Tracing recent star formation of red early-type galaxies out to z ∼ 1

Journal Article · Wed Aug 20 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/791/2/134· OSTI ID:22365273

Ko, Jongwan; Lee, Jong Chul ^[1]; Hwang, Ho Seong ^[2]; Im, Myungshin ^[3]; Le Borgne, Damien ^[4]; Elbaz, David ^[5]

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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. Center for the Exploration of the Origin of the Universe, Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)
4. Sorbonne Universités, UPMC Univ. Paris 06, UMR 7095, Institut d'Astrophysique de Paris, F-75005 Paris (France)
5. Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu, CNRS, Université Paris Diderot, CE-Saclay, F-91191 Gif-sur-Yvette (France)

We study the mid-infrared (IR) excess emission of early-type galaxies (ETGs) on the red sequence at z < 1 using a spectroscopic sample of galaxies in the fields of Great Observatories Origins Deep Survey (GOODS). In the mass-limited sample of 1025 galaxies with M {sub star} > 10{sup 10.5} M {sub ☉} and 0.4 < z < 1.05, we identify 696 Spitzer 24 μm detected (above the 5σ) galaxies and find them to have a wide range of NUV-r and r-[12 μm] colors despite their red optical u – r colors. Even in the sample of very massive ETGs on the red sequence with M {sub star} > 10{sup 11.2} M {sub ☉}, more than 18% show excess emission over the photospheric emission in the mid-IR. The combination with the results of red ETGs in the local universe suggests that the recent star formation is not rare among quiescent, red ETGs at least out to z ∼ 1 if the mid-IR excess emission results from intermediate-age stars or/and from low-level ongoing star formation. Our color-color diagram including near-UV and mid-IR emissions are efficient not only for identifying ETGs with recent star formation, but also for distinguishing quiescent galaxies from dusty star-forming galaxies.

• OSTI ID: 22365273
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 791; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COLOR
EMISSION
GALAXIES
INTERMEDIATE INFRARED RADIATION
MASS
STAR EVOLUTION
STARS
UNIVERSE