arXiv subjects

M. S. Rosito

Publications and source records attributed to M. S. Rosito.

4 recordsLinked to original sources

arXiv2022

On the application of dimensionality reduction and clustering algorithms for the classification of kinematic morphologies of galaxies

The morphological classification of galaxies is considered a relevant issue and can be approached from different points of view. The increasing growth in the size and accuracy of astronomical data sets brings with it the need for the use of automatic methods to perform these classifications. The aim of this work is to propose and evaluate a method for automatic unsupervised classification of kinematic morphologies of galaxies that yields a meaningful clustering and captures the variations of the fundamental properties of galaxies. We obtain kinematic maps for a sample of 2064 galaxies from the largest simulation of the EAGLE project that mimics integral field spectroscopy (IFS) images. These maps are the input of a dimensionality reduction algorithm followed by a clustering algorithm. We analyse the variation of physical and observational parameters among the clusters obtained from the application of this procedure to different inputs. The inputs studied in this paper are (a) line-of-sight velocity maps for the whole sample of galaxies observed at fixed inclinations, (b) line-of-sight velocity, dispersion, and flux maps together for the whole sample of galaxies observed at fixed inclinations, (c) line-of-sight velocity, dispersion, and flux maps together for two separate subsamples of edge-on galaxies with similar amount of rotation, and (d) line-of-sight velocity, dispersion, and flux maps together for galaxies from different observation angles mixed. The application of the method to solely line-of-sight velocity maps achieves a clear division between slow rotators (SRs) and fast rotators (FRs) and can differentiate rotation orientation. By adding the dispersion and flux information at the input, low rotation edge-on galaxies are separated according to their shapes. Abridged.

astro-ph.GA↗

arXiv2021

The role of AGN on the structure, kinematics and evolution of ETGs in the Horizon simulations

Feedback processes play a fundamental role in the regulation of the star formation (SF) activity in galaxies and, in particular, in the quenching of early-type galaxies (ETGs) as has been inferred by observational and numerical studies of Lambda CDM models. At z = 0, ETGs exhibit well-known fundamental scaling relations, but the connection between them and the physical processes shaping ETG evolution remains unknown.This work aims at studying the impact of the energetic feedback due to active galactic nuclei (AGN) on the formation and evolution of ETGs.We focus on assessing the impact of AGN feedback on the evolution of the mass-plane and the fundamental plane (FP, defined by using mass surface density) as well as on morphology, kinematics, and stellar age across the FP.The Horizon-AGN and Horizon-noAGN cosmological hydrodynamical simulations were performed with identical initial conditions and including the same physical processes except for the activation of the AGN feedback in the former. We select a sample of central ETGs from both simulations using the same criteria and exhaustively study their SF activity, kinematics, and scaling relations for z <= 3. We find that Horizon-AGN ETGs identified at z = 0 follow the observed fundamental scaling relations (mass-plane, FP, mass-size relation) and qualitatively reproduce kinematic features albeit conserving a rotational inner component with a mass fraction regulated by the AGN feedback. AGN feedback seems to be required to reproduce the bimodality in the spin parameter distribution reported by observational works and the mass-size relation (with more massive galaxies having older stellar populations (SPs), larger sizes, and being slower rotators). We study the evolution of the fundamental relations with redshift, finding .Abridged

astro-ph.GA↗

arXiv2019

The assembly of spheroid-dominated galaxies in the EAGLE simulation

Despite the insights gained in the last few years, our knowledge about the formation and evolution scenario for the spheroid-dominated galaxies is still incomplete. New and more powerful cosmological simulations have been developed that together with more precise observations open the possibility of more detailed study of the formation of early-type galaxies (ETGs). The aim of this work is to analyse the assembly histories of ETGs in a $Λ$-CDM cosmology, focussing on the archeological approach given by the mass-growth histories.We inspected a sample of dispersion-dominated galaxies selected from the largest volume simulation of the EAGLE project. This simulation includes a variety of physical processes such as radiative cooling, star formation (SF), metal enrichment, and stellar and active galactic nucleus (AGN) feedback. The selected sample comprised 508 spheroid-dominated galaxies classified according to their dynamical properties. Their surface brightness profile, the fundamental relations, kinematic properties, and stellar-mass growth histories are estimated and analysed. The findings are confronted with recent observations.The simulated ETGs are found to globally reproduce the fundamental relations of ellipticals. All of them have an inner disc component where residual younger stellar populations (SPs) are detected. A fraction of this inner-disc correlates with bulge-to-total ratio. We find a relation between kinematics and shape that implies that dispersion-dominated galaxies with low $V/σ_L$ (where $V$ is the average rotational velocity and $σ_L$ the one dimensional velocity dispersion) tend to have ellipticity smaller than $\sim 0.5$ and are dominated by old stars. Abridged

astro-ph.GA↗

arXiv2018

Field spheroid-dominated galaxies in a Λ-CDM Universe

Understanding the formation and evolution of early-type, spheroid-dominated galaxies is an open question within the context of the hierarchical clustering scenario, particularly, in low-density environments. Our goal is to study the main structural, dynamical, and stellar population properties and assembly histories of field spheroid-dominated galaxies formed in a LCDM scenario to assess to what extend they are consistent with observations. We selected spheroid-dominated systems from a LCDM simulation that includes star formation, chemical evolution and Supernova feedback. A sample of 18 field systems with Mstar <= 6x10^10 Msun that are dominated by the spheroid component. For this sample we estimate the fundamental relations of ellipticals and then compared with current observations. The simulated spheroid galaxies have sizes in good agreement with observations. The bulges follow a Sersic law with Sersic indexes that correlate with the bulge-to-total mass ratios. The structural-dynamical properties of the simulated galaxies are consistent with observed Faber-Jackson, Fundamental Plane, and Tully-Fisher relations. However, the simulated galaxies are bluer and with higher star formation rates than observed isolated early-type galaxies. The archaeological mass growth histories show a slightly delayed formation and more prominent inside-out growth mode than observational inferences based on the fossil record method. The main structural and dynamical properties of the simulated spheroid-dominated galaxies are consistent with observations. This is remarkable since none of them has been tuned to be reproduced. However, the simulated galaxies are blue and star-forming, and with later stellar mass growth histories as compared to observational inferences. This is mainly due to the persistence of extended discs in the simulations. Abridged

astro-ph.GA↗