ABSTRACT
We present the methodology for, and the first results from, a new imaging programme aimed at identifying and characterizing the host galaxies of damped Lyman α absorbers (DLAs) at z≳ 2. We target quasar sightlines with multiple optically thick H i absorbers and use the higher redshift system as a ‘blocking filter’ (via its Lyman-limit absorption) to eliminate all far-ultraviolet (FUV) emission from the quasar. This allows us to directly image the rest-frame FUV continuum emission of the lower redshift DLA, without any quasar contamination and with no bias towards large impact parameters. We introduce a formalism based on galaxy number counts and Bayesian statistics with which we quantify the probability that a candidate is the DLA host galaxy. This method will allow the identification of a bona fide sample of DLAs that are too faint to be spectroscopically confirmed. The same formalism can be adopted to the study of other quasar absorption-line systems (e.g. Mg ii absorbers). We have applied this imaging technique to two quasi-stellar object sightlines. For the z∼ 2.69 DLA towards J073149+285449, a galaxy with impact parameter b= 1.54 arcsec = 11.89 h−172 kpc and an implied star formation rate (SFR) of ∼5 h−272 M⊙ yr−1 is identified as the most reliable candidate. In the case of the z∼ 2.92 DLA towards J211444−005533, no likely host is found down to a 3σ SFR limit of 1.4 h−272 M⊙ yr−1. Studying the H i column density as a function of the impact parameter, including six DLAs with known hosts from the literature, we find evidence that the observed H i distribution is more extended than what is generally predicted from numerical simulation.
Description
Directly imaging damped Lyman α galaxies at z > 2 – I. Methodology and first results★ - Fumagalli - 2010 - Monthly Notices of the Royal Astronomical Society - Wiley Online Library
%0 Journal Article
%1 MNR:MNR17113
%A Fumagalli, Michele
%A O'Meara, John M.
%A Prochaska, J. Xavier
%A Kanekar, Nissim
%D 2010
%I Blackwell Publishing Ltd
%J Monthly Notices of the Royal Astronomical Society
%K dla high-z imaging myown
%N 1
%P 362--382
%R 10.1111/j.1365-2966.2010.17113.x
%T Directly imaging damped Lyman α galaxies at z > 2 – I. Methodology and first results★
%U http://dx.doi.org/10.1111/j.1365-2966.2010.17113.x
%V 408
%X ABSTRACT
We present the methodology for, and the first results from, a new imaging programme aimed at identifying and characterizing the host galaxies of damped Lyman α absorbers (DLAs) at z≳ 2. We target quasar sightlines with multiple optically thick H i absorbers and use the higher redshift system as a ‘blocking filter’ (via its Lyman-limit absorption) to eliminate all far-ultraviolet (FUV) emission from the quasar. This allows us to directly image the rest-frame FUV continuum emission of the lower redshift DLA, without any quasar contamination and with no bias towards large impact parameters. We introduce a formalism based on galaxy number counts and Bayesian statistics with which we quantify the probability that a candidate is the DLA host galaxy. This method will allow the identification of a bona fide sample of DLAs that are too faint to be spectroscopically confirmed. The same formalism can be adopted to the study of other quasar absorption-line systems (e.g. Mg ii absorbers). We have applied this imaging technique to two quasi-stellar object sightlines. For the z∼ 2.69 DLA towards J073149+285449, a galaxy with impact parameter b= 1.54 arcsec = 11.89 h−172 kpc and an implied star formation rate (SFR) of ∼5 h−272 M⊙ yr−1 is identified as the most reliable candidate. In the case of the z∼ 2.92 DLA towards J211444−005533, no likely host is found down to a 3σ SFR limit of 1.4 h−272 M⊙ yr−1. Studying the H i column density as a function of the impact parameter, including six DLAs with known hosts from the literature, we find evidence that the observed H i distribution is more extended than what is generally predicted from numerical simulation.
@article{MNR:MNR17113,
abstract = {ABSTRACT
We present the methodology for, and the first results from, a new imaging programme aimed at identifying and characterizing the host galaxies of damped Lyman α absorbers (DLAs) at z≳ 2. We target quasar sightlines with multiple optically thick H i absorbers and use the higher redshift system as a ‘blocking filter’ (via its Lyman-limit absorption) to eliminate all far-ultraviolet (FUV) emission from the quasar. This allows us to directly image the rest-frame FUV continuum emission of the lower redshift DLA, without any quasar contamination and with no bias towards large impact parameters. We introduce a formalism based on galaxy number counts and Bayesian statistics with which we quantify the probability that a candidate is the DLA host galaxy. This method will allow the identification of a bona fide sample of DLAs that are too faint to be spectroscopically confirmed. The same formalism can be adopted to the study of other quasar absorption-line systems (e.g. Mg ii absorbers). We have applied this imaging technique to two quasi-stellar object sightlines. For the z∼ 2.69 DLA towards J073149+285449, a galaxy with impact parameter b= 1.54 arcsec = 11.89 h−172 kpc and an implied star formation rate (SFR) of ∼5 h−272 M⊙ yr−1 is identified as the most reliable candidate. In the case of the z∼ 2.92 DLA towards J211444−005533, no likely host is found down to a 3σ SFR limit of 1.4 h−272 M⊙ yr−1. Studying the H i column density as a function of the impact parameter, including six DLAs with known hosts from the literature, we find evidence that the observed H i distribution is more extended than what is generally predicted from numerical simulation.},
added-at = {2011-02-23T19:48:26.000+0100},
author = {Fumagalli, Michele and O'Meara, John M. and Prochaska, J. Xavier and Kanekar, Nissim},
biburl = {https://www.bibsonomy.org/bibtex/24ff0c487f274e5c6163464b3315654c4/miki},
description = {Directly imaging damped Lyman α galaxies at z > 2 – I. Methodology and first results★ - Fumagalli - 2010 - Monthly Notices of the Royal Astronomical Society - Wiley Online Library},
doi = {10.1111/j.1365-2966.2010.17113.x},
interhash = {22195cf1b3c1e8250eed9312c2e6f0a5},
intrahash = {4ff0c487f274e5c6163464b3315654c4},
issn = {1365-2966},
journal = {Monthly Notices of the Royal Astronomical Society},
keywords = {dla high-z imaging myown},
number = 1,
pages = {362--382},
publisher = {Blackwell Publishing Ltd},
timestamp = {2011-02-23T19:48:26.000+0100},
title = {Directly imaging damped Lyman α galaxies at z > 2 – I. Methodology and first results★},
url = {http://dx.doi.org/10.1111/j.1365-2966.2010.17113.x},
volume = 408,
year = 2010
}