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An ultraviolet-selected galaxy redshift survey -- II. The physical nature of star formation in an enlarged sample

Sullivan, Mark and Treyer, Marie A. and Ellis, Richard S. and Bridges, Terry J. and Milliard, Bruno and Donas, José (2000) An ultraviolet-selected galaxy redshift survey -- II. The physical nature of star formation in an enlarged sample. Monthly Notices of the Royal Astronomical Society, 312 (2). pp. 442-464. ISSN 0035-8711.

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We present further spectroscopic observations for a sample of galaxies selected in the vacuum ultraviolet (UV) at 2000 Å from the FOCA balloon-borne imaging camera of Milliard et al. This work represents an extension of the initial study by Treyer et al. Our enlarged catalogue contains 433 sources (≃3 times as many as in our earlier study) across two FOCA fields. 273 of these are galaxies, nearly all with redshifts z≃0–0.4. Nebular emission-line measurements are available for 216 galaxies, allowing us to address issues of excitation, reddening and metallicity. The UV and Hα luminosity functions strengthen our earlier assertions that the local volume-averaged star formation rate is higher than indicated from earlier surveys. Moreover, internally within our sample, we do not find a steep rise in the UV luminosity density with redshift over 0<z<0.4. Our data are more consistent with a modest evolutionary trend, as suggested by recent redshift survey results. Investigating the emission-line properties, we find no evidence for a significant number of AGN in our sample; most UV-selected sources to z≃0.4 are intense star-forming galaxies. We find that the UV flux indicates a consistently higher mean star formation rate than that implied by the Hα luminosity for typical constant or declining star formation histories. Following Glazebrook et al., we interpret this discrepancy in terms of a starburst model for our UV-luminous sources. We develop a simple algorithm which explores the scatter in the UV flux—Hα relation in the context of various burst scenarios. Whilst we can explain most of our observations in this way, there remains a small population with extreme UV—optical colours which cannot be understood.

Item Type:Article
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URLURL TypeDescription Paper
Sullivan, Mark0000-0001-9053-4820
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2000 RAS. Received: 22 September 1999. Accepted: 01 October 1999. Published: 21 February 2000. We thank the anonymous referee for detailed comments which improved this manuscript. We also thank Chris Blake, Veronique Buat, Lawrence Cram, Gerhardt Meurer, Bianca Poggianti, and especially Max Pettini for their many helpful discussions in preparing this paper. We are also grateful for the assistance provided by the La Palma support staff in securing the optical spectra. The WIYN Observatory is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories. The William Herschel Telescope is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.
Subject Keywords:surveys, galaxies: evolution, galaxies: luminosity function, mass function, galaxies: starburst, cosmology: observations, ultraviolet: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20200526-104631323
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Official Citation:Mark Sullivan, Marie A. Treyer, Richard S. Ellis, Terry J. Bridges, Bruno Milliard, José Donas, An ultraviolet-selected galaxy redshift survey — II. The physical nature of star formation in an enlarged sample, Monthly Notices of the Royal Astronomical Society, Volume 312, Issue 2, February 2000, Pages 442–464,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103446
Deposited By: Rebecca Minjarez
Deposited On:27 May 2020 17:22
Last Modified:27 May 2020 17:22

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