相关论文: High-redshift Mini-haloes from Modulated Preheatin…
Recent observations of the high-redshift universe have uncovered a significant number of active galactic nuclei, implying that supermassive black holes (SMBHs) would have to have been formed at much earlier times than expected. Direct…
The existence of supermassive black holes at high redshifts ($z\sim7$) is difficult to accommodate in standard astrophysical scenarios. It has been shown that dark matter models with a subdominant self-interacting component are able to…
We present a new probe of primordial non-Gaussianity via the 21cm radiation from minihalos at high redshifts. We calculate the fluctuations in the brightness temperature (measured against the cosmic microwave background) of the 21cm…
The origin of the seeds which develop into the observed super-massive black holes at high redshifts may be hard to interpret in the context of the standard $\Lambda CDM$ of early universe cosmology based on Gaussian primordial…
We present a model for the formation of massive black holes ($\sim 1000 \msun$) due to stellar-dynamical processes in the first stellar clusters formed at early cosmic times ($z\sim10-20$). The high redshift black hole seeds form as a…
We demonstrate that violent kinetic preheating following inflation can lead to the formation of black holes in the early Universe. In $\alpha$-attractor models with derivative inflaton couplings, nonlinear amplification of field…
The most up to date femto- and micro-lensing constraints indicate that primordial black holes of $\sim 10^{-16} M_\odot$ and $\sim 10^{-12} M_\odot$, respectively, may constitute a large fraction of the dark matter. We describe analytically…
The astrophysical processes that led to the formation of the first seed black holes and to their growth into the supermassive variety that powers bright quasars at redshift 6 are poorly understood. In standard LCDM hierarchical cosmologies,…
The presence of massive black holes (BHs) with masses of order $10^9\rm\, M_\odot$, powering bright quasars when the Universe was less than 1 Gyr old, poses strong constraints on their formation mechanism. Several scenarios have been…
We study the production of primordial black holes (PBHs) during the preheating stage that follows a chaotic inflationary phase. The scalar fields present in the process are evolved numerically using a modified version of the HLATTICE code.…
We discuss a model for the early assembly of supermassive black holes (SMBHs) at the center of galaxies that trace their hierarchical build-up far up in the dark halo `merger tree'. Motivated by the observations of luminous quasars around…
We propose a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead…
We use high-resolution three-dimensional adaptive mesh refinement simulations to investigate the interaction of high-redshift galaxy outflows with low-mass virialized clouds of primordial composition. While atomic cooling allows star…
It has been recently pointed out that the initial value problem in new inflation models is naturally solved by supergravity effects if there exists a pre-inflation before the new inflation. We study this double inflation model in details…
In this paper, we explore the possibility of accreting primordial black holes as the source of heating for the collapsing gas in the context of the direct collapse black hole scenario for the formation of super-massive black holes (SMBHs)…
We study a double inflation model (a preinflation + a new inflation) in supergravity and discuss the formation of primordial black holes which may be identified with massive compact halo objects (MACHOs) observed in the halo of our galaxy.…
Supermassive black holes with masses $\gtrsim 10^9\,M_\odot$ have been discovered by JWST at high redshifts ($z\sim 7$). It is difficult to explain such objects as the result of accretive growth of stellar-mass seeds, as the rate at which…
Primordial black hole production in the mass range $10-10^4 \,{\rm M_\odot}$ is motivated respectively by interpretations of the LIGO/Virgo observations of binary black hole mergers and by their ability to seed intermediate black holes…
We explore the clustering properties of high redshift dark matter halos, focusing on halos massive enough to host early generations of stars or galaxies at redshift 10 and greater. Halos are extracted from an array of dark matter…
Quasars powered by massive black holes (BHs) with mass estimates above a billion solar masses have been identified at redshift 6 and beyond. The existence of such BHs requires almost continuous growth at the Eddington limit for their whole…