Search

The galactic component in clusters is commonly thought to be generally nonrotating and in a dynamical state different from that of a collisionally relaxed system. In practice, a test of such a picture is often not available. We consider the member galaxies of two clusters, Abell S1063 and MACS J1206.2$-$0847, and study the possible presence of mean rotation and some properties of their distribution in phase space. We look for empirical evidence of factors normally found in collisionally relaxed systems and others characteristic of violently-relaxed collisionless systems. Starting from the CLASH-VLT data, we obtain positions, stellar masses, and individual line-of-sight velocities for a large number of galaxies (N_{AS1063}=1200 and N_{M1206}=650) extending out to 1.6 (Abell) and 2.5 (MACS) times the radius r_{200}. We study the spatial distribution of the galaxy velocities and the properties of the available galaxy sets when divided in stellar mass bins. To test the presence of velocity dispersion anisotropy we compare the results based on the Jeans equations with those obtained by assuming a specific form of the galaxy distribution function incorporating the picture of violent relaxation, where the total gravitational potential is imposed as set by the available gravitational lensing observations. We find evidence of systematic rotation in both clusters, with significant rotation in each core (within 0.5' from the center) and no signatures of rotation at large radii. While no signs are found of energy equipartition, there is a clear indication of (stellar) mass segregation. Velocity dispersion anisotropy is present and qualitatively similar to that found in violently relaxed collisionless systems; this last conclusion is strengthened by the overall success in matching the observations with the predictions of the physically justified distribution function., 18 pages, 16 figures. Accepted for publication in A&A

Aims. The demographics of the production and escape of ionizing photons from UV-faint early galaxies is a key unknown that has hindered attempts to discover the primary drivers of reionization. With the advent of JWST, it is finally possible to observe the rest-frame optical nebular emission from individual sub-L similar to z > 3 galaxies to measure the production rate of ionizing photons, xi(ion).Methods. Here we study a sample of 370 z similar to 3 7 galaxies spanning 23 < M-UV < 15:5 (median M-UV approximate to 18) with deep multiband HST and JWST /NIRCam photometry that covers the rest-UV to the optical from the GLASS and UNCOVER JWST surveys. Our sample includes 102 galaxies with Lyman-alpha emission detected in MUSE spectroscopy. We used H ff fluxes inferred from NIRCam photometry to estimate the production rate of ionizing photons that do not escape these galaxies, xi(ion)(1 f(esc)).Results. We find median log(10) xi(ion)(1 f(esc)) = 25.33 similar to 0.47, with a broad intrinsic scatter of 0.42 dex, which implies a broad range of galaxy properties and ages in our UV-faint sample. Galaxies detected with Lyman-alpha have similar to 0.1 dex higher xi(ion)(1 f(esc)), which is explained by their higher H ff equivalent width distribution; this implies younger ages and higher specific star formation rates and, thus, more O /B stars. We find significant trends of increasing xi(ion)(1 f(esc)) with increasing H ff equivalent width, decreasing UV luminosity, and decreasing UV slope; this implies that the production of ionizing photons is enhanced in young galaxies with assumed low metallicities. We find no significant evidence for sources with very high ionizing escape fractions (f(esc) > 0.5) in our sample based on their photometric properties, even amongst the Lyman-alpha-selected galaxies.Conclusions. This work demonstrates that considering the full distribution of xi(ion) across galaxy properties is important for assessing the primary drivers of reionization.

We present the results of a first search for galaxy candidates at z similar to 9-15 on deep seven-band NIRCam imaging acquired as part of the GLASS-James Webb Space Telescope (JWST) Early Release Science Program on a flanking field of the Frontier Fields cluster A2744. Candidates are selected via two different renditions of the Lyman-break technique, isolating objects at z similar to 9-11, and z similar to 9-15, respectively, supplemented by photometric redshifts obtained with two independent codes. We find five color-selected candidates at z > 9, plus one additional candidate with photometric redshift z (phot) >= 9. In particular, we identify two bright candidates at M (UV) similar or equal to -21 that are unambiguously placed at z similar or equal to 10.6 and z similar or equal to 12.2, respectively. The total number of galaxies discovered at z > 9 is in line with the predictions of a nonevolving luminosity function. The two bright ones at z > 10 are unexpected given the survey volume, although cosmic variance and small number statistics limits general conclusions. This first search demonstrates the unique power of JWST to discover galaxies at the high-redshift frontier. The candidates are ideal targets for spectroscopic follow-up in Cycle-2.

In this paper, we assess the impact of numerical resolution and of the implementation of energy input from AGN feedback models on the inner structure of cluster sub-haloes in hydrodynamic simulations. We compare several zoom-in re-simulations of a sub-sample of the cluster-sized haloes studied in Meneghetti et al. (2020), obtained by varying mass resolution, softening length and AGN energy feedback scheme. We study the impact of these different setups on the subhalo abundances, their radial distribution, their density and mass profiles and the relation between the maximum circular velocity, which is a proxy for subhalo compactness. Regardless of the adopted numerical resolution and feedback model, subhaloes with masses Msub < 1e11Msun/h, the most relevant mass-range for galaxy-galaxy strong lensing, have maximum circular velocities ~30% smaller than those measured from strong lensing observations of Bergamini et al. (2019). We also find that simulations with less effective AGN energy feedback produce massive subhaloes (Msub> 1e11 Msun/h ) with higher maximum circular velocity and that their Vmax - Msub relation approaches the observed one. However the stellar-mass number count of these objects exceeds the one found in observations and we find that the compactness of these simulated subhaloes is the result of an extremely over-efficient star formation in their cores, also leading to larger-than-observed subhalo stellar mass. We conclude that simulations are unable to simultaneously reproduce the observed stellar masses and compactness (or maximum circular velocities) of cluster galaxies. Thus, the discrepancy between theory and observations that emerged from the analysis of Meneghetti et al. (2020) persists. It remains an open question as to whether such a discrepancy reflects limitations of the current implementation of galaxy formation models or the LCDM paradigm., 11 pages, 10 figures, abstract is redacted to fit arXiv character count limit

The detection of the accelerated expansion of the Universe has been one of the major breakthroughs in modern cosmology. Several cosmological probes (CMB, SNe Ia, BAO) have been studied in depth to better understand the nature of the mechanism driving this acceleration, and they are being currently pushed to their limits, obtaining remarkable constraints that allowed us to shape the standard cosmological model. In parallel to that, however, the percent precision achieved has recently revealed apparent tensions between measurements obtained from different methods. These are either indicating some unaccounted systematic effects, or are pointing toward new physics. Following the development of CMB, SNe, and BAO cosmology, it is critical to extend our selection of cosmological probes. Novel probes can be exploited to validate results, control or mitigate systematic effects, and, most importantly, to increase the accuracy and robustness of our results. This review is meant to provide a state-of-art benchmark of the latest advances in emerging beyond-standard cosmological probes. We present how several different methods can become a key resource for observational cosmology. In particular, we review cosmic chronometers, quasars, gamma-ray bursts, standard sirens, lensing time-delay with galaxies and clusters, cosmic voids, neutral hydrogen intensity mapping, surface brightness fluctuations, stellar ages of the oldest objects, secular redshift drift, and clustering of standard candles. The review describes the method, systematics, and results of each probe in a homogeneous way, giving the reader a clear picture of the available innovative methods that have been introduced in recent years and how to apply them. The review also discusses the potential synergies and complementarities between the various probes, exploring how they will contribute to the future of modern cosmology., Invited review article for Living Reviews in Relativity. Accepted version. 191 pages, 54 figures, 11 tables