THE MID-INFRARED AND NEAR-ULTRAVIOLET EXCESS EMISSIONS OF QUIESCENT GALAXIES ON THE RED SEQUENCE

Journal Article · Wed Apr 10 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/767/1/90· OSTI ID:22167378

Ko, Jongwan; Lee, Jong Chul ^[1]; Hwang, Ho Seong ^[2]; Sohn, Young-Jong ^[3]

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1. Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
2. Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)
3. Department of Astronomy, Yonsei University, Seoul 120-749 (Korea, Republic of)

We study the mid-infrared (IR) and near-ultraviolet (UV) excess emissions of spectroscopically selected quiescent galaxies on the optical red sequence. We use the Wide-field Infrared Survey Explorer mid-IR and Galaxy Evolution Explorer near-UV data for a spectroscopic sample of galaxies in the Sloan Digital Sky Survey Data Release 7 to study the possible connection between quiescent red-sequence galaxies with and without mid-IR/near-UV excess. Among 648 12 {mu}m detected quiescent red-sequence galaxies without H{alpha} emission, 26% and 55% show near-UV and mid-IR excess emissions, respectively. When we consider only bright (M{sub r} < -21.5) galaxies with an early-type morphology, the fraction of galaxies with recent star formation is still 39%. The quiescent red-sequence galaxies with mid-IR and near-UV excess emissions are optically fainter and have slightly smaller D{sub n} 4000 than those without mid-IR and near-UV excess emissions. We also find that mid-IR weighted mean stellar ages of quiescent red-sequence galaxies with mid-IR excess are larger than those with near-UV excess, and smaller than those without mid-IR and near-UV excess. The environmental dependence of the fraction of quiescent red-sequence galaxies with mid-IR and near-UV excess seems strong even though the trends of quiescent red-sequence galaxies with near-UV excess differ from those with mid-IR excess. These results indicate that the recent star formation traced by near-UV ({approx}< 1 Gyr) and mid-IR ({approx}< 2 Gyr) excess is not negligible among nearby, quiescent, red, early-type galaxies. We suggest a possible evolutionary scenario of quiescent red-sequence galaxies from quiescent red-sequence galaxies with near-UV excess to those with mid-IR excess to those without near-UV and mid-IR excess.

• OSTI ID: 22167378
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 767; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
EMISSION
GALAXIES
INFRARED SURVEYS
MORPHOLOGY
NEAR ULTRAVIOLET RADIATION