The deepestHerschel-PACS far-infrared survey: number counts and infrared luminosity functions from combined PEP/GOODS-H observations

Abstract

We present results from the deepest Herschel-Photodetector Array Camera and Spectrometer (PACS) far-infrared blank field extragalactic survey, obtained by combining observations of the Great Observatories Origins Deep Survey (GOODS) fields from the PACS Evolutionary Probe (PEP) and GOODS-Herschel key programmes. We describe data reduction and the construction of images and catalogues. In the deepest parts of the GOODS-S field, the catalogues reach 3σ depths of 0.9, 0.6 and 1.3 mJy at 70, 100 and 160 μm, respectively, and resolve ∼75% of the cosmic infrared background at 100 μm and 160 μm into individually detected sources. We use these data to estimate the PACS confusion noise, to derive the PACS number counts down to unprecedented depths, and to determine the infrared luminosity function of galaxies down to L IR = 10 11 L at z ∼ 1 and L IR = 10 12 L at z ∼ 2, respectively. For the infrared luminosity function of galaxies, our deep Herschel far-infrared observations are fundamental because they provide more accurate infrared luminosity estimates than those previously obtained from mid-infrared observations. Maps and source catalogues (>3σ) are now publicly released. Combined with the large wealth of multi-wavelength data available for the GOODS fields, these data provide a powerful new tool for studying galaxy evolution over a broad range of redshifts.

Dusty star-forming galaxies at high redshift

“…Figure 12 illustrates both 850-870µm number counts (from Scuba, Laboca, Scuba-2, and ALMA Blain et al, 1999;Scott et al, 2002;Chapman et al, 2002;Cowie et al, 2002;Borys et al, 2003;Webb et al, 2003;Barnard et al, 2004;Coppin et al, 2006;Scott et al, 2006;Knudsen et al, 2008;Beelen et al, 2008;Weiß et al, 2009a;Karim et al, 2013;Casey et al, 2013;Chen et al, 2013a) and 450-500µm (from Scuba, Herschel and Scuba-2 Smail et al, 2002;Oliver et al, 2010;Clements et al, 2010;Béthermin et al, 2012b;Geach et al, 2013;Casey et al, 2013;Chen et al, 2013a). Figure 13 illustrates other infrared and submillimeter number counts in the literature in direct units, from 70µm Béthermin et al, 2010a;Berta et al, 2011), 100µm (Héraudeau et al, 2004;Rodighiero & Franceschini, 2004;Kawara et al, 2004;Berta et al, 2011;Magnelli et al, 2013b), 160µm Kawara et al, 2004;Béthermin et al, 2010a;Berta et al, 2011;Magnelli et al, 2013b), 250µm and 350µm Chen+13 (850) Casey+13 (850 Figure 12: Differential submillimeter number counts at 850µm/870µm (left) and 450-500 µm (right). The 850µm and 870µm number counts come the initial Scuba surveys …”

“…The 70µm data is collated from Spitzer MIPS Béthermin et al, 2010a) and Herschel PACS . At 100µm, data are from the ISOPHOT instrument aboard ISO (Héraudeau et al, 2004;Rodighiero & Franceschini, 2004;Kawara et al, 2004) and Herschel PACS Magnelli et al, 2013b). At 160µm-170µm, data are from Spitzer MIPS Béthermin et al, 2010a), ISO ISOPHOT (Kawara et al, 2004), and Herschel PACS Magnelli et al, 2013b).…”

“…At 100µm, data are from the ISOPHOT instrument aboard ISO (Héraudeau et al, 2004;Rodighiero & Franceschini, 2004;Kawara et al, 2004) and Herschel PACS Magnelli et al, 2013b). At 160µm-170µm, data are from Spitzer MIPS Béthermin et al, 2010a), ISO ISOPHOT (Kawara et al, 2004), and Herschel PACS Magnelli et al, 2013b). At both 250µm and 350µm, data come from BLAST Béthermin et al, 2010b) and Herschel SPIRE Clements et al, 2010;Béthermin et al, 2012b).…”

“…Within uncertainty, results from the AKARI satellite out to z ∼ 1.6 agree with Spitzer results . Herschel-based luminosity functions have a clear advantage over previous Spitzer work since Herschel probes the peak of infrared emission directly rather than indirectly; work from Magnelli et al (2009), Casey et al (2012a, Magnelli et al (2013b), and Gruppioni et al (2013) have all published integrated luminosity functions all the way out to z ∼ 3.6 using SED fits to PACS and SPIRE data. These Spitzer and Herschel luminosity functions are plotted together−segregated by redshift regime−in Figure 21.…”

“…The infrared luminosity density (IRLD) may be calculated as an alternate to the SFRD, removing the uncertainty of the L IR − S FR calibration. As , Spitzer 24µm-selected samples Magnelli et al, 2009Magnelli et al, , 2011, and from Herschel via the PEP and HerMES surveys (Casey et al, 2012a;Magnelli et al, 2013b;Gruppioni et al, 2013). Here we only include data points themselves and not analytic approximations to the luminosity function, which is often given as a double power law.…”