相关论文: Probing quantum gravity at low energies

Formation of significant number of primordial black holes (PBHs) is realized if and only if primordial density fluctuations have a large amplitude, which means that tensor perturbations generated from these scalar perturbations as a second…

Superposition of gravitational waves generated by astrophysical sources is expected to give rise to the stochastic gravitational-wave background. We focus on the background generated by the ring-down of black holes produced in the stellar…

We show that density spikes begin to form from dark matter particles around primordial black holes immediately after their formation at the radiation-dominated cosmological stage. This follows from the fact that in the thermal velocity…

Black holes (BHs) play a central role in physics. However, gathering observational evidence for their existence is a notoriously difficult task. Current strategies to quantify the evidence for BHs all boil down to looking for signs of…

In this article we provide a new closed relationship between cosmic abundance of primordial gravitational waves and primordial blackholes originated from initial inflationary perturbations for inflection-point models of inflation where…

Star-forming galaxies which are too faint to be detected individually produce intensity fluctuations in the cosmic background light. This contribution needs to be taken into account as a foreground when using the primordial signal to…

If even a relatively small number of black holes were created in the early universe, they will constitute an increasingly large fraction of the total energy density as space expands. It is thus well-motivated to consider scenarios in which…

Supermassive black holes are now realized to exist in the centers of most galaxies. The recent discoveries of luminous quasars at redshifts higher than 6 require that these black holes were assembled already when the Universe was less than…

Stars that are collapsing toward forming a black hole but are frozen near the Schwarzschild horizon are termed "black stars". Collisions of black stars, in contrast to black hole collisions, may be sources of gamma ray bursts, whose basic…

Limits on the dark matter fraction of small mass primordial black holes from Hawking radiation are predominantly derived from the assumption of a Schwarzschild black hole evaporating. However, astrophysical black holes are usually much more…

Using the result obtained in a prevoius paper, in which I found an upper limit on the region of particle creation in the vicinity of the event horizon of a Schwarzschild black hole, and by assuming that all the created energy will be…

Using the BATSE survey data I find that quite small fraction of GRBs numbering 37 sources seems to emit the radiation similar to thermal bremsstrahlung in the range 20 to 300 keV. I suggest that these bursts may perhaps occur from collision…

Recent models of carbon ignition on accreting neutron stars predict superburst ignition depths that are an order of magnitude larger than observed. We explore a possible solution to this problem, that the compact stars in low mass X-ray…

The possibility that Dark Matter (DM) is partially or totally constituted by stable Planckian remnants of light Primordial Black Holes (PBHs), suggested for instance by Loop Quantum Gravity (LQG), is investigated. Distinct phenomenological…

We derive a strong upper bound on the amount of Primordial Black Holes (PBHs) that can still be present in the Universe. Gravitational capture of PBHs by the Milky Way stars during their formation and subsequent accretion would produce a…

The mass function of primordial black holes created through the near-critical gravitational collapse is calculated in a manner fairly independent of the statistical distribution of underlying density fluctuation, assuming that it has a…

We present theoretical predictions for the spectral, temporal and intensity signatures of the electromagnetic radiation emitted during the process of the gravitational collapse of a stellar core to a black hole, during which electromagnetic…

We investigate the spontaneous creation of primordial black holes in a lower-dimensional expanding early universe. We use the no-boundary proposal to construct instanton solutions for both the background and a black hole nucleated inside…

The end state of Hawking evaporation of a black hole is uncertain. Some candidate quantum gravity theories, such as loop quantum gravity and asymptotic safe gravity, hint towards Planck sized remnants. If so, the Universe might be filled…

We review the non-linear statistics of Primordial Black Holes that form from the collapse of over-densities in a radiation dominated Universe. We focus on the scenario in which large over-densities are generated by rare and Gaussian…