相关论文: What is the optimum stellar rotation rate for a co…
We performed a series of 769 full numerical simulations of high energy collision of black holes to search for the maximum gravitational energy emitted $E_{rad}$, during their merger. We consider equal mass binaries with spins pointing along…
We present numerical simulations of axisymmetric magnetised massive tori around rotating black holes taking into account the energy losses due to emission of neutrinos. A realistic equation of state is used which takes into account the…
Collapsars are fast-spinning, massive stars, whose core collapse liberates an energy, that can be channeled in the form of ultrarelativistic jets. These jets transport the energy from the collapsed core to large distances, where it is…
An atom falling freely into a Kerr black hole in a Boulware-like vacuum is shown to emit radiation with a Planck spectrum at the Hawking temperature. For a cloud of falling atoms with random initial times, the radiation is thermal. The…
We revisit the constraint on the maximum mass of cold spherical neutron stars coming from the observational results of GW170817. We develop a new framework for the analysis by employing both energy and angular momentum conservation laws as…
Supermassive stars (SMSs), with masses $>10^5$ M$_\odot$, have been proposed as the possible progenitors of the most extreme supermassive black holes observed at redshifts $z>6-7$. In this scenario ('direct collapse'), a SMS accretes at…
A key component of explaining the array of galaxies observed in the Universe is the feedback of active galactic nuclei, each powered by a massive black hole's accretion disc. For accretion to occur, angular momentum must be lost by that…
Recent calculations of gravitational radiation recoil generated during black-hole binary mergers have reopened the possibility that a merged binary can be ejected even from the nucleus of a massive host galaxy. Here we report the first…
Rapid, hyper-Eddington accretion is likely to power the central engines of gamma-ray bursts (GRBs). In the extreme conditions of densities and temperatures the accreting torus is cooled by neutrino emission rather than by radiation. Another…
We estimate the gravitational radiation signature of the electron/positron annihilation-driven neutrino burst accompanying the asymmetric collapse of an initially hydrostatic, radiation-dominated supermassive object suffering the…
Using several approximations, we calculate an estimate of the gravitational radiation emitted when two equal mass black holes coalesce at the end of their binary inspiral. We find that about 1% of the mass energy of the pair will emerge as…
We performed simulations of collapsars with different Kerr parameters a=0, 0.5, 0.9, 0.95. It is shown that a more rapidly rotating black hole is driving a more energetic jet. No jet is seen for the case of Schwartzschild black hole case,…
We study the final state of the gravitational collapse of uniformly rotating supramassive neutron stars by axisymmetric simulations in full general relativity. The rotating stars provided as the initial condition are marginally stable…
We consider the emission of gravitational waves in the two proposed models for the collapse of a massive star to a black hole: the prompt collapse, in which nearly all the star collapses to a black hole in a dynamical time scale, and the…
According to the traditional scenario for core-collapse supernovae, the core of the collapsing star forms a neutron star and its gravitational energy release sends out a shockwave into the stellar envelope. However, in a significant number…
The core collapse of massive, rapidly-rotating stars are thought to be the progenitors of long-duration gamma-ray bursts (GRB) and their associated hyper-energetic supernovae (SNe). At early times after the collapse, relatively low angular…
I consider how physical processes scale over eight orders of magnitude in black hole mass, from stellar masses in gamma-ray bursts (GRB) and black-hole X-ray binaries (BHXRB) to supermassive active galactic nuclei (AGN). Accretion rates…
It is now clear that a subset of supernovae display evidence for jets and are observed as gamma-ray bursts. The angular momentum distribution of massive stellar endpoints provides a rare means of constraining the nature of the central…
We examine the low angular momentum flow model for Sgr A* using two-dimensional hydrodynamical calculations based on the parameters of the specific angular momentum and total energy estimated in the recent analysis of stellar wind of nearby…
The end state of a coalescing binary of compact objects depends strongly on the final total mass M and angular momentum J. Since gravitational radiation emission causes a slow evolution of the binary system through quasi-circular orbits…