相关论文: Probing the physical properties of the intergalact…
We present a new investigation of the thermal history of the intergalactic medium (IGM) during and after reionization using the Lyman-$\alpha$ forest flux power spectrum at $4.0\lesssim z\lesssim5.2$. Using a sample of 15 high-resolution…
Observations of high-redshift quasars show that the IGM must have been reionized at some redshift $z>5$. If a source of radiation could be observed at the rest-frame Lya wavelength, at a sufficiently high redshift where some of the IGM in…
Observations of UV metal absorption lines have provided insight into the structure and composition of the circumgalactic medium (CGM) around galaxies. We compare these observations with the low-redshift ($z \leq 0.3$) CGM around dwarf…
The temperature of the low-density intergalactic medium is set by the balance between adiabatic cooling resulting from the expansion of the universe, and photo-heating by the UV-background. A sudden injection of entropy from the…
The temperature of the intergalactic medium (IGM) is set by the competition between photoheating and adiabatic cooling, which are usually assumed to define a tight equation of state in which the temperature increases monotonically with…
Using high redshift radio sources as background, the 21cm forest observations probe the neutral hydrogen absorption signatures of early structures along the lines of sight. Directly sensitive to the spin temperature, it complements the 21cm…
Chandra high-resolution spectra toward eight low-mass Galactic binaries have been analyzed with a photoionization model that is capable of determining the physical state of the interstellar medium. Particular attention is given to the…
In the Halo21 absorption modeling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, and density (Z, T, and nH) of the underlying gas using…
We identify a concordant model for the intergalactic medium (IGM) at redshift z=1.9 that uses popular values for cosmological and astrophysical parameters and accounts for all baryons with an uncertainty of 6%. We have measured the amount…
We characterize the properties of the intergalactic medium (IGM) around a sample of galaxies extracted from state-of-the-art hydrodynamical simulations of structure formation in a cosmological volume of 25 Mpc comoving at $z\sim 2$. The…
The interstellar medium (ISM) in starburst galaxies contains plenty of chemical elements synthesised by core-collapse supernova explosions. By measuring the abundances of these metals, we can study the chemical enrichment within galaxies…
We develop a new method to constrain the physical conditions in the cool (~10^4 K) circumgalactic medium (CGM) from measurements of ionic column densities, by assuming that the cool CGM spans a large range of gas densities and that small…
The distribution of neutral hydrogen in the intergalactic medium (IGM) is currently explored at low-z by means of UV spectroscopy of quasars. We propose an alternative approach based on UV colours of quasars as observed from GALEX surveys.…
Using the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, we measured the abundances of six ions (C III, C IV, Si III, Si IV, N V, O VI) in the low-redshift (z < 0.4) intergalactic medium and explored C and Si ionization…
Standard big bang nucleosynthesis predicts the average baryon density of the Universe to be a few percent of the critical density. Only about one tenth of the predicted baryons have been seen. A plausible respository for the missing baryons…
We have developed a new X-ray absorption model, called {\tt IONeq}, which computes the optical depth $\tau(E)$ simultaneously for ions of all abundant elements, assuming ionization equilibrium and taking into account turbulent broadening.…
The afterglows of gamma-ray bursts (GRBs) have more soft X-ray absorption than expected from the foreground gas column in the Galaxy. While the redshift of the absorption can in general not be constrained from current X-ray observations, it…
We examine the thermal energy contents of the intergalactic medium (IGM) over three orders of magnitude in both mass density and gas temperature using thermal Sunyaev-Zel'dovich effect (tSZE). The analysis is based on {\it Planck} tSZE map…
We present high-resolution spectroscopy of the neon K-shell and iron L-shell interstellar absorption edges in nine X-ray binaries using the High Energy Transmission Grating Spectrometer (HETGS) onboard the Chandra X-ray Observatory. We…
Recent observations suggest that hydrogen reionization ends late ($z \simeq 6$) and proceeds quickly. We present here a new model of the meta-galactic UV/X-ray background (UVB) that is consistent with this. It adopts the most recent…