Browsing by Author "Amber, S."

Now showing 1 - 4 of 4
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    GRAVITATIONAL 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.
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    HERSCHEL-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.
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    Herschel-ATLAS: modelling the first strong gravitational lenses
    (2014) Dye, S.; Negrello, M.; Hopwood, R.; Nightingale, J. W.; Bussmann, R. S.; Amber, S.; Bourne, N.; Cooray, A.; Dariush, A.; Dunne, L.; Eales, S. A.; Gonzalez-Nuevo, J.; Ibar, E.; Ivison, R. J.; Maddox, S.; Valiante, E.; Smith, M.
    We have determined the mass density radial profiles of the first five strong gravitational lens systems discovered by the Herschel Astrophysical Terahertz Large Area Survey. We present an enhancement of the semilinear lens inversion method of Warren & Dye which allows simultaneous reconstruction of several different wavebands and apply this to dual-band imaging of the lenses acquired with the Hubble Space Telescope. The five systems analysed here have lens redshifts which span a range 0.22 <= z <= 0.94. Our findings are consistent with other studies by concluding that: (1) the logarithmic slope of the total mass density profile steepens with decreasing redshift; (2) the slope is positively correlated with the average total projected mass density of the lens contained within half the effective radius and negatively correlated with the effective radius; (3) the fraction of dark matter contained within half the effective radius increases with increasing effective radius and increases with redshift.
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    Lens Models of Herschel-Selected Galaxies From High-Resolution Near-IR Observations.
    (2014) Calanog, J.; Kim, Sam; Fu, Hai; Cooray, Asantha; Wardlow, Julie L.; Ma, B.; Amber, S.; Baker, A. J.; Baes, M.; Bock, J.; Bourne, N.