Probing Large Galaxy Halos atZ∼ 0 with Automated Lyα-absorption Matching

Probing Galaxy evolution with Hi 21cm Absorption Spectroscopy

extinction curve of the lensing galaxy of B 1152 + 199 atz = 0 : 44 ?

the date of receipt and acceptance should be inserted later Abstract. We present UBV RIz 0 photometry of the gra-vitational lens candidate CLASS B1152+119 obtained with the Nordic Optical Telescope. The two QSO components are resolved in the B, V , R, I and z 0 bands connrming the lensing nature of the system. The z = 0:44 lens galaxy is clearly detected in B, R, I and z 0 and its position is f...

Probing the thermal history of the Intergalactic Medium with Lyα absorption lines

The Doppler parameter distribution of Lyα absorption is calculated for a set of different reionization histories. The differences in temperature between different reionization histories are as large as a factor three to four depending on the spectrum of the ionizing sources and the redshift of helium reionization. These temperature differences result in observable differences in the Doppler par...

Lyα Absorption around Nearby Galaxies

We have used STIS aboard HST to search for Lyα absorption lines in the outer regions of eight nearby galaxies using background QSOs and AGN as probes. Lyα lines are detected within a few hundred km s−1 of the systemic velocity of the galaxy in all cases. We conclude that a background line of sight which passes within 26 − 200 h−1 kpc of a foreground galaxy is likely to intercept low column dens...

Dark Halos and Galaxy Evolution

We study the evolution of disk galaxies within the frame of the cold dark matter (CDM) cosmologies. The hydrodynamics of a centrifugally supported gaseous disk and the growth of a stellar disk is calculated in detail taking into account the energy balance of the ISM and the gravitational instabilities that concern gas and stars. The halo density profile is derived from the primordial cosmologic...