Is there a massive black hole at the galactic center?

1979 ◽  
Vol 84 ◽  
pp. 395-400
Author(s):  
L. M. Ozernoy
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Dynamical Evolution ◽  
Galactic Nuclei ◽  
Black Hole Mass ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Infrared Observations ◽  
The Galaxy ◽  
Remote Past

During the past 10 years an hypothesis about the presence of a massive black hole at the center of our Galaxy (Lynden-Bell, 1969) has been an object of many exciting speculations. This hypothesis is based, firstly, on attempts to explain the nature of the “point radio source” at the galactic center (as well as a presumed much more powerful activity of the galactic nucleus in the remote past), and, secondly, on the opinion that the conditions in the course of dynamical evolution of galactic nuclei are favorable for the formation of massive black holes. However, both these approaches did not succeed in predicting with any confidence the black hole mass at the center of the Galaxy. The estimates available are based on indirect arguments and range from 107-1011 M⊙ (Novikov and Thorne, 1973) to 104 M⊙ (Shklovskii, 1976). A recent dynamical approach using NeII infrared observations of the galactic center (Wollman et al., 1977) has indicated that the black hole mass does not exceed 5×106 M⊙ (Oort, 1977), although this value may well be due to a very dense star cluster whose brightest members only are seen in the infrared.

scholarly journals Constraints to the Mass of a Black Hole at the Galactic Centre

1977 ◽  
Vol 45 ◽  
pp. 121-124 ◽  
Author(s):  
L.M. Ozernoy
Keyword(s):  
Black Hole ◽  
Point Source ◽  
Dynamical Evolution ◽  
Galactic Nuclei ◽  
Galactic Centre ◽  
Black Hole Mass ◽  
Massive Black Hole

Many speculations related to a hypothesis that there is a very massive black hole at the centre of our Galaxy have appeared during the last years. This hypothesis is based, firstly, on the opinion that the formation of a massive black hole as a result of dynamical evolution of galactic nuclei is inevitable and, secondly, on the attempts to explain the nature of the “point source” at the Galactic centre (see Oort, 1977 and references therein). However both these approaches could not predict with any confidence the black hole mass. The estimates range from 107-1011Mʘ(Novikov and Thorne, 1973) to 104Mʘ(Shklovskii, 1976).

scholarly journals Constraining the stellar mass function from the deficiency of tidal disruption flares in the nuclei of massive galaxies

2019 ◽  
Vol 485 (3) ◽  
pp. 4413-4422 ◽  
Author(s):  
Daniel J D’Orazio ◽  
Abraham Loeb ◽  
James Guillochon
Keyword(s):  
Black Hole ◽  
Mass Function ◽  
Stellar Mass ◽  
High Mass ◽  
Black Hole Mass ◽  
Tidal Disruption ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Massive Galaxies ◽  
O 10

ABSTRACT The rate of tidal disruption flares (TDFs) per mass of the disrupting black hole encodes information on the present-day mass function (PDMF) of stars in the clusters surrounding super massive black holes. We explore how the shape of the TDF rate with black hole mass can constrain the PDMF, with only weak dependence on black hole spin. We show that existing data can marginally constrain the minimum and maximum masses of stars in the cluster, and the high-mass end of the PDMF slope, as well as the overall TDF rate. With $\mathcal {O}(100)$ TDFs expected to be identified with the Zwicky Transient Facility, the overall rate can be highly constrained, but still with only marginal constraints on the PDMF. However, if ${\lesssim } 10 {{\ \rm per\ cent}}$ of the TDFs expected to be found by LSST over a decade ($\mathcal {O}(10^3)$ TDFs) are identified, then precise and accurate estimates can be made for the minimum stellar mass (within a factor of 2) and the average slope of the high-mass PDMF (to within $\mathcal {O}(10{{\ \rm per\ cent}})$) in nuclear star clusters. This technique could be adapted in the future to probe, in addition to the PDMF, the local black hole mass function and possibly the massive black hole binary population.

scholarly journals The distance to the Galactic Center

2012 ◽  
Vol 8 (S289) ◽  
pp. 29-35 ◽  
Author(s):  
Stefan Gillessen ◽  
Frank Eisenhauer ◽  
Tobias K. Fritz ◽  
Oliver Pfuhl ◽  
Thomas Ott ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Distance Estimate ◽  
Massive Black Hole ◽  
Geometric Distance ◽  
Stellar Orbits ◽  
Fundamental Parameters ◽  
The Galaxy ◽  
Error Bars ◽  
Definition Of

AbstractOne of the Milky Way's fundamental parameters is the distance of the Sun from the Galactic Center, R0. This article reviews the various ways of estimating R0, placing special emphasis on methods that have become possible recently. In particular, we focus on the geometric distance estimate made possible thanks to observations of individual stellar orbits around the massive black hole at the center of the Galaxy. The specific issues of concern there are the degeneracies with other parameters, most importantly the mass of the black hole and the definition of the reference frame. The current uncertainty is nevertheless only a few percent, with error bars shrinking every year.

scholarly journals Constraints on and Alternatives to a Massive Black Hole at the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 555-566 ◽  
Author(s):  
Leonid M. Ozernoy
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
High Mass ◽  
Broad Line ◽  
Massive Black Hole ◽  
Broad Line Region ◽  
Line Region ◽  
The Galaxy ◽  
Very High

Considerations are presented which could serve as nourishment for a “devil's advocate” with regard to the concept of a very massive (~ 106M⊙) black hole at the center of the Galaxy. Constraints on the BH mass given by various processes are summarized. Most attention is paid to a novel probe of the black hole by means of a “wind diagnostic,” i.e. by accounting for interaction of the BH with the wind responsible for the broad line region at the Galactic Center. All available data taken together do not require a very high mass for the BH, but a moderately massive black hole currently seems to present the prime candidacy from several alternatives.

scholarly journals 9.1. HST detections of massive black holes in the centers of galaxies

1998 ◽  
Vol 184 ◽  
pp. 377-384 ◽  
Author(s):  
H.C. Ford ◽  
Z.I. Tsvetanov ◽  
L. Ferrarese ◽  
W. Jaffe
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hubble Space Telescope ◽  
Spherical Aberration ◽  
Proper Motions ◽  
Black Hole Mass ◽  
Massive Black Holes ◽  
The Galaxy ◽  
Ngc 1068 ◽  
Better Than

After correcting spherical aberration in the Hubble Space Telescope in 1993, the central masses of galaxies can be measured with a resolution 5 to 10 times better than can be achieved at the best terrestrial sites. This improvement in resolution is decisive for detecting the gravitational signature of massive black holes in galaxy nuclei. The discovery of small (r ~ 100–200 pc) rotating gaseous and stellar disks in the centers of many early-type galaxies provides a new and efficient means for measuring the central potentials of galaxies. Concomitantly, VLBI observations of H2O masers in the nuclei of NGC 4258 and NGC 1068 revealed exquisite Keplerian rotation curves around massive black holes at radii as small as 0.1 pc. Recent terrestrial K-band measurements of the proper motions of stars in the cluster at the center of the galaxy provide irrefutable evidence for a black hole with a mass of 2.7 × 106M⊙. At the time of this symposium, the presence of central massive black holes has been established in 12 galaxies. The evidence suggests that there are massive black holes in the centers of all AGNs and in most, if not all, nucleated galaxies. The present data show at best a weak correlation between black hole mass and bulge luminosity.

scholarly journals Formation and Evolution of Massive Black Holes in Star Clusters

2005 ◽  
Vol 13 ◽  
pp. 350-353
Author(s):  
Holger Baumgardt ◽  
Junichiro Makino ◽  
Simon Portegies Zwart
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Initial Conditions ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Young Star ◽  
Cluster Center ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Equilibrium Profile

AbstractWe present results of N-body simulations on the formation of massive black holes by run-away merging in young star clusters and the later dynamical evolution of star clusters containing massive black holes. We determine the initial conditions necessary for run-away merging to form a massive black hole and study the equilibrium profile that is established in the cluster center as a result of the interaction of stars with the central black hole. Our results show that star clusters which contain black holes have projected luminosity profiles that can be fitted by standard King models. The presence of massive black holes in (post-)core collapse clusters is therefore ruled out by our simulations.

scholarly journals The Black Hole Grazer

1998 ◽  
Vol 188 ◽  
pp. 449-450
Author(s):  
Y. Taniguchi ◽  
O. Kaburaki
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Binary System ◽  
Galactic Center ◽  
Center Of Mass ◽  
Galactic Nuclei ◽  
Orbital Plane ◽  
Roche Lobe ◽  
Surface Charges ◽  
Massive Black Holes

We propose an alternative model for the powering of active galactic nuclei (AGN), based on the assumption that all AGN have experienced mergers. In our model (Kaburaki and Taniguchi 1996; Taniguchi and Kaburaki 1996), a close pair of super-massive black holes (the black hole grazer) orbit one another in a plane roughly perpendicular to the galactic center magnetic field. The orbital motion induces surface charges on the black holes which produce an electric field. This field is strong enough to cause pair creation so that the Roche lobe of the binary system is filled with pair plasmas. Rigid-body rotation of the Roche-lobe magnetosphere drives electrodynamically a powerful synchrotron jet emanating from the center of mass of the binary. Furthermore, a pair of equatorial jets flow from the outer Lagrangian points of the binary system. Although these jets are not so collimated, they interact with the accreting gas ring formed around the orbital plane of the binary, causing broad line regions or H2O maser emission regions (Taniguchi et al. 1996). In addition to the primary jet, two secondary jets are also driven by local accretion disks around the two black holes. The interaction among the primary and the secondary jets may explain detailed jet morphology observed by VLBI facilities.

scholarly journals On the eccentricity evolution of massive black hole binaries in stellar backgrounds

2020 ◽  
Vol 493 (1) ◽  
pp. L114-L119 ◽  
Author(s):  
Matteo Bonetti ◽  
Alexander Rasskazov ◽  
Alberto Sesana ◽  
Massimo Dotti ◽  
Francesco Haardt ◽  
...  
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Dynamical Evolution ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Black Hole Binaries ◽  
Simple Extrapolation ◽  
Sgr A ◽  
The Masses ◽  
Three Body

ABSTRACT We study the dynamical evolution of eccentric massive black hole binaries (MBHBs) interacting with unbound stars by means of an extensive set of three-body scattering experiments. Compared to previous studies, we extend the investigation down to a MBHB mass ratio of q = m2/m1 = 10−4, where m1 and m2 are the masses of the primary and secondary hole, respectively. Contrary to a simple extrapolation from higher mass ratios, we find that for q ≲ 10−3 the eccentricity growth rate becomes negative, i.e. the binary circularizes as it shrinks. This behaviour is due to the subset of interacting stars captured in metastable counter-rotating orbits; those stars tend to extract angular momentum from the binary, promoting eccentricity growth for q > 10−3, but tend to inject angular momentum into the binary driving it towards circularization for q < 10−3. The physical origin of this behaviour requires a detailed study of the orbits of this subset of stars and is currently under investigation. Our findings might have important consequences for intermediate massive black holes (IMBHs) inspiralling on to MBHs (e.g. a putative $10^3\,\rm M_{\odot }$ black hole inspiralling on to Sgr A*).

scholarly journals Manifestations of a Massive Black Hole in the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 543-553 ◽  
Author(s):  
E.S. Phinney
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Galactic Center ◽  
Young Star ◽  
Star Cluster ◽  
Point Of View ◽  
Massive Black Hole ◽  
The Galaxy ◽  
Gas Accretion

A young star cluster is a less contrived explanation than a massive black hole for many of the features seen in the Galactic center. However from a Copernican point of view, this explanation is less attractive than a black hole. The evidence for a ~ 106M⊙ black hole is becoming progressively less convincing, but the case against it is no stronger. We describe the development of a singular star cluster, as well as the processes of stellar disruption, merging, and gas accretion in such a cluster. Recently merged stars and tidally stripped giants may be detectable within an arcminute of the Galactic Center. We examine the physics of star formation in the inner parsecs of the galaxy, and the problem of maintaining the two parsec molecular torus.

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