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The origin of the Lyman α (Lyα) emission in galaxies is a long-standing issue: despite several processes known to originate this line (e.g. active galactic nucleus, star formation, cold accretion, shock heating), it is difficult to discriminate among these phenomena based on observations. Recent studies have suggested that the comparison of the ultraviolet (UV) and optical properties of these sources could solve the riddle. For this reason, we investigate the rest-frame UV and optical properties of Abell 2895b, a strongly lensed Lyα emitter at redshift z ∼ 3.7. From this study, we find that our target is a compact (r n ∼ 1.2 pkpc) star-forming (star formation rate ≃11 M⊙ yr−1) galaxy having a young stellar population. Interestingly, we measure a high ratio of the Hβ and the UV continuum monochromatic luminosities (L (Hβ)/ L (UV) ≃ 100). Based on tracks of theoretical stellar models (starburst99 and bpass), we can only partially explain this result by assuming a recent (≲10 Myr), bursty episode of star formation and considering models characterized by binary stars, a top-heavy initial mass function and subsolar metallicities (Z ≲ 0.01 Z⊙). These assumptions also explain the observed low (C/O) abundance of our target (≃0.23(C/O)⊙). By comparing the UV and optical data sets, we find that the Lyα and UV continuum are more extended (×2) than the Balmer lines, and that the peak of the Lyα is offset (≃0.6 pkpc). The multiwavelength results of our analysis suggest that the observed Lyα emission originates from a recent star formation burst, likely taking place in an off-centre clump. [ABSTRACT FROM AUTHOR]

We report the discovery of an intrinsically faint, quintuply-imaged, dusty galaxy MACS0600-z6 at a redshift z = 6.07 viewed through the cluster MACSJ0600.1–2008 (z = 0.46). A ≃ 4σ dust detection is seen at 1.2mm as part of the ALMA Lensing Cluster Survey (ALCS), an on-going ALMA Large programme, and the redshift is secured via [C  ii ] 158 μ m emission described in a companion paper. In addition, spectroscopic follow-up with GMOS/Gemini-North shows a break in the galaxy's spectrum, consistent with the Lyman break at that redshift. We use a detailed mass model of the cluster and infer a magnification μ ≳ 30 for the most magnified image of this galaxy, which provides an unprecedented opportunity to probe the physical properties of a sub-luminous galaxy at the end of cosmic reionization. Based on the spectral energy distribution, we infer lensing-corrected stellar and dust masses of |$\rm {2.9^{+11.5}_{-2.3}\times 10^9}$| and |$\rm {4.8^{+4.5}_{-3.4}\times 10^6}$| |$\rm {M_{\odot }}$|⁠ , respectively, a star formation rate of |$\rm {9.7^{+22.0}_{-6.6} \, M_{\odot } \, yr^{-1}}$|⁠ , an intrinsic size of |$\rm {0.54^{+0.26}_{-0.14}}$| kpc, and a luminosity-weighted age of 200 ± 100 Myr. Strikingly, the dust production rate in this relatively young galaxy appears to be larger than that observed for equivalent, lower redshift sources. We discuss if this implies that early supernovae are more efficient dust producers and the consequences for using dust mass as a probe of earlier star formation. [ABSTRACT FROM AUTHOR]

We present the results from the search for Lyman alpha emitters (LAEs) in the proximity of 11 C  iv absorption systems at z  > 4.7 in the spectrum of the QSO J1030+0524, using data from Multi-Unit Spectroscopic Explorer. We have found multiple LAE candidates close to four C  iv systems at |$z_{{\rm{C {\small IV}}}}=4.94$| –5.74 with |$\log _{10}(N_{{\rm{C {\small IV}}}}[$| cm−2]) > 13.5. At z  = 5–6, C  iv systems with W |$_0({\rm{C {\small IV}}})\gt 0.2$| Å seem more likely to have galaxies with Ly α emission within ρ < 200 proper kpc (4/5 cases) than the C  iv systems with W |$_0({\rm{C {\small IV}}})\lt 0.2$| Å (0/6 cases). The impact parameter of LAE–C  iv systems with equivalent widths W 0(C  iv) > 0.5 Å is in the range |$11\, \lesssim \, \rho \, \lesssim \, 200$| proper kpc (pkpc). Furthermore, all candidates are in the luminosity range 0.18–1.15 L |$^{\star }_{\rm{{Ly\alpha}}}(z=5.7)$|⁠ , indicating that the environment of C  iv systems within 200 pkpc is populated by the faint end of the Ly α luminosity function. We report a 0.28 L |$^{\star }_{\rm{{Ly\alpha}}}$| galaxy at a separation of ρ = 11 pkpc from a strong C  iv absorption (⁠|$\log _{10}(N_{{\rm{C {\small IV}}}}[$| cm−2]) = 14.52) at |$z_{{\rm{C {\small IV}}}}=5.72419$|⁠. The prevalence of sub- L |$^{\star }_{\rm{{Ly\alpha}}}$| galaxies in the proximity of z > 4.9 C  iv systems suggest that the absorbing material is rather young, likely ejected in the recent past of the identified galaxies. The connection between faint LAEs and high-ionization absorption systems reported in this work is potentially a consequence of the role of low-mass galaxies in the early evolution of the circum-galactic and intergalactic media. [ABSTRACT FROM AUTHOR]

We discovered a strongly lensed (μ ≳ 40) Ly α emission at z  = 6.629 (S/N ≃ 18) in the MUSE Deep Lensed Field (MDLF) targeting the Hubble Frontier Field (HFF) galaxy cluster MACS J0416. Dedicated lensing simulations imply that the Ly α emitting region necessarily crosses the caustic. The arc-like shape of the Ly α extends 3 arcsec on the observed plane and is the result of two merged multiple images, each one with a de-lensed Ly α luminosity L ≲ 2.8 × 1040 erg s−1 arising from a confined region (≲150 pc effective radius). A spatially unresolved Hubble Space Telescope (HST) counterpart is barely detected at S/N ≃ 2 after stacking the near-infrared bands, corresponding to an observed (intrinsic) magnitude m 1500 ≳ 30.8 (≳35.0). The inferred rest-frame Ly α equivalent width is EW0 > 1120 Å if the IGM transmission is T IGM < 0.5. The low luminosities and the extremely large Ly α EW0 match the case of a Population III (Pop III) star complex made of several dozens stars (∼104 M⊙) that irradiate an H  ii region crossing the caustic. While the Ly α and stellar continuum are among the faintest ever observed at this redshift, the continuum and the Ly α emissions could be affected by differential magnification, possibly biasing the EW0 estimate. The aforementioned tentative HST detection tends to favour a large EW0, making such a faint Pop III candidate a key target for the James Webb Space Telescope and Extremely Large Telescopes. [ABSTRACT FROM AUTHOR]

We present a VLT/X-Shooter spectroscopy of the Lyman continuum (LyC) emitting galaxy Ion2 at z  = 3.2121 and compare it to that of the recently discovered strongly lensed LyC emitter at z  = 2.37, known as the Sunburst arc. Three main results emerge from the X-Shooter spectrum: (a) the Ly α has three distinct peaks with the central one at the systemic redshift, indicating a ionized tunnel through which both Ly α and LyC radiation escape; (b) the large O32 oxygen index ([O  iii ] λλ4959, 5007/[O  ii ] λλ3727, 3729) of |$9.18_{-1.32}^{+1.82}$| is compatible to those measured in local (z ∼0.4) LyC leakers; (c) there are narrow nebular high-ionization metal lines with σ v < 20 km s−1, which confirms the presence of young hot, massive stars. The He  ii λ1640 appears broad, consistent with a young stellar component including Wolf–Rayet stars. Similarly, the Sunburst LyC emitter shows a triple-peaked Ly α profile and from VLT/MUSE spectroscopy the presence of spectral features arising from young hot and massive stars. The strong lensing magnification, (μ > 20), suggests that this exceptional object is a gravitationally bound star cluster observed at a cosmological distance, with a stellar mass M ≲ 107 M⊙ and an effective radius smaller than 20 pc. Intriguingly, sources like Sunburst but without lensing magnification might appear as Ion2 -like galaxies, in which unresolved massive star clusters dominate the ultraviolet emission. This work supports the idea that dense young star clusters can contribute to the ionization of the IGM through holes created by stellar feedback. [ABSTRACT FROM AUTHOR]

We use Multi Unit Spectroscopic Explorer (MUSE) observations of the galaxy cluster MACS J1149.5+2223 to explore the kinematics of the grand-design spiral galaxy (Sp1149) hosting the supernova 'Refsdal'. Sp1149 lies at z ⋍ 1.49, has a stellar mass M* ⋍ 5 × 109M ⊙, has a star formation rate (SFR) ⋍ 1-6 M⊙ yr-1, and represents a likely progenitor of a Milky Way-like galaxy. All the four multiple images of Sp1149 in our data show strong [O II]-line emissions pointing to a clear rotation pattern. We take advantage of the gravitational lensing magnification effect (⋍4×) on the [OII] emission of the least distorted image to fit threedimensional kinematic models to the MUSE data cube and derive the rotation curve and the velocity dispersion profile of Sp1149. We find that the rotation curve steeply rises, peaks at R ⋍ 1 kpc, and then (initially) declines and flattens to an average Vflat = 128+29 -19 km s-1. The shape of the rotation curve is well determined, but the actual value of Vflat is quite uncertain because of the nearly face-on configuration of the galaxy. The intrinsic velocity dispersion due to gas turbulence is almost constant across the entire disc with an average of 27 ± 5 kms-1. This value is consistent with z = 0 measurements in the ionized gas component and a factor of 2-4 lower than other estimates in different galaxies at similar redshifts. The average stellarto- total mass fraction is of the order of one-fifth. Our kinematic analysis returns the picture of a regular star-forming, mildly turbulent, rotation-dominated (V/s ⋍ 5) spiral galaxy in a 4-Gyr-old Universe. [ABSTRACT FROM AUTHOR]

We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses (Mstar)] of bright (S850 ≥ 4 mJy) submm galaxies in the ≃2 deg2 COSMOS and UDS fields selected with SCUBA-2/JCMT.We complete the galaxy identification process for all (≃2000) S/N ≥ 3.5 850-μm sources, but focus our scientific analysis on a high-quality subsample of 651 S/N ≥ 4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4mJy ALMA sources, our identification method has a completeness of ≃86 per cent with a reliability of ≃92 per cent, and only ≃15–20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-μmsource counts as determined with SCUBA-2 ismodest; scaling the single-dish fluxes by ≃0.9 reproduces the ALMA source counts. For our final SCUBA- 2 sample, we find median z = 2.40+0.10 −0.04, SFR = 287 ± 6M⊫ yr−1 and log(Mstar/M⊫) = 11.12 ± 0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the ‘main sequence’ of starforming galaxies out to z ≃ 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations. [ABSTRACT FROM AUTHOR]

We report the identification of extended Lyα nebulae at z ≃ 3.3 in the Hubble Ultra Deep Field (HUDF, ≃40 kpc x 80 kpc) and behind the Hubble Frontier Field galaxy cluster MACSJ0416 (≃40 kpc), spatially associated with groups of star-forming galaxies. VLT/MUSE integral field spectroscopy reveals a complex structure with a spatially varying double-peaked Lyα emission. Overall, the spectral profiles of the two Lyα nebulae are remarkably similar, both showing a prominent blue emission, more intense and slightly broader than the red peak. From the first nebula, located in the HUDF, no X-ray emission has been detected, disfavouring the possible presence of active galactic nuclei. Spectroscopic redshifts have been derived for 11 galaxies within 2 arcsec from the nebula and spanning the redshift range 1.037 < z < 5.97. The second nebula, behind MACSJ0416, shows three aligned star-forming galaxies plausibly associated with the emitting gas. In both systems, the associated galaxies reveal possible intense rest-frame-optical nebular emissions lines [O iii] λλ4959, 5007+Hβ with equivalent widths as high as 1500 Å rest frame and star formation rates ranging from a few to tens of solar masses per year. A possible scenario is that of a group of young, star-forming galaxies emitting ionizing radiation that induces Lyα fluorescence, therefore revealing the kinematics of the surrounding gas. Also Lyα powered by star formation and/or cooling radiation may resemble the double-peaked spectral properties and the morphology observed here. If the intense blue emission is associated with inflowing gas, then we may be witnessing an early phase of galaxy or a proto-cluster (or group) formation. [ABSTRACT FROM AUTHOR]

We derive the total cold gas, atomic hydrogen, and molecular gas masses of approximately 24 000 galaxies covering four decades in stellar mass at redshifts 0.5

We use percent-level precision photometric redshifts in the UltraVISTA-DR1 near-infrared survey to investigate the changing relationship between galaxy stellar mass and the dark matter haloes hosting them to z ~ 2. We achieve this by measuring the clustering properties and abundances of a series of volume-limited galaxy samples selected by stellar mass and star formation activity. We interpret these results in the framework of a phenomenological halo model and numerical simulations. Our measurements span a uniquely large range in stellar mass and redshift and reach below the characteristic stellar mass to z ~ 2. Our results are: (1) at fixed redshift and scale, clustering amplitude depends monotonically on sample stellar mass threshold; (2) at fixed angular scale, the projected clustering amplitude decreases with redshift but the comoving correlation length remains constant; (3) characteristic halo masses and galaxy bias increase with increasing median stellar mass of the sample; (4) the slope of these relationships is modified in lower mass haloes; (5) concerning the passive galaxy population, characteristic halo masses are consistent with a simply less-abundant version of the full galaxy sample, but at lower redshifts the fraction of satellite galaxies in the passive population is very different from the full galaxy sample; (6) finally,we find that the ratio between the characteristic halo mass and median stellar mass at each redshift bin reaches a peak at log (Mh/M⊙) ~ 12.2 and the position of this peak remains constant out to z ~ 2. The behaviour of the full and passively evolving galaxy samples can be understood qualitatively by considering the slow evolution of the characteristic stellar mass in the redshift range probed by our survey. [ABSTRACT FROM AUTHOR]

We report the results of a comprehensive study of the relationship between galaxy size, stellar mass and specific star formation rate (sSFR) at redshifts 1.3 < z < 1.5. Based on a mass-complete (M⋆ ≥ 6 × 1010 M⊙), spectroscopic sample from the UK Infrared Deep Sky Survey (UKIDSS) Ultradeep Survey, with accurate stellar-mass measurements derived from spectro-photometric fitting, we find that at z ≃ 1.4 the location of massive galaxies on the size–mass plane is determined primarily by their sSFR. At this epoch, we find that massive galaxies which are passive (sSFR ≤ 0.1 Gyr−1) follow a tight size–mass relation, with half-light radii a factor of fg = 2.4 ± 0.2 smaller than their local counterparts. Moreover, amongst the passive sub-sample we find no evidence that the off-set from the local size–mass relation is a function of stellar population age. In contrast, we find that massive star-forming galaxies at this epoch lie closer to the local late-type size–mass relation and are only a factor of fg = 1.6 ± 0.2 smaller than observed locally. Based on a sub-sample with dynamical-mass estimates, which consists of both passive and star-forming objects, we also derive an independent estimate of fg = 2.3 ± 0.3 for the typical growth in half-light radius between z ≃ 1.4 and the present day. Focusing on the passive sub-sample, we conclude that to produce the necessary evolution predominantly via major mergers would require an unfeasible number of merger events and overpopulate the high-mass end of the local stellar-mass function. In contrast, we find that a scenario in which mass accretion is dominated by minor mergers can comfortably produce the necessary evolution, whereby an increase in stellar mass of only a factor of ≃2, accompanied by size growth of a factor of ≃3.5, is required to reconcile the size–mass relation at z ≃ 1.4 with that observed locally. Finally, we note that a significant fraction (44 ± 12 per cent) of the passive galaxies in our sample have a disc-like morphology, providing additional evidence that separate physical processes are responsible for the quenching of star formation and morphological transformation in massive galaxies. [ABSTRACT FROM PUBLISHER]

ABSTRACT The Astronomical Thermal Emission Camera (AzTEC) 1.1 mm survey of the two SCUBA HAlf Degree Extragalactic Survey (SHADES) fields is the largest (0.7 deg2) blank-field millimetre-wavelength (mm-wavelength) survey undertaken to date at a resolution of ≃18 arcsec and a depth of ≃1 mJy. We have used the deep optical to radio multiwavelength data in the SHADES Lockman Hole East and SXDF/UDS fields to obtain galaxy identifications for ≃64 per cent (≃80 per cent including tentative identifications) of the 148 AzTEC-SHADES 1.1 mm sources reported by Austermann et al., exploiting deep radio and 24 μm data complemented by methods based on 8 μm flux density and red optical-infrared ( i − K) colour. This unusually high identification rate can be attributed to the relatively bright mm-wavelength flux density threshold, combined with the relatively deep supporting multifrequency data now available in these two well-studied fields. We have further exploited the optical-mid-infrared-radio data to derive an ≃60 per cent (≃75 per cent including tentative identifications) complete redshift distribution for the AzTEC-SHADES sources, yielding a median redshift of z ≃ 2.2, with a high-redshift tail extending to at least z ≃ 4. Despite the larger area probed by the AzTEC survey relative to the original SCUBA-SHADES imaging, the redshift distribution of the AzTEC sources is consistent with that displayed by the SCUBA sources, and reinforces tentative evidence that the redshift distribution of mm/submm sources in the Lockman Hole field is significantly different from that found in the SXDF/UDS field. Comparison with simulated surveys of similar scale extracted from semi-analytic models based on the Millennium simulation indicates that this is as expected if the mm/submm sources are massive ( M > 1011 M⊙) star-forming galaxies tracing large-scale structures over scales of 10-20 Mpc. This confirms the importance of surveys covering several deg2 (as now underway with SCUBA2) to obtain representative samples of bright (sub)mm-selected galaxies. This work provides a foundation for the further exploitation of the Spitzer and Herschel data in the SHADES fields in the study of the stellar masses and specific star formation rates of the most active star-forming galaxies in cosmic history. [ABSTRACT FROM AUTHOR]

ABSTRACT One key piece of information missing from high-redshift galaxy surveys is the galaxies' cold gas contents. We present a new method to indirectly determine cold gas surface densities and integrated gas masses from galaxy star formation rates and to separate the atomic and molecular gas components. Our predicted molecular and total gas surface densities and integrated masses are in very good agreement with direct measurements quoted in the literature for low- and high- z galaxies. We apply this method to predict the gas content for a sample of ∼57 000 galaxies in the Cosmic Evolution Survey (COSMOS) field at 0.5 < z < 2.0, selected to have I AB < 24 mag. This approach allows us to investigate in detail the redshift evolution of galaxy's cold and molecular gas content versus stellar mass and to provide fitting formulae for galaxy gas fractions. We find a clear trend between galaxy gas fraction, molecular gas fraction and stellar mass with redshift, suggesting that massive galaxies consume and/or expel their gas at higher redshift than less massive objects and have lower fractions of their gas in molecular form. The characteristic stellar mass separating gas- from stellar-dominated galaxies decreases with time. This indicates that massive galaxies reach a gas-poor state earlier than less massive objects. These trends can be considered to be another manifestation of downsizing in star formation activity. [ABSTRACT FROM AUTHOR]

ABSTRACT The COSMOS field has been the subject of a wide range of observations, with a number of studies focusing on reconstructing the 3D dark matter density field. Typically, these studies have focused on one given method or tracer. In this paper, we reconstruct the distribution of mass in the COSMOS field out to a redshift z= 1 by combining Hubble Space Telescope weak lensing measurements with zCOSMOS spectroscopic measurements of galaxy clustering. The distribution of galaxies traces the distribution of mass with high resolution (particularly in redshift, which is not possible with lensing), and the lensing data empirically calibrates the mass normalization (bypassing the need for theoretical models). Two steps are needed to convert a galaxy survey into a density field. The first step is to create a smooth field from the galaxy positions, which is a point field. We investigate four possible methods for this: (i) Gaussian smoothing, (ii) convolution with truncated isothermal sphere, (iii) fifth nearest neighbour smoothing and (iv) a multiscale entropy method. The second step is to rescale this density field using a bias prescription. We calculate the optimal bias scaling for each method by comparing predictions from the smoothed density field with the measured weak lensing data, on a galaxy-by-galaxy basis. In general, we find scale-independent bias for all the smoothing schemes, to a precision of 10 per cent. For the nearest neighbour smoothing case, we find the bias to be 2.51 ± 0.25. We also find evidence for a strongly evolving bias, increasing by a factor of ∼3.5 between redshifts 0 < z < 0.8. We believe this strong evolution can be explained by the fact that we use a flux limited sample to build the density field. [ABSTRACT FROM AUTHOR]

ABSTRACT We have analysed a sample of 1292 4.5- μm-selected galaxies at z≥ 3, over 0.6 deg 2 of the UKIRT Infrared Deep Survey (UKIDSS) Ultra Deep Survey (UDS). Using photometry from the U band through 4.5 μm, we have obtained photometric redshifts and derived stellar masses for our sources. Only two of our galaxies potentially lie at z > 5. We have studied the galaxy stellar mass function at 3 ≤ z < 5, based on the 1213 galaxies in our catalogue with 4.5- μm magnitudes ≤ 24.0. We find that (i) the number density of galaxies increased by a factor of > 10 between z= 5 and 3, indicating that the assembly rate of these galaxies proceeded > 20 times faster at these redshifts than at 0 < z < 2; (ii) the Schechter function slope α is significantly steeper than that displayed by the local stellar mass function, which is a consequence of both the steeper faint end and the absence of a pure exponential decline at the high-mass end; and (iii) the evolution of the comoving stellar mass density from z= 0 to 5 can be modelled as log10ρM=−(0.05 ± 0.09) z2−(0.22 ∓ 0.32) z+ 8.69. At 3 ≤ z < 4, more than 30 per cent of the galaxies would be missed by optical surveys with R < 27 or z < 26. Thus, our study demonstrates the importance of deep mid-infrared surveys over large areas to perform a complete census of massive galaxies at high z and trace the early stages of massive galaxy assembly. [ABSTRACT FROM AUTHOR]

We measure the spatial clustering of galaxies as a function of their morphological type at , for the first time in a deep redshift survey with full morphological information. This is obtained by combining high-resolution Hubble Space Telescope imaging and Very Large Telescope spectroscopy for about 8500 galaxies to with accurate spectroscopic redshifts from the zCOSMOS-Bright redshift survey. At this epoch, early-type galaxies already show a significantly stronger clustering than late-type galaxies on all probed scales. A comparison to the Sloan Digital Sky Survey Data at shows that the relative clustering strength between early and late morphological classes tends to increase with cosmic time at small separations, while on large scales it shows no significant evolution since . This suggests that most early-type galaxies had already formed in intermediate and dense environments at this epoch. Our results are consistent with a picture in which the relative clustering of different morphological types between and 0 reflects the evolving role of environment in the morphological transformation of galaxies, on top of a global evolution driven by mass. [ABSTRACT FROM AUTHOR]

We have selected and analysed the properties of a sample of galaxies in of the Great Observatories Origins Deep Survey (GOODS) Chandra Deep Field South (CDFS), to obtain further constraints on the evolution of Ks-selected galaxies with respect to the results already obtained in previous studies. We made use of the public deep multiwavelength imaging from the optical B through the infrared (IR) 4.5-μm bands, in conjunction with available spectroscopic and COMBO17 data in the CDFS, to construct an optimized redshift catalogue for our galaxy sample. We computed the Ks-band luminosity function and determined that its characteristic magnitude has a substantial brightening and a decreasing total density from to . We also analysed the colours and number density evolution of galaxies with different stellar masses. Within our sample, and in contrast to what is observed for less massive systems, the vast majority (∼85–90 per cent) of the most massive local galaxies appear to be in place before redshift . Around 65–70 per cent of the total assemble between redshifts and 3 and most of them display extremely red colours, suggesting that plausible star formation in these very massive systems should mainly proceed in obscured, short-time-scale bursts. The remaining fraction (up to ∼20 per cent) could be in place at even higher redshifts , pushing the first epoch of formation of massive galaxies beyond the limits of current near-IR surveys. [ABSTRACT FROM AUTHOR]

We present estimated redshifts and derived properties of a sample of 1663 galaxies with (Vega), selected from of the Great Observatories Origins Deep Survey/ Chandra Deep Field South (GOODS/CDFS) field with deep Infrared Spectrometer and Array Camera (ISAAC) imaging, and make an extensive comparison of their properties with those of the extremely red galaxies (ERGs) selected in the same field. We study in detail the evolution of -selected galaxies up to redshifts , and clarify the role of ERGs within the total -band galaxy population. We compute the total -band luminosity function (LF) and compare its evolution with the ERG LF. Up to , the bright end of the -band LF shows no sign of decline, and is progressively well reproduced by the ERGs with increasing redshift. We also explore the evolution of massive systems present in our sample: up to 20–25 per cent of the population of local galaxies with assembled stellar mass has been formed before redshift , and contains ∼45–70 per cent of the stellar mass density of the Universe at that redshift. Within our sample, the comoving number density of these massive systems is then essentially constant down to redshift , by which point most of them have apparently evolved into -selected ERGs. The remaining massive systems observed in the local Universe are assembled later, at redshifts . Our results therefore suggest a twofold assembly history for massive galaxies, in which galaxy/star formation proceeds very efficiently in high mass haloes at very high redshift. [ABSTRACT FROM AUTHOR]

We have analysed five-epoch Great Observatories Origins Deep Survey (GOODS) HST–ACS and z data sets (v. 1.0 release), in conjunction with existing VLT–ISAAC imaging in the J, H and bands, to derive estimated redshifts for the sample of 198 extremely red galaxies (ERGs) with (Vega) and selected by from 50.4 arcmin2 of the GOODS/ Chandra Deep Field South. We find that, at this depth, the ERG population spans the redshift range and over two decades in mass ( to ). Our results show that the dust-corrected red envelope of galaxy evolution is well modelled by a starburst at redshift followed thereafter by passive evolution. We explore the evolution of the ERG luminosity function (LF) from redshifts to and compare it with the global -band LF at redshifts . We find that the bright end of the ERG LF does not decrease from redshifts to and we connect this fact with the presence of progenitors of the local population at redshifts . We determine lower limits of and on the comoving densities of progenitors of local massive galaxies already assembled at redshifts and , respectively. We have investigated the existence of high-redshift Lyman-break galaxies massive enough to be included in this ERG sample. Out of an initial list of 12 potential very high redshift candidates, we have identified two ERGs which have a high probability of lying at . We discuss the advantages of multicolour to single-colour selection techniques in obtaining reliable lists of very high redshift candidate sources, and present revised lower redshift estimates for sources previously claimed as potential dropouts in recent studies. [ABSTRACT FROM AUTHOR]