Browsing by Author "Torres-Flores, S."

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    Clues on Arp 142: The spiral–elliptical merger
    (OUP, 2019) Mora, Marcelo D.; Torres-Flores, S.; Firpo, V.; Hernandez-Jimenez, J. A.; Urrutia-Viscarra, F.; Mendes de Oliveir, C.
    Nearby merging pairs are unique laboratories in which one can study the gravitational effects on the individual interacting components. In this manuscript, we report the characterization of selected H II regions along the peculiar galaxy NGC 2936, member of the galaxy pair Arp 142, an E+S interaction, known as ‘The Penguin’. Using Gemini South spectroscopy, we have derived a high enhancement of the global star formation rate (SFR) = 35.9 M ⊙ yr −1 probably stimulated by the interaction. Star-forming regions on this galaxy display oxygen abundances that are consistent with solar metallicities. The current data set does not allow us to conclude any clear scenario for NGC 2936. Diagnostic diagrams suggest that the central region of NGC 2936 is ionized by active galactic nucleus (AGN) activity and the eastern tidal plume in NGC 2936 is experiencing a burst of star formation, which may be triggered by the gas compression due to the interaction event with its elliptical companion galaxy: NGC 2937. The ionization mechanism of these sources is consistent with shock models of low velocities of 200–300 km s  −1 . The isophotal analysis shows tidal features on NGC 2937: at inner radii non-concentric (or off-centring) isophotes, and at large radii, a faint excess of the surface brightness profile with respect to de Vaucouleurs law. By comparing the radial velocity profiles and morphological characteristics of Arp 142 with a library of numerical simulations, we conclude that the current stage of the system would be about 50 ± 25 Myr after the first pericentre passage.
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    Too dense to go through: the role of low-mass clusters in the pre-processing of satellite galaxies
    (2022) Pallero, Diego; Gomez, Facundo A.; Padilla, Nelson D.; Bahe, Yannick M.; Vega-Martinez, Cristian A.; Torres-Flores, S.
    We study the evolution of satellite galaxies in clusters of the c-eagle simulations, a suite of 30 high-resolution cosmological hydrodynamical zoom-in simulations based on the eagle code. We find that the majority of galaxies that are quenched at z = 0 (greater than or similar to 80per cent) reached this state in a dense environment (log(10)M(200)[M-circle dot] >= 13.5). At low redshift, regardless of the final cluster mass, galaxies appear to reach their quenching state in low-mass clusters. Moreover, galaxies quenched inside the cluster that they reside in at z = 0 are the dominant population in low-mass clusters, while galaxies quenched in a different halo dominate in the most massive clusters. When looking at clusters at z > 0.5, their in situ quenched population dominates at all cluster masses. This suggests that galaxies are quenched inside the first cluster they fall into. After galaxies cross the cluster's r(200) they rapidly become quenched (less than or similar to 1 Gyr). Just a small fraction of galaxies (less than or similar to 15 per cent) is capable of retaining their gas for a longer period of time, but after 4 Gyr, almost all galaxies are quenched. This phenomenon is related to ram pressure stripping and is produced when the density of the intracluster medium reaches a threshold of rho(ICM) similar to 3 x10(-5) n(H) (cm(-3)). These results suggest that galaxies start a rapid-quenching phase shortly after their first infall inside r(200) and that, by the time they reach r(500), most of them are already quenched.
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    TOROS optical follow-up of the advanced LIGO–VIRGO O2 second observational campaign
    (2020) Artola, R.; Beroiz, M.; Cabral, J.; Camuccio, R.; Castillo, M.; Chavushyan, V.; Colazo, C.; Cuevas, H.; DePoy, D. L.; Díaz, M. C.; Domínguez, M.; Dultzin, D.; Fernández, D.; Ferreyra, A. C.; Fonrouge, A.; Franco, J.; Graña, D.; Girardini, C.; Gurovich, S.; Kanaan, A.; Lambas, D. G.; Lares, M.; Hinojosa, A. F.; Hinojosa, A.; Hinojosa, A. F.; López-Cruz, O.; Macri, L. M.; Marshall, J. L.; Melia, R.; Mendoza, W.; Castelló, J. L. N.; Padilla, N.; Perez, V.; Peñuela, T.; Rattray, W.; Renzi, V.; Ríos-López, E.; Rivera, A. R.; Ribeiro, T.; Rodriguez, H.; Sánchez, B.; Schneiter, M.; Schoenell, W.; Starck, M.; Vrech, R.; Quiñones, C.; Tapia, L.; Tornatore, M.; Torres-Flores, S.; Vilchis, E.; Zadrożn, A.
    We present the methods and results of the optical follow-up, conducted by the Transient Optical Robotic Observatory of the South Collaboration, of gravitational wave events detected during the Advanced LIGO–Virgo second observing run (2016 November–2017 August). Given the limited field of view (∼100 arcmin) of our observational instrumentation, we targeted galaxies within the area of high localization probability that were observable from our sites. We analysed the observations using difference imaging, followed by a random forest algorithm to discriminate between real and spurious transients. Our observations were conducted using telescopes at Estación Astrofísica de Bosque Alegre, Cerro Tololo Inter-American Observatory, the Dr. Cristina V. Torres Memorial Astronomical Observatory, and an observing station in Salta, Argentina.