相关论文: Constraining First Star Formation with 21cm-Cosmol…
An X-ray background in the early Universe enhances molecular hydrogen formation, the main coolant of primordial gas, thereby lowering the threshold for Pop III star formation. Continuing our series on X-ray impacts on Pop III star…
During Cosmic Dawn, Pop III stars could be formed in minihalos through molecular hydrogen (H$_2$) cooling. The minimum halo mass required for H$_2$ cooling is highly sensitive to Lyman-Werner (LW) radiation, which dissociates H$_2$ and…
The first stars, the chemically pristine Population III, likely played an important role in heating the intergalactic medium during the epoch of cosmic dawn. The very high effective temperatures ($\sim 10^5$ K) predicted for the most…
We describe how star formation is expected to proceed in the early metal-free Universe, focusing on the very first generations of stars. We then discuss how the star formation process may change as the effects of metallicity, external…
Observations with the JWST in lensed fields have revealed that galaxies at cosmic dawn may concentrate their star formation in highly dense, compact, star clusters. The high columns and low metallicities encountered in their birth…
Lyman-$\alpha$ spheres, i.e. regions around the first stars which are illuminated by Lyman-$\alpha$ photons and show 21cm absorption feature against the CMB, are smoking guns at the dawn of the reionization epoch. Though overwhelming radio…
According to the leading cosmological model, a first generation of stars called Population III (PopIII), condensed almost entirely out of hydrogen and helium, must have initiated the creation of all heavier chemical elements. Here we report…
The formation of the first stars in the high-redshift Universe is a sensitive probe of the small-scale, particle physics nature of dark matter (DM). We carry out cosmological simulations of primordial star formation in ultra-light,…
We investigate the impact of the recent observation of the 21cm global signal by EDGES on primordial power spectrum, particularly focusing on the running parameters $\alpha_s$ and $ \beta_s$ which characterize the detailed scale dependence…
In an earlier paper (Cen 2003) we pointed out the strong likelihood for the universal reionization to occur twice, giving rise to a larger Thomson optical depth. Here we perform a more focused analysis of the Thomson optical depth in light…
We calculate cosmic distributions in space and time of the formation sites of the first, "Pop III.1" stars, exploring a model in which these are the progenitors of all supermassive black holes (SMBHs), seen in the centers of most large…
Allowing for enhanced Ly$\alpha$ photon line emission from Population III dominated stellar systems in the first forming galaxies, we show the 21-cm cosmic dawn signal at $10<z<30$ may substantially differ from standard scenarios. Energy…
The EDGES collaboration has reported the detection of a global 21-cm signal with a plateau centered at 76 MHz (i.e., redshift 17.2), with an amplitude of 500^(+200)_(-500) mK. This anomalous measurement does not comport with standard…
The first stars form in dark matter halos of masses ~10^6 M_sun as suggested by an increasing number of numerical simulations. Radiation feedback from these stars expels most of the gas from their shallow potential well of their surrounding…
The first luminous objects forming in the universe produce radiation backgrounds in the FUV and X-ray bands that affect the formation of Population III stars. Using a grid of cosmological hydrodynamics zoom-in simulations, we explore the…
Understanding the formation and evolution of the first stars and galaxies represents one of the most exciting frontiers in astronomy. Since the universe was filled with hydrogen atoms at early times, the most promising probe of the epoch of…
New observations from the Hubble ultra deep field suggest that the star formation rate at z>7 drops off faster than previously thought. Using a newly determined star formation rate for the normal mode of Population II/I stars (PopII/I),…
We simulate a plausible cosmological model in considerable physical and numerical detail through the successive phases of reheating (at 10<z<20), formation of Pop III stars at z=15 (due to molecular hydrogen cooling), with subsequent…
First, the formation of first objects driven by dark matter is revisited by high-resolution hydrodynamic simulations. It is revealed that dark matter haloes of ~10^4M_sun can produce first luminous objects with the aid of dark matter cusps.…
Radiative feedback from massive Population III (Pop III) stars in the form of ionising and photodissociating photons is widely believed to play a central role in shutting off accretion onto these stars. Understanding whether and how this…