Showing papers by "Simon Dye published in 2013"
Harvard University1, University of La Laguna2, Spanish National Research Council3, Open University4, University of California, Berkeley5, Paris Diderot University6, University of Iowa7, University of Maryland, College Park8, University of Cambridge9, Institut d'Astrophysique de Paris10, Cornell University11, Rutgers University12, University of Bristol13, California Institute of Technology14, University of Nottingham15, Imperial College London16, INAF17, University of Canterbury18, Cardiff University19, Virginia Tech20, Pontifical Catholic University of Chile21, UK Astronomy Technology Centre22, University of Edinburgh23, University of Sussex24, University of British Columbia25, University of Oxford26
TL;DR: In this article, the authors presented a 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.
Abstract: 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 μm 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 × 1012 L ☉) and two decades in FIR luminosity surface density (median ΣFIR = 6.0 × 1011 L ☉ 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.
226 citations
University of California, Irvine1, California Institute of Technology2, Ames Research Center3, University of Edinburgh4, Paris Diderot University5, Rutgers University6, University of Paris-Sud7, Harvard University8, Jet Propulsion Laboratory9, Aix-Marseille University10, University of La Laguna11, Spanish National Research Council12, University of Hawaii13, Complutense University of Madrid14, European Space Agency15, University of Cambridge16, Imperial College London17, University of Colorado Boulder18, University of Nottingham19, Cardiff University20, University of Sussex21, Virginia Tech22, University of Padua23, First Green Bank24, Institut d'Astrophysique de Paris25, University of Maryland, College Park26, UK Astronomy Technology Centre27, University of British Columbia28, University College London29, Rutherford Appleton Laboratory30, Open University31, University of Oxford32, Commonwealth Scientific and Industrial Research Organisation33, University of the Western Cape34
TL;DR: In this paper, the authors presented 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^(
Abstract: 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 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.
193 citations
TL;DR: In this article, the authors present the results from nine years of optically monitoring the gravitationally lensed z(QSO) = 0.658 quasar RX J1131-1231.
Abstract: We present the results from nine years of optically monitoring the gravitationally lensed z(QSO) = 0.658 quasar RX J1131-1231. The R-band light curves of the four individual images of the quasar were obtained using deconvolution photometry for a total of 707 epochs. Several sharp quasar variability features strongly constrain the time delays between the quasar images. Using three different numerical techniques, we measured these delays for all possible pairs of quasar images while always processing the four light curves simultaneously. For all three methods, the delays between the three close images A, B, and C are compatible with being 0, while we measured the delay of image D to be 91 days, with a fractional uncertainty of 1.5% (1 sigma), including systematic errors. Our analysis of random and systematic errors accounts in a realistic way for the observed quasar variability, fluctuating microlensing magnification over a broad range of temporal scales, noise properties, and seasonal gaps. Finally, we find that our time-delay measurement methods yield compatible results when applied to subsets of the data.
164 citations
Institut d'Astrophysique de Paris1, Centre national de la recherche scientifique2, Harvard University3, Leiden University4, Cornell University5, California Institute of Technology6, University of Nottingham7, University of Edinburgh8, Max Planck Society9, University of Pennsylvania10, Ghent University11, Rutgers University12, University of Bonn13, University of California, Irvine14, University of Vienna15, Cardiff University16, Purple Mountain Observatory17, University of Maryland, College Park18, University of Oxford19, University of the Western Cape20, Paris Diderot University21, University of South Africa22, International School for Advanced Studies23, Open University24, Ames Research Center25, University of Canterbury26, Imperial College London27, Pontifical Catholic University of Chile28, University of Colorado Boulder29
TL;DR: Using the IRAM Plateau de Bure interferometer (PdBI), this paper detected water vapor in six new lensed ultra-luminous starburst galaxies at high redshift, discovered in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS).
Abstract: Using the IRAM Plateau de Bure interferometer (PdBI), we report the detection of water vapor in six new lensed ultra-luminous starburst galaxies at high redshift, discovered in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). The sources are detected either in the 2$_{02}$-1$_{11}$ or 2$_{11}$-2$_{02}$ H$_{2}$O emission lines with integrated line fluxes ranging from 1.8 to 14 Jy km s$^{-1}$. The corresponding apparent luminosities are {$μ$}L$_{H2}$O ~{} 3-12 { imes} 10$^{8}$ L$_{⊙}$, where {$μ$} is the lensing magnification factor (3 {lt} {$μ$} {lt} 12). These results confirm that H$_{2}$O lines are among the strongest molecular lines in high-z ultra-luminous starburst galaxies, with intensities almost comparable to those of the high-J CO lines, and similar profiles and line widths (~{}200-900 km s$^{-1}$). With the current sensitivity of the PdBI, the water lines can therefore easily be detected in high-z lensed galaxies (with F(500 {$μ$}m) {gt} 100 mJy) discovered in the Herschel surveys. Correcting the luminosities for amplification, using existing lensing models, L$_{H2}$O is found to have a strong dependence on the infrared luminosity, varying as ~{}L$_{IR}$$^{1.2}$. This relation, which needs to be confirmed with better statistics, may indicate a role of radiative (infrared) excitation of the H$_{2}$O lines, and implies that high-z galaxies with L$_{IR}$ {gsim} 10$^{13}$ L$_{⊙}$ tend to be very strong emitters in water vapor, that have no equivalent in the local universe. Herschel (Pilbratt et al. 2010) is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
89 citations
TL;DR: In this paper, the authors used IRAM PdBI to detect H2O in six new lensed ultra-luminous starburst galaxies at high redshift, discovered in the Herschel H-ATLAS survey.
Abstract: Using IRAM PdBI we report the detection of H2O in six new lensed ultra-luminous starburst galaxies at high redshift, discovered in the Herschel H-ATLAS survey. The sources are detected either in the 2_{02}-1_{11} or 2_{11}-2_{02} H_2O emission lines with integrated line fluxes ranging from 1.8 to 14 Jy.km/s. The corresponding apparent luminosities are mu x L_H2O ~ 3-12 x 10^8 Lo, where mu is the lensing magnification factor (3 100 mJy) discovered in the Herschel surveys. Correcting the luminosities for lensing amplification, L_H2O is found to have a strong dependence on the IR luminosity, varying as ~L_IR^{1.2}. This relation which needs to be confirmed with better statistics, may indicate a role of radiative (IR) excitation of the H2O lines, and implies that high-z galaxies with L_IR >~ 10^13 Lo tend to be very strong emitters in H2O, that have no equivalent in the local universe.
88 citations
University of Hertfordshire1, University of Sydney2, University of Oxford3, University of the Western Cape4, Ghent University5, Liverpool John Moores University6, Australian Astronomical Observatory7, University of California, Irvine8, University of Cambridge9, Imperial College London10, International School for Advanced Studies11, INAF12, University of St Andrews13, University of Western Australia14, University of Canterbury15, University of Nottingham16, Cardiff University17, Open University18, European Southern Observatory19, University of Edinburgh20, Institute of Cosmology and Gravitation, University of Portsmouth21
TL;DR: In this paper, the authors constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields.
Abstract: We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources (‘high-excitation radio galaxies’) have, on average, a factor of ∼4 higher 250-μm Herschel luminosity than weak-line (‘low-excitation’) radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3–4 higher than those in the weak-line objects. Our conclusion is consistent with earlier work, generally carried out using much smaller samples, and reinforces the general picture of high-excitation radio galaxies as being located in lower-mass, less evolved host galaxies than their low-excitation counterparts.
74 citations
Cardiff University1, University of Canterbury2, Spanish National Research Council3, National Radio Astronomy Observatory4, University of Pennsylvania5, Ghent University6, Rutgers University7, University of Nottingham8, Jet Propulsion Laboratory9, University of California, Irvine10, Imperial College London11, International School for Advanced Studies12, INAF13, University of Maryland, College Park14, UK Astronomy Technology Centre15, University of Oxford16, University of Rome Tor Vergata17, University of Edinburgh18, University of British Columbia19, European Space Agency20, Leiden University21, California Institute of Technology22
TL;DR: In this paper, the authors used the rest-frame spectral energy distribution (SED) of a typical H-ATLAS source and the observed Herschel fluxes to estimate the redshifts of the sources.
Abstract: Upon its completion, the Herschel Astrophysics Terahertz Large Area Survey (H-ATLAS) will be the largest sub-millimetre survey to date, detecting close to half-a-million sources. It will only be possible to measure spectroscopic redshifts for a small fraction of these sources. However, if the rest-frame spectral energy distribution (SED) of a typical H-ATLAS source is known, this SED and the observed Herschel fluxes can be used to estimate the redshifts of the H-ATLAS sources without spectroscopic redshifts. In this paper, we use a sub-set of 40 H-ATLAS sources with previously measured redshifts in the range 0.5 1, we estimate that the rms of Δz/(1 + z) = 0.12. We have used this template to estimate the redshift distribution for the sources detected in the H-ATLAS equatorial fields, finding a bimodal distribution with a mean redshift of 1.2, 1.9 and 2.5 for 250, 350 and 500 μm selected sources, respectively.
64 citations
University of Nottingham1, University of Canterbury2, University of Manchester3, Cardiff University4, University of Hertfordshire5, Ghent University6, University of South Africa7, University of Bristol8, University of California, Irvine9, University of Cambridge10, International School for Advanced Studies11, INAF12, Imperial College London13, Open University14, Pontifical Catholic University of Chile15, UK Astronomy Technology Centre16, University of the Western Cape17, University of Edinburgh18
TL;DR: In this paper, an analysis of CO molecular gas tracers in a sample of 500-μm-selected Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) galaxies at z < 0.05 (cz < 14990 km/s−1).
Abstract: We present an analysis of CO molecular gas tracers in a sample of 500 μm-selected Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) galaxies at z < 0.05 (cz < 14990 km s−1). Using 22-500 μm photometry from Wide-Field Infrared Survey Explorer, Infrared Astronomical Satellite and Herschel, with H i data from the literature, we investigate correlations between warm and cold dust, and tracers of the gas in different phases. The correlation between global CO(3–2) line fluxes and far-infrared (FIR)-submillimetre (submm) fluxes weakens with increasing infrared wavelength (λ ≳ 60 μm), as a result of colder dust being less strongly associated with dense gas. Conversely, CO(2–1) and H i line fluxes both appear to be better correlated with longer wavelengths, suggesting that cold dust is more strongly associated with diffuse atomic and molecular gas phases, consistent with it being at least partially heated by radiation from old stellar populations. The increased scatter at long wavelengths implies that submm fluxes are a poorer tracer of star formation rate (SFR). Fluxes at 22 and 60 μm are also better correlated with diffuse gas tracers than dense CO(3–2), probably due to very small grain emission in the diffuse interstellar medium, which is not correlated with SFR. The FIR/CO luminosity ratio and the dust mass/CO luminosity ratio both decrease with increasing luminosity, as a result of either correlations between mass and metallicity (changing CO/H2) or between CO luminosity and excitation [changing CO(3–2)/CO(1–0)].
39 citations
University of Edinburgh1, UK Astronomy Technology Centre2, Imperial College London3, Open University4, Cornell University5, University of Nottingham6, INAF7, European Space Agency8, Ghent University9, International School for Advanced Studies10, University of Canterbury11, Cardiff University12, Pontifical Catholic University of Chile13, Leiden University14
TL;DR: In this paper, the authors reported the redshift of HATLAS J132427.0+284452, a gravitationally lensed starburst galaxy, the first determined "blind" by the Herschel Space Observatory.
Abstract: 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.
34 citations
Spanish National Research Council1, INAF2, International School for Advanced Studies3, Queen Mary University of London4, University of Hertfordshire5, University of the Western Cape6, University of Oxford7, Max Planck Society8, University of Melbourne9, Cardiff University10, Ghent University11, University of California, Irvine12, Imperial College London13, University of Canterbury14, University of Nottingham15, Open University16, UK Astronomy Technology Centre17, University of Edinburgh18
TL;DR: In this article, the First Radio Source Catalogue (FIRST) has been used to search for blazars at sub-mm wavelengths in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS).
Abstract: The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) provides an unprecedented opportunity to search for blazars at sub-mm wavelengths. We cross-matched the FIRST radio source catalogue with the 11655 sources brighter than 35 mJy at 500{\mu}m in the \sim 135 square degrees of the sky covered by the H-ATLAS equatorial fields at 9 h and 15 h, plus half of the field at 12 h. We found that 379 of the H-ATLAS sources have a FIRST counterpart within 10 arcsec, including 8 catalogued blazars (plus one known blazar that was found at the edge of one the H-ATLAS maps). To search for additional blazar candidates we have devised new diagnostic diagrams and found that known blazars occupy a region of the log(S500{\mu}m/S350{\mu}m) vs. log(S500{\mu}m/S1.4GHz) plane separated from that of the other sub-mm sources with radio counterparts. Using this diagnostic we have selected 12 further candidates that turn out to be scattered in the (r-z) vs. (u-r) plane or in the WISE colour-colour diagram proposed by Massaro et al. (2012), where known blazars are concentrated in well defined strips. This suggests that the majority of them either are not blazars or have spectral energy distributions contaminated by their host galaxies. A significant fraction of true blazars are found to be hosted by star-forming galaxies. This finding, supported by an analysis of blazars detected in Planck 545 and 857 GHz bands, is at odds with the notion that blazar hosts are passive ellipticals and indicates that the sub-mm selection is providing a novel prospect on blazar properties. Based on an inspection of the available photometric data, including the WISE all-sky survey, the unpublished VIKING survey and new radio observations, we tentatively estimate that there are 11 blazars with synchrotron flux density S500{\mu}m > 35mJy over the considered area. This result already allows us to constrain blazar evolution models.
19 citations
Harvard University1, Spanish National Research Council2, University of La Laguna3, Open University4, University of California, Berkeley5, Paris Diderot University6, University of Iowa7, University of Maryland, College Park8, University of Cambridge9, Institut d'Astrophysique de Paris10, Cornell University11, Rutgers University12, University of Bristol13, California Institute of Technology14, University of Nottingham15, Imperial College London16, INAF17, University of Canterbury18, Cardiff University19, Virginia Tech20, Pontifical Catholic University of Chile21, UK Astronomy Technology Centre22, University of Edinburgh23, University of Sussex24, University of British Columbia25, University of Oxford26
TL;DR: In this article, a visibility-plane lens modeling technique was applied to the SMA data to recover information about the masses of the lenses as well as the intrinsic sizes and luminosities of the lensed sub-millimeter galaxies.
Abstract: 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 (multiply imaged), 4 are moderately lensed (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 (ie, 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>07, 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 500um 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=79x10^12 L_sun) and two decades in FIR luminosity surface density (median Sigma_FIR=60x10^11 L_sun 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