scholarly journals The Shortest-Known–Period Star Orbiting Our Galaxy’s Supermassive Black Hole

Science ◽  
2012 ◽  
Vol 338 (6103) ◽  
pp. 84-87 ◽  
Author(s):  
L. Meyer ◽  
A. M. Ghez ◽  
R. Schödel ◽  
S. Yelda ◽  
A. Boehle ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Gravitational Potential ◽  
Angular Resolution ◽  
Galactic Center ◽  
Data Set ◽  
Supermassive Black Hole ◽  
The Past ◽  
Orbital Periods

Stars with short orbital periods at the center of our Galaxy offer a powerful probe of a supermassive black hole. Over the past 17 years, the W. M. Keck Observatory has been used to image the galactic center at the highest angular resolution possible today. By adding to this data set and advancing methodologies, we have detected S0-102, a star orbiting our Galaxy’s supermassive black hole with a period of just 11.5 years. S0-102 doubles the number of known stars with full phase coverage and periods of less than 20 years. It thereby provides the opportunity, with future measurements, to resolve degeneracies in the parameters describing the central gravitational potential and to test Einstein’s theory of general relativity in an unexplored regime.

scholarly journals Observing AGN sources with the Event Horizon Telescope

2019 ◽  
Vol 15 (S356) ◽  
pp. 257-257
Author(s):  
Maciek Wielgus
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Angular Resolution ◽  
Galactic Center ◽  
Data Set ◽  
Supermassive Black Hole ◽  
History Of ◽  
Schwarzschild Radius ◽  
Centaurus A

AbstractIn April 2017 Event Horizon Telescope (EHT) has delivered first resolved images of a shadow of a supermassive black hole. Apart from black hole sources in M87 and in the Galactic Center, observed with resolution comparable to the Schwarzschild radius scale, EHT observed multiple AGN sources during the 2017 campaign. These include 3C279, Centaurus A, OJ287 and more. For most of the considered sources EHT 2017 data set should allow to reconstruct images with highest angular resolution in the history of their observations, approaching 20 uas. While the analysis of these data is still ongoing, I will talk about the scientific opportunities related to observing AGN sources with the extreme resolution of the EHT as well as about the astrophysical questions that these observations may help answering.

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 Mini-spiral as source of material for Sgr A* in bright state

2012 ◽  
Vol 8 (S290) ◽  
pp. 199-200 ◽  
Author(s):  
Bozena Czerny ◽  
Vladimír Karas ◽  
Devaky Kunneriath ◽  
Tapas K. Das
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Supermassive Black Hole ◽  
The Past ◽  
Accretion Process ◽  
Ring Mode ◽  
Sgr A ◽  
Bright Phase

AbstractThe question of the origin of the gas supplying the accretion process is pertinent especially in the context of enhanced activity of Galactic Center during the past few hundred years, seen now as echo from the surrounding molecular clouds, and the currently observed new cloud approaching Sgr A*. We discuss the so-called Galactic Center mini-spiral as a possible source of material feeding the supermassive black hole on a 0.1 parsec scale. The collisions between individual clumps reduce their angular momentum. and set some of the clumps on a plunging trajectory.We conclude that the amount of material contained in the mini-spiral is sufficient to sustain the luminosity of Sgr A* at the required level. The accretion episodes of relatively dense gas from the mini-spiral passing through a transient ring mode at ~ 104 Rg provide a viable scenario for the bright phase of Galactic Center.

scholarly journals Constraining scalar-tensor gravity models by S2 star orbits around the galactic center

2019 ◽  
Vol 17 (1, spec.issue) ◽  
pp. 11-20
Author(s):  
Vesna Borka-Jovanovic ◽  
Predrag Jovanovic ◽  
Dusko Borka ◽  
Salvatore Capozziello ◽  
Stefania Gravina ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Galactic Center ◽  
Newtonian Limit ◽  
Gravity Models ◽  
Kinematics And Dynamics ◽  
Supermassive Black Hole ◽  
Theories Of Gravity ◽  
Orbital Precession ◽  
Best Fit

The aim of our investigation is to derive a particular theory among the class of scalar-tensor(ST) theories of gravity, and then to test it by studying kinematics and dynamics of S-stars around a supermassive black hole (BH) at Galactic Center (GC). We also discuss the Newtonian limit of this class of ST theories of gravity, as well as its parameters. We compare the observed orbit of S2 star with our simulated orbit which we obtained theoretically with the derived ST potential and constrained parameters. Using the obtained best-fit parameters we calculated orbital precession of S2 star in ST gravity and found that it has the same direction as in General Relativity (GR) but causes much larger pericenter shift.

scholarly journals 15 years of high precision astrometry in the Galactic Center

2007 ◽  
Vol 3 (S248) ◽  
pp. 466-469
Author(s):  
S. Gillessen ◽  
R. Genzel ◽  
F. Eisenhauer ◽  
T. Ott ◽  
S. Trippe ◽  
...  
Keyword(s):  
Black Hole ◽  
Mass Distribution ◽  
Near Infrared ◽  
Galactic Center ◽  
Massive Black Hole ◽  
Data Set ◽  
Stellar Orbits ◽  
Supermassive Black Hole ◽  
Near Future ◽  
Precision Astrometry

AbstractIn 1992, we obtained the first observations of S2 a star close to the supermassive black hole at the Galactic Center. In 2002, S2 passed its periastron and in 2007, it completed a first fully observed revolution. This orbit allowed us to determine the mass of and the distance to the supermassive black hole with unprecedented accuracy. Here we present a re-analysis of the data set, enhancing the astrometric accuracy to 0.5 mas and increasing the number of well-determined stellar orbits to roughly 15. This allows to constrain the extended mass distribution around the massive black hole and will lead in the near future to the detection of post-Newtonian effects. We will also give an outlook on the potential of interferometric near-infrared astrometry with 10 microarcsecond accuracy from the VLTI.

scholarly journals Testing General Relativity with Stellar Orbits around the Supermassive Black Hole in Our Galactic Center

2017 ◽  
Vol 118 (21) ◽  
Author(s):  
A. Hees ◽  
T. Do ◽  
A. M. Ghez ◽  
G. D. Martinez ◽  
S. Naoz ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Galactic Center ◽  
Stellar Orbits ◽  
Supermassive Black Hole

scholarly journals Satellite infall and mass deposition on the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 168-170
Author(s):  
S. C. Gallego ◽  
J. Cuadra
Keyword(s):  
Black Hole ◽  
Galactic Center ◽  
Accretion Rate ◽  
Young Stars ◽  
Small Satellite ◽  
Supermassive Black Hole ◽  
The Past ◽  
Satellite Galaxy ◽  
The Galaxy

AbstractWe modeled numerically the infall of a small satellite galaxy on to the inner 200 parsec of our Galaxy, to test whether such an event perturbs gas orbiting in the central molecular zone (CMZ), as recently proposed by Lang et al. (2013). This process could have driven a large gas inflow around 10 Myr ago, explaining the past high accretion rate onto the supermassive black hole, and the presence of young stars in the inner parsecs of the Galaxy. Our simulations show a very small inflow of gas, not sufficient to produce the aforementioned effects.

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
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