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Title: A Glimpse at Quasar Host Galaxy Far-UV Emission, Using Damped Lyα's as Natural Coronagraphs

In merger-driven models of massive galaxy evolution, the luminous quasar phase is expected to be accompanied by vigorous star formation in quasar host galaxies. In this paper, we use high column density damped Lyα (DLA) systems along quasar sight lines as natural coronagraphs to directly study the far-UV (FUV) radiation from the host galaxies of luminous background quasars. Here, we have stacked the spectra of ~2000 DLA systems (N HI > 10 20.6cm –2) with a median absorption redshift $$\langle$$z$$\rangle$$ = 2.6 selected from quasars observed in the SDSS-III Baryon Oscillation Spectroscopic Survey. We detect residual flux in the dark troughs of the composite DLA spectra. The level of this residual flux significantly exceeds systematic errors in the Sloan Digital Sky Survey fiber sky subtraction; furthermore, the residual flux is strongly correlated with the continuum luminosity of the background quasar, while uncorrelated with DLA column density or metallicity. We conclude that the flux could be associated with the average FUV radiation from the background quasar host galaxies (with medium redshift $$\langle$$z$$\rangle$$ = 3.1) that is not blocked by the intervening DLA. Finally, assuming that all of the detected flux originates from quasar hosts, for the highest quasar luminosity bin ($$\langle$$L$$\rangle$$ = 2.5 × 10 13 L ), the host galaxy has an FUV intensity of 1.5 ± 0.2 × 10 40 erg s –1 Å –1; this corresponds to an unobscured UV star formation rate of 9 M yr –1.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [2] ;  [4] ;  [5] ;  [6] ;  [3] ;  [7] ;  [8] ;  [9] ;  [10] ;  [3] ;  [11]
  1. Univ. of Arizona, Tucson, AZ (United States). Steward Observatory; Univ. of Arizona, Tucson, AZ (United States). Steward Observatory
  2. Univ. of Arizona, Tucson, AZ (United States). Steward Observatory
  3. Pierre and Marie Curie Univ., Paris (France). National Scientific Research Center (CNRS), Inst. of Astrophysics
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Australian National Univ., Canberra, ACT (Australia). Research School of Astronomy and Astrophysics
  6. Catalan Inst. for Research and Advanced Studies. Barcelona (Spain); Univ. of Barcelona (Spain). Inst. of Cosmos Sciences
  7. Univ. of Chile, Santiago (Chile). Dept. of Astronomy
  8. Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Inst. for Gravitation and the Cosmos
  9. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics & Astronomy
  10. Univ. of Florida, Gainesville, FL (United States). Dept. of Astronomy
  11. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-112092-2016-JA
Journal ID: ISSN 1538-4357; KA2301020
Grant/Contract Number:
SC00112704; AST 08-06861; AST 11-07682
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 793; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; cosmology observations; galaxies high-redshift; quasars absorption lines; quasars
OSTI Identifier:
1335433

Cai, Zheng, Fan, Xiaohui, Noterdaeme, Pasquier, Wang, Ran, McGreer, Ian, Carithers, Bill, Bian, Fuyan, Miralda-Escudé, Jordi, Finley, Hayley, Pâris, Isabelle, Schneider, Donald P., Zakamska, Nadia L., Ge, Jian, Petitjean, Patrick, and Slosar, Anze. A Glimpse at Quasar Host Galaxy Far-UV Emission, Using Damped Lyα's as Natural Coronagraphs. United States: N. p., Web. doi:10.1088/0004-637X/793/2/139.
Cai, Zheng, Fan, Xiaohui, Noterdaeme, Pasquier, Wang, Ran, McGreer, Ian, Carithers, Bill, Bian, Fuyan, Miralda-Escudé, Jordi, Finley, Hayley, Pâris, Isabelle, Schneider, Donald P., Zakamska, Nadia L., Ge, Jian, Petitjean, Patrick, & Slosar, Anze. A Glimpse at Quasar Host Galaxy Far-UV Emission, Using Damped Lyα's as Natural Coronagraphs. United States. doi:10.1088/0004-637X/793/2/139.
Cai, Zheng, Fan, Xiaohui, Noterdaeme, Pasquier, Wang, Ran, McGreer, Ian, Carithers, Bill, Bian, Fuyan, Miralda-Escudé, Jordi, Finley, Hayley, Pâris, Isabelle, Schneider, Donald P., Zakamska, Nadia L., Ge, Jian, Petitjean, Patrick, and Slosar, Anze. 2014. "A Glimpse at Quasar Host Galaxy Far-UV Emission, Using Damped Lyα's as Natural Coronagraphs". United States. doi:10.1088/0004-637X/793/2/139. https://www.osti.gov/servlets/purl/1335433.
@article{osti_1335433,
title = {A Glimpse at Quasar Host Galaxy Far-UV Emission, Using Damped Lyα's as Natural Coronagraphs},
author = {Cai, Zheng and Fan, Xiaohui and Noterdaeme, Pasquier and Wang, Ran and McGreer, Ian and Carithers, Bill and Bian, Fuyan and Miralda-Escudé, Jordi and Finley, Hayley and Pâris, Isabelle and Schneider, Donald P. and Zakamska, Nadia L. and Ge, Jian and Petitjean, Patrick and Slosar, Anze},
abstractNote = {In merger-driven models of massive galaxy evolution, the luminous quasar phase is expected to be accompanied by vigorous star formation in quasar host galaxies. In this paper, we use high column density damped Lyα (DLA) systems along quasar sight lines as natural coronagraphs to directly study the far-UV (FUV) radiation from the host galaxies of luminous background quasars. Here, we have stacked the spectra of ~2000 DLA systems (NHI > 1020.6cm–2) with a median absorption redshift $\langle$z$\rangle$ = 2.6 selected from quasars observed in the SDSS-III Baryon Oscillation Spectroscopic Survey. We detect residual flux in the dark troughs of the composite DLA spectra. The level of this residual flux significantly exceeds systematic errors in the Sloan Digital Sky Survey fiber sky subtraction; furthermore, the residual flux is strongly correlated with the continuum luminosity of the background quasar, while uncorrelated with DLA column density or metallicity. We conclude that the flux could be associated with the average FUV radiation from the background quasar host galaxies (with medium redshift $\langle$z$\rangle$ = 3.1) that is not blocked by the intervening DLA. Finally, assuming that all of the detected flux originates from quasar hosts, for the highest quasar luminosity bin ($\langle$L$\rangle$ = 2.5 × 1013 L⊙), the host galaxy has an FUV intensity of 1.5 ± 0.2 × 1040 erg s–1 Å–1; this corresponds to an unobscured UV star formation rate of 9 M⊙ yr–1.},
doi = {10.1088/0004-637X/793/2/139},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 793,
place = {United States},
year = {2014},
month = {9}
}