Rauch, Michael and Haehnelt, Martin and Bunker, Andrew and Becker, George and Marleau, Francine and Graham, James and Cristiani, Stefano and Jarvis, Matt and Lacey, Cedric and Morris, Simon and Peroux, Celine and Röttgering, Huub and Theuns, Tom (2008) A population of faint extended line emitters and the host galaxies of optically thick QSO absorption systems. Astrophysical Journal, 681 (2). pp. 856-880. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090527-085852275
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We have conducted a long-slit search for low surface brightness Lyα emitters at redshift 2.67 < z < 3.75. A 92 hr long exposure with the ESO VLT FORS2 instrument down to a 1σ surface brightness detection limit of 8 × 10^(−20) erg cm^(−2) s^(−1) arcsec^(−2) per arcsec^2 aperture yielded a sample of 27 single line emitters with fluxes of a few × 10^(−18) erg s^(−1) cm^(−2). We present arguments that most objects are indeed Lyα. The large comoving number density, 3 × 10^(−2) h^3_(70) Mpc^(−3), the large covering factor, dN/dz ~ 0.2–1, and the often extended Lyα emission suggest that the emitters can be identified with the elusive host population of damped Lyα systems (DLAS) and high column density Lyman limit systems (LLS). A small inferred star formation rate, perhaps supplemented by cooling radiation, appears to energetically dominate the Lyα emission, and is consistent with the low metallicity, low dust content, and theoretically inferred low masses of DLAS, and with the relative lack of success of earlier searches for their optical counterparts. Some of the line profiles show evidence for radiative transfer in galactic outflows. Stacking surface brightness profiles, we find emission out to at least 4". The centrally concentrated emission of most objects appears to light up the outskirts of the emitters (where LLS arise) down to a column density where the conversion from UV to Lyα photon becomes inefficient. DLAS, high column density LLS, and the emitter population discovered in this survey appear to be different observational manifestations of the same low-mass, protogalactic building blocks of present-day L_* galaxies.
|Additional Information:||© 2008 The American Astronomical Society. Print publication: Issue 2 (2008 July 10). Received 2007 September 6, accepted for publication 2007 November 7. We would like to thank the following people for helpful advice and discussions during the course of this project: James Bolton, Scott Burles, Bob Carswell, Hsiao-Wen Chen, Sandro D’Odorico, Johan Fynbo, Rob Kennicutt, Juna Kollmeier, Rob Simcoe, and Neil Trentham.We thank the Director General of ESO, Catherine Cesarsky, for keeping this project afloat, and we are grateful to the observatory staff at ESO and Gemini for performing the observations, and to the time assignment committees of both observatories. M. R. thanks the IoA for hospitality in spring and summer 2007. G. D. B. and M. R. were supported by the National Science Foundation through grant AST 05-06845. This work was partially supported by the EC RTN network "The Physics of the Intergalactic Medium."|
|Subject Keywords:||diffuse radiation; galaxies: formation; intergalactic medium; quasars: individual ([HGO96] DMS 2139.0-0405)|
|Official Citation:||A Population of Faint Extended Line Emitters and the Host Galaxies of Optically Thick QSO Absorption Systems Michael Rauch, Martin Haehnelt, Andrew Bunker, George Becker, Francine Marleau, James Graham, Stefano Cristiani, Matt Jarvis, Cedric Lacey, Simon Morris, Celine Peroux, Huub Röttgering, and Tom Theuns 2008 ApJ 681 856-880 doi: 10.1086/525846.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||28 Aug 2009 23:28|
|Last Modified:||26 Dec 2012 11:01|
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