Browsing by Author "Gil Toriello, Santiago"

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    Exploring the Green Valley with the dark energy survey: studying the evolution of galaxies
    (2023) Gil Toriello, Santiago; Galaz, Gaspar; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    We investigate the properties of galaxies located at the so-called Green Valley, an intermediate region between the blue-cloud of active star- forming galaxies, and the red-sequence of quenched and "dead" galaxies, visible in a color vs stellar mass diagram for galaxies.We utilize data from multiple releases of the Dark Energy Survey (DES), to characterize galaxies based on their physical properties, and to correlate their location in a stellar mass vs color diagram with their morphologies.We selected a sample of high-quality photometric data from the Year 3 re- lease of the Dark Energy Survey, with redshifts ranging from local z ∼ 0, to intermediate z ∼ 1.5, and cleaned it by applying a set of different quality selection criteria. We obtained a number of measurements for the photometric redshifts of the galaxies, by employing different parametric algorithms, to study each evolution separately as a function of distance. With the use of LePHARE, a template fitting code, we measured a set of physical properties of the galaxies that are helpful to study their evo- lution, and to assess the transitional nature of galaxies inside the Green Valley. These are, mainly, the Absolute Magnitude, the Stellar Mass, the Star Formation Rate and the UV Luminosity.We made use of two catalogues for morphological prediction available for the Year 3 release. These catalogues allowed us to better constrain the relation between the morphological structures of galaxies and their evolutionary stage.Results show that combining SED template fitting algorithms with mor- phological analysis allows to constrain the bi-modality distribution even when working with optical surveys, up to redshifts of z = 1.5.This is a first approach on the use of these methods to pave the way more massive and intensive data treatment surveys, like the future LSST survey to be done with the Vera Rubin Telescope.
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    Water masers in the ALMA era: an excellent tool to study star formation at sub-arcsecond spatial scales
    (2023) de Gregorio-Monsalvo, Itziar; Gil Toriello, Santiago; Santamaría Miranda, Alejandro; Gómez, José Francisco; Pérez Sánchez, Andrés Felipe; Plunkett, Adele; Artur de la Villarmois, Elizabeth; Guzmán Veloso, Viviana Gabriela; Schreiber, Matthias R.
    The water molecule is one of the most common compounds in the Universe and it exhibits several maser transitions at submillimeter wavelengths, which can be observed at ALMA. Previous studies have primarily focused on water masers at 22 GHz, which are excited in regions of high density and high temperature. These masers are typically very bright, spectrally narrow, and originate from very compact regions. Consequently, they have been invaluable for studying circumstellar structure and dynamics at sub-arcsecond spatial scales. Different water maser transitions can be pumped over a range of astrophysical conditions. The submillimeter transitions at 321 GHz and 325 GHz, in particular, trace respectively warmer and lower density regions than the 22 GHz transition. They have been identified as tracers of mass-loss phenomena in a limited number of star-forming regions. Conversely, transitions such as the one at 183 GHz, which primarily undergo collisional pumping, can provide valuable insights on the physical conditions of the region where powerful molecular outflows interact with the material from the parental cloud. Observations of different water maser lines need to be used to constrain the physical conditions in the masing region and they constitute excellent tools to study common phenomena associated with the star formation process at sub-arcsecond resolution, if observed with interferometers like ALMA. In this poster we present the results of a survey searching for submillimeter water maser transitions at 321 and 325 GHz complemented with ALMA data at 183 GHz on a sample of young stellar objects spanning a wide range of masses, from high to low-mass.