arXiv subjects

F. Vivanco Cádiz

Publications and source records attributed to F. Vivanco Cádiz.

3 recordsLinked to original sources

arXiv2025

Galaxy populations in protoclusters at cosmic noon

We investigate the physical properties and redshift evolution of simulated galaxies residing in protoclusters at cosmic noon, to understand the influence of the environment on galaxy formation. This work is to build clear expectations for the ongoing ODIN survey, devoted to mapping large-scale structures at z=2.4, 3.1, and 4.5 using Ly$α$-emitting galaxies (LAEs) as tracers. From the IllustrisTNG simulations, we define subregions centered on the most massive clusters ranked by total stellar mass at z=0 and study the properties of galaxies within, including LAEs. To model the LAE population, we take a semi-analytical approach that assigns Ly$α$ luminosity and equivalent width based on the UV luminosities to galaxies in a probabilistic manner. We investigate stellar mass, star formation rate, major mergers, and specific star formation rate of the population of star-forming galaxies and LAEs in the field and protocluster environment and trace their evolution. We find that the overall shape of the UV luminosity function (LF) in simulated protocluster environments is characterized by a shallower faint-end slope and an excess on the bright end, signaling different formation histories for galaxies therein. The difference is milder for the Ly$α$ LF. While protocluster galaxies follow the same SFR-$M_{\odot}$ scaling relation as average field galaxies, a larger fraction appears to have experienced major mergers in the last 200 Myr and as a result shows enhanced star formation at a ~60% level, leading to a flatter distribution in both SFR and $M_{\odot}$ relative to galaxies in the average field. We find that protocluster galaxies, including LAEs, begin to quench much earlier (z~0.8-1.6) than field galaxies (z~0.5-0.9); our result is in agreement with recent observational results and highlights the importance of large-scale environment on the overall formation history of galaxies.

astro-ph.GA↗

arXiv2021

Inspection of 19 globular cluster candidates in the Galactic bulge with the VVV survey

The census of the globular clusters (GCs) in the Milky Way (MW) is still a work in progress. We explore the nature of 19 new GC candidates in the Galactic bulge, based on the analysis of their colour-magnitude diagrams (CMDs) in the near-IR, using the VISTA Variables in the Via Láctea Survey (VVV) database. We estimate their main astrophysical parameters: reddening and extinction, distance, total luminosity, mean cluster proper motions (PMs), metallicity and age. We obtain the cluster catalogues including the likely cluster members by applying a decontamination procedure on the observed CMDs, based upon the vector PM diagrams from VIRAC2. We estimate a wide reddening range of the $0.25 \leqslant E(J-K_s) \leqslant 2.0$ mag and extinction $0.11 \leqslant A_{Ks} \leqslant 0.86$ mag for the sample clusters as expected in the bulge regions. The range of heliocentric distances is $6.8\leqslant D\leqslant 11.4$ kpc. This allows us to place these clusters between 0.56 and 3.25 kpc from the Galactic centre, assuming $R_{\odot}=8.2$ kpc. Also, their PMs are kinematically similar to the typical motion of the Galactic bulge, apart from VVV-CL160, which shows different PMs. We also derive their metallicities and ages, finding $-1.40 \leqslant$ [Fe/H] $\leqslant 0.0$ dex and $t\approx 8-13$ Gyr respectively. The luminosities are calculated both in $K_{s}-$ and V-bands, recovering $-3.4 \leqslant M_V \leqslant -7.5$. We also examine the possible RR Lyrae members found in the cluster fields. Based on their positions, kinematics, metallicities and ages and comparing our results with the literature, we conclude that 9 candidates are real GCs, 7 need more observations to be fully confirmed as GCs, whereas 3 candidates are discarded for being younger open clusters.

astro-ph.GA↗

arXiv2021

Discovery of new globular clusters in the Sagittarius dwarf galaxy

Context. Globular clusters (GCs) are witnesses of the past accretion events onto the Milky Way (MW). In particular, the GCs of the Sagittarius (Sgr) dwarf galaxy are important probes of an on-going merger. Aims. Our main goal is to search for new GC members of this dwarf galaxy using the VISTA Variables in the Via Lactea Extended Survey (VVVX) near-infrared database combined with the Gaia Early Data Release 3 (EDR3) optical database. Methods. We investigated all VVVX-enabled discoveries of GC candidates in a region covering about 180 sq. deg. toward the bulge and the Sgr dwarf galaxy. We used multiband point-spread function photometry to obtain deep color-magnitude diagrams (CMDs) and luminosity functions (LFs) for all GC candidates, complemented by accurate Gaia-EDR3 proper motions (PMs) to select Sgr members and variability information to select RR Lyrae which are potential GC members. Results. After applying a strict PM cut to discard foreground bulge and disk stars, the CMDs and LFs for some of the GC candidates exhibit well defined red giant branches and red clump giant star peaks. We selected the best Sgr GCs, estimating their distances, reddenings, and associated RR Lyrae. Conclusions. We discover 12 new Sgr GC members, more than doubling the number of GCs known in this dwarf galaxy. In addition, there are 11 other GC candidates identified that are uncertain, awaiting better data for confirmation.

astro-ph.GA↗