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A Near-Infrared Search for Line Emission from Protogalaxies Using the W. M. Keck Telescope

Pahre, Michael A. and Djorgovski, S. G. (1995) A Near-Infrared Search for Line Emission from Protogalaxies Using the W. M. Keck Telescope. Astrophysical Journal, 449 (1). L1-L4. ISSN 0004-637X. doi:10.1086/309632.

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We present the first results from a near-infrared narrowband search for primeval galaxies (PGs) using the Keck 10 m telescope. We have targeted our fields for three QSOs and one radio galaxy at redshifts z = 2.28 to z = 4.70. We selected narrowband filters in the K band centered on strong emission lines at the redshift of the targets. We reach limiting fluxes between 1.6 × 10^(-17) and 1.0 × 10^(-16) ergs s^(-1) cm^(-2), and cover a total area of ~4 arcmin2. At the redshifts of interest, these flux limits correspond to typical rest-frame line luminosities of ~10^(42)-10^(43) ergs s^(-1), unobscured star formation rates of ~1-100 M☉ yr^(-1), and a sampled comoving volume of several tens of Mpc^3. We have found no candidate PGs at a 2 σ confidence level. We demonstrate that for moderate dust absorption (A_V 2 mag) in a simple dust-screen model, our preliminary survey puts a strong constraint on intrinsic PG luminosities during an initial burst of star formation. In the case of the QSOs, we have used point-spread function subtraction to search for the presence of faint, extended line emission surrounding these radio-quiet active galactic nuclei. We find no evidence for extended emission down to 3.7 × 10^(-17) ergs s^(-1) cm^(-2). This imposes limits on the reprocessed fraction of the QSO continuum emission ranging between 0.02% and 0.29%; if beaming effects are not important, then this implies similarly small covering factors for clouds optically thick to the QSO continuum emission.

Item Type:Article
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URLURL TypeDescription Paper
Djorgovski, S. G.0000-0002-0603-3087
Additional Information:© 1995 The American Astronomical Society. Received 1994 November 7; accepted 1995 June 1. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California. The W. M. Keck Observatory is a scientific partnership between the California Institute of Technology and the University of California. It was made possible by the generous and visionary gift of the W. M. Keck Foundation, and the support of its president, Howard Keck. It is a pleasure to thank W. Harrison, T. Chleminiak, B. Schaefer, and W. Wack for the expert work during our observing run. We would also like to thank David Thompson for many helpful discussions. This work was supported in part by the NSF PYI award AST-9157412 to S. G. D., and the Greenstein and Kingsley Fellowships to M. A. P.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Jesse L. Greenstein FellowshipUNSPECIFIED
Kingsley FellowshipUNSPECIFIED
Subject Keywords:cosmology: observations—galaxies: formation—quasars: emission lines
Issue or Number:1
Record Number:CaltechAUTHORS:20190730-145114139
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Official Citation:Michael A. Pahre and S. G. Djorgovski 1995 ApJ 449 L1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97531
Deposited By: Tony Diaz
Deposited On:01 Aug 2019 20:08
Last Modified:16 Nov 2021 17:32

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