z ∼ 7 GALAXIES IN THE HUDF: FIRST EPOCH WFC3/IR RESULTS

By P. Oesch, R. Bouwens, G. Illingworth, C. Carollo, M. Franx, I. Labbé, D. Magee, M. Stiavelli, M. Trenti, P. V. van Dokkum. 2009

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We present a sample of 16 robust z ∼ 7 z850-drop galaxies detected by the newly installed Wide Field Camera 3 (WFC3)/IR on the Hubble Space Telescope. Our analysis is based on the first epoch data of the HUDF09 program covering the Hubble Ultra Deep Field with 60 orbits of Y105, J125, and H160 observations. These remarkable data cover 4.7 arcmin2 and are the deepest near infrared images ever taken, reaching to ∼29 mag AB (5σ). The 16 z ∼ 6.5–7.5 galaxies have been identified based on the Lyman Break technique utilizing (z850 − Y105) versus (Y105 − J125) colors. They have magnitudes J125=26.0–29.0 (AB), an average apparent half-light radius of ∼0.16 arcsec (≲1 kpc), and show very blue colors (some even β ≲ −2.5), in particular at low luminosities. The WFC3/IR data confirm previous Near Infrared Camera and Multi-Object Spectrometer detections indicating that the dropout selection at z ∼ 7 is very reliable. Our data allow a first determination of the faint-end slope of the z ∼ 7 luminosity function, reaching down to MUV ∼ −18, a full magnitude fainter than previous measurements. When fixing ϕ* = 1.4 × 10−3 Mpc−3 mag−1 to the value previously measured at z ∼ 6, we find a best-fit value of α = −1.77 ± 0.20, with a characteristic luminosity of M* = −19.91 ± 0.09. This steep slope is similar to what is seen at z ∼ 2–6 and indicates that low-luminosity galaxies could potentially provide adequate flux to reionize the universe. The remarkable depth and resolution of these new images provide insights into the coming power of the James Webb Space Telescope.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2d939c5d76d43e3b52fb8c3b0fdc97785f54dad8

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Citations in the corpus

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CONNECTING THE GAMMA RAY BURST RATE AND THE COSMIC STAR FORMATION HISTORY: IMPLICATIONS FOR REIONIZATION AND GALAXY EVOLUTION (2011, background): “Good progress has been made through efforts to identify rest-frame ultraviolet (UV)-selected galaxies in deep optical and near-infrared imaging out toz ∼ 8 (e.g., Bouwens et al. 2007, 2010a,b; Oesch et al. 2010; McLure et al. 2010).”
REIONIZATION AFTER PLANCK: THE DERIVED GROWTH OF THE COSMIC IONIZING EMISSIVITY NOW MATCHES THE GROWTH OF THE GALAXY UV LUMINOSITY DENSITY (2015, background): “The greater depths of probes for z = 6–10 galaxies provided greater confidence that galaxies could provide the necessary reservoir of photons to reionize the universe (e.g., Bouwens et al. 2010, 2011, 2015 [B15]; Bunker et al. 2010; McLure et al. 2013; Oesch et al. 2010, 2013; Ellis et al. 2013).”
THE EVOLUTION OF THE GALAXY REST-FRAME ULTRAVIOLET LUMINOSITY FUNCTION OVER THE FIRST TWO BILLION YEARS (2014, methodology): “…imaging with the Advanced Camera for Surveys (ACS; Beckwith et al. 2006), and the more recent HUDF09 (PI Illingworth; e.g., Bouwens et al. 2010a; Oesch et al. 2010b) and UDF12 surveys (PI Ellis; Ellis et al. 2013; Koekemoer et al. 2013), which obtained near-infrared imaging with the Wide Field…”
DISCOVERY OF z ∼ 8 GALAXIES IN THE HUBBLE ULTRA DEEP FIELD FROM ULTRA-DEEP WFC3/IR OBSERVATIONS (2009, methodology): “…we model the pixel-by-pixel profiles of galaxies at z∼8 with similar-luminosity galaxies from the z ∼ 4 Bouwens et al. (2007) HUDF B dropout sample, but scaled in size to match the observed (1+ z)−1 size-redshift scaling (Oesch et al. 2010b; Bouwens et al. 2004, 2006; Ferguson et al. 2004).”
Star formation sustained by gas accretion (2014, background): “Dust corrections are applied, and are already negligible by z ' 7 (Oesch et al. 2010; Bouwens et al. 2010, 2009).”
CANDELS MULTI-WAVELENGTH CATALOGS: SOURCE DETECTION AND PHOTOMETRY IN THE GOODS-SOUTH FIELD (2013, background): “44 05 v1 [ tion and physical properties of galaxies place essential constraints on the reionization (e.g., Fontana et al. 2010; Oesch et al. 2010; Grazian et al. 2011; Bouwens et al. 2012; Finkelstein et al. 2012a), the accretion history of galaxies at early times (e.g., Bouwens et al. 2010a;…”
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THE HST EXTREME DEEP FIELD (XDF): COMBINING ALL ACS AND WFC3/IR DATA ON THE HUDF REGION INTO THE DEEPEST FIELD EVER (2013, methodology): “…Camera 3 (WFC3/IR) was added to Hubble in 2009 by the Shuttle astronauts in the final Hubble servicing mission (SM4) that the reionization epoch was opened up to extensive exploration (e.g. Oesch et al. 2010; Bouwens et al. 2010; McLure et al. 2010; Bunker et al. 2010; Finkelstein et al. 2010).”
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LOFAR: The LOw-Frequency ARray (2013, background): “Still the current constraints strongly suggest that the EoR roughly straddled the redshift range of z ∼ 6–12 (Komatsu et al. 2011; Fan, et al. 2003, 2006; Bolton & Haehnelt 2007; Theuns et al. 2002; Bolton et al. 2010; Oesch et al. 2010; Bunker et al. 2010).”
The extreme faint end of the UV luminosity function at z ∼ 6 through gravitational telescopes: a comprehensive assessment of strong lensing uncertainties (2018, background): “LF Thanks to the sensitivity and the high spatial resolution of the ACS and WFC3 instruments onboard HST, important progress has been made during the past years in the measurements of sizes of high-redshift galaxies (e.g., Oesch et al. 2010; Huang et al. 2013; Holwerda et al. 2015).”
THE HUBBLE SPACE TELESCOPE WIDE FIELD CAMERA 3 EARLY RELEASE SCIENCE DATA: PANCHROMATIC FAINT OBJECT COUNTS FOR 0.2–2 μm WAVELENGTH (2010, methodology): “In particular, the faint-end LF-slope α steepens significantly at higher redshifts, which was suggested by e.g., Yan & Windhorst (2004), Ryan et al. (2007), Hathi et al. (2010), and Oesch et al. (2010).”
Galaxies at z = 6 - 9 from the WFC3/IR imaging of the HUDF (2009, methodology): “Our own analysis of the NICMOS+ACS photometry for these objects in fact indicates that only the first two objects listed in Table 1 (i.e. the two galaxies confirmed by Oesch et al. 2009a) actually lie atz > 7, and SED fits and redshift constraints on these two galaxies are illustrated in Fig.”
New Measurements of the Ionizing Ultraviolet Background over 2 < z < 5 and Implications for Hydrogen Reionization (2013, background): “…> 6 indicate that the global star formation rate density declines steeply with redshift over 6 < z < 12 (e.g., Ouchi et al. 2009; Castellano et al. 2010; Bunker et al. 2010; Bouwens et al. 2006, 2008, 2011, 2012; Oesch et al. 2010; McLure et al. 2010, 2013; Schenker et al. 2013; Ellis et al. 2013).”
THE 2012 HUBBLE ULTRA DEEP FIELD (UDF12): OBSERVATIONAL OVERVIEW (2012, result): “C O ] 6 D ec 2 01 2 2004, 2007, Bunker et al. 2004, McLure et al. 2006, 2009, Yan et al. 2006, 2010, Castellano et al. 2010, Oesch et al. 2010b).”
AN INTENSELY STAR-FORMING GALAXY AT z ∼ 7 WITH LOW DUST AND METAL CONTENT REVEALED BY DEEP ALMA AND HST OBSERVATIONS (2013, background): “Their small physical sizes (≃ 0.7 kpc; Oesch et al. 2010; Ono et al. 2013) and modest stellar masses (108 − 109M⊙; Labbé et al. 2010) suggest they quickly merge into larger, more luminous systems.”