Related papers: Dusty MgII Absorbers: Implications for the GRB/Qua…
The number of strong (equivalent width > 1A) MgII absorbers observed towards Gamma-ray bursts (GRBs) has been found to be statistically larger than the number of strong absorbers towards quasi-stellar objects (QSOs). We formalize this "MgII…
We examine the recent report by Prochter et al. (2006) that gamma-ray burst (GRB) sight lines have a much higher incidence of strong MgII absorption than quasar sight lines. We propose that the discrepancy is due to the different beam sizes…
Using a sample of almost 7000 strong MgII absorbers with 0.4 < z < 2.2 detected in the SDSS DR4 dataset, we investigate the gravitational lensing and dust extinction effects they induce on background quasars. After carefully quantifying…
The incidence of strong MgII systems in gamma-ray burst (GRB) spectra is a few times higher than in quasar (QSO) spectra. We investigate several possible explanations for this effect, including: dust obscuration bias, clustering of the…
We report on a survey for strong (rest equivalent width W_r >= 1A), intervening MgII systems along the sightlines to long-duration gamma-ray bursts (GRBs). The GRB spectra which comprise the survey have a heterogeneous mix of resolution and…
Context: A significantly higher incidence of strong (rest equivalent width W_r > 1 {\AA}) intervening Mg II absorption is observed along gamma-ray burst (GRB) sight-lines relative to those of quasar sight-lines. A geometrical explanation…
Sixty percent of gamma-ray bursts (GRBs) reveal strong MgII absorbing systems, which is a factor of ~2 times the rate seen along lines-of-sight to quasars. The discrepancy in the covering factor is most likely to be the result of either…
We analyse the properties of MgII absorption systems detected along the sightlines toward GRBs using a sample of 10 GRB afterglow spectra obtained with VLT-UVES over the past six years. The S/N ratio is sufficiently high that we can extend…
Previous studies have shown that the incidence rate of intervening strong MgII absorbers towards GRBs were a factor of 2 - 4 higher than towards quasars. Exploring the similar sized and uniformly selected legacy data sets XQ-100 and XSGRB,…
We present a new determination of the dust content and near-ultraviolet/optical extinction curves associated with a sample of ~8300 strong (equivalent width > 1A) Mg II absorbers, with redshifts 0.4<z<2.2, identified in Sloan Digital Sky…
Prochter et al. 2006 recently found that the number density of strong intervening 0.5<z<2 MgII absorbers detected in gamma-ray burst (GRB) afterglow spectra is nearly 4 times larger than in QSO spectra. We have conducted a similar study…
Recent observations suggest the incidence of strong intervening MgII absorption systems along the line-of-sight to gamma ray burst (GRB) afterglows is significantly higher than expected from analogous quasar sightlines. One possible…
MgII absorbers induce reddening on background quasars. We measure this effect and infer the cosmic density of dust residing in these systems to be \Omega\ ~ 2e-6, in units of the critical density of the Universe, which is comparable to the…
It is widely believed that the cool gas clouds traced by MgII absorption, within a velocity offset of 5000 km/s relative to the background quasar are mostly associated with the quasar itself, whereas the absorbers seen at larger velocity…
The goal of the Complete Optical and Radio Absorption Line System (CORALS) survey is to quantify the potential impact on QSO absorber statistics from dust in intervening galaxies. Dust may introduce a selection bias in surveys which are…
In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sightlines to gamma-ray bursts (GRBs) relative to the in- cidence of such absorption along quasar sightlines.…
We estimate the mean dust-to-gas ratio of MgII absorbers as a function of rest equivalent width W_0 and redshift over the range 0.5<z<1.4. Using the expanded SDSS/HST sample of low-redshift Lyman-alpha absorbers we first show the existence…
We have identified 469 MgII doublet systems having W_r >= 0.02 {\AA} in 252 Keck/HIRES and UVES/VLT quasar spectra over the redshift range 0.1 < z < 2.6. Using the largest sample yet of 188 weak MgII systems (0.02 {\AA} <= W_r < 0.3 {\AA}),…
The startling discovery of Prochter et al. (2006) that the frequency of very strong (W_r(2796)>1 A) MgII absorbers along gamma-ray burst (GRB) lines of sight ([dN/dz]_{GRB} = 0.90) is more than three times the frequency along quasar lines…
GRB afterglows offer a probe of the intergalactic medium out to high redshift which complements observations along more abundant quasar lines-of-sight. Although both quasars and GRB afterglows should provide a-priori random sight-lines…