Primus

Obscured star formation on the red sequence

Guangtun Zhu, Michael R. Blanton, Scott M. Burles, Alison L. Coil, Richard J. Cool, Daniel J. Eisenstein, John Moustakas, Kenneth C. Wong, James Aird

    Research output: Contribution to journalArticle

    Abstract

    We quantify the fraction of galaxies at moderate redshifts (0.1 < z < 0.5) that appear red-and-dead in the optical, but in fact contain obscured star formation detectable in the infrared (IR), with the PRIsm MUlti-object Survey (PRIMUS). PRIMUS has measured ∼120,000 robust redshifts with a precision of σz/(1 + z) ∼ 0.5% over 9.1deg2 of the sky to the depth of i ∼ 23 (AB), up to redshift z ∼ 1. We specifically targeted 6.7deg 2 fields with existing deep IR imaging from the Spitzer Space Telescope from the SWIRE and S-COSMOS surveys. We select in these fields an i-band flux-limited sample (i < 20 mag in the SWIRE fields and i < 21 mag in the S-COSMOS field) of 3310 red-sequence galaxies at 0.1 < z < 0.5 for which we can reliably classify obscured star-forming (SF) and quiescent galaxies using IR color. Our sample constitutes the largest galaxy sample at intermediate redshift to study obscured star formation on the red sequence, and we present the first quantitative analysis of the fraction of obscured SF galaxies as a function of luminosity. We find that on average, at L ∼ L*, about 15% of red-sequence galaxies have IR colors consistent with SF galaxies. The percentage of obscured SF galaxies increases by ∼8% per mag with decreasing luminosity from the highest luminosities to L ∼ 0.2L*. Our results suggest that a significant fraction of red-sequence galaxies have ongoing star formation and that galaxy evolution studies based on optical color therefore need to account for this complication.

    Original languageEnglish (US)
    JournalAstrophysical Journal
    Volume726
    Issue number2
    DOIs
    StatePublished - Jan 10 2011

    Fingerprint

    star formation
    galaxies
    quantitative analysis
    stars
    luminosity
    color
    Space Infrared Telescope Facility
    COSMOS
    sky

    Keywords

    • Dust, extinction
    • Galaxies: distances and redshifts
    • Galaxies: evolution
    • Galaxies: fundamental parameters
    • Stars: formation

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Zhu, G., Blanton, M. R., Burles, S. M., Coil, A. L., Cool, R. J., Eisenstein, D. J., ... Aird, J. (2011). Primus: Obscured star formation on the red sequence. Astrophysical Journal, 726(2). https://doi.org/10.1088/0004-637X/726/2/110

    Primus : Obscured star formation on the red sequence. / Zhu, Guangtun; Blanton, Michael R.; Burles, Scott M.; Coil, Alison L.; Cool, Richard J.; Eisenstein, Daniel J.; Moustakas, John; Wong, Kenneth C.; Aird, James.

    In: Astrophysical Journal, Vol. 726, No. 2, 10.01.2011.

    Research output: Contribution to journalArticle

    Zhu, G, Blanton, MR, Burles, SM, Coil, AL, Cool, RJ, Eisenstein, DJ, Moustakas, J, Wong, KC & Aird, J 2011, 'Primus: Obscured star formation on the red sequence', Astrophysical Journal, vol. 726, no. 2. https://doi.org/10.1088/0004-637X/726/2/110
    Zhu G, Blanton MR, Burles SM, Coil AL, Cool RJ, Eisenstein DJ et al. Primus: Obscured star formation on the red sequence. Astrophysical Journal. 2011 Jan 10;726(2). https://doi.org/10.1088/0004-637X/726/2/110
    Zhu, Guangtun ; Blanton, Michael R. ; Burles, Scott M. ; Coil, Alison L. ; Cool, Richard J. ; Eisenstein, Daniel J. ; Moustakas, John ; Wong, Kenneth C. ; Aird, James. / Primus : Obscured star formation on the red sequence. In: Astrophysical Journal. 2011 ; Vol. 726, No. 2.
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    AU - Cool, Richard J.

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    KW - Galaxies: fundamental parameters

    KW - Stars: formation

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