Browsing by Author "Clements, D. L."
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- ItemFar-infrared spectroscopy of a lensed starburst: a blind redshift from Herschel(2013) George, R. D.; Ivison, R. J.; Hopwood, R.; Riechers, D. A.; Bussmann, R. S.; Cox, P.; Dye, S.; Krips, M.; Negrello, M.; Neri, R.; Serjeant, S.; Valtchanov, I.; Baes, M.; Bourne, N.; Clements, D. L.; De Zotti, G.; Dunne, L.; Eales, S. A.; Ibar, E.; Maddox, S.; Smith, M. W. L.; Valiante, E.; van der Werf, P.We report the redshift of HATLAS J132427.0+284452 (hereafter HATLAS J132427), a gravitationally lensed starburst galaxy, the first determined 'blind' by the Herschel Space Observatory. This is achieved via the detection of [C II] consistent with z = 1.68 in a far-infrared spectrum taken with the SPIRE Fourier Transform Spectrometer (FTS). We demonstrate that the [C II] redshift is secure via detections of CO J = 2 -> 1 and 3 -> 2 using the Combined Array for Research in Millimeter-wave Astronomy and the Institut de Radioastronomie Millimetrique's Plateau de Bure Interferometer. The intrinsic properties appear typical of high-redshift starbursts despite the high lensing-amplified fluxes, proving the ability of the FTS to probe this population with the aid of lensing. The blind detection of [C II] demonstrates the potential of the SPICA Far-infrared Instrument imaging spectrometer, proposed for the much more sensitive Space Infrared Telescope for Cosmology and Astrophysics mission, to determine redshifts of multiple dusty galaxies simultaneously without the benefit of lensing.
- ItemGRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OF HERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES AT z > 1.5(2013) Bussmann, R. S.; Perez-Fournon, I.; Amber, S.; Calanog, J.; Gurwell, M. A.; Dannerbauer, H.; De Bernardis, F.; Fu, Hai; Harris, A. I.; Krips, M.; Lapi, A.; Maiolino, R.; Omont, A.; Riechers, D.; Wardlow, J.; Baker, A. J.; Birkinshaw, M.; Bock, J.; Bourne, N.; Clements, D. L.; Cooray, A.; De Zotti, G.; Dunne, L.; Dye, S.; Eales, S.; Farrah, D.; Gavazzi, R.; Nuevo, J. Gonzalez; Hopwood, R.; Ibar, E.; Ivison, R. J.; Laporte, N.; Maddox, S.; Martinez-Navajas, P.; Michalowski, M.; Negrello, M.; Oliver, S. J.; Roseboom, I. G.; Scott, Douglas; Serjeant, S.; Smith, A. J.; Smith, Matthew; Streblyanska, A.; Valiante, E.; van der Werf, P.; Verma, A.; Vieira, J. D.; Wang, L.; Wilner, D.Strong gravitational lenses are now being routinely discovered in wide-field surveys at (sub-)millimeter wavelengths. We present Submillimeter Array (SMA) high-spatial resolution imaging and Gemini-South and Multiple Mirror Telescope optical spectroscopy of strong lens candidates discovered in the two widest extragalactic surveys conducted by the Herschel Space Observatory: the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) and the Herschel Multi-tiered Extragalactic Survey (HerMES). From a sample of 30 Herschel sources with S-500 > 100 mJy, 21 are strongly lensed (i.e., multiply imaged), 4 are moderately lensed (i.e., singly imaged), and the remainder require additional data to determine their lensing status. We apply a visibility-plane lens modeling technique to the SMA data to recover information about the masses of the lenses as well as the intrinsic (i.e., unlensed) sizes (r(half)) and far-infrared luminosities (L-FIR) of the lensed submillimeter galaxies (SMGs). The sample of lenses comprises primarily isolated massive galaxies, but includes some groups and clusters as well. Several of the lenses are located at z(lens) > 0.7, a redshift regime that is inaccessible to lens searches based on Sloan Digital Sky Survey spectroscopy. The lensed SMGs are amplified by factors that are significantly below statistical model predictions given the 500 mu m flux densities of our sample. We speculate that this may reflect a deficiency in our understanding of the intrinsic sizes and luminosities of the brightest SMGs. The lensed SMGs span nearly one decade in L-FIR (median L-FIR = 7.9 x 10(12) L-circle dot) and two decades in FIR luminosity surface density (median Sigma(FIR) = 6.0 x 10(11) L-circle dot kpc(-2)). The strong lenses in this sample and others identified via (sub-) mm surveys will provide a wealth of information regarding the astrophysics of galaxy formation and evolution over a wide range in redshift.
- ItemH-ATLAS: THE COSMIC ABUNDANCE OF DUST FROM THE FAR-INFRARED BACKGROUND POWER SPECTRUM(2013) Thacker, Cameron; Cooray, Asantha; Smidt, Joseph; De Bernardis, Francesco; Mitchell-Wynne, K.; Amblard, A.; Auld, R.; Baes, M.; Clements, D. L.; Dariush, A.; De Zotti, G.; Dunne, L.; Eales, S.; Hopwood, R.; Hoyos, C.; Ibar, E.; Jarvis, M.; Maddox, S.; Michalowski, M. J.; Pascale, E.; Scott, D.; Serjeant, S.; Smith, M. W. L.; Valiante, E.; van der Werf, P.We present a measurement of the angular power spectrum of the cosmic far-infrared background (CFIRB) anisotropies in one of the extragalactic fields of the Herschel Astrophysical Terahertz Large Area Survey at 250, 350, and 500 mu m bands. Consistent with recent measurements of the CFIRB power spectrum in Herschel-SPIRE maps, we confirm the existence of a clear one-halo term of galaxy clustering on arcminute angular scales with large-scale two-halo term of clustering at 30 arcmin to angular scales of a few degrees. The power spectrum at the largest angular scales, especially at 250 mu m, is contaminated by the Galactic cirrus. The angular power spectrum is modeled using a conditional luminosity function approach to describe the spatial distribution of unresolved galaxies that make up the bulk of the CFIRB. Integrating over the dusty galaxy population responsible for the background anisotropies, we find that the cosmic abundance of dust, relative to the critical density, to be between Omega(dust) = 10-6 and 8 x 10(-6) in the redshift range z similar to 0-3. This dust abundance is consistent with estimates of the dust content in the universe using quasar reddening and magnification measurements in the Sloan Digital Sky Survey.
- ItemHerMES: CANDIDATE HIGH-REDSHIFT GALAXIES DISCOVERED WITH HERSCHEL/SPIRE(2014) Dowell, C. Darren; Conley, A.; Glenn, J.; Arumugam, V.; Asboth, V.; Aussel, H.; Bertoldi, F.; Bethermin, M.; Bock, J.; Boselli, A.; Bridge, C.; Buat, V.; Burgarella, D.; Cabrera-Lavers, A.; Casey, C. M.; Chapman, S. C.; Clements, D. L.; Conversi, L.; Cooray, A.; Dannerbauer, H.; De Bernardis, F.; Ellsworth-Bowers, T. P.; Farrah, D.; Franceschini, A.; Griffin, M.; Gurwell, M. A.; Halpern, M.; Hatziminaoglou, E.; Heinis, S.; Ibar, E.; Ivison, R. J.; Laporte, N.; Marchetti, L.; Martinez-Navajas, P.; Marsden, G.; Morrison, G. E.; Nguyen, H. T.; O'Halloran, B.; Oliver, S. J.; Omont, A.; Page, M. J.; Papageorgiou, A.; Pearson, C. P.; Petitpas, G.; Perez-Fournon, I.; Pohlen, M.; Riechers, D.; Rigopoulou, D.; Roseboom, I. G.; Rowan-Robinson, M.; Sayers, J.; Schulz, B.; Scott, Douglas; Seymour, N.; Shupe, D. L.; Smith, A. J.; Streblyanska, A.; Symeonidis, M.; Vaccari, M.; Valtchanov, I.; Vieira, J. D.; Viero, M.; Wang, L.; Wardlow, J.; Xu, C. K.; Zemcov, M.We present a method for selecting z > 4 dusty, star-forming galaxies (DSFGs) using Herschel/Spectral and Photometric Imaging Receiver 250/350/500 mu m flux densities to search for red sources. We apply this method to 21 deg(2) of data from the HerMES survey to produce a catalog of 38 high-z candidates. Follow-up of the first five of these sources confirms that this method is efficient at selecting high-z DSFGs, with 4/5 at z = 4.3-6.3 (and the remaining source at z = 3.4), and that they are some of the most luminous dusty sources known. Comparison with previous DSFG samples, mostly selected at longer wavelengths (e. g., 850 mu m) and in single-band surveys, shows that our method is much more efficient at selecting high-z DSFGs, in the sense that a much larger fraction are at z > 3. Correcting for the selection completeness and purity, we find that the number of bright (S-500 (mu m) >= 30 mJy), red Herschel sources is 3.3 +/- 0.8 deg(-2). This is much higher than the number predicted by current models, suggesting that the DSFG population extends to higher redshifts than previously believed. If the shape of the luminosity function for high-z DSFGs is similar to that at z similar to 2, rest-frame UV based studies may be missing a significant component of the star formation density at z = 4-6, even after correction for extinction.
- ItemHerMES: COSMIC INFRARED BACKGROUND ANISOTROPIES AND THE CLUSTERING OF DUSTY STAR-FORMING GALAXIES(2013) Viero, M. P.; Wang, L.; Zemcov, M.; Addison, G.; Amblard, A.; Arumugam, V.; Aussel, H.; Bethermin, M.; Bock, J.; Boselli, A.; Buat, V.; Burgarella, D.; Casey, C. M.; Clements, D. L.; Conley, A.; Conversi, L.; Cooray, A.; De Zotti, G.; Dowell, C. D.; Farrah, D.; Franceschini, A.; Glenn, J.; Griffin, M.; Hatziminaoglou, E.; Heinis, S.; Ibar, E.; Ivison, R. J.; Lagache, G.; Levenson, L.; Marchetti, L.; Marsden, G.; Nguyen, H. T.; O'Halloran, B.; Oliver, S. J.; Omont, A.; Page, M. J.; Papageorgiou, A.; Pearson, C. P.; Perez-Fournon, I.; Pohlen, M.; Rigopoulou, D.; Roseboom, I. G.; Rowan-Robinson, M.; Schulz, B.; Scott, D.; Seymour, N.; Shupe, D. L.; Smith, A. J.; Symeonidis, M.; Vaccari, M.; Valtchanov, I.; Vieira, J. D.; Wardlow, J.; Xu, C. K.We present measurements of the auto-and cross-frequency power spectra of the cosmic infrared background (CIB) at 250, 350, and 500 mu m (1200, 860, and 600 GHz) from observations totaling similar to 70 deg(2) made with the SPIRE instrument aboard the Herschel Space Observatory. We measure a fractional anisotropy delta I/I = 14% +/- 4%, detecting signatures arising from the clustering of dusty star-forming galaxies in both the linear (2-halo) and nonlinear (1-halo) regimes; and that the transition from the 2- to 1-halo terms, below which power originates predominantly from multiple galaxies within dark matter halos, occurs at k(theta) similar to 0.10-0.12 arcmin(-1) (l similar to 2160-2380), from 250 to 500 mu m. New to this paper is clear evidence of a dependence of the Poisson and 1-halo power on the flux-cut level of masked sources-suggesting that some fraction of the more luminous sources occupy more massive halos as satellites, or are possibly close pairs. We measure the cross-correlation power spectra between bands, finding that bands which are farthest apart are the least correlated, as well as hints of a reduction in the correlation between bands when resolved sources are more aggressively masked. In the second part of the paper, we attempt to interpret the measurements in the framework of the halo model. With the aim of fitting simultaneously with one model the power spectra, number counts, and absolute CIB level in all bands, we find that this is achievable by invoking a luminosity-mass relationship, such that the luminosity-to-mass ratio peaks at a particular halo mass scale and declines toward lower and higher mass halos. Our best-fit model finds that the halo mass which is most efficient at hosting star formation in the redshift range of peak star-forming activity, z similar to 1-3, is log( M-peak/M-circle dot) similar to 12.1 +/- 0.5, and that the minimum halo mass to host infrared galaxies is log(Mmin/M-circle dot) similar to 10.1 +/- 0.6.
- ItemHERSCHEL-ATLAS: A BINARY HyLIRG PINPOINTING A CLUSTER OF STARBURSTING PROTOELLIPTICALS(2013) Ivison, R. J.; Swinbank, A. M.; Smail, Ian; Harris, A. I.; Bussmann, R. S.; Cooray, A.; Cox, P.; Fu, H.; Kovacs, A.; Krips, M.; Narayanan, D.; Negrello, M.; Neri, R.; Penarrubia, J.; Richard, J.; Riechers, D. A.; Rowlands, K.; Staguhn, J. G.; Targett, T. A.; Amber, S.; Baker, A. J.; Bourne, N.; Bertoldi, F.; Bremer, M.; Calanog, J. A.; Clements, D. L.; Dannerbauer, H.; Dariush, A.; De Zotti, G.; Dunne, L.; Eales, S. A.; Farrah, D.; Fleuren, S.; Franceschini, A.; Geach, J. E.; George, R. D.; Helly, J. C.; Hopwood, R.; Ibar, E.; Jarvis, M. J.; Kneib, J. -P.; Maddox, S.; Omont, A.; Scott, D.; Serjeant, S.; Smith, M. W. L.; Thompson, M. A.; Valiante, E.; Valtchanov, I.; Vieira, J.; van der Werf, P.Panchromatic observations of the best candidate hyperluminous infrared galaxies from the widest Herschel extragalactic imaging survey have led to the discovery of at least four intrinsically luminous z = 2.41 galaxies across an approximate to 100 kpc region-a cluster of starbursting protoellipticals. Via subarcsecond interferometric imaging we have measured accurate gas and star formation surface densities. The two brightest galaxies span similar to 3 kpc FWHM in submillimeter/radio continuum and CO J = 4-3, and double that in CO J = 1-0. The broad CO line is due partly to the multitude of constituent galaxies and partly to large rotational velocities in two counter-rotating gas disks-a scenario predicted to lead to the most intense starbursts, which will therefore come in pairs. The disks have M-dyn of several x 10(11) M-circle dot, and gas fractions of similar to 40%. Velocity dispersions are modest so the disks are unstable, potentially on scales commensurate with their radii: these galaxies are undergoing extreme bursts of star formation, not confined to their nuclei, at close to the Eddington limit. Their specific star formation rates place them greater than or similar to 5x above the main sequence, which supposedly comprises large gas disks like these. Their high star formation efficiencies are difficult to reconcile with a simple volumetric star formation law. N-body and dark matter simulations suggest that this system is the progenitor of a B(inary)-type approximate to 10(14.6)-M-circle dot cluster.
- ItemIsothermal dust models of Herschel-ATLAS☆ galaxies(2013) Smith, D. J. B.; Hardcastle, M. J.; Jarvis, M. J.; Maddox, S. J.; Dunne, L.; Bonfield, D. G.; Eales, S.; Serjeant, S.; Thompson, M. A.; Baes, M.; Clements, D. L.; Cooray, A.; De Zotti, G.; Gonzalez-Nuevo, J.; van der Werf, P.; Virdee, J.; Bourne, N.; Dariush, A.; Hopwood, R.; Ibar, E.; Valiante, E.We use galaxies from the Herschel-ATLAS (H-ATLAS) survey, and a suite of ancillary simulations based on an isothermal dust model, to study our ability to determine the effective dust temperature, luminosity and emissivity index of 250 mu m selected galaxies in the local Universe (z < 0.5). As well as simple far-infrared spectral energy distribution (SED) fitting of individual galaxies based on chi(2) minimization, we attempt to derive the best global isothermal properties of 13 826 galaxies with reliable optical counterparts and spectroscopic redshifts. Using our simulations, we highlight the fact that applying traditional SED fitting techniques to noisy observational data in the Herschel Space Observatory bands introduces artificial anti-correlation between derived values of dust temperature and emissivity index. This is true even for galaxies with the most robust statistical detections in our sample, making the results of such fitting difficult to interpret. We apply a method to determine the best-fitting global values of isothermal effective temperature and emissivity index for z < 0.5 galaxies in H-ATLAS, deriving T-eff = 22.3 +/- 0.1 K and beta = 1.98 +/- 0.02 (or T-eff = 23.5 +/- 0.1 K and beta = 1.82 +/- 0.02 if we attempt to correct for bias by assuming that T-eff and beta(eff) are independent and normally distributed). We use our technique to test for an evolving emissivity index, finding only weak evidence. The median dust luminosity of our sample is log(10)(L-dust/L-circle dot) = 10.72 +/- 0.05, which (unlike T-eff) shows little dependence on the choice of beta used in our analysis, including whether it is variable or fixed. In addition, we use a further suite of simulations based on a fixed emissivity index isothermal model to emphasize the importance of the H-ATLAS PACS data for deriving dust temperatures at these redshifts, even though they are considerably less sensitive than the SPIRE data. Finally, we show that the majority of galaxies detected by H-ATLAS are normal star-forming galaxies, though with a substantial minority (similar to 31 per cent) falling in the Luminous Infrared Galaxy category.
- ItemThe Evolution of the IR Luminosity Function and Dust-obscured Star Formation over the Past 13 Billion Years(2021) Zavala, J. A.; Casey, C. M.; Manning, S. M.; Aravena, M.; Bethermin, M.; Caputi, K. I.; Clements, D. L.; Cunha, E. da; Drew, P.; Finkelstein, S. L.; Fujimoto, S.; Hayward, C.; Hodge, J.; Kartaltepe, J. S.; Knudsen, K.; Koekemoer, A. M.; Long, A. S.; Magdis, G. E.; Man, A. W. S.; Popping, G.; Sanders, D.; Scoville, N.; Sheth, K.; Staguhn, J.; Toft, S.; Treister, E.; Vieira, J. D.; Yun, M. S.We present the first results from the Mapping Obscuration to Reionization with ALMA (MORA) survey, the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey to date (184 arcmin(2)) and the only at 2 mm to search for dusty star-forming galaxies (DSFGs). We use the 13 sources detected above 5 sigma to estimate the first ALMA galaxy number counts at this wavelength. These number counts are then combined with the state-of-the-art galaxy number counts at 1.2 and 3 mm and with a backward evolution model to place constraints on the evolution of the IR luminosity function and dust-obscured star formation in the past 13 billion years. Our results suggest a steep redshift evolution on the space density of DSFGs and confirm the flattening of the IR luminosity function at faint luminosities, with a slope of alpha(LF) = -0.42(-0.04)(+0.02). We conclude that the dust-obscured component, which peaks at z approximate to 2-2.5, has dominated the cosmic history of star formation for the past similar to 12 billion years, back to z similar to 4. At z = 5, the dust-obscured star formation is estimated to be similar to 35% of the total star formation rate density and decreases to 25%-20% at z = 6-7, implying a minor contribution of dusten-shrouded star formation in the first billion years of the universe. With the dust-obscured star formation history constrained up to the end of the epoch of reionization, our results provide a benchmark to test galaxy formation models, to study the galaxy mass assembly history, and to understand the dust and metal enrichment of the universe at early times.