroscopic binary stars, we obtained radial velocity curves of the supermassive binary system, from which we calculated orbital elements and made estimates about the masses of the components. Our analysis shows that periodic variations in the light and radial velocity curves can be accounted for by an eccentric, sub-parsec Keplerian orbit with a 15.9 year period. The flux maximum in the light curve corresponds to the approaching phase of the secondary component toward the observer. According to the obtained results, we speculate that the periodic variations in the observed Ha line shape and flux are due to shock waves generated by the supersonic motion of the components through the surrounding medium. Given the large observational effort needed to reveal this spectroscopically resolved binary orbital motion, we suggest that many such systems may exist in similar objects even if they are hard to find. Detecting more of them will provide us with insight into the BH mass growth process.",
journal = "Astrophysical Journal",
title = "The First Spectroscopically Resolved Sub-Parsec Orbit of a Supermassive Binary Black Hole",
volume = "759",
number = "2",
doi = "10.1088/0004-637X/759/2/118"
}

Bon, E., Jovanović, P., Marziani, P., Shapovalova, A. I., Bon, N., Borka Jovanović, V., Borka, D., Sulentic, J.,& Popović, L. C.. (2012). The First Spectroscopically Resolved Sub-Parsec Orbit of a Supermassive Binary Black Hole. in Astrophysical Journal, 759(2).
https://doi.org/10.1088/0004-637X/759/2/118

Bon E, Jovanović P, Marziani P, Shapovalova AI, Bon N, Borka Jovanović V, Borka D, Sulentic J, Popović LC. The First Spectroscopically Resolved Sub-Parsec Orbit of a Supermassive Binary Black Hole. in Astrophysical Journal. 2012;759(2).
doi:10.1088/0004-637X/759/2/118 .

Bon, E., Jovanović, Predrag, Marziani, P., Shapovalova, A. I., Bon, N., Borka Jovanović, Vesna, Borka, Duško, Sulentic, J., Popović, Luka C. , "The First Spectroscopically Resolved Sub-Parsec Orbit of a Supermassive Binary Black Hole" in Astrophysical Journal, 759, no. 2 (2012),
https://doi.org/10.1088/0004-637X/759/2/118 . .