Resumen:

Our current understanding is that dark matter (DM) accounts for 85\% of the total matter in the Universe. However, its presence, thus far, is only manifested through gravitational effects, where one of its strongest evidence can be observed from the rotation curves (RCs) of disk galaxies. Despite great efforts devoted to the direct and indirect detection of DM, its nature still eludes us. Realistic models of the spatial distribution of DM within galaxies are still scarce and estimating the local DM density (i.e., at $\sim$8~kpc from the Galaxy’s centre) remains a challenge, as currently these estimates rely on significant assumptions regarding the Milky-Way's DM halo. Motivated in understanding the spatial distribution of DM in galaxies like our own, we have undertaken the detailed mapping of DM in a sample of MW analogs. Our sample is derived from the combination of the following surveys: S$^4$G (mid-IR), and both VIVA and THINGS (radio). The mid-IR imaging provided by S$^4$G is the best single-band tracer of stellar mass. The data cubes from VIVA and THINGS allow us to use the dynamics of atomic hydrogen (HI) as a means to isolate and map the DM distribution. The final sample comprises 7 galaxies, selected based on the maximum HI velocity ($v_{max}$=200--280~km~s$^{-1}$) and morphological type (Sab--Sbc) in order to target systems resembling the MW. We construct RCs for the sample using $^{3D}$Barolo, a dynamical three-dimensional modelling software. By using a MCMC-based approach, we develop an analytical model to decompose the RCs into their different components (stars, gas, and DM), enabling us to construct DM radial profiles of our sample. By employing this independent and innovative approach, we obtain a new window of values for the local DM density ($\rho$~=~0.24-0.39~GeV~cm$^{-1}$) that provides tighter constraints but is still consistent with more traditional approaches found in the literature.

Resumen:

The Milky Way (MW) is the cornerstone of our understanding of disk galaxy formation. However, there is growing evidence that the MW’s relatively quiescent formation history sets it apart from its sister galaxy, Andromeda (M31). At the nexus of near- and far-field galaxy evolution, M31 provides an exquisite opportunity to expand our knowledge of hierarchical galaxy assembly and galactic chemodynamics. Outstanding questions remain concerning M31's structural assembly: has its disk survived a major merger within the last few billion years, and does this merger coincide with the formation of its Giant Stellar Stream? In this talk, I will present novel results on the nature of M31's inner stellar halo and disk based on data from the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) and Panchromatic Hubble Andromeda Treasury (PHAT) surveys. With measurements for over 3500 individual red giant branch stars, this represents the first large-scale chemodynamical analysis of M31's inner disk region. I will discuss evidence in favor of (1) an inextricable connection between the formation of M31's inner stellar halo and disk, (2) distinct channels driving the formation of the stellar halo along the major versus minor axes, and (3) a uniformly thick structure for the disk.

Resumen:

We analyze the orbital structure on three different stellar disk N-body models embedded in a live dark matter halo. During the models evolution, disks naturally form a bar that buckles out of the galactic plane at different ages of the galaxy evolution generating boxy, X, peanut and/or elongated shapes. We evaluate the orbital evolution using the frequencies analysis on phase space coordinates for all disk particles at different time intervals. We analyze the face-on, edge-on, and end-on views morphology of the 2:1 family which is populated in our models as the bar potential evolves. The disk-dominated model develops an internal boxy structure after the first Gyr of the model evolution. Afterwards, the outer part of the disk evolves to a peanut shape which lasts till the end of the simulation. The intermediary model develops the boxy structure only after 2 Gyr of evolution. The peanut shape appears around 2 Gyr later and evolve slowly. The halo-dominated model develops the boxy structure much later, around 3 Gyr and the peanut morphology is just incipient at the end of the simulation (7 Gyr).

Resumen:

Galaxies are complex stellar systems formed by several overlapping stellar components (bulge, disk, bar, etc.) whose formation and evolution process is inherently related to the individual processes undergone by each of them. We study the properties of discs and spheroids by applying two dynamical decomposition methods to a sample of galaxies with stellar masses $> 10^{10} M_\odot$ identified in the EAGLE and IllustrisTNG cosmological numerical simulations. In agreement with observational results, we find that the stellar mass fraction in the spheroidal component fsph increases systematically with galaxy stellar mass $M_*$ from fractions of $50\%$ for galaxies of $M_* \sim 10^{10} M_\odot$ to $90\%$ for $M_* \sim 10^{12} M_\odot$, although with a fair amount of scatter. For galaxies with stellar masses similar to that of the Milky Way ($M_* \sim 10^{10.6} M_\odot$) and applying isolation criteria we find $f_{sph} \sim 0.2$ at best which is only slightly higher than the lowest values estimated observationally for local galaxies $f_{sph} \sim 0.15$. This would indicate that the cosmological volume simulations are capable of reproducing a population of disk galaxies comparable to those observed. In addition, we perform the extension and analysis of the scaling relations between mass, specific angular momentum and characteristic velocity of disks and spheroids and how they compare with those of full galaxies and those obtained observationally, such as the Tully-Fisher and Faber-Jackson relations. In addition, the dimensionless spin parameter of the halo and the stellar components are analyzed, finding that there seems to be no correlation between them. These results show how closely the formation and evolution history of the galaxy is linked to that of each of its components.

Resumen:

In this work, we analyze the dynamics of galaxy populations in clusters in order to study the impact of the orbital profile on galaxy evolution. Using an ensemble cluster composed of 10,974 galaxies belonging to 143 clusters with line-of-sight gaussian velocity distributions, we obtain the spatial and velocity distributions for four classes of galaxies separated with respect to the main ionizing source of the gas, namely star-forming (SF), transition (T), quiescent (Q) and AGN. The MAMPOSSt code was used to get the mass profile of the ensemble cluster and the velocity anisotropy profile $\beta(r)$ of the galaxy populations. We also perform an inversion of the Jeans equations to obtain the $\beta(r)$ profile, using the mass profile from MAMPOSSt, in a non-parametric way. We find that all populations show similar anisotropy profiles, with more isotropic orbits near the center and increasingly radial orbits with the projected radial distance. Among the galaxy populations, the Q population exhibits the smallest spatial scattering and the lowest velocity dispersions, with the latter being well recovered by the $\beta(r)$ profile from MAMPOSSt. In contrast, SF galaxies, followed by those in the T population, display the highest spatial scatterings and velocity dispersions. While MAMPOSSt could not provide equilibrium solutions for the SF population that reproduce the line-of-sight velocity dispersion profile, a good agreement was obtained for the T class. AGN host galaxies show similar dispersions to those of the T population, but they are found closer to the central region. Equilibrium solutions were obtained for the AGN population, but with higher uncertainties. Our results suggest that environmental mechanisms affect infalling SF galaxies, transforming them into a quiescent population as they thermalize in their parent cluster. In this scenario, the T population can be interpreted as a more virialized SF population with AGN activity induced by the environment.

Resumen:

Some highly inclined ($i\geq80^{\circ}$) late-type galaxies with high star formation rates (SFR) exhibit an extraplanar diffuse ionized gas (eDIG) component, which often extends several kiloparsecs above the galactic disc. Studying the kinematic effects of the eDIG is crucial to understand its interaction with galactic properties. Although several studies using data from integral field units (IFU) spectroscopy have been made, there is currently no conclusive common result on the origin of the eDIG. We selected 14 nearby highly inclined late-type galaxies from the Catalogue of Isolated Galaxies (CIG) to investigate the environmental influences on the eDIG incidence. This sample aims to serve as a baseline for comparison with interacting galaxies, providing insights into the formation and properties of eDIG. We present the H$\alpha$ monochromatic, radial velocity and velocity dispersion maps of galaxies in our sample obtained from observations made with scanning Fabry-Perot (FP) interferometry. To highlight the stellar disc structure, we compare our FP data with near-infrared (NIR) and ultraviolet (UV) images available in the literature. We also compute the H$\alpha$ rotation curves of galaxies in our sample, and we analyse the rotation of the extraplanar component. Preliminary results show that in isolated galaxies the amplitude of the rotational lagging increases with their intrinsic SFR.

Resumen:

Associations of dwarf galaxies are extended systems composed exclusively of dwarf galaxies, which were identified in the Local Volume for the first time more than thirty years ago. We identify these particular systems using a semi-analytical model of galaxy formation coupled to a dark matter only simulation in the $\Lambda$ Cold Dark Matter cosmological model. Our systems have typical sizes of $\sim 0.2\,{\rm Mpc}\,h^{-1}$ and velocity dispersion of $\sim 30 {\rm km\,s^{-1}}$ in good agreement with observationally detected dwarf galaxy associations. Such large typical sizes suggest that individual members of a given dwarf association reside in different dark matter haloes. Furthermore, associations located in more dense environments present significantly higher velocity dispersion than those located in less dense environments, evidencing that the environment plays a fundamental role in their dynamical properties. However, this connection between velocity dispersion and the environment depends exclusively on whether the systems are gravitational bound or unbound. Although less than a dozen observationally detected associations of dwarf galaxies are currently known, our results are predictions on the eve of forthcoming large surveys of galaxies, which will enable the identification and study of these very particular systems.