相关论文: Metallicity evolution of direct collapse black hol…

We can be biased against observing massive black holes to merge in the local universe as the bounds on the maximum black hole mass ($M_{BH}^{\rm max}$) depends on the assumptions regarding the metallicity evolution of the star forming gas…

Direct collapse black holes (DCBH) have been proposed as a solution to the challenge of assembling supermassive black holes by $z>6$ to explain the bright quasars observed at this epoch. The formation of a DCBH seed with $\rm…

We use a semi-analytic model, ${\it Delphi}$, that jointly tracks the dark matter and baryonic assembly of high-redshift ($z \simeq 4-20$) galaxies to gain insight on the number density of Direct Collapse Black Hole (DCBH) hosts in three…

Massive $10^{4-5}\rm\ M_{\odot}$ black hole seeds resulting from the \textit{direct} collapse of pristine gas require a metal-free atomic cooling halo with extremely low H$_2$ fraction, allowing the gas to cool isothermally in the presence…

In the last decade, the growth of supermassive black holes (SMBHs) has been intricately linked to galaxy formation and evolution and is a key ingredient in the assembly of galaxies. To investigate the origin of SMBHs, we perform…

The assembly of supermassive black holes poses a challenge primarily because of observed quasars at high redshift, but additionally because of the current lack of observations of intermediate mass black holes. One plausible scenario for…

Massive metal-poor stars might end their life by directly collapsing into massive (~25-80 Msun) black holes (BHs). We derive the number of massive BHs (N_BH) that are expected to form per galaxy via this mechanism. We select a sample of 66…

We study the gas metallicity of quasar hosts using cosmological hydrodynamic simulations of the Lambda-cold dark matter model. Galaxy formation in the simulations is coupled with a prescription for black hole activity enabling us to study…

We present chemical abundance measurements for 47 damped Lyman-alpha systems (DLAs), 30 at z>4, observed with the Echellette Spectrograph and Imager and the High Resolution Echelle Spectrometer on the Keck telescopes. HI column densities of…

The nature of the seeds of high-redshift supermassive black holes (SMBHs) is a key question in cosmology. Direct collapse black holes (DCBH) that form in pristine, atomic-line cooling halos, illuminated by a Lyman-Werner (LW) UV flux…

CR7 is among the most luminous Lyman-$\alpha$ emitters (LAEs) known at $z = 6.6$ and consists of at least three UV components that are surrounded by Lyman-$\alpha$ (Ly$\alpha$) emission. Previous studies have suggested that it may host an…

We present the largest, publicly available, sample of Damped Lyman-$\alpha$ systems (DLAs) along Gamma-ray Bursts (GRB) line of sights in order to investigate the environmental properties of long GRBs in the $z=1.8-6$ redshift range.…

The nature of ultraluminous X-ray sources (ULXs) is still debated. Recent studies show that metal-poor massive stars can collapse into massive stellar black holes (MSBHs), that is black holes with mass > 25 Msun. Such MSBHs are sufficiently…

We demonstrate that failure to properly account for stellar evolution can bias results in determinations of the spatial morphology of Galactic bulge stars, focusing on the question of whether or not the X-shape is more pronounced among the…

The Direct Collapse Black Hole (DCBH) scenario provides a solution for forming the massive black holes powering bright quasars observed in the early Universe. A prerequisite for forming a DCBH is that the formation of (much less massive)…

We study for the first time the environment of massive black hole (BH) seeds (~10^4-5 Msun) formed via the direct collapse of pristine gas clouds in massive haloes (>10^7 Msun) at z>6. Our model is based on the evolution of dark matter…

Recent theoretical investigations have suggested that the formation of the very first stars, forming out of metal-free gas, was fundamentally different from the present-day case. In this paper, we study the effect of metallicity on the…

Direct collapse black holes (DCBHs) are excellent candidates as seeds of supermassive black holes (SMBHs) observed at $z \gsim 6$. The formation of a DCBH requires a strong external radiation field to suppress $\rm H_2$ formation and…

LIGO has detected gravitational waves from massive binary black hole mergers. In order to explain the origin of such massive stellar-mass black holes, extreme metal poor stars including first stars have been invoked. However, black holes do…

It has been proposed that supermassive black holes (SMBHs) are originated from direct-collapse black holes (DCBHs) that are formed at z gtrsim 10 in the primordial gas in the case that H2 cooling is suppressed by strong external radiation.…