相关论文: Why are Quasiperiodic Eruptions only Found in Low-…
Most large elliptical galaxies should now host a massive black hole leftover from an earlier quasar phase. Such galaxies also have an extensive hot gaseous halo. Here we consider why the nuclei of elliptical galaxies are not luminous…
Quasi-Periodic Eruptions (QPEs) are recurring bursts of soft X-ray emission from supermassive black holes (SMBHs), which a growing class of models explains via extreme mass-ratio inspirals (EMRIs). QPEs exhibit blackbody-like emission with…
Fast time variability is the most prominent characteristic of accreting systems and the presence of quasi periodic oscillations (QPOs) is a constant in all accreting systems, from cataclysmic variables to AGNs, passing through black hole…
Quiescent galaxies with little or no ongoing star formation dominate the galaxy population above $M_{*}\sim 2 \times 10^{10}~M_{\odot}$, where their numbers have increased by a factor of $\sim25$ since $z\sim2$. Once star formation is…
Quasi-Periodic Eruptions (QPEs) are recurrent X-ray eruptions discovered so far in the nuclei of low-mass galaxies. However, despite considerable observational progress, the origin of QPEs remains unclear. A variety of models have been…
Black Holes generate a particular kind of environments dominated by an accretion flow which concentrates a magnetic field. The interplay of gravity and magnetism creates this paradoxical situation where relativistic ejection is allowed and…
Quasi-periodic eruptions (QPEs) are repeating soft X-ray flares associated with galactic nuclei. Several recent works have found evidence that the accretion flow in the galactic nuclei of QPEs is of recent origin, and that it is unlike…
We consider a scenario where supermassive black holes form through direct accumulation of gas at the centre of proto-galaxies. In the first stage, the accumulated gas forms a super-massive star whose core collapses when the nuclear fuel is…
If a small compact object orbits a black hole, it is known that it can excite the black hole's quasinormal modes (QNMs), leading to high-frequency oscillations ("wiggles") in the radiated field at $\mathcal{J}^+$, and in the…
X-ray quasi-periodic eruptions (QPEs) are intense soft X-ray bursts from the nuclei of nearby low-mass galaxies typically lasting about one hour and repeating every few. Their physical origin remains debated, although so-called impacts…
I review accretion and outflow in active galactic nuclei. Accretion appears to occur in a series of very small--scale, chaotic events, whose gas flows have no correlation with the large--scale structure of the galaxy or with each other. The…
We study the time dependent properties of sub-Keplerian viscous accretion flow around the black holes. We find that rotating matter feels centrifugal barrier on the way towards the black holes and eventually, shock transition is triggered…
Planck stars form when a collapsing shell of matter within a black hole reaches the Planck density, roughly equivalent to the mass being compressed into a volumetric size near that of the proton, and rebounds outwards. These planck stars…
A modest fraction of the stars in galactic nuclei fed towards the central supermassive black hole (SMBH) approach on low-eccentricity orbits driven by gravitational-wave radiation (extreme mass ratio inspiral, EMRI). In the likely event…
Recent studies of scalar and gravitational waveforms from high-eccentricity, extreme mass-ratio black hole binaries show the presence of quasi-normal bursts (QNB) -- lingering high frequency decaying oscillations (also known as ``wiggles'')…
Quasi-periodic oscillations (QPOs), in particular, the ones with high frequencies, often observed in the power spectrum of black holes, are useful in understanding the nature of strong gravity since they are associated with the motion of…
We explore a possible scenario of the explosion as a result of core collapses of rotating massive stars that leave a black hole by performing a radiation-viscous-hydrodynamics simulation in numerical relativity. We take moderately and…
X-ray quasi-periodic eruptions (QPEs) are rare and enigmatic phenomena that increasingly show a connection to tidal disruption events (TDEs). However, the recently discovered QPEs in ZTF19acnskyy ("Ansky") appear to be linked to an active…
This study delves into the existence of dark matter around supermassive black holes in galactic cores using a novel gravitational model. By analyzing gravitational waves emitted during the ringdown phase of black holes under different field…
Supermassive black holes inhabit galactic nuclei, and their presence influences in crucial ways the evolution of the stellar distribution. The low-density cores observed in bright galaxies are probably a result of black hole infall, while…