Browsing by Author "Pedrosa, Susana E."
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- ItemMilky Way-like galaxies: stellar population properties of dynamically defined discs, bulges and stellar haloes(2022) Ortega-Martinez, Sara; Obreja, Aura; Dominguez-Tenreiro, Rosa; Pedrosa, Susana E.; Rosas-Guevara, Yetli; Tissera, Patricia B.The formation of galaxies can be understood in terms of the assembly patterns of each type of galactic component. To perform this kind of analysis, it is necessary to define some criteria to separate those components. Decomposition methods based on dynamical properties are more physically motivated than photometry-based ones. We use the unsupervised Gaussian Mixture model of galactic structure finder to extract the components of a sub-sample of galaxies with Milky Way-like masses from the eagle simulations. A clustering in the space of first- and second-order dynamical moments of all identified substructures reveals five types of galaxy components: thin and thick discs, stellar haloes, bulges and spheroids. We analyse the dynamical, morphological and stellar population (SP) properties of these five component types, exploring to what extent these properties correlate with each other, and how much they depend on the total galaxy stellar and dark matter halo masses. All galaxies contain a bulge, a stellar halo and a disc. In total, 60 per cent of objects host two discs (thin and thick), and 68 per cent host also a spheroid. The dynamical disc-to-total ratio does not depend on stellar mass, but the median rotational velocities of the two discs do. Thin discs are well separated in stellar ages, [Fe/H] and alpha-enhancement from the three dispersion-dominated components, while thick discs are in between. Except for thin discs, all components show correlations among their SP properties: older ages mean lower metallicities and larger alpha-enhancement. Finally, we quantify the weak dependence of SP properties on each component's dynamics.
- ItemPlanes 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, ArturoWe 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.
- ItemThe 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, LucasWe 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.
- ItemThe Origin of Kinematically Persistent Planes of Satellites as Driven by the Early Evolution of the Cosmic Web in ΛCDM(2024) Gamez-Marin, Matias; Santos-Santos, Isabel; Dominguez-Tenreiro, Rosa; Pedrosa, Susana E.; Tissera, Patricia B.; Gomez-Flechoso, M. Angeles; Artal, HectorKinematically persistent planes (KPPs) of satellites are fixed sets of satellites co-orbiting around their host galaxy, whose orbital poles are conserved and clustered across long cosmic time intervals. They play the role of "skeletons," ensuring the long-term durability of positional planes. We explore the physical processes behind their formation in terms of the dynamics of the local cosmic web (CW), characterized via the so-called Lagrangian volumes (LVs) built up around two zoom-in, cosmological hydro-simulations of Milky Way-mass disk galaxy + satellites systems, where three KPPs have been identified. By analyzing the LV deformations in terms of the reduced tensor of inertia (TOI), we find an outstanding alignment between the LV principal directions and the KPP satellites' orbital poles. The most compressive local mass flows (along the e 3 eigenvector) are strong at early times, feeding the so-called e 3 -structure, while the smallest TOI axis rapidly decreases. The e 3 -structure collapse marks the end of this regime and is the timescale for the establishment of satellite orbital pole clustering when the Universe is less than or similar to 4 Gyr old. KPP protosatellites aligned with e 3 are those whose orbital poles are either aligned from early times or have been successfully bent at e 3 -structure collapse. KPP satellites associated with e 1 tend to have early trajectories already parallel to e 3 . We show that KPPs can arise as a result of the Lambda CDM-predicted large-scale dynamics acting on particular sets of protosatellites, the same dynamics that shape the local CW environment.
- ItemThe stellar metallicity gradients in galaxy discs in a cosmological scenario(2016) Tissera, Patricia; Machado, Rubens E. G.; Sánchez Blazquez, Patricia; Pedrosa, Susana E.; Sánchez, Sebastián F.; Snaith, Owain N.; Vilchez, José N.