Perturbing the accretion flow onto a supermassive black hole by a passing star

恒星和中等质量黑洞扰动活动星系核吸积盘：对变脸活动星系核和准周期爆发的启示

Perturbing AGN Accretion Disks with Stars and Moderately Massive Black Holes: Implications for Changing-Look AGN and Quasi-Periodic Eruptions

该模型提出轨道伴星扰动AGN吸积盘激发螺旋波导致吸积爆发，解释变脸AGN需高偏心中等质量黑洞，而准周期爆发则源于高偏心恒星近心点经过。

A strongly magnetized pulsar within grasp of the Milky Way's supermassive black hole

The center of our Galaxy hosts a supermassive black hole, Sagittarius (Sgr) A*. Young, massive stars within 0.5 pc of SgrA* are evidence of an episode of intense star formation near the black hole a few Myr ago, which might have left behind a young neutron star traveling deep into SgrA*'s gravitational potential. On 2013 April 25, a short X-ray burst was observed from the direction of the Galactic center. Thanks to a series of observations with the Chandra and the Swift satellites, we pinpoint the associated magnetar at an angular distance of 2.4+/-0.3 arcsec from SgrA*, and refine the source …

恒星级黑洞从恒星双星遭遇中生长

Supermassive black hole growth from stellar binary encounters

研究通过双星相互作用机制探讨超大质量黑洞的生长过程，并发现大麦哲伦云中的黑洞可能通过吸积双星伙伴实现增长。

Relativistic Dynamics and Mass Exchange in Binary Black Hole Mini-Disks

We present the first exploration of relativistic gas dynamics in the immediate vicinity of binary black holes as the system inspirals close to merger in the gravitational radiation-driven regime. We focus on 2D hydrodynamical studies of comparable-mass, non-spinning systems. Relativistic effects alter the dynamics of gas in this environment in several ways. Because the gravitational potential between the two black holes becomes shallower than in the Newtonian regime, the mini-disks stretch toward the L1 point and the amount of gas passing back and forth between the mini-disks increases sharply…

Stellar transits across a magnetized accretion torus as a mechanism for plasmoid ejection

The close neighbourhood of a supermassive black hole contains not only the accreting gas and dust but also stellar-sized objects, such as late-type and early-type stars and compact remnants that belong to the nuclear star cluster. When passing through the accretion flow, these objects perturb it by the direct action of stellar winds, as well as their magnetic and gravitational effects. By performing General-Relativistic Magnetohydrodynamic (GRMHD) simulations, we investigate how the passages of a star can influence the supermassive black hole gaseous environment. We focus on the changes in the…

Comparison of different Tidal Disruption Event light curve models with TiDE, a new modular open source code

A tidal disruption event (TDE) occurs when a supermassive black hole disrupts a nearby passing star by tidal forces. The subsequent fallback accretion of the stellar debris results in a luminous transient outburst. Modeling the light curve of such an event may reveal important information, for example the mass of the central black hole. This paper presents the TiDE software based on semi-analytic modeling of TDEs. This object-oriented code contains different models for the accretion rate and the fallback timescale $t_{\rm min}$. We compare the resulting accretion rates to each other and with h…