Related papers: Reconstructing the intergalactic UV background wit…
The estimate of the ionizing UV background through the proximity effect analysis is discussed. Taking into account the correct bending of the column density distribution which appears in high resolution high s/n data, a value of the UV…
By charting the kinematic, chemical, and ionization conditions of galactic and intergalactic gas over the redshift range 0 - 4 with QSO absorption lines, the evolution of chemical abundances, the UV meta-galactic background, and the…
We present a detailed analysis of the ionization and thermal structure of the intergalactic medium (IGM) around a high-redshift QSO using a large suite of cosmological, multi-frequency radiative transfer (RT) simulations, exploring the…
The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the…
Deriving physical parameters from integrated galaxy spectra is paramount to interpret the cosmic evolution of star formation, chemical enrichment, and energetic sources. We develop modeling techniques to characterize the ionized gas…
Recently, NIRSpec PRISM/CLEAR observations by JWST have begun providing rest-frame UV continuum measurements of galaxies at $z\gtrsim7$, revealing signatures of Ly$\alpha$ damping-wing (DW) absorption by the intergalactic medium (IGM). We…
We analyze the absorption and emission-line profiles produced by a set of simple, cool gas wind models motivated by galactic-scale outflow observations. We implement monte carlo radiative transfer techniques that track the propagation of…
We study metal line absorption of CIV, CII, SiIV, and NV at redshifts z=3.5 to z=2 within the framework of a cosmological model for the Lyman alpha forest, comparing the results of numerical simulations to recent observations by Songaila &…
We present a study of NV absorption systems at 1.5 < z < 2.5 in the optical spectra of 19 QSOs. Our analysis includes both absorbers arising from the intergalactic medium as well as systems in the vicinity of the background quasar. We…
We have obtained high resolution (FWHM = 4.4 km/s) Keck spectra of images A and C of the gravitationally lensed QSO Q1422+231. The images are separated by 1.3" on the sky. In an absorption system at z = 3.538 gas column density variations…
We present the first large sample of absorption systems in paired QSOs consisting of 691 absorption systems in the spectra of 310 QSOs including 170 pairings. All these absorption systems have metal lines, usually C IV or Mg II. We see 17…
We present the results of a study of QSO Absorption Line Systems (QSOALSs) with respect to intrinsic QSO properties using an updated catalog of data in the literature. We have searched the literature for 6 and 20 cm radio flux densities and…
We have obtained Keck HIRES spectra of three images of the gravitationally lensed QSO 2237+0305 to study low ionization absorption systems and their differences in terms of projected velocity and column density across the lines of sight. We…
There exists a significant population of broad line, z~2 QSOs which have heavily absorbed X-ray spectra. Follow up observations in the submillimetre show that these QSOs are embedded in ultraluminous starburst galaxies, unlike most…
Using our photoionization code CIRRUS, we show that the study of proximity effect on metal elements provides a possibility of placing constraints on the spectral shape of the metagalactic UV background (MUVB). From theoretical point of…
We have obtained spatially resolved spectra of the z=3.911 triply imaged QSO APM08279+5255 using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). We study the line of sight equivalent width (EW)…
We study the ionization structure of galactic outflows in 37 nearby, star forming galaxies with the Cosmic Origins Spectrograph on the Hubble Space Telescope. We use the O I, Si II, Si III, and Si IV ultraviolet absorption lines to…
We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative transfer code CUBA: (1) the sawtooth…
We present a simple, largely empirical but physically motivated model to interpret the mid- and far-infrared spectral energy distributions of galaxies consistently with the emission at ultraviolet, optical and near-infrared wavelengths. Our…
We estimate the He II to H I column density ratio, \eta = N(He II)/N(H I), in the intergalactic medium towards the high redshift (z_{em} = 2.885) bright quasar QSO HE 2347-4342 using Voigt-profile fitting of the H I transitions in the Lyman…