LARGE AREA SURVEY FOR z = 7 GALAXIES IN SDF AND GOODS-N: IMPLICATIONS FOR GALAXY FORMATION AND COSMIC REIONIZATION

By M. Ouchi, B. Mobasher, K. Shimasaku, H. Ferguson, M. Fall, Yoshiaki Ono, N. Kashikawa, T. Morokuma, K. Nakajima, S. Okamura and 3 more. 2009

241 citations recorded by the source corpus.

We present results of our large area survey for z′-band dropout galaxies at z = 7 in a 1568 arcmin2 sky area covering the SDF and GOODS-N fields. Combining our ultra-deep Subaru/Suprime-Cam z′- and y-band (λeff = 1 μm) images with legacy data of Subaru and Hubble Space Telescope, we have identified 22 bright z-dropout galaxies down to y = 26, one of which has a spectroscopic redshift of z = 6.96 determined from Lyα emission. The z = 7 luminosity function yields the best-fit Schechter parameters of ϕ* = 0.69+2.62 −0.55 × 10−3 Mpc−3, M*UV = −20.10 ±  0.76 mag, and α = −1.72 ± 0.65, and indicates a decrease from z = 6 at a >95% confidence level. This decrease is beyond the cosmic variance in our two fields, which is estimated to be a factor of ≲2. We have found that the cosmic star formation rate density drops from the peak at z = 2–3 to z = 7 roughly by a factor of ∼10 but not larger than ∼100. A comparison with the reionization models suggests either that the universe could not be totally ionized by only galaxies at z = 7, or more likely that properties of galaxies at z = 7 are different from those at low redshifts having, e.g., a larger escape fraction (≳0.2), a lower metallicity, and/or a flatter initial mass function. Our SDF z-dropout galaxies appear to form 60 Mpc long filamentary structures, and the z = 6.96 galaxy with Lyα emission is located at the center of an overdense region consisting of four UV bright dropout candidates, which might suggest an existence of a well-developed ionized bubble at z = 7.

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

View Paper: https://www.semanticscholar.org/paper/57a0351241f9a559dc8ddca5daeec21d3aea55f8

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In Astronomy and Astrophysics

1. Richard S. Ellis
2. P. Hopkins
3. L. Hernquist
4. P. V. van Dokkum
5. J. Dunlop
6. M. Franx
7. P. Oesch
8. R. Bouwens

In Electrical and Electronic Engineering

1. Richard S. Ellis
2. R. Bouwens
3. J. Dunlop
4. P. Oesch
5. D. Stark
6. G. Illingworth
7. R. McLure
8. M. Ouchi

In Instrumentation

1. Richard S. Ellis
2. P. V. van Dokkum
3. M. Franx
4. J. Dunlop
5. R. Bouwens
6. I. Labbé
7. P. Oesch
8. G. Illingworth

Citations in the corpus

• THE EVOLUTION OF THE GALAXY REST-FRAME ULTRAVIOLET LUMINOSITY FUNCTION OVER THE FIRST TWO BILLION YEARS (2014, methodology): “…MUV* and α from the MCMC chains, as well as the covariance between the two parameters, along with previous determinations of MUV* and α (Bouwens et al. 2007, 2011b; McLure et al. 2009, 2013; Ouchi et al. 2009; van der Burg et al. 2010; Schenker et al. 2013; Willott et al. 2013; Bowler et al. 2014).”
• NEW CONSTRAINTS ON COSMIC REIONIZATION FROM THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN (2013, background): “As shown by Ouchi et al. (2009), escape fractions comparable to or larger thanfesc= 0.2 during the reionization epoch are required for galaxies with typical stellar populations to contribute significantly.”
• J1154+2443: a low-redshift compact star-forming galaxy with a 46 per cent leakage of Lyman continuum photons (2017, background): “…it is generally thought that numerous fainter lowmass SFGs, below the current detection limit of observations, are responsible for the bulk of the ionizing radiation at z & 6 (Ouchi et al. 2009; Wise & Chen 2009; Mitra, Ferrara & Choudhury 2013; Yajima, Choi & Nagamine 2011; Bouwens et al. 2015).”
• SPECTROSCOPIC CONFIRMATION OF z ∼ 7 LYMAN BREAK GALAXIES: PROBING THE EARLIEST GALAXIES AND THE EPOCH OF REIONIZATION (2011, background): “Together with the galaxy at z=6.96, initially found by Iye et al. (2006) as a Lyman α emitter but with continuum colors that fulfill the Lyman break selection (Ouchi et al. 2009), our galaxies form at the moment of writing the only set of spectroscopically confirmed z∼ 7 LBGs.”
• The galaxy luminosity function at z ≃ 6 and evidence for rapid evolution in the bright end from z ≃ 7 to 5 (2014, background): “…the LF at z = 5− 7 has been more successfully studied using ground-based surveys, which provide degree-scale imaging albeit to shallower depths (e.g. at z = 5 − 6: McLure et al. 2006, 2009; Willott et al. 2013, and at z ' 7: Ouchi et al. 2009; Castellano et al. 2010a,b; Bowler et al. 2012, 2014).”
• Ionization state of inter-stellar medium in galaxies: evolution, SFR-M * -Z dependence, and ionizing photon escape (2013, background): “If it is true, this would ease the tension of ionizing photon deficit problem (e.g. Ouchi et al. 2009; Robertson et al. 2010).”
• CANDELS: THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY (2011, unknown): “…data (Trenti et al. 2011; Grazian et al. 2011; Yan et al. 2011; Bouwens et al. 2011b; McLure et al. 2011; Oesch et al. 2011) and some heroic efforts from the ground (Ouchi et al. 2009, 2010; Ota et al. 2010; Castellano et al. 2010b; Vanzella et al. 2011); recent results are summarized in Figure 2.”
• STAR FORMATION RATES AND STELLAR MASSES OF z = 7–8 GALAXIES FROM IRAC OBSERVATIONS OF THE WFC3/IR EARLY RELEASE SCIENCE AND THE HUDF FIELDS (2009, background): “Until recently, only a modest number of relatively bright z & 7 galaxies were known, mostly from widearea NICMOS (Bouwens et al. 2008; Oesch et al. 2009a, R. J. Bouwens et al. in preparation) and groundbased searches(Ouchi et al. 2009; Castellano et al. 2009; Hickey et al. 2009).”
• Low-redshift Lyman continuum leaking galaxies with high [O iii]/[O ii] ratios (2018, background): “Two competitive possible sources of ionization, active galactic nuclei (AGN) (Madau & Haardt 2015) and low-mass star-forming galaxies (SFGs) (Ouchi et al. 2009; Wise & Chen 2009; Mitra, Ferrara & Choudhury 2013; Yajima, Choi & Nagamine 2011; Bouwens et al. 2015), were proposed.”
• UV LUMINOSITY FUNCTIONS AT REDSHIFTS z ∼ 4 TO z ∼ 10: 10,000 GALAXIES FROM HST LEGACY FIELDS (2014, methodology): “…the inclusion of widerarea data in these determinations quickly made it clear that some of the evolution in the LF was in the volume density φ∗ (e.g., Ouchi et al. 2009; Castellano et al. 2010; Bouwens et al. 2011b; Bradley et al. 2012; McLure et al. 2013) and in the faint-end slope α (Bouwens…”
• ESCAPE FRACTION OF IONIZING PHOTONS DURING REIONIZATION: EFFECTS DUE TO SUPERNOVA FEEDBACK AND RUNAWAY OB STARS (2014, methodology): “Ouchi et al.(2009) estimated the ionizing photon density to be log ˙nion ≃ 49.8−50.3 by integrating the UV luminosity function (UVLF) down toMUV =−18 (lower) or L = 0 (upper estimate) with a slope ofα = −1.72 atz∼ 7 with fesc= 20%.”
• THE UV LUMINOSITY FUNCTION OF STAR-FORMING GALAXIES VIA DROPOUT SELECTION AT REDSHIFTS z ∼ 7 AND 8 FROM THE 2012 ULTRA DEEP FIELD CAMPAIGN (2012, methodology): “Early surveys from Subaru (Ouchi et al. 2009), and the ESO Very Large Telescope (Castellano et al. 2010), have probed the luminous component of the star-forming population over an area > 1000 arcmin2.”
• SPECTROSCOPIC CONFIRMATION OF THREE z-DROPOUT GALAXIES AT z = 6.844–7.213: DEMOGRAPHICS OF Lyα EMISSION IN z ∼ 7 GALAXIES (2011, methodology): “We measure the 1σ sky noises from the pixel distributions around 9600 Å, the wavelength corresponding to that of Lyα at z ≈ 6.9, the expected peak of the redshift distribution for z-dropout selection (Figure 6 of Ouchi et al. 2009).”
• Great Optically Luminous Dropout Research Using Subaru HSC (GOLDRUSH). I. UV Luminosity Functions at $z \sim 4-7$ Derived with the Half-Million Dropouts on the 100 deg$^2$ Sky (2017, background): “…MUV < ∼−23 mag (e.g., Ouchi et al. 2004; Shimasaku et al. 2005; Sawicki & Thompson 2006; Yoshida et al. 2006; Iwata et al. 2007; McLure et al. 2009; Ouchi et al. 2009; Castellano et al. 2010; van der Burg et al. 2010; Willott et al. 2013; Bowler et al. 2015; Bowler et al. 2017; Stefanon et al.…”
• The difficulty of getting high escape fractions of ionizing photons from high-redshift galaxies: A view from the FIRE cosmological simulations (2015, background): “They often require high fesc in order to match the ionization state of the intergalactic medium (IGM) by z = 6 (e.g. Ouchi et al. 2009; Kuhlen & Faucher-Giguère 2012; Finkelstein et al. 2012; Robertson et al. 2013).”
• LINE-EMITTING GALAXIES BEYOND A REDSHIFT OF 7: AN IMPROVED METHOD FOR ESTIMATING THE EVOLVING NEUTRALITY OF THE INTERGALACTIC MEDIUM (2014, methodology): “For these objects, we used the photometric redshift distribution for ground-based z-drops from Ouchi et al. (2009).”
• AN INTENSELY STAR-FORMING GALAXY AT z ∼ 7 WITH LOW DUST AND METAL CONTENT REVEALED BY DEEP ALMA AND HST OBSERVATIONS (2013, methodology): “Due to the large uncertainties of photometric measurements, Ouchi et al. (2009a) cannot constrain E(B−V ), and provide only the lower limit of SFR with E(B − V ) ≥ 0.”
• DISCOVERY OF z ∼ 8 GALAXIES IN THE HUBBLE ULTRA DEEP FIELD FROM ULTRA-DEEP WFC3/IR OBSERVATIONS (2009, background): “Only ∼25 high-quality z ∼ 7 candidates are known (e.g., Bouwens et al. 2008; Oesch et al. 2009; Ouchi et al. 2009; Castellano et al. 2009; Gonzalez et al. 2009; R.J. Bouwens et al. 2009, in prep).”
• Observational evidence for intermediate-mass black holes (2017, methodology): “…of a strong Ly α emission line, virtually the only line available to confirm high redshifts, has been commonly used to detect galaxies at z > 6 (e.g., Ouchi et al. 2009, 2010; Finkelstein et al. 2013; Oesch et al. 2015) and has recently emerged as another powerful tool to discover seed BHs at…”