We describe the results of an extremely deep, 0.28 deg 2 survey for z ¼ 3:1 Ly emission-line galaxies in the Extended Chandra Deep FieldYSouth. By using a narrowband 5000 8 filter and complementary broadband photometry from the MUSYC survey, we identify a statistically complete sample of 162 galaxies with monochromatic fluxes brighter than 1:5 ; 10 À17 ergs cm À2 s À1 and observer's frame equivalent widths greater than 80 8. We show that the equivalent width distribution of these objects follows an exponential with a rest-frame scale length of w 0 ¼ 76In addition, we show that in the emission line, the luminosity function of Ly galaxies has a faint-end power-law slope of ¼ À1:49 þ0:45 À0:34 , a bright-end cutoff of log L Ã ¼ 42:64 þ0:26 À0:15 , and a space density above our detection thresholds of (1:46 AE 0:12) ; 10 À3 h 3 70 galaxies Mpc À3 . Finally, by comparing the emission-line and continuum properties of the Ly emitters, we show that the star formation rates derived from Ly are $3 times lower than those inferred from the rest-frame UV continuum. We use this offset to deduce the existence of a small amount of internal extinction within the host galaxies. This extinction, coupled with the lack of extremely high equivalent width emitters, argues that these galaxies are not primordial Population III objects, although they are young and relatively chemically unevolved.

We studied the clustering properties and multiwavelength spectral energy distributions of a complete sample of 162 Ly-emitting (LAE) galaxies at z ' 3:1 discovered in deep narrowband MUSYC imaging of the Extended Chandra Deep Field-South. LAEs were selected to have observed frame equivalent widths >80 8 and emission line fluxes >1:5 ; 10 À17 ergs cm À2 s À1. Only 1% of our LAE sample appears to host AGNs. The LAEs exhibit a moderate spatial correlation length of r 0 ¼ 3:6 þ0:8 À1:0 Mpc, corresponding to a bias factor b ¼ 1:7 þ0:3 À0:4 , which implies median dark matter halo masses of log 10 M med ¼ 10:9 þ0:5 À0:9 M . Comparing the number density of LAEs, 1:5 AE 0:3 ; 10 À3 Mpc À3, with the number density of these halos finds a mean halo occupation $1%Y10%. The evolution of galaxy bias with redshift implies that most z ¼ 3:1 LAEs evolve into present-day galaxies with L < 2:5L Ã , whereas other z > 3 galaxy populations typically evolve into more massive galaxies. Halo merger trees show that z ¼ 0 descendants occupy halos with a wide range of masses, with a median descendant mass close to that of L Ã . Only 30% of LAEs have sufficient stellar mass (>$3 ;

We present results from the semi-analytic model of galaxy formation sag applied on the MultiDark simulation MDPL2. sag features an updated supernova (SN) feedback scheme and a robust modelling of the environmental effects on satellite galaxies. This incorporates a gradual starvation of the hot gas halo driven by the action of ram pressure stripping (RPS), that can affect the cold gas disc, and tidal stripping (TS), which can act on all baryonic components. Galaxy orbits of orphan satellites are integrated providing adequate positions and velocities for the estimation of RPS and TS. The star formation history and stellar mass assembly of galaxies are sensitive to the redshift dependence implemented in the SN feedback model. We discuss a variant of our model that allows to reconcile the predicted star formation rate density at z 3 with the observed one, at the expense of an excess in the faint end of the stellar mass function at z = 2. The fractions of passive galaxies as a function of stellar mass, halo mass and the halo-centric distances are consistent with observational measurements. The model also reproduces the evolution of the main sequence of star forming central and satellite galaxies. The similarity between them is a result of the gradual starvation of the hot gas halo suffered by satellites, in which RPS plays a dominant role. RPS of the cold gas does not affect the fraction of quenched satellites but it contributes to reach the right atomic hydrogen gas content for more massive satellites (M 10 10 M ).

The Javalambre Photometric Local Universe Survey (J-PLUS ) is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern Hemisphere from the dedicated JAST/T80 telescope at the Observatorio Astrofísico de Javalambre (OAJ). The T80Cam is a camera with a field of view of 2 deg 2 mounted on a telescope with a diameter of 83 cm, and is equipped with a unique system of filters spanning the entire optical range (3500-10 000 Å). This filter system is a combination of broad-, medium-, and narrow-band filters, optimally designed to extract the rest-frame spectral features (the 3700-4000 Å Balmer break region, Hδ, Ca H+K, the G band, and the Mg b and Ca triplets) that are key to characterizing stellar types and delivering a low-resolution photospectrum for each pixel of the observed sky. With a typical depth of AB ∼21.25 mag per band, this filter set thus allows for an unbiased and accurate characterization of the stellar population in our Galaxy, it provides an unprecedented 2D photospectral information for all resolved galaxies in the local Universe, as well as accurate photo-z estimates (at the δ z/(1 + z) ∼ 0.005-0.03 precision level) for moderately bright (up to r ∼ 20 mag) extragalactic sources. While some narrow-band filters are designed for the study of particular emission features ([O ii]/λ3727, Hα/λ6563) up to z < 0.017, they also provide well-defined windows for the analysis of other emission lines at higher redshifts. As a result, J-PLUS has the potential to contribute to a wide range of fields in Astrophysics, both in the nearby Universe (Milky Way structure, globular clusters, 2D IFU-like studies, stellar populations of nearby and moderate-redshift galaxies, clusters of galaxies) and at high redshifts (emission-line galaxies at z ≈ 0.77, 2.2, and 4.4, quasi-stellar objects, etc.). With this paper, we release the first ∼1000 deg 2 of J-PLUS data, containing about 4.3 million stars and 3.0 million galaxies at r < 21 mag. With a goal of 8500 deg 2 for the total J-PLUS footprint, these numbers are expected to rise to about 35 million stars and 24 million galaxies by the end of the survey.Article published by EDP Sciences A176, page 1 of 25

Future galaxy redshift surveys aim to measure cosmological quantities from the galaxy power spectrum. A prime example is the detection of baryonic acoustic oscillations, providing a standard ruler to measure the dark energy equation of state, w(z), to high precision. The strongest practical limitation for these experiments is how quickly accurate redshifts can be measured for sufficient galaxies to map the large-scale structure. A promising strategy is to target emission-line (i.e. star-forming) galaxies at high redshift (z ∼ 0.5-2); not only is the space density of this population increasing out to z ∼ 2, but also emission lines provide an efficient method of redshift determination. Motivated by the prospect of future dark energy surveys targeting Hα emitters at near-infrared wavelengths (i.e. z > 0.5), we use the latest empirical data to model the evolution of the Hα luminosity function out to z ∼ 2 and thus provide predictions for the abundance of Hα emitters for practical limiting fluxes. We caution that the estimates presented in this work must be tempered by an efficiency factor, , giving the redshift success rate from these potential targets. For a range of practical efficiencies and limiting fluxes, we provide an estimate ofnP 0.2 , wheren is the 3D galaxy number density and P 0.2 is the galaxy power spectrum evaluated at k = 0.2 h Mpc −1 . Ideal surveys must providē nP 0.2 > 1 in order to balance shot-noise and cosmic variance errors. We show that a realistic emission-line survey ( = 0.5) could achievenP 0.2 = 1 out to z ∼ 1.5 with a limiting flux of 10 −16 erg s −1 cm −2 . If the limiting flux is a factor of 5 brighter, then this goal can only be achieved out to z ∼ 0.5, highlighting the importance of survey depth and efficiency in cosmological redshift surveys.