Browsing by Author "Bignone, Lucas"

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    Planes of Satellites around Simulated Disk Galaxies. II. Time-persistent Planes of Kinematically Coherent Satellites in ?CDM
    (2023) Santos-Santos, Isabel; Gamez-Marin, Matias; Dominguez-Tenreiro, Rosa; Tissera, Patricia B.; Bignone, Lucas; Pedrosa, Susana E.; Artal, Hector; Gomez-Flechoso, M. Angeles; Rufo-Pastor, Victor; Martinez-Serrano, Francisco; Serna, Arturo
    We use two zoom-in ?CDM hydrodynamical simulations of massive disk galaxies to study the possible existence of fixed satellite groups showing a kinematically coherent behavior across evolution (angular momentum conservation and clustering). We identify three such groups in the two simulations, defining kinematically coherent persistent planes (KPPs) that last at least from virialization to z = 0 (more than 7 Gyr). This proves that orbital pole clustering is not necessarily set in at low redshift, representing a long-lived property of galaxy systems. KPPs are thin and oblate, represent similar to 25%-40% of the total number of satellites in the system, and are roughly perpendicular to their corresponding central disk galaxies during certain periods, consistently with Milky Way z = 0 data. KPP satellite members are statistically distinguishable from satellites outside KPPs: they show higher specific orbital angular momenta, orbit more perpendicularly to the central disk galaxy, and have larger pericentric distances than the latter. We numerically prove, for the first time, that KPPs and the best-quality positional planes share the same space configuration across time, such that KPPs act as "skeletons" preventing the latter from being washed out in short timescales. In one of the satellite-host systems, we witness the late capture of a massive dwarf galaxy endowed with its own satellite system, also organized into a KPP configuration prior to its capture. We briefly explore the consequences this event has on the host's KPP and on the possible enhancement of the asymmetry in the number of satellites rotating in one sense or the opposite within the KPP.
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    The evolution of the oxygen abundance gradients in star-forming galaxies in the EAGLE simulations
    (2022) Tissera, Patricia B.; Rosas-Guevara, Yetli; Sillero, Emanuel; Pedrosa, Susana E.; Theuns, Tom; Bignone, Lucas
    We analyse the evolution of the oxygen abundance gradient of star-forming galaxies with stellar mass M-* >= 10(9)M(circle dot) in the EAGLE simulation over the redshift range z = [0, 2.5]. We find that the median metallicity gradient of the simulated galaxies is close to zero at all z, whereas the scatter around the median increases with z. The metallicity gradients of individual galaxies can evolve from strong to weak and vice versa, since mostly low-metallicity gas accretes on to the galaxy, resulting in enhanced star formation and ejection of metal-enriched gas by energy feedback. Such episodes of enhanced accretion, mainly dominated by major mergers, are more common at higher z and hence contribute to increasing the diversity of gradients. For galaxies with negative metallicity gradients, we find a redshift evolution of similar to -0.03 dex kpc(-1)/delta z. A positive mass dependence is found at z <= 0.5, which becomes slightly stronger for higher redshifts and, mainly, for M-* < 10(9.)(5) M-circle dot. Only galaxies with negative metallicity gradients define a correlation with galaxy size, consistent with an inside-out formation scenario. Our findings suggest that major mergers and/or significant gas accretion can drive strong negative or positive metallicity gradients. The first ones are preferentially associated with disc-dominated galaxies, and the second ones with dispersion-dominated systems. The comparison with forthcoming observations at high redshift will allow a better understanding of the potential role of metallicity gradients as a chemical probe of galaxy formation.