Related papers: Gaseous Galactic Halos and QSO Absorption Line Sys…
Neutral hydrogen traces gravitational potentials. In the nearby universe, 21cm emission-line surveys show that the bulk of the HI resides in well-formed, optically-luminous galaxies. At high redshift, 21cm line absorption against background…
Molecules dominate the cooling function of neutral metal-poor gas at high density. Observation of molecules at high redshift is thus an important tool toward understanding the physical conditions prevailing in collapsing gas. Up to now,…
The Hubble Deep Field images have provided us with a unique chance to relate statistical properties of high-redshift galaxies to statistical properties of \lya absorption systems. Combining an {\em empirical} measure of the galaxy surface…
HIRES/Keck spectra of Mg II (2796) absorption arising in the "halos" of 15 identified 0.4 < z < 0.9 galaxies are presented. Comparison of the galaxy and absorbing gas properties reveal that the spatial distribution of galactic/halo gas does…
We review knowledge of galaxy structures obtained by their emitted light and in the local universe where they can be studied in great detail. We discuss the shapes of, and stellar motions within, galaxies, compositional clues derived from…
Absorption-selected galaxies offer an effective way to study low-mass galaxies at high redshift. However, the physical properties of the underlying galaxy population remains uncertain. In particular, the multiphase circum-galactic medium is…
A new method, based on simulated annealing technique and aimed at the inverse problem in the analysis of intergalactic or interstellar complex spectra of hydrogen and metal lines, is outlined. We consider the process of line formation in…
Magnitude-limited galaxy redshift surveys are now providing large samples of galaxies to beyond z=2, while color-selected and emission-line-selected samples are finding galaxies to z=4.7. A broad picture is emerging of galaxy formation…
In chemodynamical evolution models it is usually assumed that the Milky Way galaxy forms from the inside-out implying that gas inflows onto the disk decrease with galactocentric distance. Similarly, to reproduce differences between chemical…
When and how did galaxies form and their metals accumulate? Over the last decade, this has moved from an archeological question to a live investigation: there is now a broad picture of the evolution of galaxies in dark matter halos: their…
Absorption-line spectroscopy of 23 background QSOs and numerous background galaxies has let us measure the spatial distribution of metals and neutral hydrogen around 1044 UV-selected galaxies at redshifts 1.8<z<3.3. The typical galaxy is…
Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm…
Evidence for the existence of low energy cosmic rays in the Galaxy comes from the COMPTEL observations of gamma ray line emission from Orion, and also from light element abundance data which seem to suggest a low energy rather than a…
We present an analysis of structural features of all known galaxies with optical polar rings. We find a clear dichotomy for objects of this peculiar class. Bulge-dominated S0 galaxies possess only short narrow rings, while disk-dominated…
We present the results of a survey of galaxies selected by their gas cross-section which give rise to MgII absorption lines in the spectra of background quasars. The sample comprises 11 galaxies covering the redshift range 0.7 < z < 1.2,…
Recent morphological studies of QSO host galaxies by the Hubble Space Telescope (HST) have revealed that a sizable fraction of QSO host galaxies possess close small companion galaxies. It is however not clear why and how these companion…
We study the physical conditions of the circum-galactic medium (CGM) around z=0.25 galaxies as traced by HI and metal line absorption, using cosmological hydrodynamic simulations that include galactic outflows. Using lines of sight targeted…
Motivated by recent observation of Lanzetta et al. that most luminous galaxies at low redshifts produce $\lya$ absorption at impact parameter $l\lsim 160 \kpch$, we propose that these absorbers are clouds confined by the pressure of ambient…
We explore the multiphase structure of the circumgalactic medium (CGM) probed by synthetic spectra through a cosmological zoom-in galaxy formation simulation. We employ a Bayesian method for modelling a combination of absorption lines to…
We present a new model for the formation of stellar halos in dwarf galaxies. We demonstrate that the stars and star clusters that form naturally in the inner regions of dwarfs are expected to migrate from the gas rich, star forming centre…