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Browsing by Author "Bridge, C. R."

Now showing 1 - 8 of 8
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    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.
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    HerMES: candidate high-redshift galaxies discovered with Herschel/SPIRE
    Dowell, C. D.; Conley, A.; Glenn, J.; Arumugam, V.; Asboth, V.; Aussel, H.; Bertoldi, F.; Bethermin, M.; Bock, J.; Boselli, A.; Bridge, C. R.; 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. A.; Rigopoulou, D.; Roseboom, I. G.; Rowan-Robinson, M.; Sayers, J.; Schulz, B.; Scott, D.; 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. (IOP Publishing Ltd., 2014-01)
    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.
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    HerMES: the contribution to the cosmic infrared background from galaxies selected by mass and redshift
    Viero, M. P.; Moncelsi, L.; Quadri, R. F.; Arumugam, V.; Assef, R. J.; Bethermin, M.; Bock, J.; Bridge, C. R.; Casey, C. M.; Conley, A.; Cooray, A.; Farrah, D.; Glenn, J.; Heinis, S.; Ibar, E.; Ikarashi, S.; Ivison, R. J.; Kohno, K.; Marsden, G.; Oliver, S. J.; Roseboom, I. G.; Schulz, B.; Scott, D.; Serra, P.; Vaccari, M.; Vieira, J. D.; Wang, L.; Wardlow, J.; Wilson, G. W.; Yun, M. S.; Zemcov, M. (IOP Publishing Ltd., 2013-12)
    We quantify the fraction of the cosmic infrared background (CIB) that originates from galaxies identified in the UV/optical/near-infrared by stacking 81,250 (similar to 35.7 arcmin(-2)) K-selected sources (K-AB < 24.0) split according to their rest-frame U-V versus V-J colors into 72,216 star-forming and 9034 quiescent galaxies, on maps from Spitzer/MIPS (24 mu m), Herschel/PACS (100, 160 mu m), Herschel/SPIRE (250, 350, 500 mu m), and AzTEC (1100 mu m). The fraction of the CIB resolved by our catalog is (69% +/- 15%) at 24 mu m, (78% +/- 17%) at 70 mu m, (58% +/- 13%) at 100 mu m, (78% +/- 18%) at 160 mu m, (80% +/- 17%) at 250 mu m, (69% +/- 14%) at 350 mu m, (65% +/- 12%) at 500 mu m, and (45% +/- 8%) at 1100 mu m. Of that total, about 95% originates from star-forming galaxies, while the remaining 5% is from apparently quiescent galaxies. The CIB at lambda less than or similar to 200 mu m appears to be sourced predominantly from galaxies at z less than or similar to 1, while at. greater than or similar to 200 mu m the bulk originates from 1 less than or similar to z less than or similar to 2. Galaxies with stellar masses log(M/M-circle dot) = 9.5-11 are responsible for the majority of the CIB, with those in the log(M/M-circle dot) = 9.5-10 bin contributing mostly at lambda < 250 mu m, and those in the log(M/M circle dot) = 10-11 bin dominating at lambda > 350 mu m. The contribution from galaxies in the log(M/M-circle dot) = 9.0-9.5 (lowest) and log(M/M-circle dot) = 11.0-12.0 (highest) stellar-mass bins contribute the least-both of order 5%-although the highest stellar-mass bin is a significant contributor to the luminosity density at z greater than or similar to 2. The luminosities of the galaxies responsible for the CIB shifts from combinations of "normal" and luminous infrared galaxies (LIRGs) at lambda less than or similar to 160 mu m, to LIRGs at 160 less than or similar to lambda less than or similar to 500 mu m, to finally LIRGs and ultra-luminous infrared galaxies at lambda greater than or similar to 500 mu m. Stacking analyses were performed using SIMSTACK, a novel algorithm designed to account for possible biases in the stacked flux density due to clustering. It is made available to the public at www.astro.caltech.edu/similar to viero/viero_homepage/toolbox.html.
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    A New Population of High-z, Dusty Lyα Emitters and Blobs Discovered by WISE: Feedback Caught in the Act?
    Bridge, C. R.; Blain, A.; Borys, C. J. K.; Petty, S.; Benford, D.; Eisenhardt, P.; Farrah, D.; Griffith, R. L.; Jarrett, T.; Lonsdale, C.; Stanford, S. A.; Stern, D.; Tsai, C. W.; Wright, E. L.; Wu, J. W. (IOP PUBLISHING LTD, 2013-06)
    By combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W. M. Keck telescope, we discover a mid-IR color criterion that yields a 78% success rate in identifying rare, typically radio-quiet, 1.6 less than or similar to z less than or similar to 4.6 dusty Ly alpha emitters (LAEs). Of these, at least 37% have emission extended on scales of 30-100 kpc and are considered Ly alpha "blobs" (LABs). The objects have a surface density of only similar to 0.1 deg(-2), making them rare enough that they have been largely missed in deep, small area surveys. We measured spectroscopic redshifts for 92 of these galaxies, and find that the LAEs (LABs) have a median redshift of 2.3 (2.5). The WISE photometry coupled with data from Herschel (Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA) reveals that these galaxies are in the Hyper Luminous IR galaxy regime (L-IR greater than or similar to 10(13)-10(14) L-circle dot) and have warm colors. They are typically more luminous and warmer than other dusty, z similar to 2 populations such as submillimeter-selected galaxies and dust-obscured galaxies. These traits are commonly associated with the dust being illuminated by intense active galactic nucleus activity. We hypothesize that the combination of spatially extended Ly alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing brief, intense "feedback" transforming them from an extreme dusty starburst/QSO into a mature galaxy.
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    A Population of z > 2 Far-Infrared Herschel-Spire-Selected Starbursts
    Casey, C. M.; Berta, S.; Bethermin, M.; Bock, J.; Bridge, C. R.; Burgarella, D.; Chapin, E.; Chapman, S. C.; Clements, D. L.; Conley, A.; Conselice, C. J.; Cooray, A.; Farrah, D.; Hatziminaoglou, E.; Ivison, R. J.; Le Floc'h, E.; Lutz, D.; Magdis, G. E.; Magnelli, B.; Oliver, S. J.; Page, M. J.; Pozzi, F.; Rigopoulou, D.; Riguccini, L.; Roseboom, I. G.; Sanders, D. B.; Scott, D.; Seymour, N.; Valtchanov, I.; Vieira, J. D.; Viero, M.; Wardlow, J. (IOP Publishing Ltd., 2012-12)
    We present spectroscopic observations for a sample of 36 Herschel-Spire 250-500 mu m selected galaxies (HSGs) at 2 < z < 5 from the Herschel Multi-tiered Extragalactic Survey. Redshifts are confirmed as part of a large redshift survey of Herschel-Spire-selected sources covering similar to 0.93 deg(2) in six extragalactic legacy fields. Observations were taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. Precise astrometry, needed for spectroscopic follow-up, is determined by identification of counterparts at 24 mu m or 1.4 GHz using a cross-identification likelihood matching method. Individual source luminosities range from log(L-IR/L-circle dot) = 12.5-13.6 (corresponding to star formation rates (SFRs) 500-9000M(circle dot) yr(-1), assuming a Salpeter initial mass function), constituting some of the most intrinsically luminous, distant infrared galaxies discovered thus far. We present both individual and composite rest-frame ultraviolet spectra and infrared spectral energy distributions. The selection of these HSGs is reproducible and well characterized across large areas of the sky in contrast to most z > 2 HyLIRGs in the literature, which are detected serendipitously or via tailored surveys searching only for high-z HyLIRGs; therefore, we can place lower limits on the contribution of HSGs to the cosmic star formation rate density (SFRD) at (7 +/- 2) x 10(-3) M-circle dot yr(-1) h(3) Mpc(-3) at z similar to 2.5, which is > 10% of the estimated total SFRD of the universe from optical surveys. The contribution at z similar to 4 has a lower limit of 3 x 10(-3) M-circle dot yr(-1) h(3) Mpc(-3), greater than or similar to 20% of the estimated total SFRD. This highlights the importance of extremely infrared-luminous galaxies with high SFRs to the buildup of stellar mass, even at the earliest epochs.
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    A redshift survey of Herschel far-infrared selected starbursts and implications for obscured star formation
    Casey, C. M.; Berta, S.; Bethermin, M.; Bock, J.; Bridge, C. R.; Budynkiewicz, J.; Burgarella, D.; Chapin, E.; Chapman, S. C.; Clements, D. L.; Conley, A.; Conselice, C. J.; Cooray, A.; Farrah, D.; Hatziminaoglou, E.; Ivison, R. J.; Le Floc'h, E.; Lutz, D.; Magdis, G. E.; Magnelli, B.; Oliver, S. J.; Page, M. J.; Pozzi, F.; Rigopoulou, D.; Riguccini, L.; Roseboom, I. G.; Sanders, D. B.; Scott, D.; Seymour, N.; Valtchanov, I.; Vieira, J. D.; Viero, M.; Wardlow, J. (IOP Publishing Ltd., 2012-12)
    We present Keck spectroscopic observations and redshifts for a sample of 767 Herschel-SPIRE selected galaxies (HSGs) at 250, 350, and 500 mu m, taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. The redshift distribution of these SPIRE sources from the Herschel Multitiered Extragalactic Survey peaks at z = 0.85, with 731 sources at z < 2 and a tail of sources out to z similar to 5. We measure more significant disagreement between photometric and spectroscopic redshifts ( = 0.29) than is seen in non-infrared selected samples, likely due to enhanced star formation rates and dust obscuration in infrared-selected galaxies. The infrared data are used to directly measure integrated infrared luminosities and dust temperatures independent of radio or 24 mu m flux densities. By probing the dust spectral energy distribution (SED) at its peak, we estimate that the vast majority (72%-83%) of z < 2 Herschel-selected galaxies would drop out of traditional submillimeter surveys at 0.85-1 mm. We find that dust temperature traces infrared luminosity, due in part to the SPIRE wavelength selection biases, and partially from physical effects. As a result, we measure no significant trend in SPIRE color with redshift; if dust temperature were independent of luminosity or redshift, a trend in SPIRE color would be expected. Composite infrared SEDs are constructed as a function of infrared luminosity, showing the increase in dust temperature with luminosity, and subtle change in near-infrared and mid-infrared spectral properties. Moderate evolution in the far-infrared (FIR)/radio correlation is measured for this partially radio-selected sample, with q(IR) proportional to (1 + z)(-0.30 +/- 0.02) at z < 2. We estimate the luminosity function and implied star formation rate density contribution of HSGs at z < 1.6 and find overall agreement with work based on 24 mu m extrapolations of the LIRG, ULIRG, and total infrared contributions. This work significantly increased the number of spectroscopically confirmed infrared-luminous galaxies at z >> 0 and demonstrates the growing importance of dusty starbursts for galaxy evolution studies and the build-up of stellar mass throughout cosmic time.
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    UV-bright nearby early-type galaxies observed in the mid-infrared: evidence for a multi-stage formation history by way of WISE and GALEX imaging
    Petty, S. M.; Neill, J. D.; Jarrett, T. H.; Blain, A. W.; Farrah, Duncan; Rich, R. M.; Tsai, C. W.; Benford, D. J.; Bridge, C. R.; Lake, S. E.; Masci, F. J.; Wright, E. L. (IOP Publishing Ltd., 2013-10)
    In the local universe, 10% of massive elliptical galaxies are observed to exhibit a peculiar property: a substantial excess of ultraviolet emission than what is expected from their old, red stellar populations. Several origins for this ultraviolet excess (UVX) have been proposed including a population of hot young stars and a population of old, blue horizontal branch or extended horizontal branch (BHB or EHB) stars that have undergone substantial mass loss from their outer atmospheres. We explore the radial distribution of UVX in a selection of 49 nearby E/S0-type galaxies by measuring their extended photometry in the UV through mid-infrared (mid-IR) with the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey, and the Wide-field Infrared Survey Explorer (WISE). We compare UV/optical and UV/mid-IR colors with the Flexible Stellar Population Synthesis models, which allow for the inclusion of EHB stars. We find that combined WISE mid-IR and GALEX UV colors are more effective in distinguishing models than optical colors, and that the UV/mid-IR combination is sensitive to the EHB fraction. There are strong color gradients, with the outer radii bluer than the inner half-light radii by similar to 1 mag. This color difference is easily accounted for with an increase in the BHB fraction of 0.25 with radius. We estimated that the average ages for the inner and outer radii are 7.0 +/- 0.3 Gyr, and 6.2 +/- 0.2 Gyr, respectively, with the implication that the outer regions are likely to have formed similar to 1 Gyr after the inner regions. Additionally, we find that metallicity gradients are likely not a significant factor in the color difference. The separation of color between the inner and outer regions, which agrees with a specific stellar population difference (e. g., higher EHB populations), and the similar to 0.5-2 Gyr age difference suggests multi-stage formation. Our results are best explained by inside-out formation: rapid star formation within the core at early epochs (>4 Gyr ago) and at least one later stage starburst event coinciding with z similar to 1.
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    WISE detections of known QSOs at redshifts greater than six
    Blain, A. W.; Assef, R.; Stern, D.; Tsai, C. W.; Eisenhardt, P.; Bridge, C. R.; Benford, D.; Jarrett, T.; Cutri, R.; Petty, S.; Wu, J. W.; Wright, E. L. (IOP Publishing Ltd., 2013-12)
    We present WISE All-Sky mid-infrared (IR) survey detections of 55% (17/31) of the known QSOs at z > 6 from a range of surveys: the SDSS, the CFHT-LS, FIRST, Spitzer, and UKIDSS. The WISE catalog thus provides a substantial increase in the quantity of IR data available for these sources: 17 are detected in the WISE W1 (3.4 mu m) band, 16 in W2 (4.6 mu m), 3 in W3 (12 mu m), and 0 in W4 (22 mu m). This is particularly important with Spitzer in its warm-mission phase and no faint follow-up capability at wavelengths longward of 5 mu m until the launch of James Webb Space Telescope (JWST). WISE thus provides a useful tool for understanding QSOs found in forthcoming large-area optical/IR sky surveys using PanSTARRS, SkyMapper, VISTA, DES, and LSST. The rest-UV properties of the WISE-detected and the WISE-non-detected samples differ: the detections have brighter i/z-band magnitudes and redder rest-UV colors. This suggests that a more aggressive hunt for very high redshift QSOs by combining WISE W1 and W2 data with red, observed optical colors could be effective at least for a subset of dusty candidate QSOs. Stacking the WISE images of the WISE-non-detected QSOs indicates that they are, on average, significantly fainter than the WISE-detected examples, and are thus not narrowly missing detection in the WISE catalog. The WISE catalog detection of three of our sample in the W3 band indicates that their mid-IR flux can be detected individually, although there is no stacked W3 detection of sources detected in W1 but not W3. Stacking analyses of WISE data for large active galactic nucleus samples will be a useful tool, and high-redshift QSOs of all types will be easy targets for JWST.