IONIZATION NEAR ZONES ASSOCIATED WITH QUASARS AT z {approx} 6

Journal Article · Sat May 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/1/834· OSTI ID:21448860

Carilli, C L; Ran, Wang ^[1]; Fan, X; Jiang, L ^[2]; Walter, F; Kurk, J; Hennawi, J ^[3]; Riechers, D ^[4]; Wagg, J ^[5]; Menten, K M ^[6]; Bertoldi, F ^[7]; Strauss, Michael A ^[8]; Cox, P ^[9]

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1. National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States)
2. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
3. Max-Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg (Germany)
4. Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
5. ESO-ALMA, Alonso de Cordova 3107 Vitacura Casilla 19001, Santiago 19 (Chile)
6. Max-Planck Institute for Radio Astronomy, Auf dem Huegel 49, Bonn (Germany)
7. Argelander Institute for Astronomy, University of Bonn, Auf dem Huegel 71, 53121 Bonn (Germany)
8. Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)
9. Institut de Radioastronomie Millimetrique, 300 rue de la Piscine, 38406 Saint Martin d'Heres (France)

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{sub NZ,corrected} = (7.4 {+-} 0.3) - (8.0 {+-} 1.1) x (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 {approx}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 {approx} 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.

• OSTI ID: 21448860
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 714; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
BOSONS
COMPUTERIZED SIMULATION
COSMIC RADIO SOURCES
ELEMENTARY PARTICLES
ELEMENTS
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
HYDROGEN
IONIZATION
LUMINOSITY
MASSLESS PARTICLES
MEAN FREE PATH
NONMETALS
OPTICAL PROPERTIES
PHOTONS
PHYSICAL PROPERTIES
QUASARS
RED SHIFT
SIMULATION
SORPTION
UNIVERSE