Erratum to The herschel* pep/hermes luminosity function - i. probing the evolution of PACS selected galaxies to z ̃ 4 [MNRAS 436, (2013) 2875-2876]
Monthly Notices of the Royal Astronomical Society 436:3 (2013) 2875-2876
HerMES: Candidate gravitationally lensed galaxies and lensing statistics at submillimeter wavelengths
Astrophysical Journal 762:1 (2013)
Abstract:
We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg2 of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 ± 0.04 deg-2. The selected sources have 500 μm flux densities (S 500) greater than 100 mJy. Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems (70%), and the lensing status of the four remaining sources is undetermined. We also present a supplementary sample of 29 (0.31 ± 0.06 deg-2) gravitationally lensed SMG candidates with S 500 = 80-100 mJy, which are expected to contain a higher fraction of interlopers than the primary candidates. The number counts of the candidate lensed galaxies are consistent with a simple statistical model of the lensing rate, which uses a foreground matter distribution, the intrinsic SMG number counts, and an assumed SMG redshift distribution. The model predicts that 32%-74% of our S 500 ≥ 100 mJy candidates are strongly gravitationally lensed (μ ≥ 2), with the brightest sources being the most robust; this is consistent with the observational data. Our statistical model also predicts that, on average, lensed galaxies with S 500 = 100 mJy are magnified by factors of ∼9, with apparently brighter galaxies having progressively higher average magnification, due to the shape of the intrinsic number counts. 65% of the sources are expected to have intrinsic 500 μm flux densities less than 30 mJy. Thus, samples of strongly gravitationally lensed SMGs, such as those presented here, probe below the nominal Herschel detection limit at 500 μm. They are good targets for the detailed study of the physical conditions in distant dusty, star-forming galaxies, due to the lensing magnification, which can lead to spatial resolutions of ∼0.″01 in the source plane. © 2013. The American Astronomical Society. All rights reserved.Hermes: Dust attenuation and star formation activity in ultraviolet-selected samples from z ~ 4 to ~1.5
Monthly Notices of the Royal Astronomical Society 437:2 (2013) 1268-1283
Abstract:
We study the link between observed ultraviolet (UV) luminosity, stellar mass and dust attenuation within rest-frame UV-selected samples at z ~ 4, ~ 3 and ~1.5.We measure by stacking at 250, 350 and 500 μm in the Herschel/Spectral and Photometric Imaging Receiver images from the Herschel Multi-Tiered Extragalactic Survey (HerMES) program the average infrared luminosity as a function of stellar mass and UV luminosity. We find that dust attenuation is mostly correlated with stellarmass. There is also a secondary dependence with UV luminosity: at a given UV luminosity, dust attenuation increases with stellar mass, while at a given stellar mass it decreases with UV luminosity. We provide new empirical recipes to correct for dust attenuation given the observed UV luminosity and the stellar mass. Our results also enable us to put new constraints on the average relation between star formation rate (SFR) and stellar mass at z ~ 4, ~3 and ~1.5. The SFR-stellar mass relations are well described by power laws (SFR α M0.7*), with the amplitudes being similar at z ~ 4 and ~3, and decreasing by a factor of 4 at z ~ 1.5 at a given stellar mass. We further investigate the evolution with redshift of the specific SFR. Our results are in the upper range of previous measurements, in particular at z ~ 3, and are consistent with a plateau at 3 < z < 4. Current model predictions (either analytic, semi-analytic or hydrodynamic) are inconsistent with these values, as they yield lower predictions than the observations in the redshift range we explore. We use these results to discuss the star formation histories of galaxies in the framework of the main sequence of star-forming galaxies. Our results suggest that galaxies at high redshift (2.5 < z < 4) stay around 1 Gyr on the main sequence. With decreasing redshift, this time increases such that z = 1 main-sequence galaxies with 108 M*M⊙ 1010 stay on the main sequence until z = 0. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.Herschel-ATLAS/GAMA: What determines the far-infrared properties of radio galaxies?
Monthly Notices of the Royal Astronomical Society 432:1 (2013) 609-625
Abstract:
We perform a stacking analysis of Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) data in order to obtain isothermal dust temperatures and rest-frame luminosities at 250 μm (L250), for a well-defined sample of 1599 radio sources over the H-ATLAS Phase 1/Galaxy and Mass Assembly (GAMA) area. The radio sample is generated using a combination of NRAO VLA Sky Survey data and K-band United Kingdom Infrared Telescope Deep Sky Survey-Large Area Survey data, over the redshift range 0.01 < z < 0.8. The far-infrared(FIR) properties of the sample are investigated as a function of 1.4-GHz luminosity, redshift, projected radio-source size and radio spectral index. In order to search for stellar mass-dependent relations, we split the parent sample into those sources which are below and above 1.5 L*K.After correcting for stellar mass and redshift, we find no relation between the 250-μm luminosity and the 1.4-GHz radio luminosity of radio active galactic nuclei. This implies thata galaxy's nominal radio luminosity has little or no bearing on the star formation rate (SFR)and/or dust mass content of the host system, although this does not mean that other variables(e.g. radio source size) related to the jets do not have an effect. The L250 of both the radio detected and non-radio-detected galaxies (defined as those sources not detected at 1.4 GHz but detected in the Sloan Digital Sky Survey with r< 22) rises with increasing redshift. Compact radio sources (<30 kpc) are associated with higher 250 μm luminosities and dust temperatures than their more extended (>30 kpc) counterparts. The higher dust temperature suggests that this may be attributed to enhanced SFRs in compact radio galaxies, but whether this is directly or indirectly due to radio activity (e.g. jet-induced or merger-driven star formation) is as yet unknown.For matched samples in LK and g-r, sub-1.5 L*K and super-1.5 L*K radio-detected galaxies have 0.89±0.18 and 0.49±0.12 times the 250μm luminosity of their non-radio-detected counterparts. Thus, while no difference in L250 is observed in sub-1.5 L*K radio-detected galaxies, a strong deficit is observed in super-1.5 L*K radio-detected galaxies. We explain these results in terms of the hotter, denser and richer halo environments massive radio galaxies maintain and are embedded in. These environments are expected to quench the cold gas and dust supply needed for further star formation and therefore dust production. Our results indicate that all massive radio galaxies (>1.5 L*K) may have systematically lower FIR luminosities(~25 per cent) than their colour-matched non-radio-detected counterparts. Finally, no relation between radio spectral index and L250 is found for the subset of 1.4-GHz radio sources with detections at 330 MHz. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.Mid to far-infrared properties of star-forming galaxies and active galactic nuclei
Astronomy and Astrophysics 558 (2013)