Related papers: Variable 21cm absorption at z=0.3127

We present a detailed model for the ionized absorbing gas evident in the 900 ksec Chandra HETGS spectrum of NGC 3783. The analysis was carried out with PHASE a new tool designed to model X-ray and UV absorption features in ionized plasmas.…

We present a detailed analysis of the intergalactic metal-line absorption systems in the archival HST/STIS and FUSE ultraviolet spectra of the low-redshift quasar PKS1302-102 (z_QSO = 0.2784). We supplement the archive data with CLOUDY…

Recent high spatial and spectral resolution investigations of the diffuse interstellar medium (ISM) have found significant evidence for small-scale variations in the interstellar gas on scales less than or equal to 1 pc. To better…

We have used the Giant Meterwave Radio Telescope (GMRT) to measure the Galactic HI 21-cm line absorption towards 102 extragalactic radio continuum sources, located at high (|b| >15deg.) Galactic latitudes. The Declination coverage of the…

Analyses of QSO absorption lines are showing that HI content has evolved over the redshift range z=5 to z= 0. The 21cm line measurements of the z=0 HI content avoid several biases inherent in the absorption line technique, such as the…

We report the discovery of two damped Ly-alpha absorption-line systems (DLAs) near redshift z=1 along a single quasar sightline (Q1727+5302) with neutral hydrogen column densities of N(HI) = (1.45\pm0.15)\times10^{21} and…

We report the discovery of variability in the OH megamaser in IRAS 21272+2514 at z=0.15. This is the first OH megamaser (OHM) observed to vary in time. The variation is broadband, spanning 0.5-1.5 MHz or 100-300 km/s in the rest frame, and…

Quasar absorption spectra at 21-cm and UV rest-wavelengths are used to estimate the time variation of x=alpha^2 g_p mu, where alpha is the fine structure constant, g_p the proton g factor, and m_e/m_p=mu the electron/proton mass ratio. Over…

This review summarizes recent studies of the cold neutral hydrogen gas associated with galaxies probed via the HI 21-cm absorption line. HI 21-cm absorption against background radio-loud quasars is a powerful tool to study the neutral gas…

In a continuing survey of active galactic nuclei observed by the Far Ultraviolet Spectroscopic Explorer, we provide a deeper analysis of intrinsic absorption features found in 35 objects. Our survey is for low-redshift and…

We report on the variability of 443 flat spectrum, compact radio sources monitored using the VLA for 3 days in 4 epochs at ~ 4 month intervals at 5 GHz as part of the Micro-Arcsecond Scintillation-Induced Variability (MASIV) survey. Over…

We present the analysis of five O VI absorbers identified across a redshift path of z $\sim (0.6 - 1.3)$ towards the background quasar PG $1522+101$ with information on five consecutive ionization stages of oxygen from O II to O VI. The…

The Westerbork Synthesis Radio Telescope finds a weak 21cm line emission feature at the coordinates (RA-Dec-velocity) of the sub-Damped Lyman-alpha absorber observed at z_abs=0.00632 in the spectrum of PG1216+069. The emission feature,…

In this paper we present an analysis of absorption line variability in mini-BAL quasar LBQS 1206+1052. The SDSS spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of $\sim$700 km…

We present UV to NIR spectroscopic observations of the quasar J0015+1842 and its proximate molecular absorber at z=2.631. The [OIII] emission line of the quasar is composed of a broad (FWHM~1600 km/s), spatially-unresolved component,…

We make use of hydrodynamical simulations of the intergalactic medium (IGM) to create model quasar absorption spectra. We compare these model spectra with the observed Keck spectra of three z>6.2 quasars with full Gunn-Peterson troughs:…

We have studied a spectrum of Q0122+0338 (z = 1.202) obtained by the FOS on board HST. We present the analysis of three associated absorption systems at z = 1.207, 1.199 and 1.166. The most complex of these at z = 1.207 shows strong…

(Abridged) We present the results of a systematic GBT and GMRT survey for 21-cm absorption in a sample of 10 DLAs at 2<z_abs<3.4. Analysis of L-band VLBA images of the background QSOs are also presented. We detect 21-cm absorption in only…

We have used the 610 MHz receivers of the Giant Metrewave Radio Telescope (GMRT) to detect associated HI 21cm absorption from the $z = 1.2230$ blazar TXS1954+513. The GMRT HI 21cm absorption is likely to arise against either the…

In this paper we study 21-cm absorption spectra and the corresponding emission spectra toward bright continuum sources in the test region (326deg< l < 333 deg) of the Southern Galactic Plane Survey. This survey combines the high resolution…