Related papers: Recovering the O VII Absorption Distributions from…
2MASS K_S band data of the inner 60 pc of the Galaxy are used to reconstruct the line-of-sight distances of the giant molecular clouds located in this region. Using the 2MASS H band image of the same region, two different populations of…
This paper considers the problem of recovering the permutation of an n-dimensional random vector X observed in Gaussian noise. First, a general expression for the probability of error is derived when a linear decoder (i.e., linear estimator…
Known as the "Missing Baryon Problem", about one-third of baryons in the local universe remain unaccounted for. The missing baryons are thought to reside in the warm-hot intergalactic medium (WHIM) of the cosmic web filaments, which are…
We have calculated the emergent X-ray properties for models of cluster cooling flows including the effects of accumulated cooled material. The opacity of this cooled gas can reduce the overall X-ray luminosity of the cooling flow, and…
A detailed study of the absorbing molecular clouds towards the radio source PKS1413+135, at a redshift z=0.247, is reported. Physical conditions are derived for the molecular gas in the frame work of two models: a homogeneous multicomponent…
We report on the performance of the statistical, X-ray absorption lines identification procedure XLINE-ID. As illustration, it is used to estimate the time averaged gas density $n_H(r)$ of a representative AGN's warm absorber ($T\approx…
We present a method to estimate the total gas column density, dust-to-gas and dust-to-metal ratios of distant galaxies from rest-frame optical spectra. The technique exploits the sensitivity of certain optical lines to changes in depletion…
Quasar absorption lines provide detailed information on the chemical, kinematic, and ionization conditions in galaxies and their environments, and provide a means for studying the evolution of these conditions back to the epoch of the first…
Every quasar (QSO) spectrum contains absorption-line signatures from the interstellar medium, disk-halo interface, and circumgalactic medium (CGM) of the Milky Way (MW). We analyze Hubble Space Telescope/Cosmic Origins Spectrograph (COS)…
Different physical processes in galaxy evolution, such as galaxy mergers that lead to coalescence of dual Active Galactic Nuclei (AGN) and outflows emanating from the narrow line region, can leave their imprint on the optical spectra of AGN…
Galactic and extra-galactic sources produce X-rays that are often absorbed by molecules and atoms in giant molecular clouds (GMCs), which provides valuable information about their composition and physical state. We mimic this phenomenon…
There is a growing consensus that in the present universe most baryons reside in galaxy clusters and groups in the form of highly ionized gas at temperatures of 10^6 ~ 10^8 K. The H-like and He-like ions of the heavy elements can produce…
Line intensity mapping is emerging as a novel method that can measure the collective intensity fluctuations of atomic/molecular line emission from distant galaxies. Several observational programs with various wavelengths are ongoing and…
We present results of an ongoing program to study the gaseous extent of galaxies and the origin of QSO absorption line systems. For \lya absorption systems, we find that absorption equivalent width depends strongly on galaxy impact…
We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the {\it Chandra} High Energy Transmission Grating Spectrometer and the {\it XMM-Newton}…
Determining accurate redshift distributions for very large samples of objects has become increasingly important in cosmology. We investigate the impact of extending cross-correlation based redshift distribution recovery methods to include…
Many of the baryons associated with a galaxy reside in its circumgalactic medium (CGM), in a diffuse volume-filling phase at roughly the virial temperature. Much of the oxygen produced over cosmic time by the galaxy's stars also ends up…
A sample of 59 sight lines to reddened Galactic OB stars was examined for correlations of the strength of the CO Fourth Positive (A - X) absorption band system with the ultraviolet interstellar extinction curve parameters. We used archival…
The neutral intergalactic medium above redshift 6 is opaque to ionizing radiation, therefore one needs indirect measurements of the escape fraction of ionizing photons from galaxies of this epoch. Low-ionization state absorption lines are a…
(Abridged) Weak gravitational lensing is an ideal probe of the dark universe. In recent years, several linear methods have been developed to reconstruct the density distribution in the Universe in three dimensions, making use of photometric…