Spitzer 24 μm detections of starburst galaxies in abell 851

Alan Dressler, Jane Rigby, Augustus Oemler, Jacopo Fritz, Bianca M. Poggianti, George H. Rieke, Lei Bai

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Spitzer-MIPS 24 μm observations and ground-based optical imaging and spectroscopy of the rich galaxy cluster Abell 851 at z = 0.41 are used to derive and compare star formation rates from the mid-IR 24 μm and from [O II] λλ3727 emission. Many cluster galaxies have star formation rates SFR(24μm)/SFR([O II]) ≫ 1, indicative of star formation in regions highly obscured by dust. We focus on the substantial minority of A851 cluster members where strong Balmer absorption points to a starburst on a 108-10 9 year timescale. As is typical, two types of galaxies with strong Balmer absorption are found in A851: with optical emission (starforming), and without optical emission (post-starburst). Our principal result is that the starforming variety, so-called e(a) galaxies, are mostly detected (9 out of 12) at 24 μm - for these we find typically SFR(24 μm)/SFR([O II]) 4. Strong Balmer absorption and high values of SFR(24 μm)/SFR([O II]) indicate moderately active starbursts (SB); both observations support the picture that e(a) galaxies are the active starbursts that feed the post-starburst population. While 24 μm detections are frequent with Balmer-strong objects (even 6 out of 18 of the supposedly "post-starburst" galaxies are detected), only two out of seven of the continuously starforming 'e(c)' galaxies (with weak Balmer absorption) are detected - for them, SFR(24 μm)/SFR([O II]) 1. Their optical spectra resemble present-epoch spirals that dominate today's universe; we strengthen this association by showing that SFR(24 μm)/SFR([O II]) 1 is the norm today. That is, not just the amount of star formation but also its mode has evolved strongly from z 0.4 to the present. We fit spectrophotometric models in order to measure the strength and duration of the bursts and to quantify the evolutionary sequence from active to post-starburst. Our results harden the evidence that moderately active starbursts are the defining feature of starforming cluster galaxies at z 0.4.

Original languageEnglish (US)
Pages (from-to)140-151
Number of pages12
JournalAstrophysical Journal
Volume693
Issue number1
DOIs
StatePublished - Mar 1 2009

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starburst galaxies
galaxies
star formation rate
light emission
star formation
spectroscopy
dust
timescale
minorities
detection
norms
optical spectrum
bursts
universe
time measurement
rate

Keywords

  • galaxies: clusters: general
  • galaxies: evolution

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Dressler, A., Rigby, J., Oemler, A., Fritz, J., Poggianti, B. M., Rieke, G. H., & Bai, L. (2009). Spitzer 24 μm detections of starburst galaxies in abell 851. Astrophysical Journal, 693(1), 140-151. https://doi.org/10.1088/0004-637X/693/1/140

Spitzer 24 μm detections of starburst galaxies in abell 851. / Dressler, Alan; Rigby, Jane; Oemler, Augustus; Fritz, Jacopo; Poggianti, Bianca M.; Rieke, George H.; Bai, Lei.

In: Astrophysical Journal, Vol. 693, No. 1, 01.03.2009, p. 140-151.

Research output: Contribution to journalArticle

Dressler, A, Rigby, J, Oemler, A, Fritz, J, Poggianti, BM, Rieke, GH & Bai, L 2009, 'Spitzer 24 μm detections of starburst galaxies in abell 851', Astrophysical Journal, vol. 693, no. 1, pp. 140-151. https://doi.org/10.1088/0004-637X/693/1/140
Dressler A, Rigby J, Oemler A, Fritz J, Poggianti BM, Rieke GH et al. Spitzer 24 μm detections of starburst galaxies in abell 851. Astrophysical Journal. 2009 Mar 1;693(1):140-151. https://doi.org/10.1088/0004-637X/693/1/140
Dressler, Alan ; Rigby, Jane ; Oemler, Augustus ; Fritz, Jacopo ; Poggianti, Bianca M. ; Rieke, George H. ; Bai, Lei. / Spitzer 24 μm detections of starburst galaxies in abell 851. In: Astrophysical Journal. 2009 ; Vol. 693, No. 1. pp. 140-151.
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