Testing the General Relativistic "No-Hair" Theorems Using the Galactic Center Black Hole Sagittarius A*

2008 ◽  
Vol 674 (1) ◽  
pp. L25-L28 ◽  
Author(s):  
Clifford M. Will
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Sagittarius A ◽  
General Relativistic

scholarly journals General Relativistic Flux Modulations in the Galactic Center Black Hole Candidate Sagittarius A*

1995 ◽  
Vol 448 (1) ◽  
Author(s):  
J. M. Hollywood, ◽  
Fulvio Melia, ◽  
Laird M. Close, ◽  
Donald W. McCarthy, Jr., ◽  
Tatia A. DeKeyser
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Black Hole Candidate ◽  
Sagittarius A ◽  
General Relativistic

scholarly journals The reflection of two past outbursts of Sagittarius A* observed by Chandra during the last decade

2013 ◽  
Vol 9 (S303) ◽  
pp. 344-348
Author(s):  
M. Clavel ◽  
R. Terrier ◽  
A. Goldwurm ◽  
M. R. Morris ◽  
G. Ponti ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Line Of Sight ◽  
High Resolution Data ◽  
The Past ◽  
Sagittarius A ◽  
Cloud Parameters ◽  
Angular Scale ◽  
Sgr A ◽  
First Time

AbstractThe supermassive black hole at the Galactic center, Sagittarius A* has experienced periods of higher activity in the past. The reflection of these past outbursts is observed in the molecular material surrounding the black hole but reconstructing its precise lightcurve is difficult since the distribution of the clouds along the line of sight is poorly constrained.Using Chandra high-resolution data collected from 1999 to 2011 we studied both the 6.4 keV and the 4–8 keV emission of the region located between Sgr A* and the Radio arc, characterizing its variations down to 15″ angular scale and 1-year time scale. The emission from the molecular clouds in the region varies significantly, showing either a 2-year peaked emission or 10-year linear variations. This is the first time that such fast variations are measured. Based on the cloud parameters, we conclude that these two behaviors are likely due to two distinct past outbursts of Sgr A* during which its luminosity rose to at least 1039 erg s−1.

scholarly journals Search for time lag in intra-day variability of Sgr A*

2013 ◽  
Vol 9 (S303) ◽  
pp. 322-323
Author(s):  
A. Miyazaki ◽  
S. S. Lee ◽  
B. W. Sohn ◽  
T. Jung ◽  
M. Tsuboi ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Time Lag ◽  
Light Curves ◽  
Time Lags ◽  
Significant Time ◽  
Sagittarius A ◽  
Receiver System ◽  
Sgr A ◽  
Plasma Blobs

AbstractWe searched the time lag between the intra-day variables (IDVs) of Sagittarius A* at 22, 43, and 86 GHz bands using the Korean VLBI Network (KVN). The time lags between the IDV flare peaks at 22 and 43 GHz are reported, and they suggest that the flare emissions come from adiabatically expanding plasma blobs, ejected close to the Galactic center black hole. We searched the time lags between light curves at 90 and 102 GHz using the Nobeyama Millimeter Array, but could not find significant time lags. In order to detect the diversity of the time lags of Sgr A* flares, we performed observations of Sgr A* in the 22, 43, and 86 GHz bands using the KVN in the winter of 2013. Because the receiver system of KVN can observe Sgr A* in these three bands simultaneously, the KVN is very useful to detect the time lags of Sgr A* flares.

scholarly journals On the prospects of imaging Sagittarius A* from space

2018 ◽  
Vol 14 (S342) ◽  
pp. 24-28
Author(s):  
Freek Roelofs ◽  
Heino Falcke ◽  
Christiaan Brinkerink ◽  
Monika Moscibrodzka ◽  
Leonid I. Gurvits ◽  
...  
Keyword(s):  
General Relativity ◽  
Galactic Center ◽  
Tests Of General Relativity ◽  
Sagittarius A ◽  
Long Baseline ◽  
General Relativistic ◽  
New Space ◽  
Sgr A ◽  
Relativistic Magnetohydrodynamics ◽  
Earth Orbits

AbstractVery Long Baseline Interferometry (VLBI) at sub-millimeter waves has the potential to image the shadow of the black hole in the Galactic Center, Sagittarius A* (Sgr A*), and thereby test basic predictions of the theory of general relativity. We investigate the imaging prospects of a new Space VLBI mission concept. The setup consists of two satellites in polar or equatorial circular Medium-Earth Orbits with slightly different radii, resulting in a dense spiral-shaped uv-coverage with long baselines, allowing for extremely high-resolution and high-fidelity imaging of radio sources. We simulate observations of a general relativistic magnetohydrodynamics model of Sgr A* for this configuration with noise calculated from model system parameters. After gridding the uv-plane and averaging visibilities accumulated over multiple months of integration, images of Sgr A* with a resolution of up to 4 μ as could be reconstructed, allowing for stronger tests of general relativity and accretion models than with ground-based VLBI.

scholarly journals Status of GRMHD simulations and radiative models of Sgr A*

2016 ◽  
Vol 11 (S322) ◽  
pp. 43-49
Author(s):  
Monika Mościbrodzka
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Kerr Black Hole ◽  
Theoretical Models ◽  
Radiative Properties ◽  
X Ray ◽  
Accretion Flows ◽  
General Relativistic ◽  
Sgr A ◽  
Magnetohydrodynamic Simulations

AbstractThe Galactic center is a perfect laboratory for testing various theoretical models of accretion flows onto a supermassive black hole. Here, I review general relativistic magnetohydrodynamic simulations that were used to model emission from the central object - Sgr A*. These models predict dynamical and radiative properties of hot, magnetized, thick accretion disks with jets around a Kerr black hole. Models are compared to radio-VLBI, mm-VLBI, NIR, and X-ray observations of Sgr A*. I present the recent constrains on the free parameters of the model such as accretion rate onto the black hole, the black hole angular momentum, and orientation of the system with respect to our line of sight.

scholarly journals Variable and polarized emission from SgrA*

2006 ◽  
Vol 2 (S238) ◽  
pp. 181-185
Author(s):  
A. Eckart ◽  
R. Schödel ◽  
L. Meyer ◽  
C. Straubmeier ◽  
M. Dovčiak ◽  
...  
Keyword(s):  
Black Hole ◽  
Near Infrared ◽  
Galactic Center ◽  
Hot Spot ◽  
Massive Black Hole ◽  
X Ray ◽  
Sagittarius A ◽  
Polarized Emission

AbstractThe super-massive black hole in the Galactic Center (Sagittarius A*) is one of the most exciting targets in the sky. At a distance of ∼ 8 kpc it is about one hundred times closer than the second nearest nucleus of a similar galaxy, M31, and therefore the closest galactic nucleus that we can study. Here we report on the modeling of polarized near-infrared flare emission from SgrA* using a model in which a hot spot is moving on a relativistic orbit around the massive black hole. We also summarize the results from simultaneous radio/near-infrared/X-ray measurements of flare emission.

Sign in / Sign up

Export Citation Format

Share Document