Detecting faint galaxies by stacking at 24 μm

X. Z. Zheng, Eric F. Bell, Hans Walter Rix, Casey Papovich, Emeric Le Floc'h, G. H. Rieke, P. G. Pérez-González

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We stack Spitzer 24 μm images for ∼7000 galaxies with 0.1 ≤ z < 1 in the Chandra Deep Field South to probe the thermal dust emission in low-luminosity galaxies over this redshift range. Through stacking, we can detect mean 24 μm fluxes that are more than an order of magnitude below the individual detection limit. We find that the correlations for low- and moderate-luminosity galaxies between the average LIR/LUV and rest-frame B-band luminosity, and between the star formation rate (SFR) and LIR/LUV, are similar to those in the local universe. This verifies that oft-used assumption in deep UV/optical surveys that the dust obscuration - SFR relation for galaxies with SFR ≤ 20 M yr-1 varies little with epoch. We have used this relation to derive the cosmic IR luminosity density from z = 1 to z = 0.1. The results also demonstrate directly that little of the bolometric luminosity of the galaxy population arises from the faint end of the luminosity function, indicating a relatively flat faint-end slope of the IR luminosity function with a power-law index of 1.2 ± 0.3.

Original languageEnglish (US)
Pages (from-to)784-800
Number of pages17
JournalAstrophysical Journal
Issue number2 I
StatePublished - Apr 1 2006


  • Galaxies: evolution
  • Galaxies: general
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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