相关论文: Temperature and Kinematics of CIV Absorption Syste…

(Abridged) We present HIRES/Keck spectra having resolution 6 km/s of Mg II 2796 absorption profiles which arise in the gas associated with 15 identified galaxies over the redshift range 0.5 < z < 0.9. Using non-parametric rank correlation…

We use the millennium Arecibo 21 cm absorption-line survey measurements to examine the issue of the non-thermal contribution to the observed Galactic HI line widths. If we assume a simple, constant pressure model for the HI in the Galaxy,…

Recent {\it ASCA} observations confirm the presence of X-ray absorption due to partially ionized gas in many Seyfert 1 galaxies; the so-called warm absorber. Constraints on the location of the warm material are presented with the conclusion…

We present a 21-cm emission-absorption study towards extragalactic sources in the Canadian Galactic Plane Survey (CGPS). We have analyzed HI spectra towards 437 sources with S > 150 mJy, giving us a source density of 0.6 sources per square…

We investigate the properties of the circumgalactic gas in the halo of quasar host galaxies from CIV absorption line systems. Optical spectroscopy of closely aligned pairs of quasars (projected distance \leq 200 kpc) obtained at the Gran…

We present a detailed analysis of three metal absorption systems observed in the spectrum of the HDF-South quasar J2233-606 (z_em = 2.238), taking advantage of new VLT-UVES high resolution data (R=45000, S/N = 40-60, \lambda\lambda…

We investigate large-scale gas kinematics in the multiphase circumgalactic medium (CGM) using the observed correlation between line width (Doppler $b$ parameter) and column density ($N$) for H I and O VI absorbers. Leveraging extensive…

Using new HST/FOS, NTT/EMMI, and Keck/HIRES spectra of the gravitationally-lensed double QSO HE 1104-1805 AB (z=2.31, \theta=3.2), and assuming UV photoionization by a metagalactic radiation field, we derive physical conditions (ionization…

We report on a survey for narrow (FWHM < 600 km/s) CIV absorption lines in a sample of bright quasars at redshifts $1.8 \le z < 2.25$ in the Sloan Digital Sky Survey. Our main goal is to understand the relationship of narrow CIV absorbers…

High resolution ultraviolet spectra with HST-GHRS of two stars in the direction of the supergiant shell LMC4 unambiguously show absorption by substantial quantities of CIV gas at velocities near the the systemic velocity of the LMC. In…

To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium (CGM), we have conducted a blind survey for C IV absorption systems in 89 QSO…

We present the detection of CII and CII* absorption in the z = 3.0543 damped Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine structure excitation temperature between 19.6 and 21.6 K. The upper value sets a…

The temperature dependence of dark conductivity at low temperatures (300-15 K) was studied on a wide microstructural range of well-characterized highly crystallized single phase undoped microcrystalline silicon samples. Our study reveals…

We study HI and metal-line absorption around $z\approx2$ star-forming galaxies by comparing an analysis of data from the Keck Baryonic Structure Survey to mock spectra generated from the EAGLE cosmological, hydrodynamical simulations. We…

We explore theoretical models of the ionization ratios of the Li-like absorbers NV, OVI, and CIV, in the Galactic halo. These ions are believed to form in nonequilibrium processes such as shocks, evaporative interfaces, or rapidly cooling…

We continue our series of papers on intergalactic medium (IGM) tracers using quasi-stellar objects (QSOs), having examined gamma-ray bursts (GRBs) and blazars in earlier studies. We have estimated the IGM properties of hydrogen column…

A consensus is developing on the nature of various populations of absorbers at different redshift regimes and in particular on their relationships to galaxies at those epochs. As one example we discuss the population of z < 1 MgII…

We searched for 21-cm absorption associated with the z_abs = 1.3647 absorption system toward PKS 0237-233 using the GMRT. A high quality UVES spectrum shows that C I and C I* are detected at this redshift together with C II*, Mg I, Mg II,…

We present the results from our search for C IV in the intergalactic medium at redshifts z=5.3-6.0. We have observed four z~6 QSOs with Keck/NIRSPEC in echelle mode. The data are the most sensitive yet taken to search for C IV at these…

We discuss physical conditions in Galactic neutral hydrogen based on deep, high velocity resolution interferometric HI 21 cm absorption spectroscopy towards 33 compact extra-galactic radio sources. The HI 21 cm optical depth spectra have…