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The Fading of Young Stellar Populations and the Luminosity Functions of Dwarf, Irregular, and Starburst Galaxies

Hogg, David W. and Phinney, E. S. (1997) The Fading of Young Stellar Populations and the Luminosity Functions of Dwarf, Irregular, and Starburst Galaxies. Astrophysical Journal, 488 (2). L95-L99. ISSN 0004-637X. doi:10.1086/310929.

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Dwarf, irregular, and infrared-luminous starburst galaxies are all known to have "steep" luminosity functions with faint-end behavior roughly φ(L)∝L^(−1.8). This form is exactly what is expected if the luminosities of these objects fade with time as L∝t^(−1.3), because the objects spend more time at low luminosities than high, even if they form with a wide range of initial masses. Models of young stellar populations show this fading behavior when the star formation has occurred in a single, short, recent burst. Steep luminosity functions therefore do not require steep mass functions if the galaxies are powered by fading bursts. The local galaxy Hα luminosity function—which is less steep than L^(−1.8)—is also well fitted by this mechanism, because ionizing photon flux fades much more quickly than broadband optical luminosity. An age-luminosity relation and a wavelength dependence of the luminosity function are both predicted. In the context of this mechanism, the slope of the luminosity function provides a constraint on the stellar initial mass function in the bursts.

Item Type:Article
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URLURL TypeDescription Paper
Hogg, David W.0000-0003-2866-9403
Additional Information:© 1997. The American Astronomical Society. Received 1997 June 2; accepted 1997 August 19; published 1997 September 22. We benefited from helpful comments from Lee Armus, Roger Blandford, Tim Heckman, Jeremy Heyl, Nick Scoville, Tom Soifer, and an anonymous referee. Claus Leitherer, Tim Heckman, and Jeff Goldader generously provided us with published data in electronic form. Support from the National Science Foundation is gratefully acknowledged (D. W. H. under AST-9529170 and E. S. P. under AST-9315455).
Funding AgencyGrant Number
Subject Keywords:galaxies: luminosity function, mass function; galaxies: starburst; galaxies: stellar content; infrared: galaxies; stars: luminosity function, mass function
Issue or Number:2
Record Number:CaltechAUTHORS:20190205-142059967
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Official Citation:David W. Hogg and E. S. Phinney 1997 ApJ 488 L95
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92687
Deposited By: George Porter
Deposited On:05 Feb 2019 22:45
Last Modified:16 Nov 2021 03:52

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