Uncovering strong MgII absorbing galaxies

Christensen, L.; Noterdaeme, P.; Petitjean, P.; Ledoux, C.; Fynbo, J. P. U.

doi:10.1051/0004-6361/200912015

Cited by 21 publications

(25 citation statements)

References 84 publications

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“…These findings have been confirmed by Gauthier, Chen & Tinker (2009) and Lundgren et al (2009). Christensen et al (2009) and O'Meara, Chen & Kaplan (2006) have attempted to measure UV continuum emission from the host galaxies of high‐redshift ( z ∼ 2) Mg ii systems found along the line of sight to QSOs whose spectra demonstrate intervening Lyman limit systems at z > 3.4. At lower redshifts ( z < 1.0), Zibetti et al (2005, 2007) have considered image stacking as a way to investigate the photometric properties of Mg ii system host galaxies.…”

Section: Introductionmentioning

confidence: 79%

Mg ii absorption systems and their neighbouring galaxies from a background-subtraction technique

Caler

Sheth

Jain

2010

Monthly Notices of the Royal Astronomical Society

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We estimate the absolute magnitude distribution and luminosity function of galaxies which lie within a few hundred kiloparsecs of Mg ii absorption systems. The absorption systems themselves lie along 1880 lines of sight to Sloan Digital Sky Survey (SDSS) Data Release 3 quasi‐stellar objects (QSOs), have rest equivalent widths greater than 0.8 Å and redshifts that range from 0.37 ≤z≤ 0.82. Our measurement is based on all galaxies identified by the SDSS photometric pipeline which lie within a projected comoving distance of about 1 h−1 Mpc of each QSO demonstrating absorption. The redshifts of these projected neighbours are not available, so we use a background‐subtraction technique to estimate the absolute magnitude distribution and luminosity function of true neighbours. Our method exploits the fact that although we do not know the redshifts of the neighbours, we do know the redshift of the absorbers. The luminosity function of Mg ii neighbours isolated by our method is well approximated by that of earlier type galaxies (Es‐Sa's) at these redshifts. However, we note that the SDSS magnitude limit of r∼ 22 means that we are not sensitive to lower luminosities L < 0.56L* where later types dominate; thus, we do not readily detect the later type neighbours of these Mg ii systems. The number of neighbours we find between 20 and 100 h−1 kpc is only about 20 per cent of the number of absorbers in our sample. Accounting for absorbers within 20 h−1 kpc will increase this number slightly, indicating that at least 70–75 per cent of the absorber host galaxies are fainter than 0.56L*; they may well be of a later type. We carry out simulations which indicate that the actual fraction of absorber host galaxies which were too faint for our survey may be even higher. When the sample is divided into half on the basis of rest‐frame equivalent width (at REW = 1.28 Å), we find that weaker systems have, within 0.02 –1 h−1 Mpc, 1.5 times as many neighbours as do stronger systems and that these neighbours tend to be more luminous than the neighbours of stronger systems. However, on scales smaller than 50 h−1 kpc it is the stronger systems that have more neighbours; this suggests that stronger systems tend to be closer to their host galaxy's centre than weaker systems. We provide an analytic description of the method which helps build intuition and show that it is generally applicable to any data set in which redshifts are only available for only a small sub‐sample of objects. Hence, we expect it to aid in the analysis of galaxy near‐environments based on photometric redshift data sets. In this respect, if Mg ii systems are not in particularly unusual environments, then our analysis represents a determination of the bright end of the z∼ 0.7 galaxy luminosity function from SDSS data alone.

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Section: Introductionmentioning

confidence: 79%

Mg ii absorption systems and their neighbouring galaxies from a background-subtraction technique

Caler

Sheth

Jain

2010

Monthly Notices of the Royal Astronomical Society

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“…Bunker et al 1999;Kulkarni et al 2000Kulkarni et al , 2006Lowenthal et al 1995;Christensen et al 2009, as well as several unpublished works) with few cases being spectroscopically confirmed by the detection of Ly-α emission (Møller et al 2002(Møller et al , 2004. Thankfully, improved selection strategies have emerged from the understanding that correlations between metallicity, mass, and luminosity observed for field galaxies also apply to DLA galaxies (Møller et al 2004;Ledoux et al 2006;Fynbo et al 2008), which has led to several new detections (Fynbo et al 2010(Fynbo et al , 2011Krogager et al, in prep.…”

Section: Introductionmentioning

confidence: 92%

Discovery of a compact gas-rich damped Lyman-αgalaxy atz = 2.2: evidence of a starburst-driven outflow

Noterdaeme

Laursen

Petitjean

et al. 2012

A&A

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144

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We present the detection of Ly α, [O iii], and H α emission associated with an extremely strong damped Lyman-α (DLA) system (N(H i) = 10 22.10 cm −2 ) at z = 2.207 towards the quasar SDSS J113520.39−001053.56. This is the largest H i column density ever measured along a quasi-stellar object (QSO) line of sight, though typical of those often found in DLAs associated to gamma-ray bursts (GRBs). This absorption system can also be classified as an ultra-strong Mg ii system with W λ2796 , and is unresolved. From the H α line, we measure a significant star formation rate (SFR) ≈ 25 M yr −1 (uncorrected for dust). The shape of the Ly α line is double-peaked, which is the signature of a resonant scattering of Ly α photons, and the Ly α emission is spatially extended. More strikingly, the blue and red Ly α peaks arise from distinct regions extended over a few kpc on either side of the star-forming region. We propose that this is the consequence of a Ly α transfer in outflowing gas. The presence of starburst-driven outflows is also in agreement with the high SFR together with the small size and low mass of the galaxy (M vir ∼ 10 10 M ). By placing constraints on the stellar UV continuum luminosity of the galaxy, we estimate an age of at most a few 10 7 yr, again consistent with a recent starburst scenario. We interpret these data as the observation of a young, gas-rich, compact starburst galaxy, from which material is expelled through collimated winds powered by the vigorous star formation activity. We substantiate this picture by modelling the radiative transfer of Ly α photons in the galactic counterpart. Though our model (a spherical galaxy with bipolar outflowing jets) is a simplistic representation of the true gas distribution and velocity field, the agreement between the observed and simulated properties is particularly good (spectral shape and width of the Lyman-α emission, spatial configuration, escape fraction as well as absorption kinematics, H i column density, and dust reddening). Finally, we propose that selecting DLAs with very high H i column densities may be an efficient way of detecting star-forming galaxies at small impact parameters from the background QSO lines of sight.

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“…This way the higher redshift absorber effectively serves as a 'blocking filter' which removes the quasar light and allows the emission from the DLA to be observed free of quasar contamination (see O'Meara et al 2006;Christensen et al 2009;Fumagalli et al 2010). Fumagalli et al find a very low in situ star formation rate, i.e., only star formation right at the absorber location is considered.…”

Section: Direct Imaging Below the Lyman Limitmentioning

confidence: 99%

Consensus report on 25 yr of searches for damped Ly α galaxies in emission: confirming their metallicity–luminosity relation at z ≳ 2

Krogager

Møller

Fynbo

et al. 2017

Monthly Notices of the Royal Astronomical Society

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154

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Starting from a summary of detection statistics of our recent X-shooter campaign, we review the major surveys, both space and ground based, for emission counterparts of high-redshift damped Lyα absorbers (DLAs) carried out since the first detection 25 years ago. We show that the detection rates of all surveys are precisely reproduced by a simple model in which the metallicity and luminosity of the galaxy associated to the DLA follow a relation of the form,3 ) − 20.8, and the DLA cross-section follows a relation of the form σ DLA ∝ L 0.8 . Specifically, our spectroscopic campaign consists of 11 DLAs preselected based on their equivalent width of Si II λ1526 to have a metallicity higher than [Si/H] > −1. The targets have been observed with the X-shooter spectrograph at the Very Large Telescope to search for emission lines around the quasars. We observe a high detection rate of 64% (7/11), significantly higher than the typical ∼10% for random, H I-selected DLA samples. We use the aforementioned model, to simulate the results of our survey together with a range of previous surveys: spectral stacking, direct imaging (using the 'double DLA' technique), long-slit spectroscopy, and integral field spectroscopy. Based on our model results, we are able to reconcile all results. Some tension is observed between model and data when looking at predictions of Lyα emission for individual targets. However, the object to object variations are most likely a result of the significant scatter in the underlying scaling relations as well as uncertainties in the amount of dust which affects the emission.

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Uncovering strong MgII absorbing galaxies

Cited by 21 publications

References 84 publications

Mg ii absorption systems and their neighbouring galaxies from a background-subtraction technique

Mg ii absorption systems and their neighbouring galaxies from a background-subtraction technique

Discovery of a compact gas-rich damped Lyman-αgalaxy atz = 2.2: evidence of a starburst-driven outflow

Consensus report on 25 yr of searches for damped Ly α galaxies in emission: confirming their metallicity–luminosity relation at z ≳ 2

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