Showing papers by "Jason Glenn published in 2013"
California Institute of Technology1, Cornell University2, Jet Propulsion Laboratory3, Imperial College London4, Spanish National Research Council5, University of La Laguna6, UK Astronomy Technology Centre7, University of Edinburgh8, University of Colorado Boulder9, University of California, Irvine10, University of Sussex11, University of Pennsylvania12, European Space Agency13, Goddard Space Flight Center14, University of Paris-Sud15, Paris Diderot University16, Aix-Marseille University17, University of Cambridge18, Virginia Tech19, University of Padua20, Institut d'Astrophysique de Paris21, Harvard University22, University of British Columbia23, University of Minnesota24, Japan Aerospace Exploration Agency25, University College London26, Johns Hopkins University27
TL;DR: Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.
Abstract: Massive present-day early-type (elliptical and lenticular) galaxies probably gained the bulk of their stellar mass and heavy elements through intense, dust-enshrouded starbursts--that is, increased rates of star formation--in the most massive dark-matter haloes at early epochs. However, it remains unknown how soon after the Big Bang massive starburst progenitors exist. The measured redshift (z) distribution of dusty, massive starbursts has long been suspected to be biased low in z owing to selection effects, as confirmed by recent findings of systems with redshifts as high as ~5 (refs 2-4). Here we report the identification of a massive starburst galaxy at z = 6.34 through a submillimetre colour-selection technique. We unambiguously determined the redshift from a suite of molecular and atomic fine-structure cooling lines. These measurements reveal a hundred billion solar masses of highly excited, chemically evolved interstellar medium in this galaxy, which constitutes at least 40 per cent of the baryonic mass. A `maximum starburst' converts the gas into stars at a rate more than 2,000 times that of the Milky Way, a rate among the highest observed at any epoch. Despite the overall downturn in cosmic star formation towards the highest redshifts, it seems that environments mature enough to form the most massive, intense starbursts existed at least as early as 880 million years after the Big Bang.
631 citations
INAF1, University of Bologna2, University of Padua3, Max Planck Society4, University of Provence5, Open University6, University of Trieste7, University of Sussex8, University of Edinburgh9, University of the Western Cape10, Spanish National Research Council11, Federal University of Rio de Janeiro12, University of Cambridge13, Ames Research Center14, Jet Propulsion Laboratory15, California Institute of Technology16, University of La Laguna17, Complutense University of Madrid18, Imperial College London19, University of Colorado Boulder20, University of California, Irvine21, Goddard Space Flight Center22, Cardiff University23, UK Astronomy Technology Centre24, European Space Research and Technology Centre25, University of Paris-Sud26, University of Manchester27, University College London28, University of Lethbridge29, Rutherford Appleton Laboratory30, University of Oxford31, University of British Columbia32, Commonwealth Scientific and Industrial Research Organisation33, University of Hertfordshire34, Harvard University35, Institut d'Astrophysique de Paris36, École Polytechnique Fédérale de Lausanne37, University of Toulouse38
TL;DR: In this article, the authors exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the GPS PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared luminosity functions (LFs) up to z ∼ 4.
Abstract: We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90- and total infrared (IR) luminosity functions (LFs) up to z ∼ 4. We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)3.55 ± 0.10 up to z ∼ 2, and ∝ (1 + z)1.62 ± 0.51 at 2 < z ≲ 4) combined with a density evolution (∝(1 + z)−0.57 ± 0.22 up to z ∼ 1 and ∝ (1 + z)−3.92 ± 0.34 at 1 < z ≲ 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ∼ 1, then flattens between z ∼ 1 and z ∼ 3 to decrease at z ≳ 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR–stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (∼20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z < 2.2 range. Sources with mass in the range 10 ≤ log(M/M⊙) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z (≳2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand, moderately star-forming galaxies containing a low-luminosity AGN have various properties suggesting they are good candidates for systems in a transition phase preceding the formation of steady spiral galaxies.
461 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, Virginia Tech21, University of Sussex22, 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, Open University30, Rutherford Appleton Laboratory31, 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
University College London1, University of Padua2, University of the Western Cape3, Max Planck Society4, Paris Diderot University5, Jet Propulsion Laboratory6, California Institute of Technology7, Aix-Marseille University8, Imperial College London9, University of Colorado Boulder10, European Space Agency11, University of California, Irvine12, Virginia Tech13, Cardiff University14, Smithsonian Astrophysical Observatory15, UK Astronomy Technology Centre16, University of Provence17, University of Oxford18, Tel Aviv University19, University of Sussex20, Institut d'Astrophysique de Paris21, University of Lethbridge22, Rutherford Appleton Laboratory23, University of La Laguna24, Spanish National Research Council25, INAF26, Ames Research Center27, University of British Columbia28, Commonwealth Scientific and Industrial Research Organisation29
TL;DR: In this paper, the authors examined the dust properties of infrared (IR)-luminous (LIR > 1010 L⊙) galaxies at 0.1 45 K.
Abstract: Using Herschel data from the deepest SPIRE and PACS surveys (HerMES and PEP) in COSMOS, GOODS-S and GOODS-N, we examine the dust properties of infrared (IR)-luminous (LIR > 1010 L⊙) galaxies at 0.1 45 K) SEDs and cold (T < 25 K), cirrus-dominated SEDs are rare, with most sources being within the range occupied by warm starbursts such as M82 and cool spirals such as M51. We observe a luminosity–temperature (L-T) relation, where the average dust temperature of log [LIR/L⊙] ∼ 12.5 galaxies is about 10 K higher than that of their log [LIR/L⊙] ∼ 10.5 counterparts. However, although the increased dust heating in more luminous systems is the driving factor behind the L-T relation, the increase in dust mass and/or starburst size with luminosity plays a dominant role in shaping it. Our results show that the dust conditions in IR-luminous sources evolve with cosmic time: at high redshift, dust temperatures are on average up to 10 K lower than what is measured locally (z ≲ 0.1). This is manifested as a flattening of the L-T relation, suggesting that (ultra)luminous infrared galaxies [(U)LIRGs] in the early Universe are typically characterized by a more extended dust distribution and/or higher dust masses than local equivalent sources. Interestingly, the evolution in dust temperature is luminosity dependent, with the fraction of LIRGs with T < 35 K showing a two-fold increase from z ∼ 0 to z ∼ 2, whereas that of ULIRGs with T < 35 K shows a six-fold increase. Our results suggest a greater diversity in the IR-luminous population at high redshift, particularly for ULIRGs.
188 citations
TL;DR: A re-reduction and expansion of the Bolocam Galactic Plane Survey (BGPS) was presented by Aguirre et al. and Rosolowsky et.al..
Abstract: We present a re-reduction and expansion of the Bolocam Galactic Plane Survey (BGPS), first presented by Aguirre et al. and Rosolowsky et al. The BGPS is a 1.1 mm survey of dust emission in the Northern galactic plane, covering longitudes –10° < l < 90° and latitudes |b| < 0.°5 with a typical 1σ rms sensitivity of 30-100 mJy in a ~33'' beam. Version 2 of the survey includes an additional ~20 deg2 of coverage in the third and fourth quadrants and ~2 deg2 in the first quadrant. The new data release has improved angular recovery, with complete recovery out to ~80'' and partial recovery to ~300'', and reduced negative bowls around bright sources resulting from the atmospheric subtraction process. We resolve the factor of 1.5 flux calibration offset between the v1.0 data release and other data sets and determine that there is no offset between v2.0 and other data sets. The v2.0 pointing accuracy is tested against other surveys and is demonstrated to be accurate and an improvement over v1.0. We present simulations and tests of the pipeline and its properties, including measurements of the pipeline's angular transfer function. The Bolocat cataloging tool was used to extract a new catalog, which includes 8594 sources, with 591 in the expanded regions. We have demonstrated that the Bolocat 40'' and 80'' apertures are accurate even in the presence of strong extended background emission. The number of sources is lower than in v1.0, but the amount of flux and area included in identified sources is larger.
166 citations
California Institute of Technology1, Durham University2, University of Sussex3, Jet Propulsion Laboratory4, University of Oxford5, Ames Research Center6, University of Edinburgh7, Paris Diderot University8, University of Paris-Sud9, University of Hawaii10, Imperial College London11, University of Colorado Boulder12, University of California, Irvine13, INAF14, Virginia Tech15, University of Padua16, Cardiff University17, European Southern Observatory18, Pontifical Catholic University of Chile19, UK Astronomy Technology Centre20, University of British Columbia21, Institut d'Astrophysique de Paris22, University College London23, Rutherford Appleton Laboratory24, Open University25, University of La Laguna26, Spanish National Research Council27, Commonwealth Scientific and Industrial Research Organisation28, University of the Western Cape29
TL;DR: In this paper, the authors measured the auto-and cross-frequency power spectra of the cosmic infrared background (CIB) at 250, 350, and 500 μm (1200, 860, and 600 GHz) from observations totaling ~70 deg2 made with the SPIRE instrument aboard the Herschel Space Observatory.
Abstract: We present measurements of the auto- and cross-frequency power spectra of the cosmic infrared background (CIB) at 250, 350, and 500 μm (1200, 860, and 600 GHz) from observations totaling ~70 deg2 made with the SPIRE instrument aboard the Herschel Space Observatory. We measure a fractional anisotropy δI/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 θ ~ 0.10-0.12 arcmin–1 (l ~ 2160-2380), from 250 to 500 μm. 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 ~ 1-3, is log(M peak/M ☉) ~ 12.1 ± 0.5, and that the minimum halo mass to host infrared galaxies is log(M min/M ☉) ~ 10.1 ± 0.6.
161 citations
California Institute of Technology1, Carnegie Learning2, University of Edinburgh3, Diego Portales University4, Jet Propulsion Laboratory5, Paris Diderot University6, University of Paris-Sud7, University of Hawaii8, University of Colorado Boulder9, University of California, Irvine10, Virginia Tech11, Centre national de la recherche scientifique12, UK Astronomy Technology Centre13, Pontifical Catholic University of Chile14, University of Tokyo15, University of British Columbia16, University of Sussex17, University of the Western Cape18, Durham University19, University of Massachusetts Amherst20
TL;DR: In this paper, the authors quantify the fraction of the cosmic infrared background (CIB) that originates from galaxies identified in the UV/optical/near-infrared by stacking 81,250 (~35.7 arcmin^(2)) K-selected sources (K_(AB) 350 μm).
Abstract: 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 (~35.7 arcmin^(–2)) K-selected sources (K_(AB) 350 μm. The contribution from galaxies in the log(M/M_☉) = 9.0-9.5 (lowest) and log(M/M_☉) = 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 ≳ 2. The luminosities of the galaxies responsible for the CIB shifts from combinations of "normal" and luminous infrared galaxies (LIRGs) at λ ≾ 160 μm, to LIRGs at 160 ≾ λ ≾ 500 μm, to finally LIRGs and ultra-luminous infrared galaxies at λ ≳ 500 μm. 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/~viero/viero_homepage/toolbox.html.
146 citations
California Institute of Technology1, Jet Propulsion Laboratory2, University of Colorado Boulder3, University of Edinburgh4, University of British Columbia5, Paris Diderot University6, University of Bonn7, Aix-Marseille University8, Spanish National Research Council9, University of La Laguna10, University of Hawaii11, University of Cambridge12, Dalhousie University13, Imperial College London14, European Space Agency15, University of California, Irvine16, University of Vienna17, Virginia Tech18, University of Padua19, Cardiff University20, Harvard University21, UK Astronomy Technology Centre22, Pontifical Catholic University of Chile23, Open University24, University of Sussex25, Institut d'Astrophysique de Paris26, University College London27, Rutherford Appleton Laboratory28, Cornell University29, University of Oxford30, Commonwealth Scientific and Industrial Research Organisation31, University of the Western Cape32
TL;DR: In this article, a method for selecting z > 4 dusty, star-forming galaxies (DSFGs) using Herschel/Spectral and Photometric Imaging Receiver 250/350/500 μm flux densities to search for red sources was presented.
Abstract: We present a method for selecting z > 4 dusty, star-forming galaxies (DSFGs) using Herschel/Spectral and Photometric Imaging Receiver 250/350/500 μm flux densities to search for red sources. We apply this method to 21 deg2 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 μm) 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 μm ≥ 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 ~ 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.
138 citations
TL;DR: A re-reduction and expansion of the Bolocam Galactic Plane Survey (BGPS) was presented by Aguirre et al. as mentioned in this paper, which includes an additional 20 square degrees of coverage in the 3rd and 4th quadrants and 2 square degrees in the 1st quadrant.
Abstract: We present a re-reduction and expansion of the Bolocam Galactic Plane Survey, first presented by Aguirre et al. (2011) and Rosolowsky et al. (2010). The BGPS is a 1.1 mm survey of dust emission in the Northern galactic plane, covering longitudes -10 < \ell < 90 and latitudes |b| < 0.5 with a typical 1-\sigma RMS sensitivity of 30-100 mJy in a 33" beam. Version 2 of the survey includes an additional 20 square degrees of coverage in the 3rd and 4th quadrants and 2 square degrees in the 1st quadrant. The new data release has improved angular recovery, with complete recovery out to 80" and partial recovery to 300", and reduced negative bowls around bright sources resulting from the atmospheric subtraction process. We resolve the factor of 1.5 flux calibration offset between the v1.0 data release and other data sets and determine that there is no offset between v2.0 and other data sets. The v2.0 pointing accuracy is tested against other surveys and demonstrated to be accurate and an improvement over v1.0. We present simulations and tests of the pipeline and its properties, including measurements of the pipeline's angular transfer function. The Bolocat cataloging tool was used to extract a new catalog, which includes 8594 sources, with 591 in the expanded regions. We have demonstrated that the Bolocat 40" and 80" apertures are accurate even in the presence of strong extended background emission. The number of sources is lower than in v1.0, but the amount of flux and area included in identified sources is larger.
107 citations
TL;DR: In this article, the authors present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO+ and N2H+ 3-2, for all 6194 sources in the Bolocam Galactic Plane Survey v1.0.
Abstract: The Bolocam Galactic Plane Survey (BGPS) is a 1.1 mm continuum survey of dense clumps of dust throughout the Galaxy covering 170 square degrees. We present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO+ and N2H+ 3-2, for all 6194 sources in the Bolocam Galactic Plane Survey v1.0.1 catalog between 7.5 0.5 K) without HCO+ 3-2 emission does not occur in this catalog. We characterize the properties of the dense molecular gas emission toward the entire sample. HCO+ is very sub-thermally populated and the 3-2 transitions are optically thick toward most BGPS clumps. The median observed line width is 3.3 km/s consistent with supersonic turbulence within BGPS clumps. We find strong correlations between dense molecular gas integrated intensities and 1.1 mm peak flux and the gas kinetic temperature derived from previously published NH3 observations. These intensity correlations are driven by the sensitivity of the 3-2 transitions to excitation conditions rather than by variations in molecular column density or abundance. We identify a subset of 113 sources with stronger N2H+ than HCO+ integrated intensity, but we find no correlations between the N2H+ / HCO+ ratio and 1.1 mm continuum flux density, gas kinetic temperature, or line width. Self-absorbed profiles are rare (1.3%).
92 citations
Institut d'Astrophysique de Paris1, Centre national de la recherche scientifique2, Harvard University3, Leiden University4, California Institute of Technology5, Cornell University6, 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 the Western Cape19, University of Oxford20, 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.
TL;DR: In this paper, a calibration framework for point source and extended source cases, and also the intermediate case of a semi-extended source profile, is presented for the Spectral and Photometric Imaging Receiver (SPIRE) on board the Herschel Space Observatory.
Abstract: Photometric instruments operating at far-infrared to millimetre wavelengths often have broad spectral passbands (λ/Δλ ∼ 3 or less), especially those operating in space. A broad passband can result in significant variation of the beam profile and aperture efficiency across the passband, effects which thus far have not generally been taken into account in the flux calibration of such instruments. With absolute calibration uncertainties associated with the brightness of primary calibration standards now in the region of 5 per cent or less, variation of the beam properties across the passband can be a significant contributor to the overall calibration accuracy for extended emission. We present a calibration framework which takes such variations into account for both antenna-coupled and absorber-coupled focal plane architectures. The scheme covers point source and extended source cases, and also the intermediate case of a semi-extended source profile. We apply the new method to the Spectral and Photometric Imaging Receiver (SPIRE) photometer on board the Herschel Space Observatory.
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.
TL;DR: In this article, the authors present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO+ and N2H+ 3-2, for all 6194 sources in the Bolocam Galactic Plane Survey (BGPS) v1.0.
Abstract: The Bolocam Galactic Plane Survey (BGPS) is a 1.1 mm continuum survey of dense clumps of dust throughout the Galaxy covering 170 deg2. We present spectroscopic observations using the Heinrich Hertz Submillimeter Telescope of the dense gas tracers, HCO+ and N2H+ 3-2, for all 6194 sources in the BGPS v1.0.1 catalog between 7.?5 ? l ? 194?. This is the largest targeted spectroscopic survey of dense molecular gas in the Milky Way to date. We find unique velocities for 3126 (50.5%) of the BGPS v1.0.1 sources observed. Strong N2H+ 3-2 emission (T mb > 0.5 K) without HCO+ 3-2 emission does not occur in this catalog. We characterize the properties of the dense molecular gas emission toward the entire sample. HCO+ is very sub-thermally populated and the 3-2 transitions are optically thick toward most BGPS clumps. The median observed line width is 3.3?km?s?1 consistent with supersonic turbulence within BGPS clumps. We find strong correlations between dense molecular gas integrated intensities and 1.1 mm peak flux and the gas kinetic temperature derived from previously published NH3 observations. These intensity correlations are driven by the sensitivity of the 3-2 transitions to excitation conditions rather than by variations in molecular column density or abundance. We identify a subset of 113 sources with stronger N2H+ than HCO+ integrated intensity, but we find no correlations between the N2H+/HCO+ ratio and 1.1 mm continuum flux density, gas kinetic temperature, or line width. Self-absorbed profiles are rare (1.3%).
TL;DR: In this article, a new distance estimation method for dust-continuum-identified molecular cloud clumps is presented, which is based on kinematic distance ambiguity (KDA) for objects in the inner Galaxy.
Abstract: We present a new distance estimation method for dust-continuum-identified molecular cloud clumps. Recent (sub-)millimeter Galactic plane surveys have cataloged tens of thousands of these objects, plausible precursors to stellar clusters, but detailed study of their physical properties requires robust distance determinations. We derive Bayesian distance probability density functions (DPDFs) for 770 objects from the Bolocam Galactic Plane Survey in the Galactic longitude range 7. Degree-Sign 5 {<=} l {<=} 65 Degree-Sign . The DPDF formalism is based on kinematic distances, and uses any number of external data sets to place prior distance probabilities to resolve the kinematic distance ambiguity (KDA) for objects in the inner Galaxy. We present here priors related to the mid-infrared absorption of dust in dense molecular regions and the distribution of molecular gas in the Galactic disk. By assuming a numerical model of Galactic mid-infrared emission and simple radiative transfer, we match the morphology of (sub-)millimeter thermal dust emission with mid-infrared absorption to compute a prior DPDF for distance discrimination. Selecting objects first from (sub-)millimeter source catalogs avoids a bias towards the darkest infrared dark clouds (IRDCs) and extends the range of heliocentric distance probed by mid-infrared extinction and includes lower-contrast sources. We derive well-constrained KDAmore » resolutions for 618 molecular cloud clumps, with approximately 15% placed at or beyond the tangent distance. Objects with mid-infrared contrast sufficient to be cataloged as IRDCs are generally placed at the near kinematic distance. Distance comparisons with Galactic Ring Survey KDA resolutions yield a 92% agreement. A face-on view of the Milky Way using resolved distances reveals sections of the Sagittarius and Scutum-Centaurus Arms. This KDA-resolution method for large catalogs of sources through the combination of (sub-)millimeter and mid-infrared observations of molecular cloud clumps is generally applicable to other dust-continuum Galactic plane surveys.« less
TL;DR: In this paper, the authors used radiative transfer models to analyze the observed CO spectral line energy distributions (SLEDs) of eleven nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel.
Abstract: We present the sub-millimeter spectra from 450GHz to 1550GHz of eleven nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel. We detect CO transitions from Jup = 4 to 12, as well as the two [C I] fine structure lines at 492 and 809GHz and the [N II]1461GHz line. We used radiative transfer models to analyze the observed CO spectral line energy distributions (SLEDs). The FTS CO data were complemented with groundbased observations of the low-J CO lines. We found that the warm molecular gas traced by the mid-J CO transitions has similar physical conditions (nH2 ∼10 3.2 –10 3.9 cm −3 and Tkin ∼300–800K) in most of our galaxies. Furthermore, we found that this warm gas is likely producing the mid-IR rotational H2 emission. We could not determine the specific heating mechanism of the warm gas, however it is possibly related to the star-formation activity in these galaxies. Our modeling of the [C I] emission suggests that it is produced in cold (Tkin 10 3 cm −3 ) molecular gas. Transitions of other molecules are often detected in our SPIRE/FTS spectra. The HF J = 1−0 transition at 1232GHz is detected in absorption in UGC 05101 and in emission in NGC 7130. In the latter, near-infrared pumping, chemical pumping, or collisional excitation with electrons are plausible excitation mechanisms likely related to the AGN of this galaxy. In some galaxies few H2O emission lines are present. Additionally, three OH + lines at 909, 971, and 1033GHz are identified in NGC 7130.
University of British Columbia1, University of Paris-Sud2, Paris Diderot University3, California Institute of Technology4, Jet Propulsion Laboratory5, Imperial College London6, University of Colorado Boulder7, University of California, Irvine8, University of Edinburgh9, Cardiff University10, Virginia Tech11, University of Padua12, Johns Hopkins University13, UK Astronomy Technology Centre14, University of Sussex15, University College London16, Spanish National Research Council17, University of La Laguna18, European Space Agency19, Leiden University20
TL;DR: In this paper, the average mass and dust content of sub-millimetre galaxies with 250μm flux densities of S_250 > 15μm were determined using data from the Herschel Multi-tiered Extragalactic Survey.
Abstract: Dust emission at submillimetre wavelengths allows us to trace the early phases of star formation in the Universe. In order to understand the physical processes involved in this mode of star formation, it is essential to gain knowledge about the dark matter structures – most importantly their masses – that submillimetre galaxies live in. Here we use the magnification effect of gravitational lensing to determine the average mass and dust content of submillimetre galaxies with 250 μm flux densities of S_250 > 15 mJy selected using data from the Herschel Multi-tiered Extragalactic Survey. The positions of hundreds of submillimetre foreground lenses are cross-correlated with the positions of background Lyman-break galaxies at z ∼ 3–5 selected using optical data from the Canada–France–Hawaii Telescope Legacy Survey. We detect a cross-correlation signal at the 7σ level over a sky area of 1 deg^2, with ∼80 per cent of this signal being due to magnification, whereas the remaining ∼20 per cent comes from dust extinction. Adopting some simple assumptions for the dark matter and dust profiles and the redshift distribution enables us to estimate the average mass of the haloes hosting the submillimetre galaxies to be log _(10)[M_200/M_⊙] =
13.17^(+0.05)_(−0.08)(stat.) and their average dust mass fraction (at radii of >10 kpc) to be M_dust/M_200 ≈ 6 × 10^(−5). This supports the picture that submillimetre galaxies are dusty, forming stars at a high rate, reside in massive group-sized haloes and are a crucial phase in the assembly and evolution of structure in the Universe.
TL;DR: In this paper, the authors derived the necessary corrections using an observed spectrum of a fully extended source with the beam profile and considering the source's light profile, and applied these correction factors for sources with angular sizes up to θD ~ 17′′.
Abstract: The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency’s Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent that is much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source’s light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and considering the source’s light profile. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to θD ~ 17′′. We demonstrate how the angular size of an extended source can be estimated using the difference between the subspectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959 < ν < 989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2′′, which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2.
University of Edinburgh1, McGill University2, Durham University3, University of British Columbia4, Leiden University5, University of Nottingham6, UK Astronomy Technology Centre7, Cardiff University8, University of Leicester9, University of Bristol10, Jet Propulsion Laboratory11, California Institute of Technology12, Dalhousie University13, University of Hertfordshire14, University of Sussex15, University of Colorado Boulder16, Virginia Tech17, Cornell University18, Kapteyn Astronomical Institute19, Ghent University20, University College London21, Herzberg Institute of Astrophysics22
TL;DR: In this article, the authors investigate the multiwavelength properties of a sample of 450-μm-selected sources from the SCUBA-2 Cosmology Legacy Survey, showing a broad peak in the redshift range 1 < z < 3 and a median of z = 1.4.
Abstract: We investigate the multiwavelength properties of a sample of 450-μm-selected sources from the SCUBA-2 Cosmology Legacy Survey. A total of 69 sources were identified above 4σ in deep SCUBA-2 450-μm observations overlapping the UDS and COSMOS fields and covering 210 arcmin2 to a typical depth of σ450 = 1.5 mJy. Reliable cross-identifications are found for 58 sources (84 per cent) in Spitzer and Hubble Space Telescope WFC3/IR data. The photometric redshift distribution (dN/dz) of 450-μm-selected sources is presented, showing a broad peak in the redshift range 1 < z < 3 and a median of z = 1.4. Combining the SCUBA-2 photometry with Herschel SPIRE data from HerMES, the submm spectral energy distribution (SED) is examined via the use of modified blackbody fits, yielding aggregate values for the IR luminosity, dust temperature and emissivity of 〈LIR〉 = 1012 ± 0.8 L⊙, 〈TD〉 = 42 ± 11 K and 〈βD〉 = 1.6 ± 0.5, respectively. The relationship between these SED parameters and the physical properties of galaxies is investigated, revealing correlations between TD and LIR and between βD and both stellar mass and effective radius. The connection between the star formation rate (SFR) and stellar mass is explored, with 24 per cent of 450-μm sources found to be ‘starbursts’, i.e. displaying anomalously high specific SFRs. However, both the number density and observed properties of these ‘starburst’ galaxies are found to be consistent with the population of normal star-forming galaxies.
TL;DR: In this article, the authors derived the necessary corrections using an observed spectrum of a fully extended source with the beam profile and the source's light profile taken into account, and applied the derived correction to several observations of planets and compared the corrected spectra with their spectral models to study the beam coupling efficiency.
Abstract: The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency's Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source's light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and the source's light profile taken into account. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to \theta_{D} ~ 17". We demonstrate how the angular size of an extended source can be estimated using the difference between the sub-spectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959<
u<989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2", which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2.
TL;DR: In this paper, the authors presented the sub-millimeter spectra from 450 GHz to 1550 GHz of eleven nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel.
Abstract: We present the sub-millimeter spectra from 450 GHz to 1550 GHz of eleven nearby active galaxies observed with the SPIRE Fourier Transform Spectrometer (SPIRE/FTS) onboard Herschel. We detect CO transitions from J_up = 4 to 12, as well as the two [CI] fine structure lines at 492 and 809 GHz and the [NII] 461 GHz line. We used radiative transfer models to analyze the observed CO spectral line energy distributions (SLEDs). The FTS CO data were complemented with ground-based observations of the low-J CO lines. We found that the warm molecular gas traced by the mid-J CO transitions has similar physical conditions (n_H2 ~ 10^3.2 - 10^3.9 cm^-3 and T_kin ~ 300 - 800 K) in most of our galaxies. Furthermore, we found that this warm gas is likely producing the mid-IR rotational H2 emission. We could not determine the specific heating mechanism of the warm gas, however it is possibly related to the star-formation activity in these galaxies. Our modeling of the [CI] emission suggests that it is produced in cold (T_kin 10^3 cm^-3) molecular gas. Transitions of other molecules are often detected in our SPIRE/FTS spectra. The HF J=1-0 transition at 1232 GHz is detected in absorption in UGC05101 and in emission in NGC7130. In the latter, near-infrared pumping, chemical pumping, or collisional excitation with electrons are plausible excitation mechanisms likely related to the AGN of this galaxy. In some galaxies few H2O emission lines are present. Additionally, three OH+ lines at 909, 971, and 1033 GHz are identified in NGC7130.
TL;DR: In this paper, the authors used the Herschel SPIRE-FTS observations of the Antennae (NGC 4038/39) to detect CO and [CI] transitions and the [NII]$205\mu m$ transition across the entire system.
Abstract: We present Herschel SPIRE-FTS observations of the Antennae (NGC 4038/39), a well studied, nearby ($22$ Mpc) ongoing merger between two gas rich spiral galaxies. We detect 5 CO transitions ($J=4-3$ to $J=8-7$), both [CI] transitions and the [NII]$205\mu m$ transition across the entire system, which we supplement with ground based observations of the CO $J=1-0$, $J=2-1$ and $J=3-2$ transitions, and Herschel PACS observations of [CII] and [OI]$63\mu m$. Using the CO and [CI] transitions, we perform both a LTE analysis of [CI], and a non-LTE radiative transfer analysis of CO and [CI] using the radiative transfer code RADEX along with a Bayesian likelihood analysis. We find that there are two components to the molecular gas: a cold ($T_{kin}\sim 10-30$ K) and a warm ($T_{kin} \gtrsim 100$ K) component. By comparing the warm gas mass to previously observed values, we determine a CO abundance in the warm gas of $x_{CO} \sim 5\times 10^{-5}$. If the CO abundance is the same in the warm and cold gas phases, this abundance corresponds to a CO $J=1-0$ luminosity-to-mass conversion factor of $\alpha_{CO} \sim 7 \ M_{\odot}{pc^{-2} \ (K \ km \ s^{-1})^{-1}}$ in the cold component, similar to the value for normal spiral galaxies. We estimate the cooling from H$_2$, [CII], CO and [OI]$63\mu m$ to be $\sim 0.01 L_{\odot}/M_{\odot}$. We compare PDR models to the ratio of the flux of various CO transitions, along with the ratio of the CO flux to the far-infrared flux in NGC 4038, NGC 4039 and the overlap region. We find that the densities recovered from our non-LTE analysis are consistent with a background far-ultraviolet field of strength $G_0\sim 1000$. Finally, we find that a combination of turbulent heating, due to the ongoing merger, and supernova and stellar winds are sufficient to heat the molecular gas.
University of Colorado Boulder1, University of Virginia2, National Radio Astronomy Observatory3, University College London4, Ghent University5, Katholieke Universiteit Leuven6, Vrije Universiteit Brussel7, University of Maryland, College Park8, University of Canterbury9, Stockholm University10, Cardiff University11, Royal Observatory of Belgium12, Imperial College London13, Harvard University14, Keele University15, University of Valencia16, Space Telescope Science Institute17, Goddard Space Flight Center18, University of Western Australia19
TL;DR: In this article, the authors reported spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant.
Abstract: We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J = 1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J = 13-12, collectively measured from the Atacama Large Millimeter Array, the Atacama Pathfinder EXperiment, and the Herschel Spectral and Photometric Imaging REceiver. Simple models show the lines are emitted from at least 0.01 M-circle dot of CO at a temperature >14 K, confined within at most 35% of a spherical volume expanding at similar to 2000 km s(-1). Moreover, we locate the emission within 1 '' of the central debris. These observations, along with a partial observation of SiO, confirm the presence of cold molecular gas within supernova remnants and provide insight into the physical conditions and chemical processes in the ejecta. Furthermore, we demonstrate the powerful new window into supernova ejecta offered by submillimeter observations.
California Institute of Technology1, Jet Propulsion Laboratory2, University of Leicester3, University of California, Irvine4, Paris Diderot University5, University of Paris-Sud6, Imperial College London7, University of Colorado Boulder8, European Space Agency9, Virginia Tech10, University of Sussex11, Cardiff University12, University of British Columbia13, Aix-Marseille University14, École Polytechnique Fédérale de Lausanne15, Lyon College16, École normale supérieure de Lyon17, University of Edinburgh18
TL;DR: In this paper, the authors measured the surface brightness of four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measured a deficit of surface brightness within their central region after removing detected sources.
Abstract: We have observed four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measure a deficit of surface brightness within their central region after removing detected sources. We simulate the effects of instrumental sensitivity and resolution, the source population, and the lensing effect of the clusters to estimate the shape and amplitude of the deficit. The amplitude of the central deficit is a strong function of the surface density and flux distribution of the background sources. We find that for the current best fitting faint end number counts, and excellent lensing models, the most likely amplitude of the central deficit is the full intensity of the cosmic infrared background (CIB). Our measurement leads to a lower limit to the integrated total intensity of the CIB of I_{250 \, \mu {m}} \gt 0.69_{-0.03}^{+0.03} ({stat.}) _{-0.06}^{+0.11} ({sys.}) MJy sr-1, with more CIB possible from both low-redshift sources and from sources within the target clusters. It should be possible to observe this effect in existing high angular resolution data at other wavelengths where the CIB is bright, which would allow tests of models of the faint source component of the CIB. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
TL;DR: In this article, the authors measured the surface brightness of four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measured a deficit of surface brightness within their central region after subtracting sources.
Abstract: We have observed four massive galaxy clusters with the SPIRE instrument on the Herschel Space Observatory and measure a deficit of surface brightness within their central region after subtracting sources. We simulate the effects of instrumental sensitivity and resolution, the source population, and the lensing effect of the clusters to estimate the shape and amplitude of the deficit. The amplitude of the central deficit is a strong function of the surface density and flux distribution of the background sources. We find that for the current best fitting faint end number counts, and excellent lensing models, the most likely amplitude of the central deficit is the full intensity of the cosmic infrared background (CIB). Our measurement leads to a lower limit to the integrated total intensity of the CIB of I(250 microns) > 0.69_(-0.03)^(+0.03) (stat.)_(-0.06)^(+0.11) (sys.) MJy/sr, with more CIB possible from both low-redshift sources and from sources within the target clusters. It should be possible to observe this effect in existing high angular resolution data at other wavelengths where the CIB is bright, which would allow tests of models of the faint source component of the CIB.
California Institute of Technology1, University of British Columbia2, University of Edinburgh3, University of Texas at Austin4, Rutgers University5, University of Paris-Sud6, University of Colorado Boulder7, University of Pennsylvania8, Virginia Tech9, Lawrence Berkeley National Laboratory10, University of Zurich11, University of Hertfordshire12, University of Toronto13, University of Rome Tor Vergata14, International School for Advanced Studies15, University of Sussex16, Texas A&M University17, Carnegie Institution for Science18, Princeton University19, Durham University20, Stanford University21
TL;DR: The first set of maps and band-merged catalog from the Herschel Stripe 82 Survey (HerS) was presented in this article. But this survey was designed to measure correlations with external tracers of the dark matter density field, either point-like (radio to X-ray) or extended (i.e., clusters and gravitational lensing) to measure the bias and redshift distribution of intensities of infrared-emitting dusty star-forming galaxies and AGN.
Abstract: We present the first set of maps and band-merged catalog from the Herschel Stripe 82 Survey (HerS). Observations at 250, 350, and 500 micron were taken with the Spectral and Photometric Imaging Receiver (SPIRE) instrument aboard the Herschel Space Observatory. HerS covers 79 deg$^2$ along the SDSS Stripe 82 to a depth of 13.0, 12.9, and 14.8 mJy beam$^{-1}$ (including confusion) at 250, 350, and 500 micron, respectively. HerS was designed to measure correlations with external tracers of the dark matter density field --- either point-like (i.e., galaxies selected from radio to X-ray) or extended (i.e., clusters and gravitational lensing) --- in order to measure the bias and redshift distribution of intensities of infrared-emitting dusty star-forming galaxies and AGN. By locating HeRS in Stripe 82, we maximize the overlap with available and upcoming cosmological surveys. The band-merged catalog contains 3.3x10$^4$ sources detected at a significance of >3 $\sigma$ (including confusion noise). The maps and catalog are available at this http URL
University of Bologna1, University of Padua2, Max Planck Society3, European Southern Observatory4, Aix-Marseille University5, Open University6, University of Sussex7, University of the Western Cape8, Federal University of Rio de Janeiro9, INAF10, University of Cambridge11, Ames Research Center12, California Institute of Technology13, University of La Laguna14, Complutense University of Madrid15, Imperial College London16, University of Colorado Boulder17, University of California, Irvine18, Goddard Space Flight Center19, Cardiff University20, European Space Research and Technology Centre21, University of Paris-Sud22, University of Manchester23, University College London24, Rutherford Appleton Laboratory25, University of Lethbridge26, University of Oxford27, University of British Columbia28, Commonwealth Scientific and Industrial Research Organisation29, University of Hertfordshire30, Harvard University31, University of Paris32, ETH Zurich33, University of Toulouse34
TL;DR: In this article, the authors exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the GPS PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90and total infrared luminosity functions (LFs) up to z ∼ 4.
Abstract: We exploit the deep and extended far-IR data sets (at 70, 100 and 160 μm) of the Herschel Guaranteed Time Observation (GTO) PACS Evolutionary Probe (PEP) Survey, in combination with the Herschel Multi-tiered Extragalactic Survey data at 250, 350 and 500 μm, to derive the evolution of the rest-frame 35-, 60-, 90and total infrared (IR) luminosity functions (LFs) up to z ∼ 4. We detect very strong luminosity evolution for the total IR LF (LIR ∝ (1 + z)3.55 ± 0.10 up to z ∼ 2, and ∝ (1 + z)1.62 ± 0.51 at 2 < z 4) combined with a density evolution (∝ (1 + z)−0.57 ± 0.22 up to z ∼ 1 and ∝ (1 + z)−3.92 ± 0.34 at 1 < z 4). In agreement with previous findings, the IR luminosity density (ρIR) increases steeply to z ∼ 1, then flattens between z ∼ 1 and z ∼ 3 to decrease at z 3. Galaxies with different spectral energy distributions, masses and specific star formation rates (SFRs) evolve in very different ways and this large and deep statistical sample is the first one allowing us to separately study the different evolutionary behaviours of the individual IR populations contributing to ρIR. Galaxies occupying the well-established SFR–stellar mass main sequence (MS) are found to dominate both the total IR LF and ρIR at all redshifts, with the contribution from off-MS sources (≥0.6 dex above MS) being nearly constant (∼20 per cent of the total ρIR) and showing no significant signs of increase with increasing z over the whole 0.8 < z < 2.2 range. Sources with mass in the range 10 ≤ log(M/M ) ≤ 11 are found to dominate the total IR LF, with more massive galaxies prevailing at the bright end of the high-z ( 2) LF. A two-fold evolutionary scheme for IR galaxies is envisaged: on the one hand, a starburst-dominated phase in which the Super Massive Black Holes (SMBH) grows and is obscured by dust (possibly triggered by a major merging event), is followed by an AGN-dominated phase, then evolving towards a local elliptical. On the other hand, moderately star-forming galaxies containing a low-luminosity AGN have various properties suggesting they are good candidates for systems in a transition phase preceding the formation of steady spiral galaxies.
Jet Propulsion Laboratory1, California Institute of Technology2, University of Colorado Boulder3, University of Edinburgh4, University of British Columbia5, Paris Diderot University6, University of Bonn7, Aix-Marseille University8, University of La Laguna9, Spanish National Research Council10, University of Hawaii11, University of Cambridge12, Dalhousie University13, Imperial College London14, European Space Agency15, University of California, Irvine16, University of Vienna17, Virginia Tech18, University of Padua19, Cardiff University20, Harvard University21, UK Astronomy Technology Centre22, Pontifical Catholic University of Chile23, Open University24, University of Sussex25, Institut d'Astrophysique de Paris26, University College London27, Rutherford Appleton Laboratory28, Cornell University29, University of Oxford30, Commonwealth Scientific and Industrial Research Organisation31, University of the Western Cape32
TL;DR: In this article, a method for selecting high-density dusty, star forming galaxies (DSFGs) using Herschel/SPIRE 250/350/500 $\mu m$ flux densities to search for red sources was presented.
Abstract: We present a method for selecting $z>4$ dusty, star forming galaxies (DSFGs) using Herschel/SPIRE 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 5 of these sources confirms that this method is efficient at selecting high-$z$ DSFGs, with 4/5 at $z=4.3$ to $6.3$ (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 ($S_{500\,\mu m} \ge 30$ mJy), red Herschel sources is $3.3 \pm 0.8$ 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 $z\sim2$, rest-frame UV based studies may be missing a significant component of the star formation density at $z=4$ to $6$, even after correction for extinction.