scholarly journals Supermassive black hole at the galactic center

2014 ◽  
Vol 12 (2) ◽  
pp. 201-210
Author(s):  
Alexander Zakharov
Keyword(s):  
Black Hole ◽  
Extra Dimensions ◽  
Galactic Center ◽  
Spot Size ◽  
Schwarzschild Black Hole ◽  
Naked Singularities ◽  
Supermassive Black Hole ◽  
Hole Charge ◽  
A Charge ◽  
Black Hole Solutions

We derive an analytical expression of a shadow size as a function of a charge in the Reissner - Nordstr?m (RN) metric. Using the derived expression we consider shadows for negative tidal charges and charges corresponding to naked singularities q=Q2/M2>1, where Q and M are black hole charge and mass, respectively. An introduction of a negative tidal charge q can describes black hole solutions in theories with extra dimensions, so following the approach we consider an opportunity to extend RN metric to negative Q2, while for the standard RN metric Q2 is always non-negative. We found that for q > 9=8 black hole shadows disappear. Significant tidal charges q=-6.4 are not consistent with observations of a minimal spot size at the Galactic Center observed in mm-band, moreover, these observations demonstrate that in comparison with the Schwarzschild black hole a Reissner-Nordstr?m black hole with a significant charge q ? 1 provides a better fit of recent observational data for the black hole at the Galactic Center.

scholarly journals Null Geodesics and Strong Field Gravitational Lensing in a String Cloud Background

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. Sharif ◽  
Sehrish Iftikhar
Keyword(s):  
Black Hole ◽  
Gravitational Lensing ◽  
Galactic Center ◽  
Deflection Angle ◽  
Orbital Motion ◽  
Strong Field ◽  
Schwarzschild Black Hole ◽  
Field Limit ◽  
Null Geodesics ◽  
Supermassive Black Hole

This paper is devoted to studying two interesting issues of a black hole with string cloud background. Firstly, we investigate null geodesics and find unstable orbital motion of particles. Secondly, we calculate deflection angle in strong field limit. We then find positions, magnifications, and observables of relativistic images for supermassive black hole at the galactic center. We conclude that string parameter highly affects the lensing process and results turn out to be quite different from the Schwarzschild black hole.

scholarly journals The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole

2017 ◽  
Vol 847 (1) ◽  
pp. 80 ◽  
Author(s):  
G. Witzel ◽  
B. N. Sitarski ◽  
A. M. Ghez ◽  
M. R. Morris ◽  
A. Hees ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Tidal Interaction ◽  
Supermassive Black Hole

scholarly journals A Deep Chandra View of a Candidate Parsec-scale Jet from the Galactic Center Supermassive Black Hole

2019 ◽  
Vol 875 (1) ◽  
pp. 44 ◽  
Author(s):  
Zhenlin Zhu ◽  
Zhiyuan Li ◽  
Mark R. Morris ◽  
Shuo Zhang ◽  
Siming Liu
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Supermassive Black Hole

scholarly journals Weak and strong deflection gravitational lensing by a renormalization group improved Schwarzschild black hole

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Xu Lu ◽  
Yi Xie
Keyword(s):  
Black Hole ◽  
Renormalization Group ◽  
Gravitational Lensing ◽  
Galactic Center ◽  
Quantum Effect ◽  
Apparent Size ◽  
Great Care ◽  
Schwarzschild Black Hole ◽  
Sgr A ◽  
Near Future

AbstractWeak and strong deflection gravitational lensing by a renormalization group improved Schwarzschild black hole is investigated and its observables are found. By taking the supermassive black holes Sgr A* and M87* respectively in the Galactic Center and at the center of M87 as lenses, we estimate these observables and analyse possibility of detecting this quantum improvement. It is not feasible to distinguish such a black hole by most observables in the near future except for the apparent size of the shadow. We also note that directly using measured shadow of M87* to constrain this quantum effect requires great care.

scholarly journals Relativistic redshift of the star S0-2 orbiting the Galactic Center supermassive black hole

Science ◽  
2019 ◽  
Vol 365 (6454) ◽  
pp. 664-668 ◽  
Author(s):  
Tuan Do ◽  
Aurelien Hees ◽  
Andrea Ghez ◽  
Gregory D. Martinez ◽  
Devin S. Chu ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
General Theory ◽  
Galactic Center ◽  
Statistical Significance ◽  
Gravitational Redshift ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Supermassive Black Hole ◽  
Newtonian Model

The general theory of relativity predicts that a star passing close to a supermassive black hole should exhibit a relativistic redshift. In this study, we used observations of the Galactic Center star S0-2 to test this prediction. We combined existing spectroscopic and astrometric measurements from 1995–2017, which cover S0-2’s 16-year orbit, with measurements from March to September 2018, which cover three events during S0-2’s closest approach to the black hole. We detected a combination of special relativistic and gravitational redshift, quantified using the redshift parameter ϒ. Our result, ϒ = 0.88 ± 0.17, is consistent with general relativity (ϒ = 1) and excludes a Newtonian model (ϒ = 0) with a statistical significance of 5σ.

scholarly journals The Stellar Cusp around the Supermassive Black Hole in the Galactic Center

2003 ◽  
Vol 594 (2) ◽  
pp. 812-832 ◽  
Author(s):  
R. Genzel ◽  
R. Schodel ◽  
T. Ott ◽  
F. Eisenhauer ◽  
R. Hofmann ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Supermassive Black Hole

scholarly journals Investigating the Relativistic Motion of the Stars Near the Supermassive Black Hole in the Galactic Center

2017 ◽  
Vol 845 (1) ◽  
pp. 22 ◽  
Author(s):  
M. Parsa ◽  
A. Eckart ◽  
B. Shahzamanian ◽  
V. Karas ◽  
M. Zajaček ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Relativistic Motion ◽  
Supermassive Black Hole

Primordial black holes and the observable features of the universe

2015 ◽  
Vol 24 (13) ◽  
pp. 1545005 ◽  
Author(s):  
K. M. Belotsky ◽  
A. A. Kirillov ◽  
S. G. Rubin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Galactic Center ◽  
Mass Range ◽  
Primordial Black Holes ◽  
Simultaneous Solution ◽  
Supermassive Black Hole ◽  
Range Distribution ◽  
The Universe

Here, we briefly discuss the possibility to solve simultaneously with primordial black holes (PBHs) the problems of dark matter (DM), reionization of the universe, origin of positron line from Galactic center and supermassive black hole (BH) in it. Discussed scenario can naturally lead to a multiple-peak broad-mass-range distribution of PBHs in mass, which is necessary for simultaneous solution of the problems.

scholarly journals DUALITIES, COMPOSITENESS AND SPACE–TIME STRUCTURE OF 4D EXTREME STRINGY BLACK HOLES

1999 ◽  
Vol 14 (07) ◽  
pp. 1015-1034 ◽  
Author(s):  
MARIANO CADONI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Bound States ◽  
Bound State ◽  
Space Time ◽  
Naked Singularities ◽  
Heterotic String Theory ◽  
Space Time Structure ◽  
Black Hole Solutions

We study the BPS black hole solutions of the (truncated) action for heterotic string theory compactified on a six-torus. The O (3,Z) duality symmetry of the theory, together with the bound state interpretation of extreme black holes, is used to generate the whole spectrum of the solutions. The corresponding space–time structures, written in terms of the string metric, are analyzed in detail. In particular, we show that only the elementary solutions present naked singularities. The bound states have either null singularities (electric solutions) or are regular (magnetic or dyonic solutions) with near-horizon geometries given by the product of two 2d spaces of constant curvature. The behavior of some of these solutions as supersymmetric attractors is discussed. We also show that our approach is very useful to understand some of the puzzling features of charged black hole solutions in string theory.

Sign in / Sign up

Export Citation Format

Share Document