VTechWorks staff will be away for the Thanksgiving holiday beginning at noon on Wednesday, November 27, through Friday, November 29. We will resume normal operations on Monday, December 2. Thank you for your patience.

Browsing by Author "Cava, A."

Now showing 1 - 2 of 2
  • Thumbnail Image
    The Complex Physics of Dusty Star-Forming Galaxies at High Redshifts as Revealed by Herschel and Spitzer
    Lo Faro, B.; Franceschini, A.; Vaccari, M.; Silva, L.; Rodighiero, G.; Berta, S.; Bock, J.; Burgarella, D.; Buat, V.; Cava, A.; Clements, D. L.; Cooray, A.; Farrah, D.; Feltre, A.; Solares, E. A. G.; Hurley, P.; Lutz, D.; Magdis, G. E.; Magnelli, B.; Marchetti, L.; Oliver, S. J.; Page, M. J.; Popesso, P.; Pozzi, F.; Rigopoulou, D.; Rowan-Robinson, M.; Roseboom, I. G.; Scott, D.; Smith, A. J.; Symeonidis, M.; Wang, L.; Wuyts, S. (IOP Publishing Ltd., 2013-01)
    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 similar to 1 and 2 selected in GOODS-S with 24 mu m 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 <= 100 M-circle dot 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 Delta A(V) similar to 0.81 and 1.14) and higher stellar masses (by Delta log(M-*) similar to 0.16 and 0.36 dex) for z similar to 1 and z similar to 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 (similar to 73% and similar to 66% of the total L-IR for z similar to 1 and z similar to 2 (U)LIRGs, respectively).
  • Thumbnail Image
    HerMES: candidate gravitationally lensed galaxies and lensing statistics at submillimeter wavelengths
    Wardlow, J. L.; Cooray, A.; De Bernardis, F.; Amblard, A.; Arumugam, V.; Aussel, H.; Baker, A. J.; Bethermin, M.; Blundell, R.; Bock, J.; Boselli, A.; Bridge, C. R.; Buat, V.; Burgarella, D.; Bussmann, R. S.; Cabrera-Lavers, A.; Calanog, J. A.; Carpenter, J. M.; Casey, C. M.; Castro-Rodriguez, N.; Cava, A.; Chanial, P.; Chapin, E.; Chapman, S. C.; Clements, D. L.; Conley, A.; Cox, P.; Dowell, C. D.; Dye, S.; Eales, S.; Farrah, D.; Ferrero, P.; Franceschini, A.; Frayer, D. T.; Frazer, C.; Fu, H.; Gavazzi, R.; Glenn, J.; Solares, E. A. G.; Griffin, M.; Gurwell, M. A.; Harris, A. I.; Hatziminaoglou, E.; Hopwood, R.; Hyde, A.; Ibar, E.; Ivison, R. J.; Kim, S.; Lagache, G.; Levenson, L.; Marchetti, L.; Marsden, G.; Martinez-Navajas, P.; Negrello, M.; Neri, R.; Nguyen, H. T.; O'Halloran, B.; Oliver, S. J.; Omont, A.; Page, M. J.; Panuzzo, P.; Papageorgiou, A.; Pearson, C. P.; Perez-Fournon, I.; Pohlen, M.; Riechers, D. A.; Rigopoulou, D.; Roseboom, I. G.; Rowan-Robinson, M.; Schulz, B.; Scott, D.; Scoville, N.; Seymour, N.; Shupe, D. L.; Smith, A. J.; Streblyanska, A.; Strom, A.; Symeonidis, M.; Trichas, M.; Vaccari, M.; Vieira, J. D.; Viero, M.; Wang, L.; Xu, C. K.; Yan, L.; Zemcov, M. (IOP Publishing Ltd., 2013-01)
    We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg(2) of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 +/- 0.04 deg(-2). The selected sources have 500 mu m 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 (mu >= 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 similar to 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 mu m 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 mu m. 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 similar to 0 ''.01 in the source plane.