THE CHANGING Lyα OPTICAL DEPTH IN THE RANGE 6 &lt;
                    <i>z</i>
                    &lt; 9 FROM THE MOSFIRE SPECTROSCOPY OF
                    <i>Y</i>
                    -DROPOUTS

Treu, Tommaso; Schmidt, Kasper B.; Trenti, Michele; Bradley, Larry; Stiavelli, M.

doi:10.1088/2041-8205/775/1/l29

Cited by 218 publications

(284 citation statements)

References 34 publications

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“…0.35 at z ∼ 7 and z ∼ 8, respectively, in agreement with the measurements of declining Lyman alpha emission fraction of high-redshift galaxies (Stark et al 2010;Treu et al 2013;Faisst et al 2014;Pentericci et al 2014;Schenker et al 2014;Tilvi et al 2014; see also the solid pentagons in Fig. 10).…”

Section: Other Reionization Constraintssupporting

confidence: 87%

“…Reionization is relatively wellconstrained to be completed at z 6 by analysis of the Gunn-Peterson effect (Gunn & Peterson 1965) in the spectra of high-redshift QSOs (e.g., Fan et al 2006;Willott et al 2007;Bolton et al 2011;McGreer et al 2015) and gammaray bursts (GRBs, e.g., Chornock et al 2013). Preliminary measurements of the IGM neutral fraction at z ∼ 7-8 have been made using the Lyα emission fraction of star-forming galaxies (e.g., Stark et al 2010;Treu et al 2013;Pentericci et al 2014;Tilvi et al 2014;Faisst et al 2014;Schenker et al 2014). On the other hand, the integrated Thomson scattering optical depth, τes, due to the scattering of CMB photons off free electrons after reionization, places an important integral constraint on the extended reionization history.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Sun

Furlanetto

2016

Mon. Not. R. Astron. Soc.

173

157

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Reionization is thought to have occurred in the redshift range of 6 < z < 9, which is now being probed by both deep galaxy surveys and CMB observations. Using halo abundance matching over the redshift range 5 < z < 8 and assuming smooth, continuous gas accretion, we develop a model for the star formation efficiency f of dark matter halos at z > 6 that matches the measured galaxy luminosity functions at these redshifts. We find that f peaks at ∼ 30% at halo masses M ∼ 10 11 -10 12 M , in qualitative agreement with its behavior at lower redshifts. We then investigate the cosmic star formation histories and the corresponding models of reionization for a range of extrapolations to small halo masses. We use a variety of observations to further constrain the characteristics of the galaxy populations, including the escape fraction of UV photons. Our approach provides an empirically-calibrated, physically-motivated model for the properties of star-forming galaxies sourcing the epoch of reionization. In the case where star formation in low-mass halos is maximally efficient, an average escape fraction ∼ 0.1 can reproduce the optical depth reported by Planck, whereas inefficient star formation in these halos requires either about twice as many UV photons to escape, or an escape fraction that increases towards higher redshifts. Our models also predict how future observations with JWST can improve our understanding of these galaxy populations.

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Section: Other Reionization Constraintssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Sun

Furlanetto

2016

Mon. Not. R. Astron. Soc.

173

157

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show abstract

“…Qualitatively, the non-negligible neutral fraction predicted by our model at z ∼ > 7 is consistent with the observed high optical depth of Lyα (Ouchi et al 2010;Treu et al 2013;Pentericci et al 2014;Schenker et al 2014;Tilvi et al 2014;Faisst et al 2014, K. B. Schmidt et al 2015, ApJ submitted), however the conversion from the Lyα emission fraction to the volume filling factor of ionized hydrogen is difficult and requires several assumptions . In particular, to make constraints on reionization it is generally assumed that there are no changes in galaxy and the Lyα emission line properties, which necessitates a rapid evolution of the global ionization fraction between z ∼ 6 and z ∼ 7.…”

Section: Q(z)supporting

confidence: 85%

The Galaxy UV Luminosity Function Before the Epoch of Reionization

Mason

Trenti²,

Treu

2015

Proc. IAU

Self Cite

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We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a mass dependent, but redshift independent, efficiency. We introduce a new self-consistent treatment of the halo star formation history, which allows us to make predictions at z > 10 (lookback time ∼ < 500 Myr), when growth is rapid. With a calibration at a single redshift to set the stellar-to-halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all available observations (0 ∼ < z ∼ < 10). The significant drop in luminosity density of currently detectable galaxies beyond z ∼ 8 is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth τ = 0.056 +0.007 −0.010 , fully consistent with the latest Planck measurement, implying that the universe is fully reionized at z = 7.84 +0.65 −0.98 . In addition, our model naturally produces smoothly rising star formation histories for galaxies with L ∼ < L * in agreement with observations and hydrodynamical simulations. Before the epoch of reionization at z > 10 we predict the LF to remain well-described by a Schechter function, but with an increasingly steep faint-end slope (α ∼ −3.5 at z ∼ 16). Finally, we construct forecasts for surveys with JWST and WFIRST and predict that galaxies out to z ∼ 14 will be observed. Galaxies at z > 15 will likely be accessible to JWST and WFIRST only through the assistance of strong lensing magnification.

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“…The sensitivity of Lyα emission to neutral gas is also used to probe the ionization state of the intergalactic medium (IGM) at z > 6. In particular, the prevalence of Lyα emitters (LAEs) among continuum-selected galaxies (Lyman break galaxies, LBGs) appears to drop very rapidly at z > 6.5, which suggests an increase in the fraction of neutral hydrogen (Stark et al 2010;Treu et al 2013;Pentericci et al 2014;Schenker et al 2014). The decline in the LAEfraction also favors a patchy rather than a smooth reionization process.…”

Section: Introductionmentioning

confidence: 99%

ARE ULTRA-FAINT GALAXIES ATz= 6–8 RESPONSIBLE FOR COSMIC REIONIZATION? COMBINED CONSTRAINTS FROM THE HUBBLE FRONTIER FIELDS CLUSTERS AND PARALLELS

Atek

Richard

Jauzac

et al. 2015

ApJ

211

229

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We use deep Hubble Space Telescope imaging of the Frontier Fields to accurately measure the galaxy rest-frame ultraviolet luminosity function (UV LF) in the redshift range z ∼ 6-8. We combine observations in three lensing clusters, A2744, MACS 0416, and MACS 0717, and their associated parallelfields to select high-redshift dropout candidates. We use the latest lensing models to estimate the flux magnification and the effective survey volume in combination with completeness simulations performed in the source plane. We report the detection of 227 galaxy candidates at z = 6-7 and 25 candidates at z ∼ 8. While the total survey area is about 4 arcmin 2 in each parallel field, it drops to about 0.6-1 arcmin 2 in the cluster core fields because of the strong lensing. We compute the UV LF at z ∼ 7 using the combined galaxy sample and perform Monte Carlo simulations to determine the best-fit Schechter parameters. We are able to reliably constrain the LF down to an absolute magnitude of M UV = −15.25, which corresponds to 0.005 L å . More importantly, we find that the faint-end slope remains steep down to this magnitude limit with 2.04 . Our results confirm the most recent results in deep blank fields but extend the LF measurements more than two magnitudes deeper. The UV LF at z ∼ 8 is not very well constrained below M UV = −18 owing to the small number statistics and incompleteness uncertainties. To assess the contribution of galaxies to cosmic reionization, we derive the UV luminosity density at z ∼ 7 by integrating the UV LF down to an observational limit of M UV = −15. We show that our determination of log(ρ UV ) = 26.2 ± 0.13 (erg s −1 Hz −1 Mpc −3 ) can be sufficient to maintain reionization with an escape fraction of ionizing radiation of f esc = 10%-15%. Future Hubble Frontier Fields observations will certainly improve the constraints on the UV LF at the epoch of reionization, paving the way to more ambitious programs using cosmic telescopes with the next generation of large aperture telescopes such as the James Webb Space Telescope and the European Extremely Large Telescope.

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THE CHANGING Lyα OPTICAL DEPTH IN THE RANGE 6 < z < 9 FROM THE MOSFIRE SPECTROSCOPY OF Y -DROPOUTS

Cited by 218 publications

References 34 publications

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Constraints on the star formation efficiency of galaxies during the epoch of reionization

The Galaxy UV Luminosity Function Before the Epoch of Reionization

ARE ULTRA-FAINT GALAXIES ATz= 6–8 RESPONSIBLE FOR COSMIC REIONIZATION? COMBINED CONSTRAINTS FROM THE HUBBLE FRONTIER FIELDS CLUSTERS AND PARALLELS

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