相关论文: The First Miniquasar
Winds from pregalactic starbursts and 'miniquasars' may pollute the IGM with metals and raise its temperature to a high adiabat, and so inhibit the formation of early galaxies. We compute the thermal history of the IGM when it experiences a…
We present high-resolution simulations of the first star-forming clouds in 15 minihalos with masses ranging from $\sim 10^5$ to $10^7\ \text{M}_{\odot}$ at redshifts $z \sim 17-20$, using the GIZMO code. Our simulations incorporate detailed…
The density distribution of the inter-galactic medium is an uncertain but highly important issue in the study of cosmic reionization. It is expected that there are abundant gas clouds hosted by low-mass "minihalos" in the early universe,…
We use three dimensional hydrodynamic simulations to investigate the effects of a soft X-ray background, that could have been produced by an early generation of mini-quasars, on the subsequent cooling and collapse of high redshift…
In two previous papers, we presented simulations of the first galaxies in a representative volume of the Universe. The simulations are unique because we model feedback-regulated galaxy formation, using time-dependent,…
We employ cosmological hydrodynamical simulations to investigate the effects of AGN feedback on the formation of massive galaxies with present-day stellar masses of $M_{stel} = 8.8 \times 10^{10} - 6.0 \times 10^{11} M_{sun}$. Using…
We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a LCDM universe especially selected to contain a rich cluster by the present day. The…
We consider cosmological implications of the formation of first stellar size black holes (BHs) in the universe. Such BHs form and grow by accretion in minihaloes of masses $\simeq 10^5-10^7~M_\odot$, and emit non-thermal radiation which…
We summarize cm through submm observations of the host galaxies of z ~ 6 quasars. These observations reveal the cool molecular gas (the fuel for star formation), the warm dust (heated by star formation), the fine structure line emission…
We calculate X-ray properties of present-day galaxy clusters from hydrodynamical cosmological simulations of the LCDM cosmology and compare these with recent X-ray observations. Results from three simulations are presented, each of which…
We examine the temperature structure of the intergalactic medium IGM) surounding a hard radiation source, such as a Quasi-Stellar Object (QSO), as it responds to the onset of helium reionization by the source. We model the reionization…
Using a large set of high resolution numerical simulations incorporating non-equilibrium molecular hydrogen chemistry and a constant source of external radiation, we study gas collapse in previously photo-ionized mini-galaxies with virial…
The knowledge of the X-ray properties of the hot gas halos of early-type galaxies has significantly advanced in the past years, for large and homogeneously investigated samples. We compare these results with the X-ray properties of an…
We use a set of Monte Carlo simulations to follow the cascade produced by a primary electron of energy E_in in the intergalactic medium. We choose E_in=3-10 keV as expected from the decay of one of the most popular Warm Dark Matter (WDM)…
A one dimensional radiative transfer code is developed to track the ionization and heating pattern around the first miniquasars and Population III stars. The code follows the evolution of the ionization of the species of hydrogen and helium…
(abridged) We use a one-dimensional hydrodynamical code to investigate the effects of preheating on gas accretion and cooling in cold dark matter halos. In the absence of radiative cooling, preheating reduces the amount of gas that can be…
Using a reliably measured intrinsic (i.e. corrected for absorption effects) present-day luminosity function of high-mass X-ray binaries (HMXBs) in the 0.25-2 keV energy band per unit star-formation rate, we estimate the preheating of the…
Population III stars are the first stars in the Universe to form at z=20-30 out of a pure hydrogen and helium gas in minihalos of 10^5-10^6 M$_\odot$ . Cooling and fragmentation is thus regulated via molecular hydrogen. At densities above…
We explore the impact of a cosmic ray (CR) background generated by supernova explosions from the first stars on star-forming metal-free gas in a minihalo at $z\sim25$. Starting from cosmological initial conditions, we use the smoothed…
We consider the physical conditions under which supermassive black holes could have formed inside the first galaxies. Our SPH simulations indicate that metal-free galaxies with a virial temperature ~10^4 K and with suppressed H2 formation…