THE GREAT OBSERVATORIES ORIGINS DEEP SURVEY: CONSTRAINTS ON THE LYMAN CONTINUUM ESCAPE FRACTION DISTRIBUTION OF LYMAN-BREAK GALAXIES AT 3.4 < z < 4.5

Journal Article · Fri Dec 10 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/1/1011· OSTI ID:21474380

Vanzella, E; Nonino, M; Fontanot, F; Cristiani, S; Tozzi, P ^[1]; Giavalisco, M ^[2]; Inoue, A K ^[3]; Grazian, A; Giallongo, E; Boutsia, K; Fontana, A; Pentericci, L ^[4]; Dickinson, M ^[5]; Stern, D ^[6]; Ferguson, H ^[7]; Spinrad, H ^[8]; Rosati, P ^[9]

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1. INAF-Trieste Astronomical Observatory, via G.B. Tiepolo 11, 40131 Trieste (Italy)
2. Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
3. College of General Education, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka 574-8530 (Japan)
4. INAF-Rome Astronomical Observatory, Via Frascati 33, I-00040 Monteporzio, Roma (Italy)
5. NOAO, P.O. Box 26732, Tucson, AZ 85726 (United States)
6. Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 169-527, Pasadena, CA 91109 (United States)
7. STScI, 3700 San Martin Dr., Baltimore, MD 21218 (United States)
8. Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
9. ESO, Karl Schwarzschild Strasse 2, 85748, Garching (Germany)

We use ultra-deep ultraviolet VLT/VIMOS intermediate-band and VLT/FORS1 narrowband imaging in the GOODS Southern field to derive limits on the distribution of the escape fraction (f{sub esc}) of ionizing radiation for L {>=} L*{sub z=3} Lyman-break galaxies (LBGs) at redshift 3.4-4.5. Only one LBG, at redshift z = 3.795, is detected in its Lyman continuum (LyC; S/N {approx_equal} 5.5), the highest redshift galaxy currently known with a direct detection. Its ultraviolet morphology is quite compact (R{sub eff} = 0.8 kpc physical). Three out of seven active galactic nuclei are also detected in their LyC, including one at redshift z = 3.951 and z{sub 850} = 26.1. From stacked data (LBGs), we set an upper limit to the average f{sub esc} in the range 5%-20%, depending on how the data are selected (e.g., by magnitude and/or redshift). We undertake extensive Monte Carlo simulations that take into account intergalactic attenuation, stellar population synthesis models, dust extinction, and photometric noise in order to explore the moments of the distribution of the escaping radiation. Various distributions (exponential, log-normal, and Gaussian) are explored. We find that the median f{sub esc} is lower than {approx_equal}6% with an 84% percentile limit not larger than 20%. If this result remains valid for fainter LBGs down to current observational limits, then the LBG population might be not sufficient to account for the entire photoionization budget at the redshifts considered here, with the exact details dependent upon the assumed ionizing background and QSO contribution thereto. It is possible that f{sub esc} depends on the UV luminosity of the galaxies, with fainter galaxies having higher f{sub esc}, and estimates of f{sub esc} from a sample of faint LBGs from HUDF (i{sub 775} {<=}28.5) are in broad quantitative agreement with such a scenario.

• OSTI ID: 21474380
• Journal Information: Astrophysical Journal, Vol. 725, Issue 1; Other Information: DOI: 10.1088/0004-637X/725/1/1011; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COMPUTERIZED SIMULATION
DUSTS
GALACTIC EVOLUTION
GALAXIES
GALAXY NUCLEI
IONIZING RADIATIONS
LUMINOSITY
LYMAN LINES
MONTE CARLO METHOD
PHOTOIONIZATION
RED SHIFT
ULTRAVIOLET RADIATION
CALCULATION METHODS
ELECTROMAGNETIC RADIATION
EVOLUTION
IONIZATION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
SIMULATION