THE LACK OF INTENSE Ly{alpha} IN ULTRADEEP SPECTRA OF z = 7 CANDIDATES IN GOODS-S: IMPRINT OF REIONIZATION?

Journal Article · Mon Dec 20 04:00:00 EST 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/725/2/L205· OSTI ID:21454870

Fontana, A; Pentericci, L; Castellano, M; Grazian, A; Boutsia, K; Giallongo, E; Maiolino, R; Santini, P ^[1]; Vanzella, E; Cristiani, S ^[2]; Giavalisco, M ^[3]; Dickinson, M ^[4]; Moorwood, A ^[5]

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1. INAF Osservatorio Astronomico di Roma, Via Frascati 33000 40 Monteporzio (Italy)
2. INAF Osservatorio Astronomico di Trieste, Via G.B.Tiepolo 11, 34131 Trieste (Italy)
3. Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States)
4. National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726 (United States)
5. European Southern Observatory, Karl-Schwarzschild Strasse, 85748 Garching bei Munchen (Germany)

We present ultradeep optical spectroscopy obtained with FORS2 on the Very Large Telescope (VLT) of seven Lyman-break galaxy (LBG) candidates at z>6.5 selected in the GOODS-S field from Hawk-I/VLT and WFC3/HST imaging. For one galaxy we detect a low significance emission line (S/N {<=} 7), located at {lambda} = 9691.5 {+-} 0.5 A and with flux 3.4 x 10{sup -18} erg cm{sup -2} s{sup -1}. If identified as Ly{alpha}, it places the LBG at redshift z = 6.972 {+-} 0.002, with a rest-frame equivalent width EW{sub rf} = 13 A. Using Monte Carlo simulations and conservative EW distribution functions at 2 < z < 6, we estimate that the probability of observing no galaxies in our data with S/N>10 is {approx_equal}2%, and that of observing only one galaxy out of seven with S/N = 5 is {approx_equal}4%, but these can be as small as {approx}10{sup -3}, depending on the details of the EW distribution. We conclude that either a significant fraction of the candidates is not at high redshift or that some physical mechanism quenches the Ly{alpha} emission emerging from the galaxies at z>6.5, abruptly reversing the trend of the increasing fraction of strong emitters with increasing redshift observed up to z {approx} 6.5. We discuss the possibility that an increasingly neutral intergalactic medium is responsible for such quenching.

• OSTI ID: 21454870
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 725; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CALCULATION METHODS
COMPUTERIZED SIMULATION
DISTRIBUTION FUNCTIONS
EVOLUTION
FUNCTIONS
GALACTIC EVOLUTION
GALAXIES
MONTE CARLO METHOD
RED SHIFT
SIMULATION
SPECTROSCOPY
TELESCOPES