The Hubble Deep Field: Observations, Data Reduction, and Galaxy Photometry

Williams, Robert E.; Blacker, Brett S.; Dickinson, Mark; Dixon, W. V.; Ferguson, Henry C.; Fruchter, A. S.; Giavalisco, Mauro; Gilliland, Ronald L.; Heyer, I.; Katsanis, Rocio; Levay, Zolt; Lucas, Ray A.; McElroy, D. B.; Petro, L.; Postman, Marc; Adorf, Hans Martin; Hook, R. N.

doi:10.1086/118105

Cited by 966 publications

(756 citation statements)

References 20 publications

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“…It covers ≈160 arcmin 2 centred on the Hubble Deep Field North (HDF-N, 12 h 36 m , +62 • 14 ; Williams et al 1996) and it includes very deep X-ray Chandra data (2 Ms; A59, page 2 of 28 Alexander et al 2003), optical Hubble Space Telescope (HST; Giavalisco et al 2004) and mid-infrared (MIR) Spitzer observations (PI: M. Dickinson); the GOODS-N field has also been the target of several deep optical imaging and spectroscopic campaigns from 8-10 m ground-based telescopes. Recently, new deep observations of this field in the far-infrared (FIR) band with Herschel ) and the radio band with VLA (Morrison et al 2010) have usefully increased the potential of the GOODS-N data set.…”

Section: Observations and Catalogsmentioning

confidence: 99%

GOODS-Herschel: radio-excess signature of hidden AGN activity in distant star-forming galaxies

Moro

Alexander

Mullaney

et al. 2012

A&A

129

111

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Context. A tight correlation exists between far-infrared and radio emission for star-forming galaxies (SFGs), which seems to hold out to high redshifts (z ≈ 2). Any excess of radio emission over that expected from star formation processes is most likely produced by an active galactic nucleus (AGN), often hidden by large amounts of dust and gas. Identifying these radio-excess sources will allow us to study a population of AGN unbiased by obscuration and thus find some of the most obscured, Compton-thick AGN, which are in large part unidentified even in the deepest X-ray and infrared (IR) surveys. Aims. We present here a new spectral energy distribution (SED) fitting approach that we adopt to select radio-excess sources amongst distant star-forming galaxies in the GOODS-Herschel (North) field and to reveal the presence of hidden, highly obscured AGN. Methods. Through extensive SED analysis of 458 galaxies with radio 1.4 GHz and mid-IR 24 µm detections using some of the deepest Chandra X-ray, Spitzer and Herschel infrared, and VLA radio data available to date, we have robustly identified a sample of 51 radio-excess AGN (∼1300 deg −2 ) out to redshift z ≈ 3. These radio-excess AGN have a significantly lower far-IR/radio ratio (q < 1.68, 3σ) than the typical relation observed for star-forming galaxies (q ≈ 2.2). Results. We find that ≈45% of these radio-excess sources have a dominant AGN component in the mid-IR band, while for the remainders the excess radio emission is the only indicator of AGN activity. The presence of an AGN is also confirmed by the detection of a compact radio core in deep VLBI 1.4 GHz observations for eight of our radio-excess sources (≈16%; ≈66% of the VLBI detected sources in this field), with the excess radio flux measured from our SED analysis agreeing, to within a factor of two, with the radio core emission measured by VLBI. We find that the fraction of radio-excess AGN increases with X-ray luminosity reaching ∼60% at L X ≈ 10 44 −10 45 erg s −1 , making these sources an important part of the total AGN population. However, almost half (24/51) of these radio-excess AGN are not detected in the deep Chandra X-ray data, suggesting that some of these sources might be heavily obscured. Amongst the radio-excess AGN we can distinguish three groups of objects: i) AGN clearly identified in infrared (and often in X-rays), a fraction of which are likely to be distant Compton-thick AGN; ii) moderate luminosity AGN (L X 10 43 erg s −1 ) hosted in strong star-forming galaxies; and iii) a small fraction of low accretion-rate AGN hosted in passive (i.e. weak or no star-forming) galaxies. We also find that the specific star formation rates (sSFRs) of the radio-excess AGN are on average lower that those observed for X-ray selected AGN hosts, indicating that our sources are forming stars more slowly than typical AGN hosts, and possibly their star formation is progressively quenching.

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Section: Observations and Catalogsmentioning

confidence: 99%

GOODS-Herschel: radio-excess signature of hidden AGN activity in distant star-forming galaxies

Moro

Alexander

Mullaney

et al. 2012

A&A

129

111

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“…where light is generated by stars) at high redshifts has seen a tremendous progress in the last years thanks to programs employing the Lyman break technique (cf. Steidel et al 1995Steidel et al , 1996Steidel et al , 1999, and projects like the Hubble Deep Field (HDF, Williams et al 1996). Steidel and collaborators (1996) have shown that on the order of a few percent of the galaxies at faint optical magnitudes (R ∼ 25) are actively star forming galaxies at redshift greater than 3.…”

Section: Star Forming Galaxies At High Redshiftmentioning

confidence: 99%

The most metal-poor galaxies

Kunth

Östlin

2000

Astronomy and Astrophysics Review

374

428

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Metallicity is a key parameter that controls many aspects in the formation and evolution of stars and galaxies. In this review we focus on the metal deficient galaxies, in particular the most metal-poor ones, because they play a crucial rôle in the cosmic scenery. We first set the stage by discussing the difficult problem of defining a global metallicity and how this quantity can be measured for a given galaxy. The mechanisms that control the metallicity in a galaxy are reviewed in detail and involve many aspects of modern astrophysics: galaxy formation and evolution, massive star formation, stellar winds, chemical yields, outflows and inflows etc. Because metallicity roughly scales as the galactic mass, it is among the dwarfs that the most metalpoor galaxies are found. The core of our paper reviews the considerable progress made in our understanding of the properties and the physical processes that are at work in these objects. The question on how they are related and may evolve from one class of objects to another is discussed. While discussing metal-poor galaxies in general, we present a more detailed discussion of a few very metal-poor blue compact dwarf galaxies like IZw18. Although most of what is known relates to our local universe, we show that it pertains to our quest for primeval galaxies and is connected to the question of the origin of structure in the universe. We discuss what QSO absorption lines and known distant galaxies tell us already? We illustrate the importance of star-forming metal-poor galaxies for the determination of the primordial helium abundance, their use as distance indicator and discuss the possibility to detect nearly metal-free galaxies at high redshift from Lyα emission.

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“…York et al 2000), the Hubble Deep Fields (e.g. Williams et al 1996), COSMOS (e.g. Scoville et al 2007), or GOODS (e.g.…”

Section: Introductionmentioning

confidence: 99%

Photometric redshifts for gamma-ray burst afterglows from GROND andSwift/UVOT

Krühler

Schady

Greiner

et al. 2011

A&A

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Aims. We present a framework to obtain photometric redshifts (photo-zs) for gamma-ray burst afterglows. Using multi-band photometry from GROND and Swift/UVOT, photo-zs are derived for five GRBs for which spectroscopic redshifts are not available. Methods. We use UV/optical/NIR data and synthetic photometry based on afterglow observations and theory to derive the photometric redshifts of GRBs and their accuracy. Taking into account the afterglow synchrotron emission properties, we investigate the application of photometry to derive redshifts in a theoretical range between z ∼ 1 to z ∼ 12.Results. The measurement of photo-zs for GRB afterglows provides a quick, robust and reliable determination of the distance scale to the burst, particularly in those cases where spectroscopic observations in the optical/NIR range cannot be obtained. Given a sufficiently bright and mildly reddened afterglow, the relative photo-z accuracy η = Δz/(1 + z) is better than 10% between z = 1.5 and z ∼ 7 and better than 5% between z = 2 and z = 6. We detail the approach on 5 sources without spectroscopic redshifts observed with UVOT on-board Swift and/or GROND. The distance scale to those same afterglows is measured to be z = 4.31 +0.14 −0.15 for GRB 080825B, z = 2.13 +0.14 −0.20 for GRB 080906, z = 3.44 +0.15 −0.32 for GRB 081228, z = 2.03 +0.16 −0.14 for GRB 081230 and z = 1.28 +0.16 −0.15 for GRB 090530. Conclusions. Due to the exceptional luminosity and simple continuum spectrum of GRB afterglows, photometric redshifts can be obtained to an accuracy as good as η ∼ 0.03 over a large redshift range including robust (η ∼ 0.1) measurements in the ultra-high redshift regime (z 7). Combining the response from UVOT with ground-based observatories and in particular GROND operating in the optical/NIR wavelength regime, reliable photo-zs can be obtained from z ∼ 1.0 out to z ∼ 10, and possibly even at higher redshifts in some favorable cases, provided that these GRBs exist, are localized quickly, have sufficiently bright afterglows and are not heavily obscured.

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The Hubble Deep Field: Observations, Data Reduction, and Galaxy Photometry

Cited by 966 publications

References 20 publications

GOODS-Herschel: radio-excess signature of hidden AGN activity in distant star-forming galaxies

GOODS-Herschel: radio-excess signature of hidden AGN activity in distant star-forming galaxies

The most metal-poor galaxies

Photometric redshifts for gamma-ray burst afterglows from GROND andSwift/UVOT

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