Deep GALEX Imaging of the COSMOS HST Field: A First Look at the Morphology of z ~ 0.7 Star-forming Galaxies

By M. Zamojski, David Schiminovich, R. Rich, B. Mobasher, A. Koekemoer, P. Capak, Yoshiaki Taniguchi, S. Sasaki, H. McCracken, Y. Mellier and 27 more. 2007

154 citations recorded by the source corpus.

We present a study of the morphological nature of redshift z ~ 0.7 star-forming galaxies using a combination of HST ACS, GALEX, and ground-based images of the COSMOS field. Our sample consists of 8146 galaxies, 5777 of which are detected in the GALEX near-ultraviolet band (2310 Å or ~1360 Å rest frame) down to a limiting magnitude of 25.5 (AB), and all of which have a brightness of F814W(HST) < 23 mag and photometric redshifts in the range 0.55 < z < 0.8. We make use of the UV to estimate star formation rates, correcting for the effect of dust using the UV slope, and of the ground-based multiband data to calculate masses. For all galaxies in our sample, we compute, from the ACS F814W images, their concentration (C), asymmetry (A), and clumpiness (S), as well as their Gini coefficient (G) and the second moment of the brightest 20% of their light (M20). We observe a bimodality in the galaxy population in asymmetry and in clumpiness, although the separation is most evident when either of those parameters is combined with a concentration-like parameter (C, G, or M20). We further show that this morphological bimodality has a strong correspondence with the FUV-g color bimodality and conclude that UV-optical color predominantly evolves concurrently with morphology. We observe many of the most star-forming galaxies to have morphologies approaching that of early-type galaxies, and we interpret this as evidence that strong starburst events are linked to bulge growth and constitute a process through which galaxies can be brought from the blue to the red sequence while simultaneously modifying their morphology accordingly. We conclude that the red sequence has continued growing at z ≲ 0.7. We also observe z ~ 0.7 galaxies to have physical properties similar to that of local galaxies, except for higher star formation rates. Whence we infer that the dimming of star-forming galaxies is responsible for most of the evolution in star formation rate density since that redshift, although our data are also consistent with a mild number evolution.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/f5a430bbc3aa21341c5aae3c58de6331cd1b392b

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In Astronomy and Astrophysics

1. P. V. van Dokkum
2. P. Hopkins
3. L. Hernquist
4. D. M. Alexander
5. M. Franx
6. Christopher J. Conselice
7. C. Conroy
8. P. Capak

In Instrumentation

1. P. V. van Dokkum
2. M. Franx
3. Christopher J. Conselice
4. C. Conroy
5. P. Capak
6. A. Koekemoer
7. Richard S. Ellis
8. I. Labbé

In Statistical and Nonlinear Physics

1. M. Franx
2. P. V. van Dokkum
3. I. Labbé
4. M. Kriek
5. J. Newman
6. K. Whitaker
7. G. Illingworth
8. R. Quadri

Citations in the corpus

• CANDELS: THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY (2011, unknown): “Additional multi-wavelength data in the COSMOS field include X-ray observations with XMM-Newton (Hasinger et al. 2007), UV observations with GALEX (Zamojski et al. 2007), mid-IR (3.6–24 µm) observations with Spitzer (Sanders et al. 2007), submillimeter observations from the Caltech Submillimeter…”
• The DEEP2 Galaxy Redshift Survey: the role of galaxy environment in the cosmic star formation history (2007, background): “…galaxies to the blue luminosity density to be subdominant at z ∼ 1; for instance, results from Conselice et al. (2005), Wolf et al. (2005), and Zamojski et al. (2007) all indicate that the drop in the global SFR at z < 1 (as traced by the B–band and UV luminosity densities) is driven by a…”
• THE CHANDRA COSMOS SURVEY. III. OPTICAL AND INFRARED IDENTIFICATION OF X-RAY POINT SOURCES (2012, methodology): “…using the vast Cosmic Evolutionary Survey (COSMOS, Scoville et al. 2007) multiwavelength photometric and spectroscopic database (Schinnerer et al. 2007, Sanders et al. 2007, Taniguchi et al. 2007, Capak et al. 2007, Koekemoer et al. 2007, Zamojski et al. 2007, Lilly et al. 2007, Trump et al. 2007).”
• Photometric Redshifts of Galaxies in COSMOS (2006, background): “…2007), to study the evolution of density-morphology relation (Capak et al. 2007a), to study dependence of the star formation activity on the environment (Mobasher et al. 2007) and to study morphologies and rest-frame properties of individual galaxies (Scarlata et al. 2007; Zamojski et al. 2007).”
• Two-dimensional kinematics of SLACS lenses – III. Mass structure and dynamics of early-type lens galaxies beyond z ≃ 0.1 (2011, background): “0.8, can sometimes be late-type systems characterized by clumpy, irregular and flocculent appearances (cf. e.g. Zamojski et al.2007; Elmegreen et al. 2009).”
• THE NEWFIRM MEDIUM-BAND SURVEY: PHOTOMETRIC CATALOGS, REDSHIFTS, AND THE BIMODAL COLOR DISTRIBUTION OF GALAXIES OUT TO z ∼ 3 (2011, methodology): “Finally, we incorporate NUV and FUV Galaxy Evolution Explorer (GALEX; Martin et al. 2005) data in both fields from the Multimission Archive at Space Telescope Science Institute (MAST) into the catalogs (see also Zamojski et al. 2007, for a description of the COSMOS GALEX data).”
• PHOTOMETRIC REDSHIFT AND CLASSIFICATION FOR THE XMM–COSMOS SOURCES (2008, methodology): “For each optical/infrared counterpart of a source in the XMM-COSMOS sample, the closest GALEX source from the de-blended, PSF-fitted GALEX-COSMOS catalog of Zamojski et al. (2007) was considered for inclusion in the photometry data set.”
• The structures of distant galaxies – III. The merger history of over 20 000 massive galaxies at z < 1.2 (2008, result): “This bimodality is present within all redshifts, and is the same bimodality found using similar structural parameters by Zamojski et al. (2007) within COSMOS.”
• THE STAR FORMATION HISTORY OF MASS-SELECTED GALAXIES IN THE COSMOS FIELD (2010, methodology): “Deep UV GALEX (Zamojski et al. 2007) to ground-based optical and nearinfrared (NIR) (Taniguchi et al. 2007; Capak et al. 2007) imaging of the equatorial field23 yielded accurate photometric data products for ∼ 1 × 106 galaxies down to 26.5th magnitude in the i-band (Ilbert et al. 2009; Capak et al.…”
• THE CHANDRA COSMOS SURVEY. I. OVERVIEW AND POINT SOURCE CATALOG (2009, methodology): “…undertaken in the F840W (∼ i-band) with Hubble Space Telescope (HST, Scoville et al. 2007b), in the 3.5 µm-70µm infrared using Spitzer IRAC and MIPS (Sanders et al. 2007), in the UV using GALEX (Zamojski et al. 2007), and in 0.5-10 keV X-rays with XMM (Hasinger et al. 2007, Cappelluti et al. 2007).”
• zCOSMOS – 10k-bright spectroscopic sample - The bimodality in the galaxy stellar mass function: exploring its evolution with redshift (2009, methodology): “COSMOS observations include good coverage of the field with multiband photometry from the UV (with GALEX, Zamojski et al. 2007), optical (with Subaru and CFHT, Taniguchi et al. 2007, Capak et al. 2007), NIR (with CTIO, KPNO, Capak et al. 2007, and CFHT, McCracken et al. 2010), to MIR and FIR (S-COSM”
• EVOLUTION OF GALAXIES AND THEIR ENVIRONMENTS AT z = 0.1–3 IN COSMOS (2013, methodology): “The mock catalog includes photometric magnitudes in the COSMOS filter passbands from FUV to IRAC1-4 and rest frame absolute magnitudes, with and without dust extinction.”
• THE COSMOS2015 CATALOG: EXPLORING THE 1 < z < 6 UNIVERSE WITH HALF A MILLION GALAXIES (2016, methodology): “However, in contrast to optical and NIR data, GALEX and IRAC data provide total magnitudes or fluxes, which require an estimate of the total flux from the corrected 3′′ aperture fluxes to be consistent over the full wavelength range.”
• The First Release COSMOS Optical and Near-IR Data and Catalog (2007, methodology): “…519, 1 Steidel et al., 2003, ApJ, 592, 728 Steidel et al., 1996, AJ, 112, 352 Taniguchi et al., 2007, astro-ph/0612295 Westera et al., 2002, A&A, 381, 524 Williams et al., 1996, AJ, 112, 1335 Wolf et al., 2001, A&A, 365, 681 Yasuda et al., 2001, AJ, 122, 1104 Zamojski et al., 2007, astro-ph/0701478”
• The COSMOS2015 galaxy stellar mass function . Thirteen billion years of stellar mass assembly in ten snapshots (2017, methodology): “Space-based facilities provided data in near-UV (from the GALEX satellite, Zamojski et al. 2007) and MIR (from IRAC on board the Spitzer Space Telescope), along with high-resolution optical images (ACS camera on board HST, see Sect.”
• PRIMUS: CONSTRAINTS ON STAR FORMATION QUENCHING AND GALAXY MERGING, AND THE EVOLUTION OF THE STELLAR MASS FUNCTION FROM z = 0–1 (2013, methodology): “EMphot has been used successfully in several previous studies to analyze deep GALEX imaging (Xu et al. 2005; Zamojski et al. 2007; Salim et al. 2009; Hammer et al. 2010), so we refer the interested reader to those papers for additional details.”
• DISSECTING PHOTOMETRIC REDSHIFT FOR ACTIVE GALACTIC NUCLEUS USING XMM- AND CHANDRA-COSMOS SAMPLES (2011, methodology): “To create the GALEX catalog, the U -band image was used as a prior, via PSF fitting.”
• THE VLA-COSMOS SURVEY. IV. DEEP DATA AND JOINT CATALOG (2010, background): “…of 2 deg2 (for an overview, see Scoville et al. 2007b) ranging from X-ray XMM-Newton and Chandra (Hasinger et al. 2007; Elvis et al. 2009), UV GALEX (Zamojski et al. 2007), optical and near-infrared groundbased (Taniguchi et al. 2007; Capak et al. 2007), optical HST (Scoville et al. 2007a;…”