arXiv subjects

Julio E. Rodríguez-Martín

Publications and source records attributed to Julio E. Rodríguez-Martín.

2 recordsLinked to original sources

arXiv2024

The environment as a driver of galaxy evolution with the miniJPAS survey

This thesis aims at discerning the effect of environment on galaxy evolution and on the properties of galaxies, using the data from the miniJPAS survey, a 1~deg$^2$ survey that uses the same photometric filter system as the incoming J-PAS survey, which is already in its scientific verification phase. This system is composed of 56 narrow-band filters that provide an spectral resolution comparable to low-resolution spectroscopy. We study the effect of environment using two approaches. First, we study the spatially resolved galaxies from miniJPAS. Secondly, we studied the galaxy population in the most massive galaxy cluster detected in the miniJPAS footprint, that is, the cluster mJPC2470-1771. We have developed a tool that automatises all the required processes for the analysis of the data. After probing the accuracy and reliability of the photmetry obtained with our tool, we apply it to a miniJPAS sample of spatially resolved galaxies, divided into four sub-samples according to their spectral-type (red/quiescent and blue/star forming), and environment (field or galaxy group). We find that redder, denser regions are usually older, more metal rich, and show lower values of the intensity of the star formation rate and the specific star formation rate than bluer and less dense regions. Regarding the mJPC2470-1771 cluster, our results point that more massive, redder and older galaxies typically populate the inner regions of the cluster. As a conclusion, our results suggest that galaxies in clusters are formed at a similar epoch, but have experienced different star formation histories. We conclude that the environment plays a role on galaxy evolution, but it is mainly reflected through the galaxy populations found in high density environments, such as galaxy clusters and groups, where the fraction of red, quiescent galaxies is larger in comparison to the field.

astro-ph.GA↗

arXiv2020

Study of the low-order $Δν$-${\bar ρ}$ relation for moderately-rotating $δ$ Scuti stars and its impact on their characterisation

The large separation in the low radial order regime is considered as a highly valuable observable to derive mean densities of $δ$ Scuti stars, due to its independence with rotation. Up to now, theoretical studies of this $Δν$-${\bar ρ}$ relation have been limited to 1D non-rotating models, and 2D pseudo-evolutionary models. The present work aims at completing this scenario by investigating quantitatively the impact of rotation in this relation on a large grid of 1D asteroseismic models representative of $δ$ Scuti stars. These include rotation effects on both the stellar evolution and the interaction with pulsation. This allowed us to compute the stellar deformation, get the polar and equatorial radii, and correct the stellar mean densities. We found that the new $Δν$-${\bar ρ}$ relation for rotating models is compatible with previous works. We explained the dispersion of the points around the linear fits as caused mainly by the distribution of the stellar mass, and partially by the evolutionary stage. The new fit is found to be close to the previous theoretical studies for lower masses ($1.3-1.81\,\mathrm{M}_{\odot}$). However, the opposite holds for the observations: for the higher masses ($1.81-3\,\mathrm{M}_{\odot}$) the fit is more compatible with the empirical relation. We applied these results to characterise the two well-known $δ$ Scuti stars observed by CoRoT, HD174936 and HD174966, and compared the physical parameters with those of previous works. Inclusion of rotation in the modelling causes a tendency towards greater masses, radii, luminosities and lower density values. Comparison between $Δν$ and Gaia's luminosities also allowed us to constraint the inclination angles and rotational velocities of both stars. The present results pave the way to systematically constrain the angle of inclination of $δ$ Scuti stars

astro-ph.SR↗