HerMES: The Contribution to the Cosmic Infrared Background from Galaxies Selected by Mass and Redshift

Abstract

We quantify the fraction of the cosmic infrared background (CIB) that originates from galaxies identified in the UV/optical/near-infrared by stacking 81,250 (~35.7 arcmin^(–2)) K-selected sources (K_(AB) < 24.0) split according to their rest-frame U – V versus V – J colors into 72,216 star-forming and 9034 quiescent galaxies, on maps from Spitzer/MIPS (24 μm), Herschel/PACS (100, 160 μm), Herschel/SPIRE (250, 350, 500 μm), and AzTEC (1100 μm). The fraction of the CIB resolved by our catalog is (69% ± 15%) at 24 μm, (78% ± 17%) at 70 μm, (58% ± 13%) at 100 μm, (78% ± 18%) at 160 μm, (80% ± 17%) at 250 μm, (69% ± 14%) at 350 μm, (65% ± 12%) at 500 μm, and (45% ± 8%) at 1100 μm. Of that total, about 95% originates from star-forming galaxies, while the remaining 5% is from apparently quiescent galaxies. The CIB at λ ≾ 200 μm appears to be sourced predominantly from galaxies at z ≾ 1, while at λ ≳ 200 μm the bulk originates from 1 ≾ z ≾ 2. Galaxies with stellar masses log(M/M_☉) = 9.5-11 are responsible for the majority of the CIB, with those in the log(M/M_☉) = 9.5-10 bin contributing mostly at λ < 250 μm, and those in the log(M/M_☉) = 10-11 bin dominating at λ > 350 μm. The contribution from galaxies in the log(M/M_☉) = 9.0-9.5 (lowest) and log(M/M_☉) = 11.0-12.0 (highest) stellar-mass bins contribute the least—both of order 5%—although the highest stellar-mass bin is a significant contributor to the luminosity density at z ≳ 2. The luminosities of the galaxies responsible for the CIB shifts from combinations of "normal" and luminous infrared galaxies (LIRGs) at λ ≾ 160 μm, to LIRGs at 160 ≾ λ ≾ 500 μm, to finally LIRGs and ultra-luminous infrared galaxies at λ ≳ 500 μm. Stacking analyses were performed using SIMSTACK, a novel algorithm designed to account for possible biases in the stacked flux density due to clustering. It is made available to the public at www.astro.caltech.edu/~viero/viero_homepage/toolbox.html.

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