Browsing by Author "Hurley, P."

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    The complex physics of dusty star-forming galaxies at high redshifts as revealed by Herschel and Spitzer
    (IOP Publishing, 2013) Lo Faro, Barbara; Franceschini, Alberto; Vaccari, M.; Silva, L.; Rodighiero, G.; Berta, S.; Bock, J.; Burgarella, D.; Buat, V.; Cava, A.; Clements, D.L.; Cooray, Asantha; Farrah, D.; Feltre, Anna; Gonzalez-Solares, Eduardo A.; Hurley, P.; Lutz, D.; Magdis, G.; Magnelli, B.; Marchetti, L.; Oliver, S.J.; Page, Matthew J.; Popesso, P.; Pozzi, F.; Rigopoulou, D.; Rowan-Robinson, M.; Roseboom, I.G.; Scott, Douglas; Smith, A.J.; Symeonidis, Myrto; Wang, L.; Wuyts, S.
    We combine far-infrared photometry from Herschel (PEP/HerMES) with deep mid-infrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared galaxies ((U)LIRGs) at z ∼ 1 and 2 selected in GOODS-S with 24μm fluxes between 0.2 and 0.5 mJy.We model the data with a self-consistent physical model (GRASIL) which includes a state-of-the-art treatment of dust extinction and reprocessing. We find that all of our galaxies appear to require massive populations of old (>1 Gyr) stars and, at the same time, to host a moderate ongoing activity of star formation (SFR 100M yr−1). The bulk of the stars appear to have been formed a few Gyr before the observation in essentially all cases. Only five galaxies of the sample require a recent starburst superimposed on a quiescent star formation history.We also find discrepancies between our results and those based on optical-only spectral energy distribution (SED) fitting for the same objects; by fitting their observed SEDs with our physical model we find higher extinctions (by ΔAV ∼ 0.81 and 1.14) and higher stellar masses (by Δlog(M ) ∼ 0.16 and 0.36 dex) for z ∼ 1 and z ∼ 2 (U)LIRGs, respectively. The stellar mass difference is larger for the most dust-obscured objects. We also find lower SFRs than those computed from LIR using the Kennicutt relation due to the significant contribution to the dust heating by intermediate-age stellar populations through “cirrus” emission (∼73% and ∼66% of the total LIR for z ∼ 1 and z ∼ 2 (U)LIRGs, respectively).