SPECTROSCOPIC CONFIRMATION OF<i>z</i>∼ 7 LYMAN BREAK GALAXIES: PROBING THE EARLIEST GALAXIES AND THE EPOCH OF REIONIZATION

Pentericci, L.; Fontana, A.; Vanzella, E.; Castellano, M.; Grazian, A.; Dijkstra, Mark; Boutsia, K.; Cristiani, S.; Dickinson, Mark; Giallongo, E.; Giavalisco, Mauro; Maiolino, R.; Moorwood, A. F. M.; Paris, D.; Santini, P.

doi:10.1088/0004-637x/743/2/132

Cited by 327 publications

(433 citation statements)

References 49 publications

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“…At 6.5 < z < 7.5, this feature is sampled by the large Z − Y color, as shown by a number of works using ground based imaging (Ouchi et al 2009;Castellano et al 2010a,b) and from space Mannucci et al 2007;Oesch et al 2009Oesch et al , 2010Bunker et al 2010;McLure et al 2010;Bouwens et al 2011). The spectroscopic confirmations of these candidates (shown in Fontana et al 2010;Vanzella et al 2011;Pentericci et al 2011;Stark et al 2011;Ono et al 2012) ensures that this technique is robust and the fraction of expected interlopers is quite low (less than 20% at z ∼ 6, as shown in Pentericci et al 2011).…”

Section: Selecting Galaxies At Z = 7: Color Criteriamentioning

confidence: 85%

The size-luminosity relation atz = 7 in CANDELS and its implication on reionization

Grazian

Castellano

Fontana

et al. 2012

A&A

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102

157

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Context. The exploration of the relation between galaxy sizes and other physical parameters (luminosity, mass, star formation rate) has provided important clues for understanding galaxy formation, but such exploration has until recently been limited to intermediate redshift objects. Aims. We use the currently available CANDELS Deep+Wide surveys in the GOODS-South, UDS and EGS fields, complemented by data from the HUDF09 program, to address the relation between size and luminosity at z ∼ 7. Methods. The six different fields used for this study are characterized by a wide combination of depth and areal coverage, well suited for reducing the biases on the observed size-magnitude plane. From these fields, we select 153 z-band dropout galaxies. Detailed simulations have been carried out for each of these six fields, inserting simulated galaxies at different magnitudes and half light radius in the two dimensional images for all the Hubble Space Telescope (HST) bands available and recovering them as carried out for the real galaxies. These simulations allow us to derive precisely the completeness as a function of size and magnitude and to quantify measurements errors/biases, under the assumption that the 2D profile of z = 7 galaxies is well represented by an exponential disk function. Results. We find in a rather robust way that the half light radius distribution function of z ∼ 7 galaxies fainter than J = 26.6 is peaked at ≤0.1 arcsec (or equivalently 0.5 kpc proper), while at brighter magnitudes high-z galaxies are typically larger than ∼0.15 arcsec. We also find a well defined size-luminosity relation, Rh ∝ L 1/2 . We compute the luminosity function (LF) in the HUDF and P12HUDF fields, finding large spatial variation on the number density of faint galaxies. Adopting the size distribution and the size-luminosity relation found for faint galaxies at z = 7, we derive a mean slope of −1.7 ± 0.1 for the LF of LBGs at this redshift. Conclusions. Using this LF, we find that the number of ionizing photons emitted from galaxies at z ∼ 7 cannot keep the Universe re-ionized if the IGM is clumpy (C HII ≥ 3) and the Lyman continuum escape fraction of high-z LBGs is relatively low ( f esc ≤ 0.3). If these results are confirmed and strengthened by future CANDELS data, in particular by the forthcoming deep observations in GOODS-South and North and the wide field COSMOS, we can put severe limits to the role of galaxies in the reionization of the Universe.

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Section: Selecting Galaxies At Z = 7: Color Criteriamentioning

confidence: 85%

The size-luminosity relation atz = 7 in CANDELS and its implication on reionization

Grazian

Castellano

Fontana

et al. 2012

A&A

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102

157

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“…We find that the fraction of LAEs is ∼10% at these redshifts, which is consistent with previous studies (e.g., Reddy et al 2008), and is in accordance with the general picture where the Lyα fraction increases with redshift (e.g., Stark et al 2010;Curtis-Lake et al 2012;Cassata et al 2015). The Lyα fraction apparently starts to decrease at higher redshift (z > ∼ 6.5; e.g., Pentericci et al 2011), where great amounts of neutral hydrogen start to affect the visibility of Lyα line indicating the onset of the reionization epoch.…”

Section: Resultsmentioning

confidence: 99%

The VIMOS Ultra Deep Survey: Lyαemission and stellar populations of star-forming galaxies at 2 < z < 2.5

Fèvre

Ilbert

Cassata

et al. 2016

A&A

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The aim of this paper is to investigate spectral and photometric properties of 854 faint (i AB < ∼ 25 mag) star-forming galaxies (SFGs) at 2 < z < 2.5 using the VIMOS Ultra-Deep Survey (VUDS) spectroscopic data and deep multi-wavelength photometric data in three extensively studied extragalactic fields (ECDFS, VVDS, COSMOS). These SFGs were targeted for spectroscopy as a result of their photometric redshifts. The VUDS spectra are used to measure the UV spectral slopes (β) as well as Lyα equivalent widths (EW). On average, the spectroscopically measured β (-1.36 ± 0.02), is comparable to the photometrically measured β (-1.32 ± 0.02), and has smaller measurement uncertainties. The positive correlation of β with the spectral energy distribution (SED)-based measurement of dust extinction E s (B − V) emphasizes the importance of β as an alternative dust indicator at high redshifts. To make a proper comparison, we divide these SFGs into three subgroups based on their rest-frame Lyα EW: SFGs with no Lyα emission (SFG N ; EW ≤ 0 Å), SFGs with Lyα emission (SFG L ; EW > 0 Å), and Lyα emitters (LAEs; EW ≥ 20 Å). The fraction of LAEs at these redshifts is ∼10%, which is consistent with previous observations. We compared best-fit SED-estimated stellar parameters of the SFG N , SFG L and LAE samples. For the luminosities probed here (∼L * ), we find that galaxies with and without Lyα in emission have small but significant differences in their SED-based properties. We find that LAEs have less dust, and lower star-formation rates (SFR) compared to non-LAEs. We also find that LAEs are less massive compared to non-LAEs, though the difference is smaller and less significant compared to the SFR and E s (B − V). When we divide the LAEs according to their Spitzer/IRAC 3.6 μm fluxes, we find that the fraction of IRAC-detected (m 3.6 < ∼ 25 mag) LAEs is much higher than the fraction of IRAC-detected narrow band (NB)-selected LAEs at z 2-3. This could imply that UV-selected LAEs host a more evolved stellar population, which represents a later stage of galaxy evolution, compared to NB-selected LAEs.

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“…At z ∼ 7 Ono et al (2012), Pentericci et al (2011), andSchenker et al (2012) all find that the fraction decreases from z ∼ 6 to z ∼ 7. Currently, there is a factor of two discrepancy between the fraction of luminous dropout sources with EW Lyα,0 > 25 Å at z ∼ 6 (Curtis-Lake et al 2012; Stark et al 2010).…”

Section: Fraction Of Lbgs With Lyαmentioning

confidence: 92%

Lyα EMISSION FROM HIGH-REDSHIFT SOURCES IN COSMOS

Mallery

Mobasher

Capak

et al. 2012

ApJ

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We investigate spectroscopically measured Lyα equivalent widths (EWs) and escape fractions of 244 sources of which 95 are Lyman break galaxies (LBGs) and 106 Lyman alpha emitters (LAEs) at z ∼ 4.2, z ∼ 4.8, and z ∼ 5.6 selected from intermediate and narrowband observations. The sources were selected from the Cosmic Evolution Survey and observed with the DEIMOS spectrograph. We find that the distribution of EWs shows no evolution with redshift for both the LBG selected sources and the intermediate/narrowband LAEs. We also find that the Lyα escape fraction of intermediate/narrowband LAEs is on average higher and has a larger variation than the escape fraction of LBG selected sources. The escape fraction does not show a dependence with redshift. Similar to what has been found for LAEs at low redshifts, the sources with the highest extinctions show the lowest escape fractions. The range of escape fractions increases with decreasing extinction. This is evidence that the dust extinction is the most important factor affecting the escape of Lyα photons, but at low extinctions other factors, such as the H i covering fraction and gas kinematics, can be just as effective at inhibiting the escape of Lyα photons.

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SPECTROSCOPIC CONFIRMATION OFz∼ 7 LYMAN BREAK GALAXIES: PROBING THE EARLIEST GALAXIES AND THE EPOCH OF REIONIZATION

Cited by 327 publications

References 49 publications

The size-luminosity relation atz = 7 in CANDELS and its implication on reionization

The size-luminosity relation atz = 7 in CANDELS and its implication on reionization

The VIMOS Ultra Deep Survey: Lyαemission and stellar populations of star-forming galaxies at 2 < z < 2.5

Lyα EMISSION FROM HIGH-REDSHIFT SOURCES IN COSMOS

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