相关论文: Mass and Angular Momentum of Sgr A*

Measurements of stellar velocities and variable X-ray emission near the centre of the Milky Way have provided the strongest evidence so far that the dark mass concentrations seen in many galactic nuclei are likely supermassive black holes,…

Empirically determining the averaged variations of the orbital parameters of the stars orbiting the Supermassive Black Hole (SBH) hosted by the Galactic Centre (GC) in Sgr A* is, in principle, a valuable tool to put on the test the General…

For a particle of mass mu and scalar charge q, we compute the effects of the scalar field self-force upon circular orbits, upon slightly eccentric orbits and upon the innermost stable circular orbit of a Schwarzschild black hole of mass M.…

We estimated the radiative efficiency and spin value for a number of local active galactic nuclei with z < 0.34 using 3 popular models connecting the radiative efficiency with such parameters of AGNs as mass of supermassive black hole,…

We investigate a compelling model of a rotating black hole that is deformed by the effects of loop quantum gravity (LQG). We present a simplified metric and explore two distinct geometries: one in which the masses of the black hole and…

The Event Horizon Telescope (EHT) recently released an image of the supermassive black hole Sgr A* showing an angular shadow diameter $d_{sh}= 48.7 \pm 7\,\mu$as and Schwarzschild shadow deviation $\delta =…

We model the dynamical structure of M87 (NGC4486) using high spatial resolution long-slit observations of stellar light in the central regions, two-dimensional stellar light kinematics out to half of the effective radius, and globular…

Gravitational waves (GWs) from the inspiral of compact remnants (CRs) into massive black holes (MBHs) will be observable to cosmological distances. While a CR spirals in, 2-body scattering by field stars may cause it to fall into the MBH…

Mergers of spinning black holes can give recoil velocities from gravitational radiation up to several thousand km/s. A recoiling supermassive black hole in an AGN can retain the inner part of its accretion disk, providing fuel for…

The innermost stable circular orbit (ISCO) of a test particle around a Schwarzschild black hole of mass $M$ has (areal) radius $r_{\rm isco}= 6M G/c^2$. If the particle is endowed with mass $\mu(\ll M)$, it experiences a gravitational…

Black holes described by the Kerr metric can have a theoretical maximum dimensionless spin parameter of $a_\bullet = 1$, but several effects may limit the maximum spin parameter in astrophysical systems. We perform general relativistic…

We report on 85-101 GHz light curves of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), observed in April 2017 with the Atacama Large Millimeter/submillimeter Array (ALMA). This study of high-cadence full-Stokes data…

We present the highest resolution VLBI imaging observations of Sgr A* made at both 7 and 3.5 mm. These data reveal wavelength-dependent intrinsic sizes with an intrinsic emitting region at 3.5 mm of about 1 AU (at a distance of 8 kpc to the…

Using the astrometry of microlensing events we study the effect of angular momentum as compared to that of the parallax. For a rotating lens it is shown that the effect of the angular momentum deviates the center of images from that in the…

Although it is widely accepted that most galaxies have supermassive black holes (SMBHs) at their centers^{1-3}, concrete proof has proved elusive. Sagittarius A* (Sgr A*)^4, an extremely compact radio source at the center of our Galaxy, is…

Variable emission from Sgr~A*, the luminous counterpart to the super-massive black hole at the center of our Galaxy, arises from the innermost portions of the accretion flow. Better characterization of the variability is important for…

In its final year of inspiral, a stellar mass ($1 - 10 M_\odot$) body orbits a massive ($10^5 - 10^7 M_\odot$) compact object about $10^5$ times, spiralling from several Schwarzschild radii to the last stable orbit. These orbits are deep in…

We present a new constraint on the mass of the black hole in the active S0 galaxy NGC 5273. Due to the proximity of the galaxy at $16.6 \pm 2.1$ Mpc, we were able to resolve and extract the bulk motions of stars near the central black hole…

The Event Horizon Telescope (EHT) observation unveiled the first image of supermassive black hole Sgr A* showing a shadow of diameter $\theta_{sh}= 48.7 \pm 7\,\mu$as with fractional deviation from the Schwarzschild black hole shadow…

We note that the recently discovered 450 Hz frequency in the X-ray flux of the black hole candidate GRO J1655-40 is in a 3:2 ratio to the previously known 300 Hz frequency of quasi-periodic oscillations (QPO) in the same source. If the…