Examinando por Autor "Artale, M. Celeste"

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    Anisotropic correlation functions as tracers of central galaxy alignments in simulations
    (Oxford University Press, 2023-06) Rodriguez, Facundo; Merchán, Manuel; Artale, M. Celeste; Andrews, Moira
    Motivated by observational results, we use IllustrisTNG hydrodynamical numerical simulations to study the alignment of the central galaxies in groups with the surrounding structures. This approach allows us to analyse galaxy and group properties not available in observations. To perform this analysis, we use a modified version of the two-point cross-correlation function and a measure of the angle between the semimajor axes of the central galaxies and the larger structures. Overall, our results reproduce observational ones, as we find large-scale anisotropy, which is dominated by the red central galaxies. In addition, the latter is noticeably more aligned with their group than the blue ones. In contrast to the observations, we find a strong dependence of the anisotropy on the central galaxy with mass, probably associated with the inability of observational methods to determine them. This result allows us to link the alignment to the process of halo assembly and the well-known dependence of halo anisotropy on mass. When we include the dark matter distribution in our analysis, we conclude that the galaxy alignment found in simulations (and observations) can be explained by a combination of physical processes at different scales: the central galaxy aligns with the dark matter halo it inhabits, and this, in turn, aligns with the surrounding structures at large scales.
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    Binary neutron star populations in the Milky Way
    (Oxford University Press, 2023-09-01) Sgalletta, Cecilia; Iorio, Giuliano; Mapelli, Michela; Artale, M. Celeste; Boco, Lumen; Chattopadhyay, Debatri; Lapi, Andrea; Possenti, Andrea; Rinaldi, Stefano; Spera, Mario
    Galactic binary neutron stars (BNSs) are a unique laboratory to probe the evolution of BNSs and their progenitors. Here, we use a new version of the population synthesis code sevn to evolve the population of Galactic BNSs, by modelling the spin up and down of pulsars self-consistently. We analyse the merger rate, orbital period Porb, eccentricity e, spin period P, and spin period derivative of the BNS population. Values of the common envelope parameter α = 1-3 and an accurate model of the Milky Way star formation history best reproduce the BNS merger rate in our Galaxy (Myr-1). We apply radio-selection effects to our simulated BNSs and compare them to the observed population. Using a Dirichlet process Gaussian mixture method, we evaluate the four-dimensional likelihood in the space, by comparing our radio-selected simulated pulsars against Galactic BNSs. Our analysis favours an uniform initial distribution for both the magnetic field (1010-13 G) and the spin period (10-100 ms). The implementation of radio selection effects is critical to match not only the spin period and period derivative, but also the orbital period and eccentricity of Galactic BNSs. According to our fiducial model, the Square Kilometre Array will detect ∼20 new BNSs in the Milky Way.