Publications by Dimitra Rigopoulou


In-flight calibration of the Herschel-SPIRE instrument

Astronomy and Astrophysics 518 (2010)

BM Swinyard, A Dowell, M Ferlet, D Griffin, S Guest, K King, S Leeks, TL Lim, C Pearson, E Polehampton, D Rigopoulou, S Ronayette, S Sidher, P Ade, M Griffin, K Isaak, A Papageorgiou, M Pohlen, A Rykala, L Spencer, J-P Baluteau, D Benielli, D Pouliquen, MJ Barlow, G Savini, R Wesson, GJ Bendo, M Trichas, J Bock, D Dowell, H Nguyen, D Brisbin, A Conley, L Conversi, I Valtchanov, T Fulton, P Imhof, J Glenn, M Zemcov, L Levenson, N Lu, B Schulz, A Schwartz, D Shupe, CK Xu, L Zhang, S Jones, G Makiwa, D Naylor, S Oliver, AJ Smith, H Aussel, P Panuzzo, H Triou, H Roussel, A Woodcraft, A Glauser, B Sibthorpe

SPIRE, the Spectral and Photometric Imaging REceiver, is the Herschel Space Observatory's submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier-transform spectrometer (FTS) covering 194-671 μm (447-1550 GHz). In this paper we describe the initial approach taken to the absolute calibration of the SPIRE instrument using a combination of the emission from the Herschel telescope itself and the modelled continuum emission from solar system objects and other astronomical targets. We present the photometric, spectroscopic and spatial accuracy that is obtainable in data processed through the "standard" pipelines. The overall photometric accuracy at this stage of the mission is estimated as 15% for the photometer and between 15 and 50% for the spectrometer. However, there remain issues with the photometric accuracy of the spectra of low flux sources in the longest wavelength part of the SPIRE spectrometer band. The spectrometer wavelength accuracy is determined to be better than 1/10th of the line FWHM. The astrometric accuracy in SPIRE maps is found to be 2 arcsec when the latest calibration data are used. The photometric calibration of the SPIRE instrument is currently determined by a combination of uncertainties in the model spectra of the astronomical standards and the data processing methods employed for map and spectrum calibration. Improvements in processing techniques and a better understanding of the instrument performance will lead to the final calibration accuracy of SPIRE being determined only by uncertainties in the models of astronomical standards. © 2010 ESO.


First results from HerMES on the evolution of the submillimetre luminosity function

ASTRONOMY & ASTROPHYSICS 518 (2010) ARTN L23

SA Eales, G Raymond, IG Roseboom, B Altieri, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, D Brisbin, V Buat, D Burgarella, N Castro-Rodriguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Dye, D Elbaz, D Farrah, M Fox, A Franceschini, W Gear, J Glenn, EAG Solares, M Griffin, M Harwit, E Hatziminaoglou, J Huang, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, CJ Lonsdale, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, GE Morrison, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, FN Owen, MJ Page, M Pannella, P Panuzzo, A Papageorgiou, CP Pearson, I Perez-Fournon, M Pohlen, JI Rawlings, D Rigopoulou, D Rizzo, M Rowan-Robinson, M Sanchez Portal, B Schulz, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, V Strazzullo, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu, M Zemcov


Herschel unveils a puzzling uniformity of distant dusty galaxies

Astronomy and Astrophysics 518 (2010)

D Elbaz, HS Hwang, B Magnelli, E Daddi, H Aussel, B Altieri, A Amblard, P Andreani, V Arumugam, R Auld, T Babbedge, S Berta, A Blain, J Bock, A Bongiovanni, A Boselli, V Buat, D Burgarella, N Castro-Rodriguez, A Cava, J Cepa, P Chanial, RR Chary, A Cimatti, DL Clements, A Conley, L Conversi, A Cooray, M Dickinson, H Dominguez, CD Dowell, JS Dunlop, E Dwek, S Eales, D Farrah, N Förster Schreiber, M Fox, A Franceschini, W Gear, R Genzel, J Glenn, M Griffin, C Gruppioni, M Halpern, E Hatziminaoglou, E Ibar, K Isaak, RJ Ivison, G Lagache, D Le Borgne, E Le Floc'H, L Levenson, N Lu, D Lutz, S Madden, B Maffei, G Magdis, G Mainetti, R Maiolino, L Marchetti, AMJ Mortier, HT Nguyen, R Nordon, B O'Halloran, K Okumura, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Perez Fournon, AM Pérez García, A Poglitsch, M Pohlen, P Popesso, F Pozzi, JI Rawlings, D Rigopoulou, L Riguccini, D Rizzo, G Rodighiero, IG Roseboom, M Rowan-Robinson, A Saintonge, M Sanchez Portal, P Santini, M Sauvage, B Schulz

The Herschel Space Observatory enables us to accurately measure the bolometric output of starburst galaxies and active galactic nuclei (AGN) by directly sampling the peak of their far-infrared (IR) emission. Here we examine whether the spectral energy distribution (SED) and dust temperature of galaxies have strongly evolved over the last 80% of the age of the Universe. We discuss possible consequences for the determination of starformation rates (SFR) and any evidence for a major change in their star-formation properties. We use Herschel deep extragalactic surveys from 100 to 500 μm to compute total IR luminosities in galaxies down to the faintest levels, using PACS and SPIRE in the GOODS-North field (PEP and HerMES key programs). An extension to fainter luminosities is done by stacking images on 24 μm prior positions. We show that measurements in the SPIRE bands can be used below the statistical confusion limit if information at higher spatial resolution is used, e.g. at 24 μm, to identify isolated ± galaxies whose flux is not boosted by bright neighbors. Below ∼1.5, mid-IR extrapolations are correct for star-forming galaxies with a dispersion of only 40% (0.15 dex), therefore similar to ∼0 galaxies, over three decades in luminosity below the regime of ultra-luminous IR galaxies (ULIRGs, LIR ¡Ý 1012 L). This narrow distribution is puzzling when considering the range of physical processes that could have affected the SED of these galaxies. Extrapolations from only one of the 160 μm, 250 μm or 350 μm bands alone tend to overestimate the total IR luminosity. This may be explained by the lack of far-IR constraints around and above ∼150 μm (rest-frame) before Herschel on those templates. We also note that the dust temperature of luminous IR galaxies (LIRGs, LIR 10 11 L) around ∼1 is mildly colder by 10̈C15% than their local analogs and up to 20% for ULIRGs at ∼1.6 (using a single modified blackbody-fit to the peak far-IR emission with an emissivity index of ≥ = 1.5). Above z = 1.5, distant galaxies are found to exhibit a substantially larger mid-over far-IR ratio, which could either result from stronger broad emission lines or warm dust continuum heated by a hidden AGN. Two thirds of the AGNs identified in the field with a measured redshift exhibit the same behavior as purely star-forming galaxies. Hence a large fraction of AGNs harbor coeval star formation at very high SFR and in conditions similar to purely star-forming galaxies. © 2010 ESO.


HerMES: Far infrared properties of known AGN in the HerMES fields

Astronomy and Astrophysics 518 (2010)

E Hatziminaoglou, A Omont, JA Stevens, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, D Burgarella, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Dye, S Eales, D Elbaz, D Farrah, M Fox, A Franceschini, W Gear, J Glenn, EA González Solares, M Griffin, M Halpern, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, JI Rawlings, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, M Sanchez Portal, B Schulz, D Scott, N Seymour, DL Shupe, AJ Smith, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu, M Zemcov

Nuclear and starburst activity are known to often occur concomitantly. Herschel-SPIRE provides sampling of the far-infrared (FIR) spectral energy distributions (SEDs) of type 1 and type 2 AGN, allowing for the separation between the hot dust (torus) and cold dust (starburst) emission. We study large samples of spectroscopically confirmed type 1 and type 2 AGN lying within the Herschel Multi-tiered Extragalactic Survey (HerMES) fields observed during the science demonstration phase, aiming to understand their FIR colour distributions and constrain their starburst contributions. We find that one third of the spectroscopically confirmed AGN in the HerMES fields have 5σ detections at 250 μm, in agreement with previous (sub)mm AGN studies. Their combined Spitzer-MIPS and Herschel-SPIRE colours (specifically S250/S 70 vs S70/S24) quite clearly separate them from the non-AGN, star forming galaxy population, as their 24 μm flux is dominated by the hot torus emission. However, their SPIRE colours alone do not differ from those of non-AGN galaxies. SED fitting shows that all those AGN need a starburst component to fully account for their FIR emission. For objects at z > 2 we find a correlation between the infrared luminosity attributed to the starburst component, LSB, and the AGN accretion luminosity, L acc, with LSB proptoLacc0.35. Type 2 AGN detected at 250 μm show on average higher LSB than type 1 objects but their number is still too low to establish whether this trend indicates stronger star formation activity. © 2010 ESO.


The HerMES SPIRE submillimeter local luminosity function

Astronomy and Astrophysics 518 (2010)

M Vaccari, L Marchetti, A Franceschini, B Altieri, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, D Burgarella, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Dye, S Eales, D Elbaz, D Farrah, M Fox, W Gear, J Glenn, EA González Solares, M Griffin, M Halpern, E Hatziminaoglou, J Huang, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, N Lu, S Madden, B Maffei, G Mainetti, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, JI Rawlings, G Raymond, D Rigopoulou, D Rizzo, G Rodighiero, IG Roseboom, M Rowan-Robinson, M Sánchez Portal, B Schulz, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, M Symeonidis, M Trichas, KE Tugwell, E Valiante, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu, M Zemcov

Local luminosity functions are fundamental benchmarks for high-redshift galaxy formation and evolution studies as well as for models describing these processes. Determining the local luminosity function in the submillimeter range can help to better constrain in particular the bolometric luminosity density in the local Universe, and Herschel offers the first opportunity to do so in an unbiased way by imaging large sky areas at several submillimeter wavelengths. We present the first Herschel measurement of the submillimeter 0 < z < 0.2 local luminosity function and infrared bolometric (8-1000 μm) local luminosity density based on SPIRE data from the HerMES Herschel key program over 14.7 deg2. Flux measurements in the three SPIRE channels at 250, 350 and 500 μm are combined with Spitzer photometry and archival data. We fit the observed optical-to-submillimeter spectral energy distribution of SPIRE sources and use the 1/Vmax estimator to provide the first constraints on the monochromatic 250, 350 and 500 μm as well as on the infrared bolometric (8-1000 μm) local luminosity function based on Herschel data. We compare our results with modeling predictions and find a slightly more abundant local submillimeter population than predicted by a number of models. Our measurement of the infrared bolometric (8-1000 μm) local luminosity function suggests a flat slope at low luminosity, and the inferred local luminosity density, 1.31-0.21+0.24 × 108 L ⊙ Mpc-3, is consistent with the range of values reported in recent literature. © 2010 ESO.


The HerMES SPIRE submillimeter local luminosity function

Astronomy and Astrophysics 518 (2010)

M Vaccari, L Marchetti, A Franceschini, B Altieri, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, D Burgarella, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Dye, S Eales, D Elbaz, D Farrah, M Fox, W Gear, J Glenn, EA González Solares, M Griffin, M Halpern, E Hatziminaoglou, J Huang, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, N Lu, S Madden, B Maffei, G Mainetti, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, JI Rawlings, G Raymond, D Rigopoulou, D Rizzo, G Rodighiero, IG Roseboom, M Rowan-Robinson, M Sánchez Portal, B Schulz, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, M Symeonidis, M Trichas, KE Tugwell, E Valiante, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu, M Zemcov

Local luminosity functions are fundamental benchmarks for high-redshift galaxy formation and evolution studies as well as for models describing these processes. Determining the local luminosity function in the submillimeter range can help to better constrain in particular the bolometric luminosity density in the local Universe, and Herschel offers the first opportunity to do so in an unbiased way by imaging large sky areas at several submillimeter wavelengths. We present the first Herschel measurement of the submillimeter 0 < z < 0.2 local luminosity function and infrared bolometric (8-1000 μm) local luminosity density based on SPIRE data from the HerMES Herschel key program over 14.7 deg2. Flux measurements in the three SPIRE channels at 250, 350 and 500?m are combined with Spitzer photometry and archival data. We fit the observed optical-to-submillimeter spectral energy distribution of SPIRE sources and use the 1/Vmax estimator to provide the first constraints on the monochromatic 250, 350 and 500?m as well as on the infrared bolometric (81000 μm) local luminosity function based on Herschel data. We compare our results with modeling predictions and find a slightly more abundant local submillimeter population than predicted by a number of models. Our measurement of the infrared bolometric (8-1000 7mu;m) local luminosity function suggests a flat slope at low luminosity, and the inferred local luminosity density, 1.31+0.24-0.21× 108 L-Mpc-3, is consistent with the range of values reported in recent literature. © 2010 ESO.


HerMES: The SPIRE confusion limit

Astronomy and Astrophysics 518 (2010)

HT Nguyen, B Schulz, L Levenson, A Amblard, V Arumugam, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, N Castro-Rodriguez, A Cava, P Chanial, E Chapin, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Eales, D Elbaz, M Fox, A Franceschini, W Gear, J Glenn, M Griffin, M Halpern, E Hatziminaoglou, E Ibar, K Isaak, RJ Ivison, G Lagache, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, G Marsden, J Marshall, B O'Halloran, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Perez Fournon, M Pohlen, N Rangwala, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, I Valtchanov, L Vigroux, L Wang, R Ward, D Wiebe, G Wright, CK Xu, M Zemcov

We report on the sensitivity of SPIRE photometers on the Herschel Space Observatory. Specifically, we measure the confusion noise from observations taken during the science demonstration phase of the Herschel Multi-tiered Extragalactic Survey. Confusion noise is defined to be the spatial variation of the sky intensity in the limit of infinite integration time, and is found to be consistent among the different fields in our survey at the level of 5.8, 6.3 and 6.8 mJy/beam at 250, 350 and 500 μm, respectively. These results, together with the measured instrument noise, may be used to estimate the integration time required for confusion limited maps, and provide a noise estimate for maps obtained by SPIRE. © 2010 ESO.


HerMES: SPIRE galaxy number counts at 250, 350, and 500 μ m

Astronomy and Astrophysics 518 (2010)

SJ Oliver, L Wang, AJ Smith, B Altieri, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, D Burgarella, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Eales, D Elbaz, M Fox, A Franceschini, W Gear, J Glenn, M Griffin, M Halpern, E Hatziminaoglou, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, K Mitchell-Wynne, AMJ Mortier, HT Nguyen, B O'Halloran, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, JI Rawlings, G Raymond, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, M Sánchez Portal, R Savage, B Schulz, D Scott, N Seymour, DL Shupe, JA Stevens, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, E Valiante, I Valtchanov, JD Vieira, L Vigroux, R Ward, G Wright, CK Xu, M Zemcov

Emission at far-infrared wavelengths makes up a significant fraction of the total light detected from galaxies over the age of Universe. Herschel provides an opportunity for studying galaxies at the peak wavelength of their emission. Our aim is to provide a benchmark for models of galaxy population evolution and to test pre-existing models of galaxies. With the Herschel Multi-tiered Extra-galactic survey, HerMES, we have observed a number of fields of different areas and sensitivity using the SPIRE instrument on Herschel. We have determined the number counts of galaxies down to ~20 mJy. Our constraints from directly counting galaxies are consistent with, though more precise than, estimates from the BLAST fluctuation analysis. We have found a steep rise in the Euclidean normalised counts <100 mJy. We have directly resolved ~15% of the infrared extra-galactic background at the wavelength near where it peaks. © 2010 ESO.


HerMES: Halo occupation number and bias properties of dusty galaxies from angular clustering measurements

Astronomy and Astrophysics 518 (2010)

A Cooray, A Amblard, L Wang, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, D Burgarella, N Castro-Rodriguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, CD Dowell, E Dwek, S Eales, D Elbaz, D Farrah, M Fox, A Franceschini, W Gear, J Glenn, M Griffin, M Halpern, E Hatziminaoglou, E Ibar, K Isaak, RJ Ivison, AA Khostovan, G Lagache, L Levenson, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, G Marsden, K Mitchell-Wynne, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Perez Fournon, M Pohlen, JI Rawlings, G Raymond, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, B Schulz, D Scott, P Serra, N Seymour, DL Shupe, AJ Smith, JA Stevens, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, I Valtchanov, JD Vieira, L Vigroux, R Ward, G Wright, CK Xu, M Zemcov

We measure the angular correlation function, w(θ), from 0.5 to 30 arcmin of detected sources in two wide fields of the Herschel Multi-tiered Extragalactic Survey (HerMES). Our measurements are consistent with the expected clustering shape from a population of sources that trace the dark matter density field, including non-linear clustering at arcminute angular scales arising from multiple sources that occupy the same dark matter halos. By making use of the halo model to connect the spatial clustering of sources to the dark matter halo distribution, we estimate source bias and halo occupation number for dusty sub-mm galaxies at z ∼ 2. We find that sub-mm galaxies with 250 μm flux densities above 30 mJy reside in dark matter halos with mass above (5±4)×1012 M⊙, while (14±8)% of such sources appear as satellites in more massive halos. © 2010 ESO.


HerMES: The submillimeter spectral energy distributions of Herschel/SPIRE-detected galaxies

Astronomy and Astrophysics 518 (2010)

B Schulz, CP Pearson, DL Clements, B Altieri, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, V Buat, D Burgarella, N Castro-Rodríguez, A Cava, P Chanial, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Eales, D Elbaz, M Fox, A Franceschini, W Gear, E Giovannoli, J Glenn, M Griffin, M Halpern, E Hatziminaoglou, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, G Marsden, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, I Pérez-Fournon, M Pohlen, N Rangwala, JI Rawlings, G Raymond, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, M Sánchez Portal, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, E Valiante, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu, M Zemcov

We present colours of sources detected with the Herschel/SPIRE instrument in deep extragalactic surveys of the Lockman Hole, Spitzer-FLS, and GOODS-N fields in three photometric bands at 250, 350 and 500 μm. We compare these with expectations from the literature and discuss associated uncertainties and biases in the SPIRE data. We identify a 500 μm flux limited selection of sources from the HerMES point source catalogue that appears free from neighbouring/blended sources in all three SPIRE bands. We compare the colours with redshift tracks of various contemporary models. Based on these spectral templates we show that regions corresponding to specific population types and redshifts can be identified better in colour-flux space. The redshift tracks as well as the colour-flux plots imply a majority of detected objects with redshifts at 1 < z < 3.5, somewhat depending on the group of model SEDs used. We also find that a population of sources with S250/S 350 < 0.8 at fluxes above 50 mJy as observed by SPIRE are not well represented by contemporary models and could consist of a mix of cold and lensed galaxies. © 2010 ESO.


First results from HerMES on the evolution of the submillimetre luminosity function

Astronomy and Astrophysics 518 (2010)

SA Eales, G Raymond, IG Roseboom, B Altieri, A Amblard, V Arumugam, R Auld, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, D Brisbin, V Buat, D Burgarella, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Dye, D Elbaz, D Farrah, M Fox, A Franceschini, W Gear, J Glenn, EA González Solares, M Griffin, M Harwit, E Hatziminaoglou, J Huang, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, CJ Lonsdale, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, GE Morrison, AMJ Mortier, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, FN Owen, MJ Page, M Pannella, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, JI Rawlings, D Rigopoulou, D Rizzo, M Rowan-Robinson, M Sánchez Portal, B Schulz, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, V Strazzullo, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu

We have carried out two extremely deep surveys with SPIRE, one of the two cameras on Herschel, at 250 μm, close to the peak of the far-infrared background. We have used the results to investigate the evolution of the rest-frame 250-μm luminosity function out to z = 2. We find evidence for strong evolution out to z $\simeq$ 1 but evidence for at most weak evolution beyond this redshift. Our results suggest that a significant part of the stars and metals in the universe today were formed at z 1.4 in spiral galaxies. © 2010 ESO.


Herschel and SCUBA-2 imaging and spectroscopy of a bright, lensed submillimetre galaxy at z = 2.3

Astronomy and Astrophysics 518 (2010)

RJ Ivison, AM Swinbank, B Swinyard, I Smail, CP Pearson, D Rigopoulou, E Polehampton, JP Baluteau, MJ Barlow, AW Blain, J Bock, DL Clements, K Coppin, A Cooray, A Danielson, E Dwek, AC Edge, A Franceschini, T Fulton, J Glenn, M Griffin, K Isaak, S Leeks, T Lim, D Naylor, SJ Oliver, MJ Page, I Pérez Fournon, M Rowan-Robinson, G Savini, D Scott, L Spencer, I Valtchanov, L Vigroux, GS Wright

We present a detailed analysis of the far-infrared (-IR) properties of the bright, lensed, z = 2.3, submillimetre-selected galaxy (SMG), SMM J2135-0102 (hereafter SMM J2135), using new observations with Herschel, SCUBA-2 and the Very Large Array (VLA). These data allow us to constrain the galaxy's spectral energy distribution (SED) and show that it has an intrinsic rest-frame 8-1000-μm luminosity, Lbol, of (2.3±0.2) × 10 12 L⊙ and a likely star-formation rate (SFR) of ∼400 M⊙ yr-1. The galaxy sits on the far-IR/radio correlation for far-IR-selected galaxies. At ≥70 μm, the SED can be described adequately by dust components with dust temperatures, Td ∼ 30 and 60 k. Using SPIRE's Fourier- transform spectrometer (FTS) we report a detection of the [C ii] 158 μm cooling line. If the [C ii], CO and far-IR continuum arise in photo-dissociation regions (PDRs), we derive a characteristic gas density, n ∼ 103 cm-3, and a far-ultraviolet (-UV) radiation field, G0, 103× stronger than the Milky Way. L[CII]/Lbol is significantly higher than in local ultra-luminous IR galaxies (ULIRGs) but similar to the values found in local star-forming galaxies and starburst nuclei. This is consistent with SMM J2135 being powered by starburst clumps distributed across ∼2 kpc, evidence that SMGs are not simply scaled-up ULIRGs. Our results show that SPIRE's FTS has the ability to measure the redshifts of distant, obscured galaxies via the blind detection of atomic cooling lines, but it will not be competitive with ground-based CO-line searches. It will, however, allow detailed study of the integrated properties of high-redshift galaxies, as well as the chemistry of their interstellar medium (ISM), once more suitably bright candidates have been found. © ESO 2010.


On the stellar masses of IRAC detected Lyman Break Galaxies at z similar to 3

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 401 (2010) 1521-1531

GE Magdis, D Rigopoulou, J-S Huang, GG Fazio


Herschel-ATLAS: Evolution of the 250 μm luminosity function out to z = 0.5

Astronomy and Astrophysics 518 (2010)

S Dye, L Dunne, S Eales, DJB Smith, A Amblard, R Auld, M Baes, IK Baldry, S Bamford, AW Blain, DG Bonfield, M Bremer, D Burgarella, S Buttiglione, E Cameron, A Cava, DL Clements, A Cooray, S Croom, A Dariush, G De Zotti, S Driver, JS Dunlop, D Frayer, J Fritz, JP Gardner, HL Gomez, J Gonzalez-Nuevo, D Herranz, D Hill, A Hopkins, E Ibar, RJ Ivison, MJ Jarvis, DH Jones, L Kelvin, G Lagache, L Leeuw, J Liske, M Lopez-Caniego, J Loveday, S Maddox, MJ Michałowski, M Negrello, P Norberg, MJ Page, H Parkinson, E Pascale, JA Peacock, M Pohlen, C Popescu, M Prescott, D Rigopoulou, A Robotham, E Rigby, G Rodighiero, S Samui, D Scott, S Serjeant, R Sharp, B Sibthorpe, P Temi, MA Thompson, R Tuffs, I Valtchanov, PP Van Der Werf, E Van Kampen, A Verma

We have determined the luminosity function of 250 μm-selected galaxies detected in the ∼14 deg2science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 μm luminosity density out to z = 0.2 where it is 3.6+1.4-0.9times higher than the local value. © 2010 ESO.


A MULTI-WAVELENGTH VIEW OF THE STAR FORMATION ACTIVITY AT z similar to 3

ASTROPHYSICAL JOURNAL 714 (2010) 1740-1745

GE Magdis, D Elbaz, E Daddi, GE Morrison, M Dickinson, D Rigopoulou, R Gobat, HS Hwang


Measures of star formation rates from infrared (Herschel) and UV (GALEX) emissions of galaxies in the HerMES fields

Monthly Notices of the Royal Astronomical Society: Letters 409 (2010)

V Buat, E Giovannoli, D Burgarella, B Altieri, A Amblard, V Arumugam, H Aussel, T Babbedge, A Blain, J Bock, A Boselli, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Eales, D Elbaz, M Fox, A Franceschini, W Gear, J Glenn, M Griffin, M Halpern, E Hatziminaoglou, S Heinis, E Ibar, K Isaak, RJ Ivison, G Lagache, L Levenson, CJ Lonsdale, N Lu, S Madden, B Maffei, G Magdis, G Mainetti, L Marchetti, GE Morrison, HT Nguyen, B O'Halloran, SJ Oliver, AA Omont, FN Owen, MJ Page, M Pannella, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, M Sánchez Portal, B Schulz, N Seymour, DL Shupe, AJ Smith, JA Stevens, V Strazzullo, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, E Valiante, I Valtchanov, L Vigroux, L Wang, R Ward, G Wright, CK Xu, M Zemcov

The reliability of infrared (IR) and ultraviolet (UV) emissions to measure star formation rates (SFRs) in galaxies is investigated for a large sample of galaxies observed with the Spectral and Photometric Imaging Receiver (SPIRE) and the Photodetector Array Camera and Spectrometer (PACS) instruments on Herschel as part of the Herschel Multi-Tiered Extragalactic Survey (HerMES) project. We build flux-limited 250-jj.m samples of sources at redshift z < 1, crossmatched with the Spitzer/MIPS and GALEX catalogues. About 60 per cent of the Herschel sources are detected in UV. The total IR luminosities, LIR, of the sources are estimated using a spectral energy distribution (SED) fitting code that fits to fluxes between 24 and 500 μm. Dust attenuation is discussed on the basis of commonly used diagnostics: the LIR/LUV ratio and the slope, β, of the UV continuum. A mean dust attenuation AUV of ≃3 mag is measured in the samples. LIR/LUV LIR. Galaxies with LIR > 1011 L⊙ and 0.5 < z < 1 exhibit a mean dust attenuation AUV of about 0.7 mag lower than that found for their local counterparts, although with a large dispersion. Our galaxy samples span a large range of β and LIR/LUV values which, for the most part, are distributed between the ranges defined by the relations found locally for starburst and normal star-forming galaxies. As a consequence the recipe commonly applied to local starbursts is found to overestimate the dust attenuation correction in our galaxy sample by a factor of ~2-3. The SFRs deduced from LIR are found to account for about 90 per cent of the total SFR; this percentage drops to 71 per cent for galaxies with SFR < 1 M⊙ yr-1 (or LIR < 1010L⊙). For these faint objects, one needs to combine UV and IR emissions to obtain an accurate measure of the SFR. © 2010 The Authors. Journal compilation © 2010 RAS.


A FIRST GLIMPSE INTO THE FAR-IR PROPERTIES OF HIGH-z UV-SELECTED GALAXIES: HERSCHEL/PACS OBSERVATIONS OF z similar to 3 LBGS

ASTROPHYSICAL JOURNAL LETTERS 720 (2010) L185-L189

GE Magdis, D Elbaz, HS Hwang, E Daddi, D Rigopoulou, B Altieri, P Andreani, H Aussel, S Berta, A Cava, A Bongiovanni, J Cepa, A Cimatti, M Dickinson, H Dominguez, NF Schreiber, R Genzel, J-S Huang, D Lutz, R Maiolino, B Magnelli, GE Morrison, R Nordon, AMP Garcia, A Poglitsch, P Popesso, F Pozzi, L Riguccini, G Rodighiero, A Saintonge, P Santini, M Sanchez-Portal, L Shao, E Sturm, L Tacconi, I Valtchanov


Herschel unveils a puzzling uniformity of distant dusty galaxies

Astronomy and Astrophysics 518 (2010)

D Elbaz, HS Hwang, B Magnelli, E Daddi, H Aussel, B Altieri, A Amblard, P Andreani, V Arumugam, R Auld, T Babbedge, S Berta, A Blain, J Bock, A Bongiovanni, A Boselli, V Buat, D Burgarella, N Castro-Rodriguez, A Cava, J Cepa, P Chanial, RR Chary, A Cimatti, DL Clements, A Conley, L Conversi, A Cooray, M Dickinson, H Dominguez, CD Dowell, JS Dunlop, E Dwek, S Eales, D Farrah, N Förster Schreiber, M Fox, A Franceschini, W Gear, R Genzel, J Glenn, M Griffin, C Gruppioni, M Halpern, E Hatziminaoglou, E Ibar, K Isaak, RJ Ivison, G Lagache, D Le Borgne, E Le Floc'H, L Levenson, N Lu, D Lutz, S Madden, B Maffei, G Magdis, G Mainetti, R Maiolino, L Marchetti, AMJ Mortier, HT Nguyen, R Nordon, B O'Halloran, K Okumura, SJ Oliver, A Omont, MJ Page, P Panuzzo, A Papageorgiou, CP Pearson, I Perez Fournon, AM Pérez García, A Poglitsch, M Pohlen, P Popesso, F Pozzi, JI Rawlings, D Rigopoulou, L Riguccini, D Rizzo, G Rodighiero, IG Roseboom, M Rowan-Robinson, A Saintonge, M Sanchez Portal, P Santini, M Sauvage, B Schulz, D Scott, N Seymour, L Shao, DL Shupe, AJ Smith, JA Stevens, E Sturm, M Symeonidis, L Tacconi, M Trichas, KE Tugwell

The Herschel Space Observatory enables us to accurately measure the bolometric output of starburst galaxies and active galactic nuclei (AGN) by directly sampling the peak of their far-infrared (IR) emission. Here we examine whether the spectral energy distribution (SED) and dust temperature of galaxies have strongly evolved over the last 80% of the age of the Universe. We discuss possible consequences for the determination of starformation rates (SFR) and any evidence for a major change in their star-formation properties. We use Herschel deep extragalactic surveys from 100 to 500 μ m to compute total IR luminosities in galaxies down to the faintest levels, using PACS and SPIRE in the GOODS-North field (PEP and HerMES key programs). An extension to fainter luminosities is done by stacking images on 24 μ m prior positions. We show that measurements in the SPIRE bands can be used below the statistical confusion limit if information at higher spatial resolution is used, e.g. at 24 μ m, to identify "isolated" galaxies whose flux is not boosted by bright neighbors. Below z ∼ 1.5, mid-IR extrapolations are correct for star-forming galaxies with a dispersion of only 40% (0.15 dex), therefore similar to z ∼ 0 galaxies, over three decades in luminosity below the regime of ultra-luminous IR galaxies (ULIRGs, LIR ≥ 1012 L⊙). This narrow distribution is puzzling when considering the range of physical processes that could have affected the SED of these galaxies. Extrapolations from only one of the 160 μ m, 250 μ m or 350 μ m bands alone tend to overestimate the total IR luminosity. This may be explained by the lack of far-IR constraints around and above ∼150 μ m (rest-frame) before Herschel on those templates. We also note that the dust temperature of luminous IR galaxies (LIRGs, LIR ≥ 1011 L⊙) around z ∼ 1 is mildly colder by 10-15% than their local analogs and up to 20% for ULIRGs at z ∼ 1.6 (using a single modified blackbody-fit to the peak far-IR emission with an emissivity index of β = 1.5). Above z = 1.5, distant galaxies are found to exhibit a substantially larger mid- over far-IR ratio, which could either result from stronger broad emission lines or warm dust continuum heated by a hidden AGN. Two thirds of the AGNs identified in the field with a measured redshift exhibit the same behavior as purely star-forming galaxies. Hence a large fraction of AGNs harbor coeval star formation at very high SFR and in conditions similar to purely star-forming galaxies. © 2010 ESO.


Herschel reveals a T<inf>dust</inf>-unbiased selection of z~ 2 ultraluminous infrared galaxies

Monthly Notices of the Royal Astronomical Society 409 (2010) 22-28

GE Magdis, D Elbaz, HS Hwang, A Amblard, V Arumugam, H Aussel, A Blain, J Bock, A Boselli, V Buat, N Castro-Rodríguez, A Cava, P Chanial, DL Clements, A Conley, L Conversi, A Cooray, CD Dowell, E Dwek, S Eales, D Farrah, A Franceschini, J Glenn, M Griffin, M Halpern, E Hatziminaoglou, J Huang, E Ibar, K Isaak, E Le Floc'h, G Lagache, L Levenson, CJ Lonsdale, N Lu, S Madden, B Maffei, G Mainetti, L Marchetti, GE Morrison, HT Nguyen, B O'Halloran, SJ Oliver, A Omont, FN Owen, MJ Page, M Pannella, P Panuzzo, A Papageorgiou, CP Pearson, I Pérez-Fournon, M Pohlen, D Rigopoulou, D Rizzo, IG Roseboom, M Rowan-Robinson, B Schulz, D Scott, N Seymour, DL Shupe, AJ Smith, JA Stevens, V Strazzullo, M Symeonidis, M Trichas, KE Tugwell, M Vaccari, I Valtchanov, L Vigroux, L Wang, G Wright, CK Xu, M Zemcov

Using Herschel Photodetector Array Camera (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) observations of Lockman Hole-North and Great Observatories Origins Deep Survey-North (GOODS-N) as part of the Herschel Multi-tiered Extragalactic Survey (HerMES) project, we explore the far-infrared (IR) properties of a sample of mid-IR-selected starburst-dominated ultraluminous infrared galaxies (ULIRGs) at z~ 2. The selection of the sample is based on the detection of the stellar bump that appears in the spectral energy distribution of star-forming galaxies at 1.6 μm. We derive robust estimates of infrared luminosities (LIR) and dust temperatures (Td) of the population and find that while the luminosities in our sample span less than an order of magnitude (12.24 ≤ log(LIR/L·) ≤ 12.94), they cover a wide range of dust temperatures (25 ≤Td≤ 62 K). Galaxies in our sample range from those that are as cold as high-z submillimetre galaxies (SMGs) to those that are as warm as optically faint radio galaxies (OFRGs) and local ULIRGs. Nevertheless, our sample has median Td= 42.3 K, filling the gap between SMGs and OFRGs, bridging the two populations. We demonstrate that a significant fraction of our sample would be missed from ground-based (sub)mm surveys (850-1200 μm), showing that the latter introduce a bias towards the detection of colder sources. We conclude that Herschel observations confirm the existence of high-z ULIRGs warmer than SMGs, show that the mid-IR selection of high-z ULIRGs is not Td dependent, reveal a large dispersion in Td of high-z ULIRGs and provide the means to characterize the bulk of the ULIRG population, free from selection biases introduced by ground-based (sub)mm surveys. © 2010 The Authors. Journal compilation © 2010 RAS.


A first glimpse into the far-IR properties of high-z UV-selected galaxies: Herschel/PACS observations of z ∼ 3 LBGS

Astrophysical Journal Letters 720 (2010)

GE Magdis, D Elbaz, HS Hwang, E Daddi, D Rigopoulou, B Altieri, P Andreani, H Aussel, S Berta, A Cava, A Bongiovanni, J Cepa, A Cimatti, M Dickinson, H Dominguez, N Förster Schreiber, R Genzel, JS Huang, D Lutz, R Maiolino, B Magnelli, GE Morrison, R Nordon, AM Pérez García, A Poglitsch, P Popesso, F Pozzi, L Riguccini, G Rodighiero, A Saintonge, P Santini, M Sanchez-Portal, L Shao, E Sturm, L Tacconi, I Valtchanov

We present first insights into the far-IR properties for a sample of IRAC and MIPS 24 μm detected Lyman break galaxies (LBGs) at z ∼ 3, as derived from observations in the northern field of the Great Observatories Origins Survey (GOODS-N) carried out with the PACS instrument on board the Herschel Space Observatory. Although none of our galaxies are detected by Herschel, we employ a stacking technique to construct, for the first time, the average spectral energy distribution (SED) of infrared luminous LBGs from UV to radio wavelengths. We derive a median IR luminosity of LIR = 1.6 × 1012 L⊙, placing the population in the class of ultra-luminous infrared galaxies (ULIRGs). Complementing our study with existing multi-wavelength data, we put constraints on the dust temperature of the population and find that for their LIR, MIPS-LBGs are warmer than submillimeter-luminous galaxies while they fall in the locus of the L IR-Td relation of the local ULIRGs. This, along with estimates based on the average SED, explains the marginal detection of LBGs in current submillimeter surveys and suggests that these latter studies introduce a bias toward the detection of colder ULIRGs in the high-z universe, while missing high-z ULIRGS with warmer dust. © 2010. The American Astronomical Society. All rights reserved.

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