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Ionization near zones associated with quasars at z ~ 6

Carilli, C. L. and Wang, Ran and Fan, X. and Walter, F. and Kurk, J. and Riechers, D. and Wagg, J. and Hennawi, J. and Jiang, L. and Menten, K. M. and Bertoldi, F. and Strauss, Michael A. and Cox, P. (2010) Ionization near zones associated with quasars at z ~ 6. Astrophysical Journal, 714 (1). pp. 834-839. ISSN 0004-637X.

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We analyze the size evolution of H II regions around 27 quasars between z = 5.7 and 6.4 ("quasar near zones" or NZs). We include more sources than previous studies, and we use more accurate redshifts for the host galaxies, with eight CO molecular line redshifts and nine Mg II redshifts. We confirm the trend for an increase in NZ size with decreasing redshift, with the luminosity-normalized proper size evolving as R _(NZ,corrected) = (7.4 ± 0.3) – (8.0 ± 1.1) × (z – 6) Mpc. While derivation of the absolute neutral fraction remains difficult with this technique, the evolution of the NZ sizes suggests a decrease in the neutral fraction of intergalactic hydrogen by a factor ~9.4 from z = 6.4 to 5.7, in its simplest interpretation. Alternatively, recent numerical simulations suggest that this rapid increase in NZ size from z = 6.4 to 5.7 is due to the rapid increase in the background photo-ionization rate at the end of the percolation or overlap phase, when the average mean-free path of ionizing photons increases dramatically. In either case, the results are consistent with the idea that z ~ 6-7 corresponds to the tail end of cosmic reionization. The scatter in the normalized NZ sizes is larger than expected simply from measurement errors, and likely reflects intrinsic differences in the quasars or their environments. We find that the NZ sizes increase with quasar UV luminosity, as expected for photo-ionization dominated by quasar radiation.

Item Type:Article
Related URLs:
URLURL TypeDescription
Carilli, C. L.0000-0001-6647-3861
Wang, Ran0000-0003-4956-5742
Fan, X.0000-0003-3310-0131
Walter, F.0000-0003-4793-7880
Riechers, D.0000-0001-9585-1462
Hennawi, J.0000-0002-7054-4332
Jiang, L.0000-0003-4176-6486
Menten, K. M.0000-0001-6459-0669
Bertoldi, F.0000-0002-1707-1775
Strauss, Michael A.0000-0002-0106-7755
Cox, P.0000-0003-2027-8221
Additional Information:© 2010 The American Astronomical Society. Received 2010 January 2; accepted 2010 February 26; published 2010 April 15. The Very Large Array of the National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. C.C. thanks the Max-Planck-Gesellschaft and the Humboldt- Stiftung for support through the Max-Planck-Forschungspreis, and the Max-Planck Institute for Astronomie in Heidelberg for their hospitality. The authors thank J. Bolton, S. Wyithe, C. Willott, and the referee for useful comments. D.R. acknowledges support from NASA through Hubble Fellowship grant HST-HF- 51235.01 awarded by the STScI, operated by AURA for NASA, under contract NAS 5-26555. R.W. acknowledges support of the National Natural Science Foundation of China grant 10833006 and grant 0816341034.
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF-51235.01
NASANAS 5-26555
National Natural Science Foundation of China10833006
National Natural Science Foundation of China0816341034
Subject Keywords:galaxies: formation; galaxies: high-redshift; large-scale structure of universe; quasars: absorption lines
Issue or Number:1
Classification Code:PACS; 98.54.Aj; 98.62.Py; 98.62.Qz; 98.58.Hf; 98.80.Cq
Record Number:CaltechAUTHORS:20100519-151647641
Persistent URL:
Official Citation:C. L. Carilli et al 2010 ApJ 714 834 doi: 10.1088/0004-637X/714/1/834
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18357
Deposited By: Ruth Sustaita
Deposited On:20 May 2010 19:44
Last Modified:03 Oct 2019 01:41

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