arXiv subjects

Gissel P. Montaguth

Publications and source records attributed to Gissel P. Montaguth.

8 recordsLinked to original sources

arXiv2026

Star formation and morphological trends in the Antlia cluster: Probing environmental influence out to 5R200

Galaxy evolution in dense environments such as clusters is strongly affected by environmental processes that can alter both morphology and star formation activity. We investigate these effects in the Antlia cluster out to 5R200 using Southern Photometric Local Universe Survey (S-PLUS) data. We derive H-alpha-based star formation rates from the J0660 band and Sersic indices with GALFITM. Our analysis focuses on 154 spectroscopically confirmed galaxies brighter than mr = 16. We classify galaxies as early- or late-type systems using colour and Sersic index, and as quenched or star-forming using specific star formation rate. We examine their dependence on clustercentric distance, projected phase-space, substructure, and local density. We find that star-forming galaxies dominate from 1 to 5R200, while quenched galaxies are more common within 1R200. Early- and late-type galaxies show similar radial trends, with comparable fractions within 1R200 and a higher late-type fraction at larger radii. Quenched galaxies dominate at log(Sigma10 [Mpc^-2]) >= 1.5, whereas late-type galaxies dominate at log(Sigma10 [Mpc^-2]) <= 1.0. We identify substructures extending from the cluster centre to the outskirts. Substructures outside the central region are dominated by star-forming and late-type galaxies, with fractions similar to those of galaxies not associated with detected substructures. However, when the massive central structure is included, the fraction of star-forming galaxies in substructures decreases, indicating a more environmentally processed population in the central region. Altogether, the presence of a massive central substructure together with additional substructures detected out to 5R200 indicates that Antlia is still undergoing mass assembly through group accretion, consistent with a dynamically active and young cluster that is still assembling its galaxy population.

astro-ph.GA↗

arXiv2026

Characterizing the Formation and Evolution of S0-galaxies (CaFES-0): Revealing the origin of the mass-size relation for S0 galaxies

We investigate the structural evolution and formation pathways of lenticular (S0) galaxies using the Hydrangea suite of cosmological hydrodynamical simulations. Simulated galaxies reproduce the observed mass-size relation from the SAMI and MaNGA surveys, enabling a direct comparison between morphology, angular momentum, and size growth. We show that the S0 population occupies a characteristic V-shaped locus in the mass-size plane, which arises from the superposition of two physically distinct channels. Low-mass S0s are predominantly faded-formed S0s, quenched after infall into their present-day host halo and retaining the disk sizes of their star-forming progenitors. In contrast, high-mass S0s formed through mergers exhibit structural properties and size evolution similar to ellipticals, and typically quench before infall, consistent with pre-processing in group environments. By tracing their histories back to $z=1$, we find that faded-formed S0s experience minimal structural evolution after quenching, whereas merger-formed S0s grow significantly in size through dissipationless interactions. These divergent evolutionary pathways explain both the slope break and the overall scatter of the S0 mass-size relation, demonstrating that lenticular galaxies arise from multiple formation mechanisms that leave distinct structural imprints.

astro-ph.GA↗

arXiv2026

Caught in the web: galaxy mergers along cosmic filaments

Galaxy clusters grow through the accretion of galaxies from groups, filaments, and other clusters. During this process, galaxies may undergo pre-processing in lower-density environments, where galaxy-galaxy mergers and other interactions can significantly alter their properties prior to cluster infall. We investigate the role of galaxy mergers in the pre-processing of galaxies prior to cluster infall by studying the spatial distribution of mergers across the cosmic web. We use a sample of 43,922 galaxies targeted by the 4MOST CHANCES survey in and around 33 low-redshift clusters (z < 0.07). Using Zoobot, a deep-learning framework trained on Galaxy Zoo data, we identify 698 galaxy mergers. We measure their distances to cosmic web filaments and compare them with those of non-merging galaxies. We find that galaxy mergers are significantly closer to filaments than the non-merging galaxy population, with this trend being strongest beyond the cluster virial radius. This suggests that filaments provide conditions conducive to mergers, possibly moderating relative velocities and enhancing gas availability. Our findings support a scenario in which filaments play a key role in transforming galaxies through pre-processing by promoting mergers before they enter cluster cores where star formation quenches.

astro-ph.GA↗

arXiv2026

Galaxies caught in transition: the role of group environment in shaping the mass-size relation in the local Universe

The stellar mass-size relation is a sensitive probe of how environment shapes galaxy structure. We analyse this relation in the local Universe for galaxies in compact groups (CGs), low-mass groups ($M_{\rm vir} \leq 10^{13}~M_{\odot}$), and high-mass groups, comparing them to field galaxies using data from the Southern Photometric Local Universe Survey. Galaxies are classified as early types (ETGs; $n \geq 2.5$, $(u-r)_0 \geq 2.3$), late types (LTGs; $n < 2.5$, $(u-r)_0 < 2.3$), transition galaxies (TGs; $n < 2.5$, $(u-r)_0 \geq 2.3$), and others (OGs; $n \geq 2.5$, $(u-r)_0 < 2.3$). We find that ETGs and OGs show no significant environmental dependence: their mass-size slopes and intercepts are statistically consistent across CGs, groups, and the field. LTGs also follow similar relations in the field and in most groups, with only a modest tendency for LTGs in CGs to be smaller at fixed stellar mass. By contrast, TGs display a clear environmental signal: in groups the slope steepens to $α\sim 0.4$ (versus $α\sim 0.2$ in the field) and their sizes are smaller than in the field, with non-overlapping 95\% posterior intervals. These trends suggest that TGs in denser environments are more structurally evolved, likely owing to enhanced bulge prominence and fading of the outer disc, consistent with the Sérsic-index distributions, which show an excess of TGs with $n_r \gtrsim 1.5$ in groups and CGs. Our findings highlight TGs as an environmentally sensitive population, providing insight into the structural transformation of galaxies in group environments.

astro-ph.GA↗

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 Sérsic 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) Sérsic 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 $Re(λ)$ 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

Galaxy evolution in compact groups II. Witnessing the influence of major structures in their evolution

Compact groups (CGs) of galaxies are extreme environments for morphological transformations and the cessation of star formation. Though initially considered isolated, it is now recognised that many CGs are embedded in larger structures. We aim to understand the dynamics of CGs and how their surrounding environments impact their physical properties. We selected 316 CGs in the Stripe 82 region (1011 galaxies) and 2281 field galaxies as a control sample. At least 41% of CGs are part of major structures (non-isolated CGs). We find a bimodal distribution in the effective radius ($R_e$)-Sersic index ($n$) plane for transition galaxies ($(u-r) > 2.3$ and $n<2.5$) in CGs. Transition galaxies in isolated CGs are denser in the $R_e-n$ plane for $n < 1.75$, while those in non-isolated CGs show a smoother increase in $n$, with 62% having $n > 1.5$. This suggests that many have undergone morphological transformation, contributing to the compact galaxy population. Galaxies in CGs have lower mean specific star formation rates (sSFR) than the control sample, with non-isolated CGs showing even lower sSFR, indicating stronger star formation suppression. Non-isolated CGs also have a higher fraction of quenched galaxies. When dividing by morphology, significant differences arise only for early-type galaxies (ETGs; $(u-r) > 2.3$ and $n>2.5$). In isolated CGs, ETGs show lower quenched fractions and higher sSFR in low-mass bins ($\log(M_/M_{\odot}) < 11$), suggesting sustained star formation. In non-isolated CGs, ETGs show higher quenched fractions and lower sSFR in high-mass bins ($\log(M_/M_{\odot}) > 11$), underscoring the environmental suppression of star formation. We propose that major structures accelerate morphological transformations and facilitate preprocessing. Our results highlight the need to consider larger structures when analysing CGs, as they significantly affect galaxy evolution.

astro-ph.GA↗

arXiv2023

Bulge-disc decomposition of the Hydra cluster galaxies in 12 bands

When a galaxy falls into a cluster, its outermost parts are the most affected by the environment. In this paper, we are interested in studying the influence of a dense environment on different galaxy's components to better understand how this affects the evolution of galaxies. We use, as laboratory for this study, the Hydra cluster which is close to virialization; yet it still shows evidence of substructures. We present a multi-wavelength bulge-disc decomposition performed simultaneously in 12 bands from S-PLUS data for 52 galaxies brighter than m$_{r}$= 16. We model the galaxies with a Sersic profile for the bulge and an exponential profile for the disc. We find that the smaller, more compact, and bulge-dominated galaxies tend to exhibit a redder colour at a fixed stellar mass. This suggests that the same mechanisms (ram-pressure stripping and tidal stripping) that are causing the compaction in these galaxies are also causing them to stop forming stars. The bulge size is unrelated to the galaxy's stellar mass, while the disc size increases with greater stellar mass, indicating the dominant role of the disc in the overall galaxy mass-size relation found. Furthermore, our analysis of the environment unveils that quenched galaxies are prevalent in regions likely associated with substructures. However, these areas also harbour a minority of star-forming galaxies, primarily resulting from galaxy interactions. Lastly, we find that ~37 percent of the galaxies exhibit bulges that are bluer than their discs, indicative of an outside-in quenching process in this type of dense environments.

astro-ph.GA↗

arXiv2023

Galaxy evolution in compact groups I: Revealing a transitional galaxy population through a multiwavelength approach

Compact groups of galaxies (CGs) show members with morphological disturbances, mainly products of galaxy-galaxy interactions, thus making them ideal systems to study galaxy evolution, in high-density environment. To understand how this environment affects the properties of galaxies, we select a sample of 340 CGs in the Stripe 82 region, for a total of 1083 galaxies, and a sample of 2281 field galaxies as a control sample. By performing a multi-wavelength morphological fitting process using S-PLUS data, we divide our sample into early-type (ETG), late-type (LTG), and transition galaxies using the r-band Sérsic index and the colour (u-r). We find a bimodal distribution in the plane of the effective radius-Sérsic index, where a secondary "peculiar" galaxy population of smaller and more compact galaxies is found in CGs, which is not observed in the control sample. This indicates that galaxies are undergoing a morphological transformation in CGs. In addition, we find significant statistical differences in the distribution of specific Star Formation Rate (sSFR) when we compare both environments for LTGs and ETGs. We also find a higher fraction of quenched galaxies and a lower median sSFR in CGs than in the control sample, suggesting the existence of environmental effects favoring the cessation of star formation, regardless of galaxy type. Our results support the notion that CGs promote morphological and physical transformations, highlighting their potential as ideal systems for galaxy pre-processing.

astro-ph.GA↗