arXiv subjects

S. V. Werner

Publications and source records attributed to S. V. Werner.

7 recordsLinked to original sources

arXiv2026

Intracluster light in the infall region of simulated protoclusters of galaxies

Intracluster light (ICL) is a diffuse stellar component in galaxy clusters, made of stars following the potential of the cluster. Despite its potential to unveil the accretion history of clusters, the ICL in protoclusters remains poorly understood in simulations and observations. We analyse protoclusters in TNG-Cluster and Manhattan Suite simulations to investigate when ICL forms, its host progenitors, and environments where it forms. We find a considerable amount of ICL in the infall region of protoclusters at 2<z<4, ranging from $\rm 0.1\times10^{11}$<$M_{*}/M_{\odot}$<$3\times10^{11}$. ICL star formation in protoclusters peaks at 3<z<4, with stars formed in the main halo forming earlier than those born in the infall regions. We find that $74.2_{-1.7}^{+1.7}\%$ of ICL stars in TNG-Cluster and $69.2_{-3.7}^{+3.6}\%$ in Manhattan Suite were stripped from galaxies within the main halo. However, most ICL stars in protoclusters at z=2 formed in the infall region, accounting for $57.6_{-1.6}^{+1.7}\%$ and $55.6_{-2.3}^{+2.3}\%$ in TNG-Cluster and Manhattan Suite, respectively. By the time the ICL stars are stripped, their host galaxies are 3-4 times more massive than the galaxies in which the stars originally formed, implying growth of the progenitor galaxies and/or accretion of the stars onto more massive galaxies prior to stripping. The ICL stellar masses measured in simulations agree with observations at z$\leq$2. Our findings highlight the importance of investigating the diffuse light in the outer regions of protoclusters to constrain the formation and assembly of the ICL and galaxy clusters.

astro-ph.GA↗

arXiv2025

The S-PLUS Fornax Project (S+FP): Mapping globular clusters systems within 5 virial radii around NGC 1399

We present the largest sample ($\sim$13,000 candidates, $\sim$3000 of wich are bona-fide candidates) of globular cluster (GCs) candidates reported in the Fornax Cluster so far. The survey is centered on the NGC 1399 galaxy, extending out to 5 virial radii (\rv) of the cluster. We carried out a photometric study using images observed in the 12-bands system of the Southern Photometric Local Universe Survey (S-PLUS), corresponding to 106 pointings, covering a sky area of $\sim$208 square degrees. Studying the properties of spectroscopically confirmed GCs, we have designed a method to select GC candidates using structural and photometric parameters. We found evidence of color bimodality in 2 broad bands colors, namely $(g-i)_{0}$ and $(g-z)_{0}$, while, in the narrow bands, we did not find strong statistical evidence to confirm bimodality in any color. We analyzed the GCs luminosity functions (GCLF) in the 12-bands of S-PLUS, and we can highlight two points: a) due to the relatively shallow depth of S-PLUS, it is only possible to observe the bright end of the GCLF and, b) at that level, in all the bands it can be appreciated the log-normal distribution typical for GC systems. With the spatial coverage reached in this study, we are able for the first time explore the large scale distribution of GCs within and around a galaxy cluster. In particular, we noted that the GCs might be clustered along substructures, which traces the current cluster build up.

astro-ph.GA↗

arXiv2023

An Extended Catalogue of galaxy morphology using Deep Learning in Southern Photometric Local Universe Survey Data Release 3

The morphological diversity of galaxies is a relevant probe of galaxy evolution and cosmological structure formation. However, in large sky surveys, even the morphological classification of galaxies into two classes, like late-type (LT) and early-type (ET), still represents a significant challenge. In this work we present a Deep Learning (DL) based morphological catalog built from images obtained by the Southern Photometric Local Universe Survey (S-PLUS) Data Release 3 (DR3). Our DL method achieves an precision rate of 98.5$\%$ in accurately distinguishing between spiral, as part of the larger category of late type (LT) galaxies, and elliptical, belonging to early type (ET) galaxies. Additionally, we have implemented a secondary classifier that evaluates the quality of each galaxy stamp, which allows to select only high-quality images when studying properties of galaxies on the basis of their DL morphology. From our LT/ET catalog of galaxies, we recover the expected color--magnitude diagram in which LT galaxies display bluer colors than ET ones. Furthermore, we also investigate the clustering of galaxies based on their morphology, along with their relationship to the surrounding environment. As a result, we deliver a full morphological catalog with $164314$ objects complete up to $r_{petro}<18$, covering $\sim 1800$ deg$^2$, including a significant area of the Southern hemisphere that was not covered by previous morphology catalogues.

astro-ph.GA↗

arXiv2023

Intracluster light in the core of z~2 galaxy proto-clusters

Intracluster light is thought to originate from stars that were ripped away from their parent galaxies by gravitational tides and galaxy interactions during the build up of the cluster. The stars from such interactions will accumulate over time, so semi-analytic models suggest that the abundance of intracluster stars is negligible in young proto-clusters at z~2 and grows to around a quarter of the stellar mass in the oldest, most mature clusters. In contrast to these theoretical expectations, we report on the detection of intracluster light within two proto-clusters at z=2 using deep HST images. We use the colour of the intracluster light to estimate its mass-to-light ratio in annuli around the brightest cluster galaxies (BCG), up to a radius of 100 kpc. We find that $54\pm5$% and $71\pm3$% of the stellar mass in these regions is located more than 10 kpc away from the BCGs in the two proto-clusters. This low concentration is similar to BCGs in lower redshift clusters, and distinct from other massive proto-cluster galaxies. This suggests that intracluster stars are already present within the core 100 kpc of proto-clusters. We compare these observations to the Hydrangea hydrodynamical galaxy cluster simulations and find that intracluster stars are predicted to be a generic feature of group-sized halos at z=2. These intracluster stars will gradually move further away from the BCG as the proto-cluster assembles into a cluster.

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arXiv2022

S-PLUS DR1 galaxy clusters and groups catalogue using PzWav

We present a catalogue of 4499 groups and clusters of galaxies from the first data release of the multi-filter (5 broad, 7 narrow) Southern Photometric Local Universe Survey (S-PLUS). These groups and clusters are distributed over 273 deg$^2$ in the Stripe 82 region. They are found using the PzWav algorithm, which identifies peaks in galaxy density maps that have been smoothed by a cluster scale difference-of-Gaussians kernel to isolate clusters and groups. Using a simulation-based mock catalogue, we estimate the purity and completeness of cluster detections: at S/N>3.3 we define a catalogue that is 80% pure and complete in the redshift range 0.1 10^{14}$ M$_\odot$. We also assessed the accuracy of the catalogue in terms of central positions and redshifts, finding scatter of $σ_R=12$ kpc and $σ_z=8.8 \times 10^{-3}$, respectively. Moreover, less than 1% of the sample suffers from fragmentation or overmerging. The S-PLUS cluster catalogue recovers ~80% of all known X-ray and Sunyaev-Zel'dovich selected clusters in this field. This fraction is very close to the estimated completeness, thus validating the mock data analysis and paving an efficient way to find new groups and clusters of galaxies using data from the ongoing S-PLUS project. When complete, S-PLUS will have surveyed 9300 deg$^{2}$ of the sky, representing the widest uninterrupted areas with narrow-through-broad multi-band photometry for cluster follow-up studies.

astro-ph.GA↗

arXiv2021

Satellite quenching was not important for z$\sim$1 clusters: most quenching occurred during infall

We quantify the relative importance of environmental quenching versus pre-processing in $z\sim1$ clusters by analysing the infalling galaxy population in the outskirts of 15 galaxy clusters at $0.8 10^{11}M_{\odot}$ were quenched prior to infall, whilst up to half of lower mass galaxies were environmentally quenched after passing the virial radius. This means most of the massive quiescent galaxies in $z\sim1$ clusters were self-quenched or pre-processed prior to infall.

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arXiv2019

Assessing the photometric redshift precision of the S-PLUS survey: the Stripe-82 as a test-case

In this paper we present a thorough discussion about the photometric redshift (photo-z) performance of the Southern Photometric Local Universe Survey (S-PLUS). This survey combines a 7 narrow + 5 broad passband filter system, with a typical photometric-depth of r$\sim$21 AB. For this exercise, we utilize the Data Release 1 (DR1), corresponding to 336 deg$^{2}$ from the Stripe-82 region. We rely on the \texttt{BPZ2} code to compute our estimates, using a new library of SED models, which includes additional templates for quiescent galaxies. When compared to a spectroscopic redshift control sample of $\sim$100k galaxies, we find a precision of $σ_{z}<$0.8\%, $<$2.0\% or $<$3.0\% for galaxies with magnitudes r$<$17, $<$19 and $<$21, respectively. A precision of 0.6\% is attained for galaxies with the highest \texttt{Odds} values. These estimates have a negligible bias and a fraction of catastrophic outliers inferior to 1\%. We identify a redshift window (i.e., 0.26$<z<$0.32) where our estimates double their precision, due to the simultaneous detection of two emission-lines in two distinct narrow-bands; representing a window opportunity to conduct statistical studies such as luminosity functions. We forecast a total of $\sim$2M, $\sim$16M and $\sim$32M galaxies in the S-PLUS survey with a photo-z precision of $σ_{z}<$1.0\%, $<$2.0\% and $<$2.5\% after observing 8000 $deg^{2}$. We also derive redshift Probability Density Functions, proving their reliability encoding redshift uncertainties and their potential recovering the $n(z)$ of galaxies at $z<0.4$, with an unprecedented precision for a photometric survey in the southern hemisphere.

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