Work

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

Year: 1997

Type: article

Abstract: 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.

Source: The Astrophysical Journal

DOI: 10.1086/310929

Authors: David W. Hogg, E. S. Phinney

Institution: California Institute of Technology

Language: English

Topic: Galaxies: Formation, Evolution, Phenomena

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: bronze

Funder: National Science Foundation

Awards: Interacting Binary Stars and Star Formation in Galactic Nuclei, Astrophysical Studies of Gravitational Lenses, Faint Galaxies, Active Galactic Nuclei, and Pulsars