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Journal articles on the topic 'Galactic Black Holes'

Author: Grafiati
Published: 6 September 2023

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1

Ziółkowski, Janusz. "News from Galactic Black Holes." Chinese Journal of Astronomy and Astrophysics 3, S1 (2003): 245–56. http://dx.doi.org/10.1088/1009-9271/3/s1/245.

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2

Rees, Martin J. "Black Holes in Galactic Centers." Scientific American 263, no. 5 (1990): 56–66. http://dx.doi.org/10.1038/scientificamerican1190-56.

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3

van der Marel, Roeland P. "Black Holes in Galactic Nuclei." Highlights of Astronomy 10 (1995): 527–30. http://dx.doi.org/10.1017/s1539299600011953.

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AbstractThe dynamical evidence for black holes (BHs) in galactic nuclei is reviewed, with emphasis on recent improvements in spatial resolution, methods for analyzing galaxy spectra and dynamical modeling. M31, M32 and M87 are discussed in some detail.
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4

Le Delliou, M., R. N. Henriksen, and J. D. MacMillan. "Black holes and galactic density cusps." Astronomy & Astrophysics 522 (October 28, 2010): A28. http://dx.doi.org/10.1051/0004-6361/200913648.

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5

Le Delliou, M., R. N. Henriksen, and J. D. MacMillan. "Black holes and galactic density cusps." Astronomy & Astrophysics 526 (December 14, 2010): A13. http://dx.doi.org/10.1051/0004-6361/200913649.

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6

Lacey, C. G., and J. P. Ostriker. "Massive black holes in galactic halos?" Astrophysical Journal 299 (December 1985): 633. http://dx.doi.org/10.1086/163729.

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7

Hemsendorf, M., S. Sigurdsson, and R. Spurzem. "Binary Black Holes in Galactic Centres." EAS Publications Series 1 (2001): 173. http://dx.doi.org/10.1051/eas:2001019.

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8

Begelman, Mitchell C., and Marta Volonteri. "Hyperaccreting black holes in galactic nuclei." Monthly Notices of the Royal Astronomical Society 464, no. 1 (2016): 1102–7. http://dx.doi.org/10.1093/mnras/stw2446.

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9

Valtonen, M. J., S. Mikkola, D. Merritt, et al. "Black holes in active galactic nuclei." Proceedings of the International Astronomical Union 5, S261 (2009): 260–68. http://dx.doi.org/10.1017/s1743921309990482.

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AbstractSupermassive black holes are common in centers of galaxies. Among the active galaxies, quasars are the most extreme, and their black hole masses range as high as to 6⋅1010M⊙. Binary black holes are of special interest but so far OJ287 is the only confirmed case with known orbital elements. In OJ287, the binary nature is confirmed by periodic radiation pulses. The period is twelve years with two pulses per period. The last four pulses have been correctly predicted with the accuracy of few weeks, the latest in 2007 with the accuracy of one day. This accuracy is high enough that one may test the higher order terms in the Post Newtonian approximation to General Relativity. The precession rate per period is 39°.1 ± 0°.1, by far the largest rate in any known binary, and the (1.83 ± 0.01)⋅1010M⊙primary is among the dozen biggest black holes known. We will discuss the various Post Newtonian terms and their effect on the orbit solution. The over 100 year data base of optical variations in OJ287 puts limits on these terms and thus tests the ability of Einstein's General Relativity to describe, for the first time, dynamic binary black hole spacetime in the strong field regime. The quadrupole-moment contributions to the equations of motion allows us to constrain the ‘no-hair’ parameter to be 1.0 ± 0.3 which supports the black hole no-hair theorem within the achievable precision.
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10

Cavaliere, A., and V. Vittorini. "Supermassive Black Holes in Galactic Nuclei." Astrophysical Journal 570, no. 1 (2002): 114–18. http://dx.doi.org/10.1086/339494.

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11

Lacey, C. G., and J. P. Ostriker. "Massive Black Holes in Galactic Halos?" Symposium - International Astronomical Union 117 (1987): 412. http://dx.doi.org/10.1017/s0074180900150612.

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We consider the idea that galaxy halos are composed of massive black holes, as a possible resolution of two problems: the composition of dark halos, and the heating of stellar disks. Scattering of disk stars by halo black holes with mass MH, velocity dispersion σH and number density nH causes the stellar velocity dispersion to increase with time t as σ≈(Dt)1/2 for t large, where D α nHM2H in Λ/σH, and in Λ is the Coulomb logarithm. This time-dependence is in good agreement with observations, as is the prediction for the axial ratios of the velocity ellipsoid σu: σv: σw. To account for the magnitude of the disk velocity dispersion in the solar neighbourhood, we require MH≈2 × 106M⊙. The stellar distribution function is predicted to be approximately isothermal at low epicyclic energies, in the Fokker-Planck regime in which the effect of the many distant, weak encounters dominates, but with a power-law tail at high energies produced by the relatively rare close encounters. This tail has the form N(E)αE−2, where E is the horizontal or vertical epicyclic energy, and N(E) is the number of stars per unit area of the disk, per unit E. The fraction of stars in this power-law tail depends only on the value of in Λ, and is about 1% for typical values. This provides a possible explanation for the high velocity A stars found in the solar neighbourhood. This disk heating mechanism can also account for the approximate constancy of the disk scaleheight with radius that is observed in other spiral galaxies, although this does not result as naturally as the other properties.
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12

McHardy, I. M., E. Koerding, C. Knigge, P. Uttley, and R. P. Fender. "Active galactic nuclei as scaled-up Galactic black holes." Nature 444, no. 7120 (2006): 730–32. http://dx.doi.org/10.1038/nature05389.

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13

Courvoisier, T. J. L., and B. Wilkes. "High-Energy Radiation from Black Holes: From Supermassive Black Holes to Galactic Solar Mass Black Holes." Advances in Space Research 38, no. 7 (2006): 1345. http://dx.doi.org/10.1016/j.asr.2006.06.001.

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14

Richstone, Douglas. "11.1. Black holes and galaxy centers." Symposium - International Astronomical Union 184 (1998): 451–58. http://dx.doi.org/10.1017/s0074180900085557.

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The study of supermassive galactic black holes (BH) has moved beyond discovery to maturity. The are now ∼ 15 reliable detections. The mass of a central black hole apparently correlates with the mass of the hot component of its galactic host. It may be that every normal galaxy has a supermassive black hole carrying about 10−3 of its bulge mass, with important consequences for the structure and evolution of the core of the galaxy. The most recent major review is by Kormendy & Richstone (1995, KR).
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15

Haehnelt, Martin G. "The connection between the formation of galaxies and that of their central supermassive black holes." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1828 (2005): 705–13. http://dx.doi.org/10.1098/rsta.2004.1522.

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Massive black holes appear to be an essential ingredient of massive galactic bulges but little is known yet to what extent massive black holes reside in dwarf galaxies and globular clusters. Massive black holes most likely grow by a mixture of merging and accretion of gas in their hierarchically merging host galaxies. While the hierarchical merging of dark matter structures extends to sub-galactic scales and very high redshift, it is uncertain if the same is true for the build–up of massive black holes. I discuss here some of the relevant problems and open questions.
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16

Fenyves, Ervin J., Stephen N. Balog, David B. Cline, and M. Atac. "Study of the Galactic Center with a High Resolution Gamma Ray Telescope." Symposium - International Astronomical Union 136 (1989): 639–43. http://dx.doi.org/10.1017/s0074180900187145.

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It is generally accepted that massive black holes are the most likely source for the energy radiated from active galactic nuclei, and may explain the enormous amount of energy emitted by quasars, radio galaxies, Seyfert galaxies, and BL Lacertid objects. Although the detailed mechanisms of the black hole formation in galactic nuclei are not clear at present, it seems to be quite possible that the formation of massive black holes is a general outcome of the evolution of galactic nuclei.
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17

Kuncic, Zdenka. "Black Holes in Galactic Nuclei, X-Ray Binaries and Ultraluminous X-Ray Sources." Publications of the Astronomical Society of Australia 22, no. 3 (2005): 195–98. http://dx.doi.org/10.1071/as05002.

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AbstractThis review summarizes the astrophysical evidence for the existence of black holes provided by their gravitational influence on nearby matter. Two classes of accreting black holes have now been observationally verified: supermassive black holes (SMBHs) in galactic nuclei, and stellar-mass black holes in X-ray binaries (XRBs). With the recent re-discovery of ultra-luminous X-ray (ULX) sources, fresh evidence has also emerged for the existence of a third class of accreting black holes: intermediate-mass black holes (IMBHs). The properties of the three classes of accreting black holes are briefly discussed.
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18

Cowen, R. "Galactic and Stellar Black Holes Get Real." Science News 151, no. 3 (1997): 39. http://dx.doi.org/10.2307/3980679.

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19

Bian, Weihao. "Supermassive Black Holes in Active Galactic Nuclei." Publications of the Astronomical Society of the Pacific 117, no. 831 (2005): 544. http://dx.doi.org/10.1086/429642.

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20

Haehnelt, M. G., and G. Kauffmann. "Multiple supermassive black holes in galactic bulges." Monthly Notices of the Royal Astronomical Society 336, no. 3 (2002): L61—L64. http://dx.doi.org/10.1046/j.1365-8711.2002.06056.x.

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21

Morris, Mark R. "Bounteous black holes at the Galactic Centre." Nature 556, no. 7701 (2018): 319–20. http://dx.doi.org/10.1038/d41586-018-04341-8.

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22

Pelupessy, Inti. "Enhancing galactic simulations: Black holes and molecules." New Astronomy Reviews 51, no. 1-2 (2007): 179–84. http://dx.doi.org/10.1016/j.newar.2006.11.005.

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23

Greene, Jenny E., Luis C. Ho, and Aaron J. Barth. "Intermediate-mass black holes in galactic nuclei." Proceedings of the International Astronomical Union 2004, IAUS222 (2004): 33–36. http://dx.doi.org/10.1017/s1743921304001395.

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24

Faber, S. M. "The demography of massive galactic black holes." Advances in Space Research 23, no. 5-6 (1999): 925–36. http://dx.doi.org/10.1016/s0273-1177(99)00217-3.

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25

McKernan, B., K. E. S. Ford, T. Yaqoob, and L. M. Winter. "On minor black holes in galactic nuclei." Monthly Notices of the Royal Astronomical Society: Letters 413, no. 1 (2011): L24—L28. http://dx.doi.org/10.1111/j.1745-3933.2011.01024.x.

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26

McClintock, Jeffrey. "X-ray properties of galactic black holes." Advances in Space Research 8, no. 2-3 (1988): 191–95. http://dx.doi.org/10.1016/0273-1177(88)90405-x.

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27

Mapelli, M., A. Ferrara, and N. Rea. "Constraints on Galactic intermediate mass black holes." Monthly Notices of the Royal Astronomical Society 368, no. 3 (2006): 1340–50. http://dx.doi.org/10.1111/j.1365-2966.2006.10201.x.

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28

WALDROP, M. M. "Black Holes Swarming at the Galactic Center?" Science 251, no. 4990 (1991): 166. http://dx.doi.org/10.1126/science.251.4990.166.

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29

Rees, Martin J. "Black Holes, Galactic Evolution and Cosmic Coincidence." Interdisciplinary Science Reviews 14, no. 2 (1989): 148–61. http://dx.doi.org/10.1179/isr.1989.14.2.148.

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30

Blandford, R. D. "Black Hole Models of Quasars." Symposium - International Astronomical Union 119 (1986): 359–69. http://dx.doi.org/10.1017/s0074180900153021.

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Observations of active galactic nuclei are interpreted in terms of a theoretical model involving accretion onto a massive black hole. Optical quasars and Seyfert galaxies are associated with holes accreting near the Eddington rate and radio galaxies with sub-critical accretion. It is argued that magnetic fields are largely responsible for extracting energy and angular momentum from black holes and disks. Recent studies of electron-positron pair plasmas and their possible role in establishing the emergent X-ray spectrum are reviewed. The main evolutionary properties of active galactic nuclei can be interpreted in terms of a simple model in which black holes accrete gas at a rate dictated by the rate of gas supply which decreases with cosmic time. It may be worth searching for eclipsing binary black holes in lower power Seyferts.
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31

SOHN, Bong Won. "Black Hole, Observed." Physics and High Technology 29, no. 12 (2020): 23–28. http://dx.doi.org/10.3938/phit.29.046.

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The author explains black holes in the context of astronomy and astrophysics. The history of black hole research and black hole discovery are covered briefly. The author explains why supermassive black holes in active galactic nuclei are the most promising candidates for imaging black holes. The principles of radio interferometers used as observation methods are covered. The Event Horizon Telescope Collaboration, its future plans, and the role of the Korean members are introduced.
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32

Fragione, Giacomo, and Alessia Gualandris. "Hypervelocity stars from star clusters hosting intermediate-mass black holes." Monthly Notices of the Royal Astronomical Society 489, no. 4 (2019): 4543–56. http://dx.doi.org/10.1093/mnras/stz2451.

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ABSTRACT Hypervelocity stars (HVSs) represent a unique population of stars in the Galaxy reflecting properties of the whole Galactic potential. Determining their origin is of fundamental importance to constrain the shape and mass of the dark halo. The leading scenario for the ejection of HVSs is an encounter with the supermassive black hole in the Galactic centre. However, new proper motions from the Gaia mission indicate that only the fastest HVSs can be traced back to the Galactic centre and the remaining stars originate in the disc or halo. In this paper, we study HVSs generated by encounters of stellar binaries with an intermediate-mass black hole (IMBH) in the core of a star cluster. For the first time, we model the effect of the cluster orbit in the Galactic potential on the observable properties of the ejected population. HVSs generated by this mechanism do not travel on radial orbits consistent with a Galactic centre origin, but rather point back to their parent cluster, thus providing observational evidence for the presence of an IMBH. We also model the ejection of high-velocity stars from the Galactic population of globular clusters, assuming that they all contain an IMBH, including the effects of the cluster’s orbit and propagation of the star in the Galactic potential up to detection. We find that high-velocity stars ejected by IMBHs have distinctive distributions in velocity, Galactocentric distance and Galactic latitude, which can be used to distinguish them from runaway stars and stars ejected from the Galactic Centre.
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33

Carr, Bernard, Florian Kühnel, and Luca Visinelli. "Constraints on stupendously large black holes." Monthly Notices of the Royal Astronomical Society 501, no. 2 (2020): 2029–43. http://dx.doi.org/10.1093/mnras/staa3651.

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ABSTRACT We consider the observational constraints on stupendously large black holes (SLABs) in the mass range $M \gtrsim 10^{11}\, \mathrm{ M_{\odot}}$. These have attracted little attention hitherto, and we are aware of no published constraints on a SLAB population in the range (1012–$10^{18})\, \mathrm{ M_{\odot}}$. However, there is already evidence for black holes of up to nearly $10^{11}\, \mathrm{ M_{\odot}}$ in galactic nuclei, so it is conceivable that SLABs exist and they may even have been seeded by primordial black holes. We focus on limits associated with (i) dynamical and lensing effects, (ii) the generation of background radiation through the accretion of gas during the pre-galactic epoch, and (iii) the gamma-ray emission from the annihilation of the halo of weakly interacting massive particles expected to form around each SLAB if these provide the dark matter. Finally, we comment on the constraints on the mass of ultralight bosons from future measurements of the mass and spin of SLABs.
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34

LEE, Hyung Mok. "Black Holes: From Imagnation to Reality." Physics and High Technology 29, no. 12 (2020): 17–22. http://dx.doi.org/10.3938/phit.29.045.

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Supermassive black holes in the central parts of galaxies have been extensively studied after a quasar was discovered in 1963. Quasars and active galactic nuclei are known to emit large amounts of electromagnetic radiation over a wide range of wavelengths within a very small volume. These objects are suggested to harbor massive black holes because a plausible mechanism for producing energy efficiently is conversion of the deep gravitational energy of a massive and compact object right after the discovery of the quasar. Astronomers also discovered that the central part of our galaxy has a strong concentration of mass as initially inferred from the rapid motion of the ionized gas near the center. In order to investigate the nature of that concentrated mass, a German group led by Reinhard Genzel and a US group led by Andrea Ghez improved the angular resolution by adopting speckle interferometry and adaptive optics in the near infrared so that very high resolution imaging of the stars in a small region around the Galactic center became possible. Since the mid 1990s, these two groups have made precision measurements of the positions of a large number of stars in the Galactic center and obtained their trajectories accurately. The gravitational field is found to be consistent with that due to a nearly point mass of about 4 million solar masses. Together with gravitational wave observations, imaging of the black hole shadow by with the Event Horizon Telescope, we now have firm observational evidence for the existence of black holes with a huge range of masses in the universe. Another big question to be answered is how these supermassive black holes are formed.
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35

Lee, Jae-Weon, Hyeong-Chan Kim, and Jungjai Lee. "The M-sigma relation of supermassive black holes from the scalar field dark matter." Modern Physics Letters A 35, no. 19 (2020): 2050155. http://dx.doi.org/10.1142/s0217732320501552.

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We show a relation between the mass of supermassive black holes in galaxies and the velocity dispersions of their bulges in the scalar field or the Bose–Einstein condensate dark matter model. The gravity of the central black holes changes boundary conditions of the scalar field at the galactic centers. Owing to the wave nature of the dark matter, this significantly changes the galactic dark matter halo profiles even though the black holes are much lighter than the bulges. As a result the heavier the black holes are, the more compact the bulges are, and hence the larger the velocity dispersions are. This tendency is verified by a numerical study showing the M-sigma relation reproduced with the dark matter particle mass [Formula: see text] eV.
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36

Makishima, Kazuo. "Observational evidence for intermediate-mass black holes: ultra-luminous X-ray sources." Proceedings of the International Astronomical Union 2, S238 (2006): 209–18. http://dx.doi.org/10.1017/s1743921307004991.

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AbstractIncorporating early data from the Suzaku satellite launched in July 2005, properties of Ultra-Luminous compact X-ray sources (ULXs) were studied in close comparison with those of Galactic and Magellanic black-hole binaries. Based on an analogy between these two types of X-ray sources, ULXs showing power-law type spectra are considered to host Comptonized accretion disks, while those with multicolor-disk type spectra are interpreted to harbor “slim” disks. The analogy also suggests that ULXs are radiating near their Eddington limits, and hence their central black holes are significantly more massive than the ordinary stellar-mass black holes contained in Galactic and Magellanic black-hole binaries. In this sense, ULXs can be regarded as intermediate-mass black holes.
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37

Pepe, Carolina, and Leonardo J. Pellizza. "Intermediate-mass black holes in Galactic globular clusters." Proceedings of the International Astronomical Union 5, S266 (2009): 491–94. http://dx.doi.org/10.1017/s1743921309991797.

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AbstractOver the last few years, different observations have suggested the existence of intermediate-mass (~103 M⊙) black holes in the centers of globular clusters. However, the issue is still a matter of debate, as current observations have alternative explanations. We previously developed a hydrodynamical model for the interstellar medium in these systems to explain the luminosity of the central X-ray source found in NGC 6388, assuming a black hole accreting from the insterstellar medium. Here, we explore the predictions of our model regarding the flow of the interstellar matter in the inner cluster regions and find that the density and velocity profiles could help to determine the presence of a central black hole as well as its mass.
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38

Narzilloev, Bakhtiyor, and Bobomurat Ahmedov. "Observational and Energetic Properties of Astrophysical and Galactic Black Holes." Symmetry 15, no. 2 (2023): 293. http://dx.doi.org/10.3390/sym15020293.

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The work reviews the investigation of electromagnetic, optical, and energetic properties of astrophysical and galactic black holes and surrounding matter. The astrophysical applications of the theoretical models of black hole environment to the description of various observed phenomena, such as cosmic rays of the ultra-high-energy, black hole shadow, gravitational lensing, quasinormal modes, jets showing relativistic effects such as the Doppler beaming, thermal radiation from the accretion discs, quasiperiodic oscillations are discussed. It has been demonstrated that the observational data strongly depends on the structure and evolution of the accretion disk surrounding the central black hole. It has been shown that the simulated images of supermassive black holes obtained are in agreement with the observational images obtained by event horizon telescope collaboration. High energetic activity from supermassive black holes due to the magnetic Penrose process discussed in the work is in agreement with the highly energetic cosmic rays observed. The astronomical observation of black holes provides rich fundamental physics laboratories for experimental tests and verification of various models of black hole accretion and different theories of gravity in the regime of strong gravity.
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39

Mahto, Dipo, Amresh Kumar Singh, Kumari Vineeta, and Ashok Kumar. "Change in Entropy of the Spinning Black Holes." International Letters of Chemistry, Physics and Astronomy 32 (April 2014): 95–103. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.32.95.

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Aims: To derive an expression for change in entropy of spinning black holes on the basis of the model for the energy of spinning black holes ( Mahto et al. 2011a) & the model for entropy change ( Mahto et al. 2011b) and then calculate their values for different test spinning black holes. Study Design: Data for the mass of black holes have collected from the research paper entitled :Super massive Black Holes in Galactic Nuclei: Past Present & Future Research(2005), Space Science Reviews by L. Ferrarese & H. Ford and Black holes in Astrophysics(2005), New Journal Physics by R. Narayan. The data for black hole constant for spinning black holes () is taken from the paper entitled: Study of Schwarzschild radius with reference to the spinning black holes. Bulletin of Pure and Applied Sciences (2011a). Place and Duration of Study: Department of Physics, Marwari College Bhagalpur and University Department of Physics, T.M.B.U. Bhagalpur, between December 2013 and March 2014. Methodology: A theoretical based work using Laptop to calculate the calculation for change in entropy of different test spinning black holes at Marwari College Bhagalpur and the residential research chamber of the first author. Results: The calculation shows that the change in entropy of spinning black holes of the rest masses for stellar – mass black holes (M ~ 5 ­ 20 Mʘ) in X-ray binaries is to J/K and for the super massive black holes (M ~ 106 – 109.5 Mʘ) in active galactic nuclei is to J/K. The nature of the graph for XRBs is the same to the Hawking entropy with the event horizon and straight line for AGN which confirms the validity of equations and . Conclusion: The change in energy and entropy of black holes are mainly dependent on the mass and independent of their event horizons.
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40

Mahto, Dipo, Amresh Kumar Singh, Kumari Vineeta, and Ashok Kumar. "Change in Entropy of the Spinning Black Holes." International Letters of Chemistry, Physics and Astronomy 32 (April 22, 2014): 95–103. http://dx.doi.org/10.56431/p-60i6ib.

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Aims: To derive an expression for change in entropy of spinning black holes on the basis of the model for the energy of spinning black holes ( Mahto et al. 2011a) & the model for entropy change ( Mahto et al. 2011b) and then calculate their values for different test spinning black holes. Study Design: Data for the mass of black holes have collected from the research paper entitled :Super massive Black Holes in Galactic Nuclei: Past Present & Future Research(2005), Space Science Reviews by L. Ferrarese & H. Ford and Black holes in Astrophysics(2005), New Journal Physics by R. Narayan. The data for black hole constant for spinning black holes () is taken from the paper entitled: Study of Schwarzschild radius with reference to the spinning black holes. Bulletin of Pure and Applied Sciences (2011a). Place and Duration of Study: Department of Physics, Marwari College Bhagalpur and University Department of Physics, T.M.B.U. Bhagalpur, between December 2013 and March 2014. Methodology: A theoretical based work using Laptop to calculate the calculation for change in entropy of different test spinning black holes at Marwari College Bhagalpur and the residential research chamber of the first author. Results: The calculation shows that the change in entropy of spinning black holes of the rest masses for stellar – mass black holes (M ~ 5 ­ 20 Mʘ) in X-ray binaries is to J/K and for the super massive black holes (M ~ 106 – 109.5 Mʘ) in active galactic nuclei is to J/K. The nature of the graph for XRBs is the same to the Hawking entropy with the event horizon and straight line for AGN which confirms the validity of equations and . Conclusion: The change in energy and entropy of black holes are mainly dependent on the mass and independent of their event horizons.
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41

Romero, G. E., F. L. Vieyro, and G. S. Vila. "Non-thermal processes around accreting galactic black holes." Astronomy and Astrophysics 519 (September 2010): A109. http://dx.doi.org/10.1051/0004-6361/200913663.

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42

Kondrat’ev, A. S., and V. V. Orlov. "Migration of supermassive black holes in galactic nuclei." Astronomy Letters 34, no. 8 (2008): 537–41. http://dx.doi.org/10.1134/s1063773708080045.

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43

Sridhar, S., and J. Touma. "Stellar dynamics around black holes in galactic nuclei." Monthly Notices of the Royal Astronomical Society 303, no. 3 (1999): 483–94. http://dx.doi.org/10.1046/j.1365-8711.1999.02218.x.

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44

Koch, F. Elliott, and Bradley M. S. Hansen. "Mergers of Black Holes in the Galactic Center." Astrophysical Journal 687, no. 1 (2008): 252–61. http://dx.doi.org/10.1086/591781.

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45

Piotrovich, M. Yu, V. L. Afanasiev, S. D. Buliga, and T. M. Natsvlishvili. "Determination of supermassive black hole spins in active galactic nuclei." International Journal of Modern Physics A 35, no. 02n03 (2020): 2040054. http://dx.doi.org/10.1142/s0217751x20400540.

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Based on spectropolarimetry for a number of active galactic nuclei in Seyfert 1 type galaxies observed with the 6-m BTA telescope, we have estimated the spins of the supermassive black holes at the centers of these galaxies. We have determined the spins based on the standard Shakura-Sunyaev accretion disk model. More than 70% of the investigated active galactic nuclei are shown to have Kerr supermassive black holes with a dimensionless spin greater than 0.9.
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46

Mahto, Di Po, Rama Nand Mehta, Umakant Prasad, Krishna Murari Singh, and Mirza Sarfaraz Hussain John. "Internal Energy of the Non-Spinning Black Holes." Advanced Materials Research 787 (September 2013): 681–86. http://dx.doi.org/10.4028/www.scientific.net/amr.787.681.

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The present paper derives an expression for internal energy of the Non-spinning black holes using first law of black hole thermodynamics and calculates their values of different test Non-spinning holes existing in X-ray binaries (XRBs) and Active Galactic Nuclei (AGN).
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47

Morris, Mark, A. M. Ghez, and E. E. Becklin. "The galactic center black hole: Clues for the evolution of black holes in Galactic nuclei." Advances in Space Research 23, no. 5-6 (1999): 959–68. http://dx.doi.org/10.1016/s0273-1177(99)00219-7.

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48

Olejak, A., K. Belczynski, T. Bulik, and M. Sobolewska. "Synthetic catalog of black holes in the Milky Way." Astronomy & Astrophysics 638 (June 2020): A94. http://dx.doi.org/10.1051/0004-6361/201936557.

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Aims. We present an open-access database that includes a synthetic catalog of black holes (BHs) in the Milky Way, divided by the components disk, bulge, and halo. Methods. To calculate the evolution of single and binary stars, we used the updated population synthesis code StarTrack. We applied a new model of the star formation history and chemical evolution of Galactic disk, bulge, and halo that was synthesized from observational and theoretical data. This model can be easily employed for other studies of population evolution. Results. We find that at the current Milky Way (disk+bulge+halo) contains about 1.2 × 108 single BHs with an average mass of about 14 M⊙, and 9.3 × 106 BHs in binary systems with an average mass of 19 M⊙. We present basic statistical properties of the BH population in three Galactic components such as the distributions of BH masses, velocities, or the numbers of BH binary systems in different evolutionary configurations. Conclusions. The metallicity of a stellar population has a significant effect on the final BH mass through the stellar winds. The most massive single BH in our simulation of 113 M⊙ originates from a merger of a BH and a helium star in a low-metallicity stellar environment in the Galactic halo. We constrain that only ∼0.006% of the total Galactic halo mass (including dark matter) can be hidden in the form of stellar origin BHs. These BHs cannot be detected by current observational surveys. We calculated the merger rates for current Galactic double compact objects (DCOs) for two considered common-envelope models: ∼3–81 Myr−1 for BH-BH, ∼1–9 Myr−1 for BH-neutron star (NS), and ∼14–59 Myr−1 for NS-NS systems. We show the evolution of the merger rates of DCOs since the formation of the Milky Way until the current moment with the new star formation model of the Galaxy.
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Scaringi, Simone, Thomas J. Maccarone, Elmar Körding, et al. "Accretion-induced variability links young stellar objects, white dwarfs, and black holes." Science Advances 1, no. 9 (2015): e1500686. http://dx.doi.org/10.1126/sciadv.1500686.

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The central engines of disc-accreting stellar-mass black holes appear to be scaled down versions of the supermassive black holes that power active galactic nuclei. However, if the physics of accretion is universal, it should also be possible to extend this scaling to other types of accreting systems, irrespective of accretor mass, size, or type. We examine new observations, obtained withKepler/K2and ULTRACAM, regarding accreting white dwarfs and young stellar objects. Every object in the sample displays the same linear correlation between the brightness of the source and its amplitude of variability (rms-flux relation) and obeys the same quantitative scaling relation as stellar-mass black holes and active galactic nuclei. We also show that the most important parameter in this scaling relation is the physical size of the accreting object. This establishes the universality of accretion physics from proto-stars still in the star-forming process to the supermassive black holes at the centers of galaxies.
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Eisenhauer, Frank. "The galactic center: The ideal laboratory for studying supermassive black holes." Proceedings of the International Astronomical Union 5, S261 (2009): 269–70. http://dx.doi.org/10.1017/s1743921309990494.

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AbstractThe Galactic Center constitutes the best astrophysical evidence for the existence of black holes, and it is the ideal laboratory for studying physics in the vicinity of such objects. The combination of infrared observations of three dimensional orbits of stars within the central light days and the extreme compactness and motionlessness of the radio-counterpart of the gravitational center have shown beyond any reasonable doubt that the Galactic Center harbors a supermassive black hole. The flaring activity from the black hole gives first insights to the physical processes close to the last stable orbit. Here I review the current state of observations and theory of the Galactic Center black hole and give an update on the latest results. I also outline the next steps towards even higher angular resolution observations, which give promise to directly probe the physics and space-time curvature just outside the event horizon.
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