The clustering properties of high-redshift passive galaxies

We investigate the clustering properties of 3<z<5 candidate passive galaxies from the Merlin et al. (2019) sample residing in the GOODS-North (35 sources) and GOODS-South (33 sources) fields. Within the large uncertainties due to the paucity of sources we do not detect clustering signal in GOODS-North, while this is present in GOODS-South, highlighting the importance of the effects of cosmic variance. The estimated correlation length in GOODS-South is r_0=12^+4_-5 Mpc, while the estimated minimum mass for a halo capable to host one of such high-redshift quenched galaxies is log10(M_min/M_sun) =13.0\pm 0.3, once also the constraints from their space density are taken into account. Both values are compatible with the results from GOODS-North. Putting the above findings in a cosmological context, these suggest no evolution of the dark matter content of the hosts of passive galaxies during the past 12.5 Gyr, i.e. during more than 90% of the age of the Universe. We discuss possible scenarios for the observed trend.Comment: 6 pages, 3 figures, letter to appear in MNRA

The parallelism between galaxy clusters and early-type galaxies: III. The Mass-Radius Relationship

Context. This is the third study of a series dedicated to the observed parallelism of properties between Galaxy Clusters and Groups(GCGs) and early-type galaxies (ETGs). Aims. Here we investigate the physical origin of the Mass-Radius Relation (MRR). Methods. Having collected literature data on masses and radii for objects going from Globular Clusters (GCs) to ETGs and GCGs, we set up the MR-plane and compare the observed distribution with the MRR predicted by theoretical models both for the monolithic and hierarchical scenarios. Results. We argue that the distributions of stellar systems in the MR-plane is due to complementary mechanisms: (i) on one hand, as shown in paper II, the relation of the virial equilibrium does intersect with a relation that provides the total luminosity as a function of the star formation history; (ii) on the other hand, the locus predicted for the collapse of systems should be convolved with the statistical expectation for the maximum mass of the halos at each comsic epoch. This second aspect provides a natural boundary limit explaining either the curved distribution observed in the MR-plane and the existence of a zone of avoidance. Conclusions. The distribution of stellar systems in the MR-plane is the result of two combined evolution, that of the stellar component and that of the halo component.Comment: 21 pages, 10 figures, 8 table

FORECAST: a flexible software to forward model cosmological hydrodynamical simulations mimicking real observations

We present FORECAST, a new flexible and adaptable software package that performs forward modeling of the output of any cosmological hydrodynamical simulations to create a wide range of realistic synthetic astronomical images. With customizable options for filters, field of view size and survey parameters, it allows users to tailor the synthetic images to their specific requirements. FORECAST constructs light-cone exploiting the output snapshots of a simulation and computes the observed flux of each simulated stellar element, modeled as a Single Stellar Population, in any chosen set of pass-band filters, including k-correction, IGM absorption and dust attenuation. As a first application, we emulated the GOODS-South field as observed for the CANDELS survey exploiting the IllustrisTNG simulation. We produce images of 200 sq. arcmin., in 13 bands (eight Hubble Space Telescope optical and near-infrared bands from ACS B435 to WFC3 H160, the VLT HAWK-I Ks band, and the four IRAC filters from Spitzer), with depths consistent with the real data. We analysed the images with the same processing pipeline adopted for real data in CANDELS and ASTRODEEP publications, and we compared the results against both the input data used to create the images, and real data, generally finding good agreement with both, with some interesting exceptions which we discuss. As part of this work, we release the FORECAST code and two datasets: the CANDELS dataset analyzed in this study, and 10 JWST CEERS survey-like images (8 NIRCam and 2 MIRI) in a field of view of 200 sq. arcmin. between z=0-20. FORECAST is a flexible tool: it creates images that can then be processed and analysed using standard photometric algorithms, allowing for a consistent comparison among observations and models, and for a direct estimation of the biases introduced by such techniques.Comment: 21 pages, 15 figures, 6 tables, submitted to A&

The Evolution of the Galaxy Stellar Mass Function at z= 4-8: A Steepening Low-mass-end Slope with Increasing Redshift

We present galaxy stellar mass functions (GSMFs) at $z=$ 4-8 from a rest-frame ultraviolet (UV) selected sample of $\sim$4500 galaxies, found via photometric redshifts over an area of $\sim$280 arcmin$^2$ in the CANDELS/GOODS fields and the Hubble Ultra Deep Field. The deepest Spitzer/IRAC data yet-to-date and the relatively large volume allow us to place a better constraint at both the low- and high-mass ends of the GSMFs compared to previous space-based studies from pre-CANDELS observations. Supplemented by a stacking analysis, we find a linear correlation between the rest-frame UV absolute magnitude at 1500 \AA\ ($M_{\rm UV}$) and logarithmic stellar mass ($\log M_*$) that holds for galaxies with $\log(M_*/M_{\odot}) \lesssim 10$. We use simulations to validate our method of measuring the slope of the $\log M_*$-$M_{\rm UV}$ relation, finding that the bias is minimized with a hybrid technique combining photometry of individual bright galaxies with stacked photometry for faint galaxies. The resultant measured slopes do not significantly evolve over $z=$ 4-8, while the normalization of the trend exhibits a weak evolution toward lower masses at higher redshift. We combine the $\log M_*$-$M_{\rm UV}$ distribution with observed rest-frame UV luminosity functions at each redshift to derive the GSMFs, finding that the low-mass-end slope becomes steeper with increasing redshift from $\alpha=-1.55^{+0.08}_{-0.07}$ at $z=4$ to $\alpha=-2.25^{+0.72}_{-0.35}$ at $z=8$. The inferred stellar mass density, when integrated over $M_*=10^8$-$10^{13} M_{\odot}$, increases by a factor of $10^{+30}_{-2}$ between $z=7$ and $z=4$ and is in good agreement with the time integral of the cosmic star formation rate density.Comment: 27 pages, 17 figures, ApJ, in pres

Spitzer UltRa Faint SUrvey Program (SURFS UP). II. IRAC-Detected Lyman-Break Galaxies at 6 < z < 10 Behind Strong-Lensing Clusters

We study the stellar population properties of the IRAC-detected $6 \lesssim z \lesssim 10$ galaxy candidates from the Spitzer UltRa Faint SUrvey Program (SURFS UP). Using the Lyman Break selection technique, we find a total of 16 new galaxy candidates at $6 \lesssim z \lesssim 10$ with $S/N \geq 3$ in at least one of the IRAC $3.6\mu$m and $4.5\mu$m bands. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors of $\sim 1.2$--$5.5$. We find that the IRAC-detected $6 \lesssim z \lesssim 10$ sample is likely not a homogeneous galaxy population: some are relatively massive (stellar mass as high as $4 \times 10^9\,M_{\odot}$) and evolved (age $\lesssim 500$ Myr) galaxies, while others are less massive ($M_{\text{stellar}}\sim 10^8\,M_{\odot}$) and very young ($\sim 10$ Myr) galaxies with strong nebular emission lines that boost their rest-frame optical fluxes. We identify two Ly$\alpha$ emitters in our sample from the Keck DEIMOS spectra, one at $z_{\text{Ly}\alpha}=6.76$ (in RXJ1347) and one at $z_{\text{Ly}\alpha}=6.32$ (in MACS0454). We show that IRAC $[3.6]-[4.5]$ color, when combined with photometric redshift, can be used to identify galaxies likely with strong nebular emission lines within certain redshift windows.Comment: ApJ in pres

First Light And Reionisation Epoch Simulations (FLARES) VIII. The Emergence of Passive Galaxies at z⩾5z \geqslant 5

Passive galaxies are ubiquitous in the local universe, and various physical channels have been proposed that lead to this passivity. To date, robust passive galaxy candidates have been detected up to $z \leqslant 5$, but it is still unknown if they exist at higher redshifts, what their relative abundances are, and what causes them to stop forming stars. We present predictions from the First Light And Reionisation Epoch Simulations (FLARES), a series of zoom simulations of a range of overdensities using the EAGLE code. Passive galaxies occur naturally in the EAGLE model at high redshift, and are in good agreement with number density estimates from HST and early JWST results at $3 \leqslant z \leqslant 5$. Due to the unique FLARES approach, we extend these predictions to higher redshifts, finding passive galaxy populations up to $z \sim 8$. Feedback from supermassive black holes is the main driver of passivity, leading to reduced gas fractions and star forming gas reservoirs. We find that passive galaxies at $z \geqslant 5$ are not identified in the typical UVJ selection space due to their still relatively young stellar populations, and present new rest--frame selection regions. We also present NIRCam and MIRI fluxes, and find that significant numbers of passive galaxies at $z \geqslant 5$ should be detectable in upcoming wide surveys with JWST. Finally, we present JWST colour distributions, with new selection regions in the observer--frame for identifying these early passive populations.Comment: 21 pages, 20 figures. Accepted to MNRA

ALMA Observation of a z≳10z\gtrsim10 Galaxy Candidate Discovered with JWST

We report the ALMA observation of a $z\gtrsim10$ galaxy candidate (GHZ1) discovered from the GLASS-JWST Early Release Science Program. Our ALMA program aims to detect the [OIII] emission line at the rest-frame 3393.0062 GHz ($88.36\mu$m) and far-IR continuum emission with the spectral window setup seamlessly covering a 26.125 GHz frequency range ($10.10<z<11.14$). A total of 7 hours of on-source integration was employed, using four frequency settings to cover the full range (1.7 hours per setting), with $0''.7$ angular resolution. No line or continuum is clearly detected, with a 5$\sigma$ upper limit of the line emission of 0.93 mJy beam$^{-1}$ at 25 km s$^{-1}$ channel$^{-1}$ and of the continuum emission of 30$\mu$Jy beam$^{-1}$. We report marginal spectral (at 225 km s$^{-1}$ resolution) and continuum features ($4.1\sigma$ and $2.6\sigma$ peak signal-to-noise ratio, respectively), within $0''.17$ from the JWST position of GHZ1. This spectral feature implies $z=10.38$ and needs to be verified with further observations. Assuming that the best photometric redshift estimate ($z=10.60^{+0.52}_{-0.60}$) is correct, the broadband galaxy spectral energy distribution model for the $3\sigma$ upper limit of the continuum flux from GHZ1 suggests that GHZ1 has a small amount of dust ($M_d\lesssim10^4 M_{\odot}$) with high temperature ($T_d\gtrsim90$K). The $5\sigma$ upper limit of the [OIII]$_{88\mu m}$ line luminosity and the inferred star formation rate of GHZ1 is consistent with the properties of the low metallicity dwarf galaxies. We also report serendipitous clear detections of six continuum sources at the locations of the JWST galaxy counterparts in the field.Comment: Accepted to ApJ after revising the figures and the analysi