Showing papers by "European Southern Observatory published in 2011"
Space Telescope Science Institute1, University of California, Santa Cruz2, Johns Hopkins University3, Rutgers University4, Durham University5, University of Nottingham6, Harvard University7, University of Innsbruck8, University of Michigan9, DSM10, University of Edinburgh11, University of Massachusetts Amherst12, California Institute of Technology13, UK Astronomy Technology Centre14, University of California, Irvine15, Swinburne University of Technology16, University of Arizona17, The Catholic University of America18, Goddard Space Flight Center19, Hebrew University of Jerusalem20, University of Victoria21, University of California, Berkeley22, Texas A&M University23, University of Notre Dame24, Carnegie Institution for Science25, Smithsonian Institution26, Yale University27, University of Missouri–Kansas City28, University of California, Riverside29, Max Planck Society30, University of Pittsburgh31, Inter-University Centre for Astronomy and Astrophysics32, University of Barcelona33, European Southern Observatory34, University of Minnesota35, National Research Council36, Western Kentucky University37, Stanford University38, Atacama Large Millimeter Submillimeter Array39, University of Missouri40
TL;DR: The Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) as discussed by the authors was designed to document the first third of galactic evolution, from z approx. 8 - 1.5 to test their accuracy as standard candles for cosmology.
Abstract: The Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) is designed to document the first third of galactic evolution, from z approx. 8 - 1.5. It will image > 250,000 distant galaxies using three separate cameras on the Hubble Space Tele8cope, from the mid-UV to near-IR, and will find and measure Type Ia supernovae beyond z > 1.5 to test their accuracy as standard candles for cosmology. Five premier multi-wavelength sky regions are selected, each with extensive ancillary data. The use of five widely separated fields mitigates cosmic variance and yields statistically robust and complete samples of galaxies down to a stellar mass of 10(exp 9) solar mass to z approx. 2, reaching the knee of the UV luminosity function of galaxies to z approx. 8. The survey covers approximately 800 square arc minutes and is divided into two parts. The CANDELS/Deep survey (5(sigma) point-source limit H =27.7mag) covers approx. 125 square arcminutes within GOODS-N and GOODS-S. The CANDELS/Wide survey includes GOODS and three additional fields (EGS, COSMOS, and UDS) and covers the full area to a 50(sigma) point-source limit of H ? or approx. = 27.0 mag. Together with the Hubble Ultradeep Fields, the strategy creates a three-tiered "wedding cake" approach that has proven efficient for extragalactic surveys. Data from the survey are non-proprietary and are useful for a wide variety of science investigations. In this paper, we describe the basic motivations for the survey, the CANDELS team science goals and the resulting observational requirements, the field selection and geometry, and the observing design.
2,088 citations
Space Telescope Science Institute1, University of California, Santa Cruz2, Johns Hopkins University3, Western Kentucky University4, University of Massachusetts Amherst5, Carnegie Institution for Science6, European Southern Observatory7, Ohio State University8, Rutgers University9, Durham University10, University of Nottingham11, Max Planck Society12, University of Innsbruck13, University of Michigan14, French Alternative Energies and Atomic Energy Commission15, University of Edinburgh16, Harvard University17, California Institute of Technology18, University of California, Irvine19, Swinburne University of Technology20, University of Arizona21, Goddard Space Flight Center22, Hebrew University of Jerusalem23, Victoria University, Australia24, DSM25, University of California, Berkeley26, Texas A&M University27, University of Notre Dame28, Smithsonian Institution29, Yale University30, University of Missouri–Kansas City31, University of California, Riverside32, Imperial College London33, University of Pittsburgh34, Inter-University Centre for Astronomy and Astrophysics35, National Research Council36, Stanford University37
TL;DR: In this paper, the authors describe the Hubble Space Telescope imaging data products and data reduction procedures for the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS).
Abstract: This paper describes the Hubble Space Telescope imaging data products and data reduction procedures for the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). This survey is designed to document the evolution of galaxies and black holes at z 1.5-8, and to study Type Ia supernovae at z > 1.5. Five premier multi-wavelength sky regions are selected, each with extensive multi-wavelength observations. The primary CANDELS data consist of imaging obtained in the Wide Field Camera 3 infrared channel (WFC3/IR) and the WFC3 ultraviolet/optical channel, along with the Advanced Camera for Surveys (ACS). The CANDELS/Deep survey covers ~125 arcmin2 within GOODS-N and GOODS-S, while the remainder consists of the CANDELS/Wide survey, achieving a total of ~800 arcmin2 across GOODS and three additional fields (Extended Groth Strip, COSMOS, and Ultra-Deep Survey). We summarize the observational aspects of the survey as motivated by the scientific goals and present a detailed description of the data reduction procedures and products from the survey. Our data reduction methods utilize the most up-to-date calibration files and image combination procedures. We have paid special attention to correcting a range of instrumental effects, including charge transfer efficiency degradation for ACS, removal of electronic bias-striping present in ACS data after Servicing Mission 4, and persistence effects and other artifacts in WFC3/IR. For each field, we release mosaics for individual epochs and eventual mosaics containing data from all epochs combined, to facilitate photometric variability studies and the deepest possible photometry. A more detailed overview of the science goals and observational design of the survey are presented in a companion paper.
2,011 citations
TL;DR: Observations of a quasar at a redshift of 7.3 are reported, suggesting that the neutral fraction of the intergalactic medium in front of ULAS J1120+0641 exceeded 0.1.
Abstract: Quasars have historically been identified in optical surveys, which are insensitive to sources at z > 6.5. Infrared deep-sky survey data now make it possible to explore higher redshifts, with the result that a luminous quasar (ULAS J1120+0641) with a redshift z = 7.085, beyond the previous high of z = 6.44, has now been identified. Further observations of this and other distant quasars should reveal the ionization state of the Universe as it was only about 0.75 billion years after the Big Bang. The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed1 by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts, however, because quasars have historically been identified2,3,4 in optical surveys, which are insensitive to sources at redshifts exceeding 6.5. Here we report observations of a quasar (ULAS J112001.48+064124.3) at a redshift of 7.085, which is 0.77 billion years after the Big Bang. ULAS J1120+0641 has a luminosity of 6.3 × 1013L⊙ and hosts a black hole with a mass of 2 × 109M⊙ (where L⊙ and M⊙ are the luminosity and mass of the Sun). The measured radius of the ionized near zone around ULAS J1120+0641 is 1.9 megaparsecs, a factor of three smaller than is typical for quasars at redshifts between 6.0 and 6.4. The near-zone transmission profile is consistent with a Lyα damping wing5, suggesting that the neutral fraction of the intergalactic medium in front of ULAS J1120+0641 exceeded 0.1.
1,537 citations
TL;DR: X-shooter as mentioned in this paper is the first 2nd generation instrument of the ESO Very Large Telescope (VLT), which was installed at the Cassegrain focus of UT2 in 2009.
Abstract: X-shooter is the first 2nd generation instrument of the ESO Very Large Telescope(VLT). It is a very efficient, single-target, intermediate-resolution spectrograph that was installed at the Cassegrain focus of UT2 in 2009. The instrument covers, in a single exposure, the spectral range from 300 to 2500 nm. It is designed to maximize the sensitivity in this spectral range through dichroic splitting in three arms with optimized optics, coatings, dispersive elements and detectors. It operates at intermediate spectral resolution (R~4,000 - 17,000, depending on wavelength and slit width) with fixed echelle spectral format (prism cross-dispersers) in the three arms. It includes a 1.8"x4" Integral Field Unit as an alternative to the 11" long slits. A dedicated data reduction package delivers fully calibrated two-dimensional and extracted spectra over the full wavelength range. We describe the main characteristics of the instrument and present its performance as measured during commissioning, science verification and the first months of science operations.
1,031 citations
University of St Andrews1, European Southern Observatory2, University of Edinburgh3, Liverpool John Moores University4, University of Nottingham5, Australian Astronomical Observatory6, University of Sussex7, Max Planck Society8, University of Sydney9, Monash University, Clayton campus10, École Polytechnique Fédérale de Lausanne11, Cardiff University12, University of Queensland13, Swinburne University of Technology14, University of Portsmouth15, University of Bristol16, University of Central Lancashire17, University of Melbourne18, Durham University19, University of Hertfordshire20, Carnegie Institution for Science21, University of Western Australia22, Queen Mary University of London23, Imperial College London24
TL;DR: The Galaxy and Mass Assembly (GAMA) survey has been operating since 2008 February on the 3.9m Anglo-Australian Telescope using the AAOmega fibre-fed spectrograph facility to acquire spectra with a resolution of R ≈ 1300 for 120 862 Sloan Digital Sky Survey selected galaxies.
Abstract: The Galaxy and Mass Assembly (GAMA) survey has been operating since 2008 February on the 3.9-m Anglo-Australian Telescope using the AAOmega fibre-fed spectrograph facility to acquire spectra with a resolution of R ≈ 1300 for 120 862 Sloan Digital Sky Survey selected galaxies. The target catalogue constitutes three contiguous equatorial regions centred at 9h (G09), 12h (G12) and 14.5h (G15) each of 12 × 4 deg2 to limiting fluxes of rpet < 19.4, rpet < 19.8 and rpet <19.4 mag, respectively (and additional limits at other wavelengths). Spectra and reliable redshifts have been acquired for over 98 per cent of the galaxies within these limits. Here we present the survey footprint, progression, data reduction, redshifting, re-redshifting, an assessment of data quality after 3 yr, additional image analysis products (including ugrizYJHK photometry, S´ersic profiles and photometric redshifts), observing mask and construction of our core survey catalogue (GamaCore). From this we create three science-ready catalogues: GamaCoreDR1 for public release, which includes data acquired during year 1 of operations within specified magnitude limits (2008 February to April); GamaCoreMainSurvey containing all data above our survey limits for use by the GAMA Team and collaborators; and GamaCore-AtlasSV containing year 1, 2 and 3 data matched to Herschel-ATLAS science demonstration data. These catalogues along with the associated spectra, stamps and profiles can be accessed via the GAMA website: http://www.gama-survey.org/
988 citations
University of Oxford1, European Southern Observatory2, University of Lyon3, École Normale Supérieure4, University of California, Berkeley5, Paris Diderot University6, Leiden University7, Max Planck Society8, Kapteyn Astronomical Institute9, ASTRON10, University of Hertfordshire11, University of Toronto12
TL;DR: The ATLAS3D project as discussed by the authors is a multi-wavelength survey combined with a theoretical modelling effort, which provides multicolour imaging, two-dimensional kinematics of the atomic (H i), molecular (CO) and ionized gas (H beta, [O iii] and [N i]), together with the kinematic and population of the stars (H β, Fe5015 and Mg b), for a carefully selected, volume-limited (1.16 x 105 Mpc3) sample of 260 early-type (elliptical E
Abstract: The ATLAS3D project is a multiwavelength survey combined with a theoretical modelling effort. The observations span from the radio to the millimetre and optical, and provide multicolour imaging, two-dimensional kinematics of the atomic (H i), molecular (CO) and ionized gas (H beta, [O iii] and [N i]), together with the kinematics and population of the stars (H beta, Fe5015 and Mg b), for a carefully selected, volume-limited (1.16 x 105 Mpc3) sample of 260 early-type (elliptical E and lenticular S0) galaxies (ETGs). The models include semi-analytic, N-body binary mergers and cosmological simulations of galaxy formation. Here we present the science goals for the project and introduce the galaxy sample and the selection criteria. The sample consists of nearby (D 15 degrees) morphologically selected ETGs extracted from a parent sample of 871 galaxies (8 per cent E, 22 per cent S0 and 70 per cent spirals) brighter than M-K <-21.5 mag (stellar mass M-star greater than or similar to 6 x109 M-circle dot). We analyse possible selection biases and we conclude that the parent sample is essentially complete and statistically representative of the nearby galaxy population. We present the size-luminosity relation for the spirals and ETGs and show that the ETGs in the ATLAS3D sample define a tight red sequence in a colour-magnitude diagram, with few objects in the transition from the blue cloud. We describe the strategy of the SAURON integral field observations and the extraction of the stellar kinematics with the ppxf method. We find typical 1 Sigma errors of delta V approximate to 6 km s-1, delta Sigma approximate to 7 km s-1, delta h(3) approximate to delta h(4) approximate to 0.03 in the mean velocity, the velocity dispersion and Gauss-Hermite (GH) moments for galaxies with effective dispersion Sigma(e) greater than or similar to 120 km s-1. For galaxies with lower Sigma(e) (approximate to 40 per cent of the sample) the GH moments are gradually penalized by ppxf towards zero to suppress the noise produced by the spectral undersampling and only V and Sigma can be measured. We give an overview of the characteristics of the other main data sets already available for our sample and of the ongoing modelling projects.
954 citations
TL;DR: In this article, the relative contribution of star formation rate (SFR)-driven and starburst-driven galaxies to the global SFR density in the redshift interval 1.5 1000 M ☉ yr-1 was quantified.
Abstract: Two main modes of star formation are know to control the growth of galaxies: a relatively steady one in disk-like galaxies, defining a tight star formation rate (SFR)-stellar mass sequence, and a starburst mode in outliers to such a sequence which is generally interpreted as driven by merging. Such starburst galaxies are rare but have much higher SFRs, and it is of interest to establish the relative importance of these two modes. PACS/Herschel observations over the whole COSMOS and GOODS-South fields, in conjunction with previous optical/near-IR data, have allowed us to accurately quantify for the first time the relative contribution of the two modes to the global SFR density in the redshift interval 1.5 1000 M ☉ yr-1, off-sequence sources significantly contribute to the SFR density (46% ± 20%). We conclude that merger-driven starbursts play a relatively minor role in the formation of stars in galaxies, whereas they may represent a critical phase toward the quenching of star formation and morphological transformation in galaxies.
927 citations
TL;DR: In this article, the Geneva-Copenhagen survey was used for a re-analysis of the spectral properties of the stars in the solar neighborhood and the results showed that the stars are on average 100 K hotter and 0.1 dex more metal rich, which shifted the peak of the metallicity distribution function around the solar value.
Abstract: We present a re-analysis of the Geneva-Copenhagen survey, which benefits from the infrared flux method to improve the accuracy of the derived stellar effective temperatures and uses the latter to build a consistent and improved metallicity scale. Metallicities are calibrated on high-resolution spectroscopy and checked against four open clusters and a moving group, showing excellent consistency. The new temperature and metallicity scales provide a better match to theoretical isochrones, which are used for a Bayesian analysis of stellar ages. With respect to previous analyses, our stars are on average 100 K hotter and 0.1 dex more metal rich, which shift the peak of the metallicity distribution function around the solar value. From Stromgren photometry we are able to derive for the first time a proxy for [alpha/Fe] abundances, which enables us to perform a tentative dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha-enhanced population that extends to super solar metallicities, in agreement with spectroscopic studies. Our revision offers the largest existing kinematically unbiased sample of the solar neighbourhood that contains full information on kinematics, metallicities, and ages and thus provides better constraints on the physical processes relevant in the build-up of the Milky Way disc, enabling a better understanding of the Sun in a Galactic context. (Less)
827 citations
European Southern Observatory1, École normale supérieure de Lyon2, University of Oxford3, University of California, Berkeley4, Paris Diderot University5, Leiden University6, Max Planck Society7, Space Telescope European Coordinating Facility8, ASTRON9, Kapteyn Astronomical Institute10, University of Hertfordshire11, University of Toronto12, New Mexico Institute of Mining and Technology13
TL;DR: The definitive version of this paper can be found at : http://onlinelibrary.wiley.com/ Copyright Royal Astronomical Society (RAS) 2013 as mentioned in this paper.
Abstract: The definitive version can be found at : http://onlinelibrary.wiley.com/ Copyright Royal Astronomical Society
718 citations
Pennsylvania State University1, Pontifical Catholic University of Chile2, Space Science Institute3, Goddard Space Flight Center4, Johns Hopkins University5, Durham University6, Max Planck Society7, INAF8, University of Cambridge9, Space Telescope Science Institute10, University of Science and Technology of China11, European Southern Observatory12, Leiden University13, University of North Texas14, Institute for the Physics and Mathematics of the Universe15, University of Bologna16
TL;DR: In this article, the authors presented a source catalog for the 4Ms Chandra Deep Field-South (CDF-S) survey, which is the deepest Chandra survey to date and covers an area of 464.5 arcmin2.
Abstract: We present source catalogs for the 4 Ms Chandra Deep Field-South (CDF-S), which is the deepest Chandra survey to date and covers an area of 464.5 arcmin2. We provide a main Chandra source catalog, which contains 740 X-ray sources that are detected with WAVDETECT at a false-positive probability threshold of 10–5 in at least one of three X-ray bands (0.5-8 keV, full band; 0.5-2 keV, soft band; and 2-8 keV, hard band) and also satisfy a binomial-probability source-selection criterion of P 75% of the main-catalog sources are active galactic nuclei (AGNs); of the 300 new main-catalog sources, about 35% are likely normal and starburst galaxies, reflecting the rise of normal and starburst galaxies at the very faint flux levels uniquely accessible to the 4 Ms CDF-S. Near the center of the 4 Ms CDF-S (i.e., within an off-axis angle of 3'), the observed AGN and galaxy source densities have reached 9800+1300 – 1100 deg–2 and 6900+1100 – 900 deg–2, respectively. Simulations show that our main catalog is highly reliable and is reasonably complete. The mean backgrounds (corrected for vignetting and exposure-time variations) are 0.063 and 0.178 counts Ms–1 pixel–1 (for a pixel size of 0492) for the soft and hard bands, respectively; the majority of the pixels have zero background counts. The 4 Ms CDF-S reaches on-axis flux limits of 3.2 × 10–17, 9.1 × 10–18, and 5.5 × 10–17 erg cm–2 s–1 for the full, soft, and hard bands, respectively. An increase in the CDF-S exposure time by a factor of 2-2.5 would provide further significant gains and probe key unexplored discovery space.
716 citations
TL;DR: In this paper, the authors explore the redshift evolution of specific star formation rate (SSFR) for galaxies of different stellar mass by drawing on a deep 3.6 µm-selected sample of > 10 5 galaxies in the 2 deg 2 COSMOS field.
Abstract: We explore the redshift evolution of the specific star formation rate (SSFR) for galaxies of different stellar mass by drawing on a deep 3.6 µm-selected sample of > 10 5 galaxies in the 2 deg 2 COSMOS field. The average star formation rate (SFR) for sub-sets of these galaxies is estimated with stacked 1.4 GHz radio continuum emission. We separately consider the total sample and a subset of galaxies that shows evidence for substantive recent star formation in the rest-frame optical spectral energy distributions. At redshifts 0.2 2, at least for high-mass (M� & 4 � 10 10 M� ) systems where our conclusions are most robust. Our data show that there is a tight correlation with power-law dependence, SSFR / M� � , between
University of Sydney1, University of Melbourne2, ASTRON3, Liverpool John Moores University4, Monash University5, University of St Andrews6, University of Portsmouth7, European Southern Observatory8, University of Sussex9, University of Edinburgh10, University of Nottingham11, ETH Zurich12, Durham University13, Leiden University14, University of Bristol15, University of Central Lancashire16, Queen Mary University of London17, Max Planck Society18
TL;DR: The first catalogue of photometrically derived stellar mass estimates for intermediate-redshift (z < 0.65; median z= 0.2) galaxies in the Galaxy And Mass Assembly (GAMA) spectroscopic redshift survey is described in this paper.
Abstract: This paper describes the first catalogue of photometrically derived stellar mass estimates for intermediate-redshift (z < 0.65; median z= 0.2) galaxies in the Galaxy And Mass Assembly (GAMA) spectroscopic redshift survey. These masses, as well as the full set of ancillary stellar population parameters, will be made public as part of GAMA data release 2. Although the GAMA database does include near-infrared (NIR) photometry, we show that the quality of our stellar population synthesis fits is significantly poorer when these NIR data are included. Further, for a large fraction of galaxies, the stellar population parameters inferred from the optical-plus-NIR photometry are formally inconsistent with those inferred from the optical data alone. This may indicate problems in our stellar population library, or NIR data issues, or both; these issues will be addressed for future versions of the catalogue. For now, we have chosen to base our stellar mass estimates on optical photometry only. In light of our decision to ignore the available NIR data, we examine how well stellar mass can be constrained based on optical data alone. We use generic properties of stellar population synthesis models to demonstrate that restframe colour alone is in principle a very good estimator of stellar mass-to-light ratio, M*/Li. Further, we use the observed relation between restframe (g−i) and M*/Li for real GAMA galaxies to argue that, modulo uncertainties in the stellar evolution models themselves, (g−i) colour can in practice be used to estimate M*/Li to an accuracy of ≲0.1 dex (1σ). This ‘empirically calibrated’ (g−i)–M*/Li relation offers a simple and transparent means for estimating galaxies’ stellar masses based on minimal data, and so provides a solid basis for other surveys to compare their results to z≲0.4 measurements from GAMA.
TL;DR: The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009 as mentioned in this paper, and it will continue to gather scientific data until the end of its cryogenic lifetime.
Abstract: The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009. Its performance is well in line with expectations, and it will continue to gather scientific data until the end of its cryogenic lifetime. We give an overview of the history of Planck in its first year of operations, and describe some of the key performance aspects of the satellite. This paper is part of a package submitted in conjunction with Planck's Early Release Compact Source Catalogue, the first data product based on Planck to be released publicly. The package describes the scientific performance of the Planck payload, and presents results on a variety of astrophysical topics related to the sources included in the Catalogue, as well as selected topics on diffuse emission.
TL;DR: The PACS Evolutionary Probe (PEP) guaranteed time key program as discussed by the authors has been used in the entire set of Herschel surveys, and the field selection that includes popular multi-wavelength fields such as GOODS, COSMOS, Lockman Hole, ECDFS, and EGS.
Abstract: Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. We describe the scientific motivation for the PACS Evolutionary Probe (PEP) guaranteed time key program and its role within the entire set of Herschel surveys, and the field selection that includes popular multiwavelength fields such as GOODS, COSMOS, Lockman Hole, ECDFS, and EGS. We provide an account of the observing strategies and data reduction methods used. An overview of first science results illustrates the potential of PEP in providing calorimetric star formation rates for high-redshift galaxy populations, thus testing and superseding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies.
TL;DR: In this paper, the authors conducted a legacy survey for molecular gas in nearby galaxies using the IRAM 30-m telescope, measuring the CO(1-0) line in a sample of similar to 350 nearby (D-L similar or equal to 100-200 Mpc), massive galaxies (log(M-*/M-circle dot) > 10.0).
Abstract: We are conducting COLD GASS, a legacy survey for molecular gas in nearby galaxies. Using the IRAM 30-m telescope, we measure the CO(1-0) line in a sample of similar to 350 nearby (D-L similar or equal to 100-200 Mpc), massive galaxies (log(M-*/M-circle dot) > 10.0). The sample is selected purely according to stellar mass, and therefore provides an unbiased view of molecular gas in these systems. By combining the IRAM data with Sloan Digital Sky Survey (SDSS) photometry and spectroscopy, GALEX imaging and high-quality Arecibo HI data, we investigate the partition of condensed baryons between stars, atomic gas and molecular gas in 0.1-10L* galaxies. In this paper, we present CO luminosities and molecular hydrogen masses for the first 222 galaxies. The overall CO detection rate is 54 per cent, but our survey also uncovers the existence of sharp thresholds in galaxy structural parameters such as stellar mass surface density and concentration index, below which all galaxies have a measurable cold gas component but above which the detection rate of the CO line drops suddenly. The mean molecular gas fraction MH2/M* of the CO detections is 0.066 +/- 0.039, and this fraction does not depend on stellar mass, but is a strong function of (NUV - r) colour. Through stacking, we set a firm upper limit of MH2/M-* = 0.0016 +/- 0.0005 for red galaxies with NUV - r > 5.0. The average molecular-to-atomic hydrogen ratio in present-day galaxies is 0.3, with significant scatter from one galaxy to the next. The existence of strong detection thresholds in both the HI and CO lines suggests that 'quenching' processes have occurred in these systems. Intriguingly, atomic gas strongly dominates in the minority of galaxies with significant cold gas that lie above these thresholds. This suggests that some re-accretion of gas may still be possible following the quenching event.
TL;DR: The HERMES high-resolution spectrograph project as discussed by the authors is based on the white-pupil beam folding for high resolution spectroscopy with a spectral resolution of 85'000 (63'000) for the low-resolution fiber.
Abstract: The HERMES high-resolution spectrograph project aims at exploiting the specific potential of small but flexible telescopes in observational astrophysics. The optimised optical design of the spectrograph is based on the well-proven concept of white-pupil beam folding for high-resolution spectroscopy. In this contribution we present the complete project, including the spectrograph design and procurement details, the telescope adaptor and calibration unit, the detector system, as well as the optimised data-reduction pipeline. We present a detailed performance analysis to show that the spectrograph performs as specified both in optical quality and in total efficiency. With a spectral resolution of 85 000 (63 000 for the low-resolution fibre), a spectral coverage from 377 to 900 nm in a single exposure and a peak efficiency of 28%, HERMES proves to be an ideal instrument for building up time series of high-quality data of variable (stellar) phenomena.
TL;DR: In this article, deep near-IR (NIR) medium-bandwidth photometry over the wavelength range 1-1.8 μm in the All-wavelength Extended Groth strip International Survey (AEGIS) and Cosmic Evolution Survey (COSMOS) fields was carried out using the NOAO Extremely Wide Field Infrared Imager (NewFIRM) on the Mayall 4 m Telescope on Kitt Peak as part of the NEWFIRM Medium-Band Survey.
Abstract: We present deep near-IR (NIR) medium-bandwidth photometry over the wavelength range 1-1.8 μm in the All-wavelength Extended Groth strip International Survey (AEGIS) and Cosmic Evolution Survey (COSMOS) fields. The observations were carried out using the NOAO Extremely Wide-Field Infrared Imager (NEWFIRM) on the Mayall 4 m Telescope on Kitt Peak as part of the NEWFIRM Medium-Band Survey (NMBS), an NOAO survey program. In this paper, we describe the full details of the observations, data reduction, and photometry for the survey. We also present a public K-selected photometric catalog, along with accurate photometric redshifts. The redshifts are computed with 37 (20) filters in the COSMOS (AEGIS) fields, combining the NIR medium-bandwidth data with existing UV (Galaxy Evolution Explorer), visible and NIR (Canada-France-Hawaii Telescope and Subaru Telescope), and mid-IR (Spitzer/IRAC) imaging. We find excellent agreement with publicly available spectroscopic redshifts, with σ z /(1 + z) ~ 1%-2% for ~4000 galaxies at z = 0-3. The NMBS catalogs contain ~13,000 galaxies at z > 1.5 with accurate photometric redshifts and rest-frame colors. Due to the increased spectral resolution obtained with the five NIR medium-band filters, the median 68% confidence intervals of the photometric redshifts of both quiescent and star-forming galaxies are a factor of about two times smaller when comparing catalogs with medium-band NIR photometry to NIR broadband photometry. We show evidence for a clear bimodal color distribution between quiescent and star-forming galaxies that persists to z ~ 3, a higher redshift than has been probed so far.
TL;DR: In this paper, an all sky map of the apparent temperature and optical depth of thermal dust emission is constructed using the Planck-HFI (350μm to 2 mm) and IRAS(100μm) data.
Abstract: An all sky map of the apparent temperature and optical depth of thermal dust emission is constructed using the Planck-HFI (350μm to 2 mm) andIRAS(100μm) data. The optical depth maps are correlated with tracers of the atomic (Hi) and molecular gas traced by CO. The correlation with the column density of observed gas is linear in the lowest column density regions at high Galactic latitudes. At high N(H), the correlation is consistent with that of the lowest NH, for a given choice of the CO-to-H(2) conversion factor. In the intermediate NH range, a departure from linearity is observed, with the dust optical depth in excess of the correlation. This excess emission is attributed to thermal emission by dust associated with a dark gas phase, undetected in the available Hi and CO surveys. The 2D spatial distribution of the dark gas in the solar neighbourhood (|b(II)| > 10°) is shown to extend around known molecular regions traced by CO. The average dust emissivity in the Hi phase in the solar neighbourhood is found to be τ(D)/N(H)(tot) = 5.2×10(-26) cm(2) at 857 GHz. It follows roughly a power law distribution with a spectral index β = 1.8 all the way down to 3 mm, although the SED flattens slightly in the millimetre. Taking into account the spectral shape of the dust optical depth, the emissivity is consistent with previous values derived fromFIRAS measurements at high latitudes within 10%. The threshold for the existence of the dark gas is found at N(H)(tot) = (8.0±0.58)×10(20) H cm(−2) (A(V )= 0.4mag). Assuming the same high frequency emissivity for the dust in the atomic and the molecular phases leads to an average X(CO) = (2.54 ± 0.13) × 10(20) H(2) cm(-2)/(K km s(-1)). The mass of dark gas is found to be 28% of the atomic gas and 118% of the CO emitting gas in the solar neighbourhood. The Galactic latitude distribution shows that its mass fraction is relatively constant down to a few degrees from the Galactic plane. A possible explanation for the dark gas lies in a dark molecular phase, where H2 survives photodissociation but CO does not. The observed transition for the onsetof this phase in the solar neighbourhood (AV = 0.4mag) appears consistent with recent theoretical predictions. It is also possible that up to half of the dark gas could be in atomic form, due to optical depth effects in the Hi measurements.
TL;DR: The first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies was presented in this paper.
Abstract: We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6 to 29. Its high reliability (purity above 95%) is further ensured by an extensive validation process based on Planck internal quality assessments and by external cross-identification and follow-up observations. Planck provides the first measured SZ signal for about 80% of the 169 previouslyknown ESZ clusters. Planck furthermore releases 30 new cluster candidates, amongst which 20 meet the ESZ signal-to-noise selection criterion. At the submission date, twelve of the 20 ESZ candidates were confirmed as new clusters, with eleven confirmed using XMM-Newton snapshot observations, most of them with disturbed morphologies and low luminosities. The ESZ clusters are mostly at moderate redshifts (86% with z below 0.3) and span more than a decade in mass, up to the rarest and most massive clusters with masses above 1 × 10 15 M� .
European Southern Observatory1, École normale supérieure de Lyon2, University of Oxford3, University of California, Berkeley4, Paris Diderot University5, Leiden University6, Max Planck Society7, Space Telescope European Coordinating Facility8, Kapteyn Astronomical Institute9, ASTRON10, University of Hertfordshire11, University of Toronto12, New Mexico Institute of Mining and Technology13
TL;DR: In this paper, the authors used the ATLAS3D data set of 260 early-type galaxies to study the apparent kinematic misalignment angle, defined as the angle between the photometric and kinematics major axes.
Abstract: We use the ATLAS3D sample of 260 early-type galaxies to study the apparent kinematic misalignment angle, Ψ, defined as the angle between the photometric and kinematic major axes. We find that 71 per cent of nearby early-type galaxies are strictly aligned systems (Ψ≤ 5°), an additional 14 per cent have 5° <Ψ≤ 10° and 90 per cent of galaxies have Ψ≤ 15°. Taking into account measurement uncertainties, 90 per cent of galaxies can be considered aligned to better than 5°, suggesting that only a small fraction of early-type galaxies (˜10 per cent) are not consistent with the axisymmetry within the projected half-light radius. We identify morphological features such as bars and rings (30 per cent), dust structures (16 per cent), blue nuclear colours (6 per cent) and evidence of interactions (8 per cent) visible on ATLAS3D galaxies. We use KINEMETRY to analyse the mean velocity maps and separate galaxies into two broad types of regular and non-regular rotators. We find 82 per cent of regular rotators and 17 per cent of non-regular rotators, with two galaxies that we were not able to classify due to the poor data quality. The non-regular rotators are typically found in dense regions and are massive. We characterize the specific features in the mean velocity and velocity dispersion maps. The majority of galaxies do not have any specific features, but we highlight here the frequency of the kinematically distinct cores (7 per cent of galaxies) and the aligned double peaks in the velocity dispersion maps (4 per cent of galaxies). We separate galaxies into five kinematic groups based on the kinemetric features, which are then used to interpret the (Ψ-ɛ) diagram. Most of the galaxies that are misaligned have complex kinematics and are non-regular rotators. In addition, some show evidence of the interaction and might not be in equilibrium, while some are barred. While the trends are weak, there is a tendency that large values of Ψ are found in galaxies at intermediate environmental densities and among the most massive galaxies in the sample. Taking into account the kinematic alignment and the kinemetric analysis, the majority of early-type galaxies have velocity maps more similar to that of the spiral discs than to that of the remnants of equal-mass mergers. We suggest that the most common formation mechanism for early-type galaxies preserves the axisymmetry of the disc progenitors and their general kinematic properties. Less commonly, the formation process results in a triaxial galaxy with much lower net angular momentum.
Lawrence Berkeley National Laboratory1, Pennsylvania State University2, University of California, Berkeley3, University of Warwick4, University of Leicester5, George Washington University6, Goddard Space Flight Center7, Harvard University8, Max Planck Society9, European Southern Observatory10, University of Cambridge11, Purple Mountain Observatory12, University of Copenhagen13, University of Iceland14, Space Telescope Science Institute15, Arizona State University16, McGill University17, Australian National University18, University of Oxford19, California Institute of Technology20, Brera Astronomical Observatory21
TL;DR: In this article, the authors presented a photometric redshift of 9.4 for the Swift detected GRB 090429B based on deep observations with Gemini-North, the Very Large Telescope, and the GRB Optical and Near-infrared Detector.
Abstract: Gamma-ray bursts (GRBs) serve as powerful probes of the early universe, with their luminous afterglows revealing the locations and physical properties of star-forming galaxies at the highest redshifts, and potentially locating first-generation (Population III) stars. Since GRB afterglows have intrinsically very simple spectra, they allow robust redshifts from low signal-to-noise spectroscopy, or photometry. Here we present a photometric redshift of z ~ 9.4 for the Swift detected GRB 090429B based on deep observations with Gemini-North, the Very Large Telescope, and the GRB Optical and Near-infrared Detector. Assuming a Small Magellanic Cloud dust law (which has been found in a majority of GRB sight lines), the 90% likelihood range for the redshift is 9.06 7. The non-detection of the host galaxy to deep limits (Y(AB) ~ 28, which would correspond roughly to 0.001L* at z = 1) in our late-time optical and infrared observations with the Hubble Space Telescope strongly supports the extreme-redshift origin of GRB 090429B, since we would expect to have detected any low-z galaxy, even if it were highly dusty. Finally, the energetics of GRB 090429B are comparable to those of other GRBs and suggest that its progenitor is not greatly different from those of lower redshift bursts.
New Mexico Institute of Mining and Technology1, University of Oxford2, University of California, Berkeley3, École normale supérieure de Lyon4, European Southern Observatory5, Paris Diderot University6, Leiden University7, Max Planck Society8, Kapteyn Astronomical Institute9, ASTRON10, University of Hertfordshire11, University of Toronto12
TL;DR: The definitive version of this paper can be found at : http://onlinelibrary.wiley.com/ Copyright Royal Astronomical Society (RAS) 2013 as mentioned in this paper.
Abstract: The definitive version can be found at : http://onlinelibrary.wiley.com/ Copyright Royal Astronomical Society
TL;DR: In this paper, the relation between molecular gas and star formation in a volume-limited sample of 222 galaxies from the COLD GASS survey, with measurements of the CO(1-0) line from the IRAM 30-m telescope.
Abstract: We study the relation between molecular gas and star formation in a volume-limited sample of 222 galaxies from the COLD GASS survey, with measurements of the CO(1–0) line from the IRAM 30-m telescope. The galaxies are at redshifts 0.025 < z < 0.05 and have stellar masses in the range 10.0 < log M� /M� < 11.5. The IRAM measurements are complemented by deep Arecibo H I observations and homogeneous Sloan Digital Sky Survey and GALEX photometry. A reference sample that includes both ultraviolet (UV) and far-infrared data is used to calibrate our estimates of star formation rates from the seven optical/UV bands. The mean molecular gas depletion time-scale [tdep(H2)] for all the galaxies in our sample is 1 Gyr; however, tdep(H2) increases by a factor of 6 from a value of ∼0.5 Gyr for galaxies with stellar –
TL;DR: The Tiny Tim PSF simulation software package has been the standard HST modeling software since its release in early 1992 as mentioned in this paper, and has been used extensively for HST data analysis.
Abstract: Point spread function (PSF) models are critical to Hubble Space Te lescope (HST) data analysis. Astronomers unfamiliar with optical simulation techniques need access to PSF models that properly match the conditions of their observations, so any HST modeling software needs to be both easy-to-use and have detailed information on the telescope and instruments. The Tiny Tim PSF simulation software package has been the standard HST modeling software since its release in early 1992. We discuss the evolution of Tiny Tim over the years as new instruments and optical properties have been incorporated. We also dem onstrate how Tiny Tim PSF models have be en used for HST data analysis. Tiny Tim is freely available from tinytim.stsci.edu. Keywords: Hubble Space Telescope, point spread function 1. INTRODUCTION The point spread function (PSF) is the fundamental unit of imag e formation for an optical syst em such as a telescope. It encompasses the diffraction from obscurations, which is modified by aberrations, and the scattering from mid-to-high spatial frequency optical errors . Imaging performance is often described in terms of PSF properties, such as resolution and encircled energy. Optical engineering software, includi ng ray tracing and physical optic s propagation packages, are employed during the design phase of the system to predict the PSF to ensure that the imag ing requirements are met. But once the system is complete and operational, the software is usually packed away and the point spread function considered static, to be described in documentation for reference by the scientist. In this context, an optical engineer runs software to compute PSFs while the user of the optical system simply needs to know its basic characteristics. For the Hubble Space Telescope (HST), that is definitely not the case. To extract the maximum information out of an observation, even the smallest details of the PSF are important. Some examples include: deconvolvin g the PSF from an observed image to remove the blurring caused by diffraction and reveal fine structure; convolving a model image by the PSF to compare to an observed one; subtracting the PSF of an unresolved source (star or compact galactic nucleus) to reveal extended structure (a circumstellar disk or host galaxy) that would otherwise be unseen within the halo of diffracted and scattered light; and fitting a PSF to a star imag e to obtain accurate photometry and astrometry, especially if it is a binary star with blended PSFs Compared to ground-based telescopes HST is extremely stable, so the structure in its PSF is largely time-invariant. This allows the use of PSF models for data analysis. On the ground, the variable PSF structure due to the atmosphere and thermal-and-gravitationally-induced optical perturbations make it more difficult to produce a model that accurately matches the data. The effective HST PSF, though, is dependent on many parameters, including obscurations, aberrations, pointing errors, system wavelength response, object color, and detector pixel effects. An accurate PSF model must account for all of these, some of which may depend on time (focus, obscuration positions) or on field position within the camera (aberrations, CCD detector charge diffusion, obscuration patterns, geometric distortion). 1.1 Early HST PSF modeling: TIM Before launch of HST in 1990, a variety of commercial and proprietary software packages were used to compute PSFs. These provided predictions of HSTs imaging performance and guided the design, but they were not used by future HST observers. These programs were too complicated for general HS T users, and either were not publicly available or were too expensive. They also did not provide PSF models in forms that scientists would find useful, such as including the effects of detector pixelization and broadband system responses.
University of Oxford1, École normale supérieure de Lyon2, European Southern Observatory3, ASTRON4, University of California, Berkeley5, Paris Diderot University6, Leiden University7, Max Planck Society8, Space Telescope European Coordinating Facility9, Kapteyn Astronomical Institute10, University of Hertfordshire11, University of Toronto12, New Mexico Institute of Mining and Technology13
TL;DR: In this paper, the authors studied the kinematic morphology-density T-Sigma relation using fast and slow rotators to replace lenticulars and elliptical galaxies and found that the segregation is driven by local effects at the small-group scale.
Abstract: In Paper I of this series we introduced a volume-limited parent sample of 871 galaxies from which we extracted the ATLAS(3D) sample of 260 early-type galaxies (ETGs). In Papers II and III we classified the ETGs using their stellar kinematics, in a way that is nearly insensitive to the projection effects, and we separated them into fast and slow rotators. Here we look at galaxy morphology and note that the edge-on fast rotators generally are lenticular galaxies. They appear like spiral galaxies with the gas and dust removed, and in some cases are flat ellipticals (E5 or flatter) with discy isophotes. Fast rotators are often barred and span the same full range of bulge fractions as spiral galaxies. The slow rotators are rounder (E4 or rounder, except for counter-rotating discs) and are generally consistent with being genuine, namely spheroidal-like, elliptical galaxies. We propose a revision to the tuning-fork diagram by Hubble as it gives a misleading description of ETGs by ignoring the large variation in the bulge sizes of fast rotators. Motivated by the fact that only one third (34 per cent) of the ellipticals in our sample are slow rotators, we study for the first time the kinematic morphology-density T-Sigma relation using fast and slow rotators to replace lenticulars and ellipticals. We find that our relation is cleaner than using classic morphology. Slow rotators are nearly absent at the lowest density environments [f(SR) less than or similar to 2 per cent] and generally constitute a small fraction [f (SR) approximate to 4 per cent] of the total galaxy population in the relatively low-density environments explored by our survey, with the exception of the densest core of the Virgo cluster [f(SR) approximate to 20 per cent]. This contrasts with the classic studies that invariably find significant fractions of (misclassified) ellipticals down to the lowest environmental densities. We find a clean log-linear relation between the fraction f(Sp) of spiral galaxies and the local galaxy surface density Sigma(3), within a cylinder enclosing the three nearest galaxies. This holds for nearly four orders of magnitude in the surface density down to Sigma(3) approximate to 0.01 Mpc(-2), with f(Sp) decreasing by 10 per cent per dex in Sigma(3), while f(FR) correspondingly increases. The existence of a smooth kinematic T-Sigma relation in the field excludes processes related to the cluster environment, like e.g. ram-pressure stripping, as main contributors to the apparent conversion of spirals into fast rotators in low-density environments. It shows that the segregation is driven by local effects at the small-group scale. This is supported by the relation becoming shallower when using a surface density estimator Sigma(10) with a cluster scale. Only at the largest densities in the Virgo core does the f(Sp) relation break down and steepen sharply, while the fraction of slow rotators starts to significantly increase. This suggests that a different mechanism is at work there, possibly related to the stripping of the gas from spirals by the hot intergalactic medium in the cluster core and the corresponding lack of cold accretion.
TL;DR: In this article, the authors study the buildup of the bimodal galaxy population using the NEWFIRM Medium-Band Survey, which provides excellent redshifts and well-sampled spectral energy distributions of {approx}27, 000 galaxies with K 3 x 10{sup 10} M{sub sun} increases by a factor of {approximately}10 from z − 2 to the present day, whereas the mass density in star-forming galaxies is flat or decreases over the same time period.
Abstract: We study the buildup of the bimodal galaxy population using the NEWFIRM Medium-Band Survey, which provides excellent redshifts and well-sampled spectral energy distributions of {approx}27, 000 galaxies with K 3 x 10{sup 10} M{sub sun} increases by a factor of {approx}10 from z {approx} 2 to the present day, whereas the mass density in star-forming galaxies is flat or decreases over the same time period. Modest mass growth by a factor of {approx}2 of individual quiescent galaxies can explain roughly half of the strong density evolution at masses >10{sup 11} M{sub sun}, due to the steepness of the exponential tail of the mass function. The rest of the density evolution of massive, quiescent galaxies is likely due to transformation (e.g., quenching) of the massive star-forming population, a conclusion which ismore » consistent with the density evolution we observe for the star-forming galaxies themselves, which is flat or decreasing with cosmic time. Modest mass growth does not explain the evolution of less massive quiescent galaxies ({approx}10{sup 10.5} M{sub sun}), which show a similarly steep increase in their number densities. The less massive quiescent galaxies are therefore continuously formed by transforming galaxies from the star-forming population.« less
INAF1, University of Colorado Boulder2, California Institute of Technology3, Hoffmann-La Roche4, University of Toulouse5, University of Toronto6, European Southern Observatory7, University College London8, Liverpool John Moores University9, University of Calgary10, University of Provence11, Agenzia Spaziale Italiana12, University of Ferrara13, Sapienza University of Rome14, University of Rome Tor Vergata15, University of New South Wales16, Nagoya University17, Chinese Academy of Sciences18, Paris Diderot University19, University of Florida20, University of Hertfordshire21, Cardiff University22, Open University23
TL;DR: In this paper, an elliptical shape having semi-major axes of 100 and 60 pc is deduced, and the major axis of this 100 pc ring is inclined by about 40 degrees with respect to the plane of sky and is oriented perpendicular to the major axes of the Galactic Bar.
Abstract: Thermal images of cold dust in the Central Molecular Zone of the Milky Way, obtained with the far-infrared cameras on board the Herschel satellite, reveal a similar to 3 x 10(7) M-circle dot ring of dense and cold clouds orbiting the Galactic center. Using a simple toy model, an elliptical shape having semi-major axes of 100 and 60 pc is deduced. The major axis of this 100 pc ring is inclined by about 40 degrees with respect to the plane of the sky and is oriented perpendicular to the major axes of the Galactic Bar. The 100 pc ring appears to trace the system of stable x(2) orbits predicted for the barred Galactic potential. Sgr A* is displaced with respect to the geometrical center of symmetry of the ring. The ring is twisted and its morphology suggests a flattening ratio of 2 for the Galactic potential, which is in good agreement with the bulge flattening ratio derived from the 2MASS data.
University College London1, Goddard Space Flight Center2, Space Telescope Science Institute3, University of Wisconsin-Madison4, University of Arizona5, Max Planck Society6, Keele University7, European Southern Observatory8, Louisiana State University9, Stockholm University10, Institute for the Physics and Mathematics of the Universe11, Commissariat à l'énergie atomique et aux énergies alternatives12
TL;DR: Observations of supernova 1987A reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun, implying that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.
Abstract: We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.
TL;DR: It is shown that low-mass stars can be formed at very low metallicity, that is, below the critical value of Z, which implies that the stellar material must have experienced temperatures above two million kelvin in its history, given that this is necessary to destroy lithium.
Abstract: The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium; almost all other elements were subsequently created in stars and supernovae. The mass fraction of elements more massive than helium, Z, is known as 'metallicity'. A number of very metal-poor stars has been found, some of which have a low iron abundance but are rich in carbon, nitrogen and oxygen. For theoretical reasons and because of an observed absence of stars with Z < 1.5 × 10(-5), it has been suggested that low-mass stars cannot form from the primitive interstellar medium until it has been enriched above a critical value of Z, estimated to lie in the range 1.5 × 10(-8) to 1.5 × 10(-6) (ref. 8), although competing theories claiming the contrary do exist. (We use 'low-mass' here to mean a stellar mass of less than 0.8 solar masses, the stars that survive to the present day.) Here we report the chemical composition of a star in the Galactic halo with a very low Z (≤ 6.9 × 10(-7), which is 4.5 × 10(-5) times that of the Sun) and a chemical pattern typical of classical extremely metal-poor stars--that is, without enrichment of carbon, nitrogen and oxygen. This shows that low-mass stars can be formed at very low metallicity, that is, below the critical value of Z. Lithium is not detected, suggesting a low-metallicity extension of the previously observed trend in lithium depletion. Such lithium depletion implies that the stellar material must have experienced temperatures above two million kelvin in its history, given that this is necessary to destroy lithium.
Commonwealth Scientific and Industrial Research Organisation1, University of Sydney2, Australian Astronomical Observatory3, University of Lisbon4, National Radio Astronomy Observatory5, University of Nottingham6, University of Hertfordshire7, University of the Western Cape8, Victoria University of Wellington9, Ruhr University Bochum10, European Southern Observatory11, INAF12, University of Minnesota13, University College London14, Universidad de Guanajuato15, Durham University16, California Institute of Technology17, Institute of Cosmology and Gravitation, University of Portsmouth18, Max Planck Society19, Monash University, Clayton campus20, Cardiff University21, University of Washington22, UK Astronomy Technology Centre23, University of Edinburgh24, University of Cambridge25, Space Telescope Science Institute26, Macquarie University27, University of Tasmania28, University of Sussex29, National Centre for Radio Astrophysics30, Mount Stromlo Observatory31, University of British Columbia32
TL;DR: The EMU project as discussed by the authors is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope, with a resolution of 10 arcsec.
Abstract: EMU is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The primary goal of EMU is to make a deep (rms ~10 μJy/beam) radio continuum survey of the entire Southern sky at 1.3 GHz, extending as far North as +30° declination, with a resolution of 10 arcsec. EMU is expected to detect and catalogue about 70 million galaxies, including typical star-forming galaxies up to z ~ 1, powerful starbursts to even greater redshifts, and active galactic nuclei to the edge of the visible Universe. It will undoubtedly discover new classes of object. This paper defines the science goals and parameters of the survey, and describes the development of techniques necessary to maximise the science return from EMU.