Journal Article

Constraints on the star formation histories of galaxies from <i>z</i>∼ 1 to 0

Yan-Mei Chen, Vivienne Wild, Guinevere Kauffmann, Jérémy Blaizot, Marc Davis, Kai Noeske, Jian-Min Wang and Christopher Willmer

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 393, issue 2, pages 406-418
Published in print February 2009 | ISSN: 0035-8711
Published online February 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.14247.x
Constraints on the star formation histories of galaxies from z∼ 1 to 0

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We present a new method to estimate the average star formation rate per unit stellar mass (SSFR) of a stacked population of galaxies. We combine the spectra of 600–1000 galaxies with similar stellar masses and parametrize the star formation history of this stacked population using a set of exponentially declining functions. The strength of the hydrogen Balmer absorption-line series in the rest-frame wavelength range 3750–4150 Å is used to constrain the SSFR by comparing with a library of models generated using the BC03 stellar population code. Our method, based on a principal component analysis, can be applied in a consistent way to spectra drawn from local galaxy surveys and from surveys at z∼ 1, and is only weakly influenced by attenuation due to dust. We apply our method to galaxy samples drawn from Sloan Digital Sky Survey and DEEP2 to study the mass-dependent growth of galaxies from z∼ 1 to 0. We find that (i) high-mass galaxies have lower SSFRs than low-mass galaxies and (ii) the average SSFR has decreased from z= 1 to 0 by a factor of ∼3–4, independent of galaxy mass. Additionally, at z∼ 1, our average SSFRs are a factor of 2–2.5 lower than those derived from multiwavelength photometry using similar data sets. We then compute the average time [in units of the Hubble time, tH(z)] needed by galaxies of a given mass to form their stars at their current rate. At both z= 0 and 1, this time-scale decreases strongly with stellar mass from values close to unity for galaxies with masses ∼1010 M, to more than 10 for galaxies more massive than 1011 M. Our results are in good agreement with models in which active galactic nuclei feedback is more efficient at preventing gas from cooling and forming stars in high-mass galaxies.

Keywords: galaxies: evolution

Journal Article.  10151 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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