Caruana, Joseph, Bunker, Andrew J, Wilkins, Stephen M, Stanway, Elizabeth, Lacy, Mark, Jarvis, Matt J, Lorenzoni, Silvio and Hickey, Samantha (2012) No evidence for Lyman emission in spectroscopy of z > 7 candidate galaxies. Monthly Notices of the Royal Astronomical Society, 427 (4). pp. 3055-3070. ISSN 0035-8711

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Abstract

We present Gemini/Gemini Near Infrared Spectrograph (GNIRS) spectroscopic observations of four z-band (z ≈ 7) dropout galaxies and Very Large Telescope (VLT)/XSHOOTER observations of one z-band dropout and three Y-band (z ≈ 8–9) dropout galaxies in the Hubble Ultra Deep Field, which were selected with Wide Field Camera 3 imaging on the Hubble Space Telescope. We find no evidence of Lyman α emission with a typical 5σ sensitivity of 5 × 10−18 erg cm−2 s−1, and use the upper limits on Lyman α flux and the broad-band magnitudes to constrain the rest-frame equivalent widths for this line emission. Accounting for incomplete spectral coverage, we survey 3.0 z-band dropouts and 2.9 Y-band dropouts to a Lyman α rest-frame equivalent width limit >120 Å (for an unresolved emission line); for an equivalent width limit of 50 Å the effective numbers of drop-outs surveyed fall to 1.2 z-band drop-outs and 1.5 Y-band drop-outs. A simple model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z = 3–6.5 is inconsistent with our non-detections at z = 7–9 at the ≈1σ level for spectrally unresolved lines, which may indicate that a significant neutral H I fraction in the intergalactic medium suppresses the Lyman α line in z-drop and Y-drop galaxies at z > 7.

Item Type:	Article
Schools and Departments:	School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Depositing User:	Stephen Wilkins
Date Deposited:	26 Apr 2013 10:00
Last Modified:	07 Mar 2017 08:50
URI:	http://srodev.sussex.ac.uk/id/eprint/44501

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