arXiv subjects

Rodrigo F. Haack

Publications and source records attributed to Rodrigo F. Haack.

4 recordsLinked to original sources

arXiv2025

Galaxy evolution in compact groups - III. Structural analysis of galaxies and dynamical state of non-isolated compact groups

Compact Groups (CGs) of galaxies are dense systems where projected separations are comparable to their optical diameters. A subset - non-isolated CGs - are embedded within major structures. Using multi-band S-PLUS data, we analyse galaxies in 122 non-isolated CGs within more massive systems such as larger groups and clusters. We compare them to galaxies in the host structures, hereafter surrounding group galaxies. Structural parameters were obtained with MorphoPLUS, a pipeline for multi-wavelength S\'ersic profile fitting. Dividing galaxies into early (ETG), transition, or late types (LTG), we find: (1) Non-isolated CGs host higher quenched fractions and more ETGs, especially for stellar masses $\log(M/M_\odot) > 10.2$, than surrounding groups. (2) S\'ersic indices increase with wavelength for all morphological types in both environments, whereas effective radii show a stronger morphology-dependent behaviour - ETGs become more compact towards redder bands, while LTGs exhibit flatter $Re(\lambda)$ trends. Environmental differences remain weak, with only a modest enhancement of the gradients for ETGs in non-isolated CGs. (3) Transition galaxies in CGs show a concentrated $R_e$-$n$ distribution and faint-end bimodality, consistent with ongoing morphological transformation absent in surrounding groups. (4) Phase-space analysis indicates that some CGs in clusters are projection artefacts, while others are genuine dense systems at various infall stages, from recent arrivals to ancient remnants. These results show that galaxies in non-isolated CGs follow distinct evolutionary paths compared to their surrounding groups galaxies, suggesting that the compact configuration plays a unique role beyond the influence of the larger-scale environment.

astro-ph.GA↗

arXiv2025

Targeting cluster galaxies for the 4MOST CHANCES Low-z sub-survey with photometric redshifts

The evolution of galaxies is shaped by both internal processes and their external environments. Galaxy clusters and their surroundings provide ideal laboratories to study these effects, particularly mechanisms such as quenching and morphological transformation. The Chilean Cluster galaxy Evolution Survey (CHANCES) Low-z sub-survey is part of the CHileAN Cluster galaxy Evolution Survey, a 4MOST community survey designed to uncover the relationship between the formation and evolution of galaxies and hierarchical structure formation as it happens, through deep and wide multi-object spectroscopy. We present the target selection strategy followed to select galaxy cluster candidate members for the CHANCES low-z sub-survey, in and around 50 clusters and two superclusters at z<0.07, out to (5XR200) and down to mr= 20.4. Combining public photometric redshift estimates from the DESI Legacy Imaging Survey and T80S/S-PLUS iDR5, with custom photometric redshifts, we identify likely galaxy cluster candidate members whose photometric redshifts are consistent with being at the known redshift of the cluster and measure the average deviations of their photometric redshifts with respect to the spectroscopic redshift measurements {\sigma}NMAD. We have successfully compiled our CHANCES-low-redshift catalogues, split into three different sub-surveys: low-z bright (mr<18.5), low-z faint (18.5<=mr<20.4) and low-z faint supplementary, by selecting>= 500,000 galaxy cluster candidate members and including confirmed spectroscopic galaxy cluster members, from which we expect to obtain 4MOST low-resolution (R~6500) spectra for ~320,000 galaxies. The CHANCES Low-z target catalogues form a statistically robust sample for spectroscopic follow-up, allowing studies of galaxy evolution and environmental effects in nearby cluster and supercluster environments.

astro-ph.GA↗

arXiv2024

CHANCES, the Chilean Cluster Galaxy Evolution Survey: Selection and initial characterisation of clusters and superclusters

CHANCES, the CHileAN Cluster galaxy Evolution Survey, will study the evolution of galaxies in and around 100 massive galaxy clusters from the local Universe out to $z = 0.45$, and two superclusters at $z \sim 0.05$ that contain roughly 25 Abell clusters each. CHANCES will use the new 4MOST Spectroscopic Survey Facility on the VISTA 4m telescope to obtain spectra for $\sim$500,000 galaxies with magnitudes $r_\mathrm{AB} < 20.4$, providing comprehensive spectroscopic coverage of each cluster out to $5r_{200}$. Its wide and deep scope will trace massive and dwarf galaxies from the surrounding filaments and groups to the cores of galaxy clusters. This will enable the study of galaxy preprocessing and of the role of the evolving environment on galaxy evolution. In this paper, we present and characterise the sample of clusters and superclusters to be targeted by CHANCES. We used literature catalogues based on X-ray emission and the Sunyaev-Zel'dovich effect to define the cluster sample in a homogeneous way, with attention to cluster mass and redshift, as well as the availability of ancillary data. We calibrated literature mass estimates from various surveys against each other and provide an initial mass estimate for each cluster, which we used to define the radial extent of the 4MOST coverage. We also present an initial assessment of the structure surrounding these clusters based on the redMaPPer red-sequence algorithm as a preview of some of the science CHANCES will enable.

astro-ph.GA↗

arXiv2024

Systematic analysis of jellyfish galaxy candidates in Fornax, Antlia, and Hydra from the S-PLUS survey: A self-supervised visual identification aid

We study 51 jellyfish galaxy candidates in the Fornax, Antlia, and Hydra clusters. These candidates are identified using the JClass scheme based on the visual classification of wide-field, twelve-band optical images obtained from the Southern Photometric Local Universe Survey. A comprehensive astrophysical analysis of the jellyfish (JClass > 0), non-jellyfish (JClass = 0), and independently organized control samples is undertaken. We develop a semi-automated pipeline using self-supervised learning and similarity search to detect jellyfish galaxies. The proposed framework is designed to assist visual classifiers by providing more reliable JClasses for galaxies. We find that jellyfish candidates exhibit a lower Gini coefficient, higher entropy, and a lower 2D S\'ersic index as the jellyfish features in these galaxies become more pronounced. Jellyfish candidates show elevated star formation rates (including contributions from the main body and tails) by $\sim$1.75 dex, suggesting a significant increase in the SFR caused by the ram-pressure stripping phenomenon. Galaxies in the Antlia and Fornax clusters preferentially fall towards the cluster's centre, whereas only a mild preference is observed for Hydra galaxies. Our self-supervised pipeline, applied in visually challenging cases, offers two main advantages: it reduces human visual biases and scales effectively for large datasets. This versatile framework promises substantial enhancements in morphology studies for future galaxy image surveys.

astro-ph.GA↗