Examinando por Autor "Pellizza, L.J."

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    Redshift evolution of the dark matter haloes shapes
    (Oxford University Press, 2023-08-01) Cataldi, P.; Pedrosa, S.E.; Tissera, P.B.; Artale, M.C.; Padilla, N.D.; Dominguez-Tenreiro, R.; Bignone, L.; Gonzalez, R.; Pellizza, L.J.
    In this work, we aim at investigating the morphology evolution of Milky Way mass-like dark matter haloes selected from the CIELO and ILLUSTRISTNG projects. The connection between halo shapes and their environment has been studied in previous works at z = 0 but their connection remains yet to be fully understood. We focus on the evolution across cosmic time of the halo shapes and the relation with the infalling material, using hydrodynamical simulations. Our findings show that haloes tend to be more triaxial at earlier times as a consequence of stronger accretion in the direction of the filaments. As the haloes evolve towards a dominant isotropic accretion mode and relaxation, their shape at 20 per cent of the virial radius becomes more spherical. In agreement with previous results, baryons have an important effect within the inner regions of the haloes, driving them from triaxial to rounder shapes. We also find a correlation between the strength of the quadrupole infalling mode and the degree of ellipticity of the haloes: as the filament strength decreases steadily with redshift, the haloes became more spherical and less elliptical. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
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    Stellar feedback from high-mass X-ray binaries in cosmological hydrodynamical simulations
    (Artale, M.C., 2015-04) Artale, M.C.; Tissera, P.B.; Pellizza, L.J.
    We explored the role of X-ray binaries composed by a black hole and a massive stellar companion [black hole X-ray binaries (BHXs)] as sources of kinetic feedback by using hydrodynamical cosmological simulations. Following previous results, our BHX model selects metal-poor stars (Z = [0, 10-4]) as possible progenitors. The model that better reproduces observations assumes that an ~20 per cent fraction of low-metallicity black holes are in binary systems which produces BHXs. These sources are estimated to deposit ~1052 erg of kinetic energy per event. With these parameters and in the simulated volume, we find that the energy injected by BHXs represents ~30 per cent of the total energy released by Type II supernova and BHX events at redshift z ~ 7 and then decreases rapidly as baryons get chemically enriched. Haloes with virial masses smaller than ~1010M{bull's eye} (or Tvir ≤105 K) are the most directly affected ones by BHX feedback. These haloes host galaxies with stellar masses in the range 107-108 M{bull's eye}. Our results show that BHX feedback is able to keep the interstellar medium warm, without removing a significant gas fraction, in agreement with previous analytical calculations. Consequently, the stellar-to-dark matter mass ratio is better reproduced at high redshift. Our model also predicts a stronger evolution of the number of galaxies as a function of the stellar mass with redshift when BHX feedback is considered. These findings support previous claims that the BHXs could be an effective source of feedback in early stages of galaxy evolution. © 2015 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.