On the physical properties of<i>z</i><i>≈</i>6–8 galaxies

Schaerer, D.; Barros, S. de

doi:10.1051/0004-6361/200913946

Cited by 186 publications

(256 citation statements)

References 75 publications

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“…We then computed the SFR from the Kennicutt (1998) relationship between UV luminosity and SFR. Our candidates have an SFR ≤ 25 M /yr, which is consistent with previous results (Labbé et al 2010, Schaerer & de Barros 2010.…”

Section: Star Formation Rate and Sizesupporting

confidence: 93%

“…For all of the objects in our sample, the best-fit SED is found at very high-redshift (z > 8.0) with a small 1σ confidence interval (dz < 1), meaning a good estimation of the photo-z. For most of the objects, the best-fit SED is found to have negligible dust content (A v = 0), as expected for very high-redshift objects (e.g., Schaerer & de Barros 2010). We also inspected the redshift probability distribution, P(z) to evaluate the probability that they are low-z interlopers.…”

Section: Sed-fittingmentioning

confidence: 84%

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Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Laporte

Streblyanska

Kim

et al. 2015

A&A

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Context. The Hubble Space Telescope (HST) Frontier Fields (HFFs) project started at the end of 2013 with the aim of providing extremely deep images of six massive galaxy clusters. One of the main goals of this program is to push several telescopes to their limits to provide the best current view of the earliest stages of the Universe. The analysis of the initial data has already demonstrated the huge capabilities of the program. Aims. We present a detailed analysis of z ∼ 8 objects behind the HFFs lensing cluster, MACSJ0416.1-2403, combining 0.3−1.6 µm imaging from HST, ground-based K s imaging from VLT HAWK-I, and 3.6 µm and 4.5 µm Spitzer Space Telescope. The images probe to 5σ depths of ≈29 AB for HST, 25.6 AB for HAWK-I, and ≈0.310 and 0.391 µJy at 3.6 and 4.5 µm, respectively. With these datasets, we assess the photometric properties of z ∼ 8 galaxies in this field, as well as their distribution in luminosity, to unprecedented sensitivity. Methods. We applied the classical Lyman break (LB) technique, which combines non detection criteria in bands blueward of the Lyman break at z ∼ 8 and color-selection in bands redward of the break. To avoid contamination by mid-z interlopers, we required a strong break between optical and near-infrared data. We determined the photometric properties of z ∼ 8 selected candidates using spectral energy distribution (SED)-fitting with standard library templates. The luminosity function at z ∼ 8 is computed using a Monte-Carlo method taking advantage of the SED-fitting results. A piece of cautionary information is gleaned from new deep optical photometry of a previously identified z ∼ 8 galaxy in this cluster, which is now firmly detected as a mid-z interloper with a strong ≈1.5 mag Balmer break (between F606W and F125W). Using the SED of this interloper, we estimated the contamination rate of our MACSJ0416.1−2403 sample, and that of previous samples in Abell 2744 that were based on HFF data, we highlight the dangers of pushing the LB technique too close to the photometry limits. Results. Our selection reliably recovers four objects with m F160W ranging from 26.0 to 27.9 AB that are located in modestamplification regions (µ < 2.4). Two of the objects display a secondary break between the IRAC 3.6 µm and 4.5 µm bands, which could be associated to the Balmer break or emission lines at z ∼ 8. The SED-fitting analysis suggests that all of these objects favor high-z solutions with no reliable secondary solutions. The candidates generally have star formation rates around ∼10 M /yr and sizes ranging from 0.2 to 0.5 kpc, which agrees well with previous observations and expectations for objects in the early Universe. The sample size and luminosity distribution are consistent with previous findings.

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Section: Star Formation Rate and Sizesupporting

confidence: 93%

Section: Sed-fittingmentioning

confidence: 84%

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Laporte

Streblyanska

Kim

et al. 2015

A&A

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“…21 Nebular continuum emission could be an important component for very young (∼10 Myr) starbursts and can contribute up to ∼1/3 of the total continuum just blueward of the rest-frame 4000 Å break. Nebular continuum emission also makes the rest-frame UV slope redder than expected from stars alone (Schaerer & De Barros 2010).…”

Section: Modeling Proceduresmentioning

confidence: 99%

“…Recent studies have shown that for some galaxy candidates, strong nebular emission lines contribute significantly to broadband fluxes and therefore influence the inferred galaxy properties (e.g., Schaerer & De Barros 2010;Smit et al 2014). Therefore, we use galaxy templates that include nebular emission lines in the modeling.…”

Section: Modeling Proceduresmentioning

confidence: 99%

SPITZER ULTRA FAINT SURVEY PROGRAM (SURFS UP). II. IRAC-DETECTED LYMAN-BREAK GALAXIES AT 6 ≲ z ≲ 10 BEHIND STRONG-LENSING CLUSTERS

Huang

Bradač

Lemaux

et al. 2016

ApJ

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We study the stellar population properties of the IRAC-detected 6  z  10 galaxy candidates from the Spitzer UltRa Faint SUrvey Program. Using the Lyman Break selection technique, we find a total of 17 galaxy candidates at 6  z  10 from Hubble Space Telescope images (including the full-depth images from the Hubble Frontier Fields program for MACS 1149 and MACS 0717) that have detections at signal-to-noise ratios  3 in at least one of the IRAC 3.6 and 4.5 μm channels. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors of ∼1.2-5.5. Due to the magnification of the foreground galaxy clusters, the rest-frame UV absolute magnitudes M 1600 are between −21.2 and −18.9 mag, while their intrinsic stellar masses are between 2×10 8 M e and 2.9×10 9 M e . We identify two Lyα emitters in our sample from the Keck DEIMOS spectra, one at z Lyα =6.76 (in RXJ 1347) and one at z Lyα =6.32 (in MACS 0454). We find that 4 out of 17 z  6 galaxy candidates are favored by z  1 solutions when IRAC fluxes are included in photometric redshift fitting. We also show that IRAC [3.6]-[4.5] color, when combined with photometric redshift, can be used to identify galaxies which likely have strong nebular emission lines or obscured active galactic nucleus contributions within certain redshift windows.

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“…Recent studies have given the first estimates of masses, ages, and SFRs for single z > ∼ 6.5 objects, the first constraints on the stellar mass density at these epochs, and have also raised an interesting debate about the possibilty that the first galaxes might be characterized by peculiar properties, like a very low dust content, nearly primordial metallicity or top-heavy stellar initial mass functions (Finkelstein et al 2010;Bouwens et al 2010a;González et al 2010;Salvaterra et al 2010;Schaerer & de Barros 2010).…”

Section: Introductionmentioning

confidence: 99%

The bright end of thez ~ 7UVluminosity function from a wide and deep HAWK-I survey

Castellano

Fontana

Paris

et al. 2010

A&A

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Aims. We perform a deep search for galaxies in the redshift range 6.5 ≤ z ≤ 7.5 to measure the evolution of the number density of luminous galaxies in this redshift range and derive useful constraints on the evolution of their luminosity function. Methods. We present here the second half of an ESO Large Programme, which exploits the unique combination of area and sensitivity provided in the near-IR by the camera Hawk-I at the VLT. We have obtained ∼30 observing hours with Hawk-I in the Y-band of two high galactic latitude fields. We combined the Y-band data with deep J and K Hawk-I observations, as well as FORS1/FORS2 U, B, V, R, I, and Z observations to select z-drop galaxies with Z − Y > 1, no optical detection, and flat Y − J and Y − K colour terms. Results. We detect eight high-quality candidates in the magnitude range Y = 25.5−26.5 that we add to the z-drop candidates selected in two Hawk-I pointings over the GOODS-South field. We use this full sample of 15 objects found in ∼161 arcmin 2 of our survey to constrain the average physical properties and the evolution of the number density of z ∼ 7 LBGs. A stacking analysis yields a best-fit SED with photometric redshift z = 6.85 +0.20 −0.15 and an E(B − V) = 0.05 +0.15 −0.05 . We compute a binned estimate of the z ∼ 7 LF and explore the effects of photometric scatter and model uncertainties on the statistical constraints. After accounting for the expected incompleteness through MonteCarlo simulations, we strengthen our previous finding that a Schechter luminosity function constant from z = 6 to z = 7 is ruled out at a > ∼ 99% confidence level, even including the effects of cosmic variance. For galaxies brighter than M 1500 = −19.0, we derive a luminosity density ρ UV = 1.5 +2.1 −0.8 × 10 25 erg s −1 Hz −1 Mpc −3 , implying a decrease by a factor 3.5 from z = 6 to z 6.8. We find that under standard assumptions, the emission rate of ionizing photons coming from UV bright galaxies is lower by at least a factor of two than the value required for reionization. Finally, we exploit deep Hawk-I J and K band observations to derive an upper limit on the number density of M 1500 < ∼ −22.0 LBGs at z ∼ 8 (Y-dropouts).

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On the physical properties ofz≈6–8 galaxies

Cited by 186 publications

References 75 publications

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

Frontier Fields: Combining HST, VLT, andSpitzerdata to explore thez~ 8 Universe behind the lensing cluster MACSJ0416.1−2403

SPITZER ULTRA FAINT SURVEY PROGRAM (SURFS UP). II. IRAC-DETECTED LYMAN-BREAK GALAXIES AT 6 ≲ z ≲ 10 BEHIND STRONG-LENSING CLUSTERS

The bright end of thez ~ 7UVluminosity function from a wide and deep HAWK-I survey

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