Resumen:

Galaxy evolution and star formation are tightly intertwined. However, star formation is a local process, acting on single H II regions and molecular clouds ($\sim$ 10 pc); how it can have affect galactic properties on kcp scales and drive their evolution is still one of the key open questions in astronomy. Multiwavelength observations of galaxies that can resolve the key actors in the star formation process (e.g. molecular clouds, star-forming regions, young clusters) while keeping the view of galaxies as a whole are key to understand the interplay between such small scale process and its large scale effects. In this talk, I will present a new MUSE survey of the closest starburst galaxy to the Milky Way: NGC 253. The survey covers a total area of 20$\times$5 arcmin$^2$ (20$\times$5 kpc$^2$ at the distance of the galaxy, 3.5 Mpc) at a resolution of $\sim$15 pc, giving us a detailed view of the galactic interstellar medium that is only second to what is possible in the Milky Way and a handful of other extremely nearby objects. At the same time, the external point of view allowed us to cover the entire extension of the star-forming disk. Preliminary results show that the mosaic, which is the largest contiguous mosaic ever observed by MUSE so far, includes $\sim$6500 ionized nebulae that will be instrumental to investigate topics, among others, like the ionization and temperature structure of HII regions, the small and large scale effects of stellar feedback, and the local and galactic scale matter cycle.

Resumen:

The recent infall of the Large Magellanic Cloud (LMC) onto the Milky Way provides us a unique opportunity to observe dynamical friction in action and trace large scale dark matter halo (DM) distortions in the Galaxy through observations of the stellar halo. The DM halo wake induced by the LMC's infall is thought to extend between 50 kpc all the way to the virial radius, a region still poorly explored due to the paucity of tracers at large distances. Currently, all predictions of the Milky Way's DM halo wake have relied on the poor/simplifying assumption of a smooth stellar halo, which is clearly broken beyond 30 kpc where the stellar halo is primarily constituted of substructure and non-phase mixed stellar debris. Any hope of detecting the global DM halo wake of the MW thus relies on a careful identification of known stellar debris beyond 50 kpc and models taking into account the non-smooth nature of galactic stellar halos. In this contribution, I present the first predictions of the response of a statistical sample of Galactic stellar halos formed through hierarchical accretions reacting to the DM halo wake induced by the LMC on a first infall. I will present full-sky maps in kinematic, density space of the stellar halo in the presence/absence of the LMC and how these can be used to probe large-scale DM halo distortions. Furthermore, I will show that the LMC induces remarkably pronounced isophotal twisting of the entire Galactic stellar halo in the orbital plane of the LMC, tracing the global DM halo wake, a signature awaiting detection with LSST and EUCLID. Finally, I will present a recent fully probabilistic analysis of the stellar halo using BHBs in DECaLS which successfully discerns the local wake behind the LMC but with no conclusive signs of a global wake.

Resumen:

Stellar streams play in dynamics a similar role as stellar clusters do in stellar evolution: they are relatively simple systems of stars whose common properties allow rewinding evolutionary or dynamical processes much harder to disentangle in the Galactic field. Formed as stars are stripped from a dwarf galaxy or globular cluster by the Milky Way’s tidal forces, stellar streams are fossil records of accretion that are best preserved in the halo, where streams are long lived. Unearthing this record is essential to reconstructing the Galaxy’s accretion history, and modeling its dynamics is key to constrain the distribution of dark matter at the scales of the Galaxy and its satellites. In this contribution I will showcase the latest version of the galstreams library, a compilation that collates information scattered across the literature for nearly a hundred stellar streams known in the Milky Way, and use it to provide an ensemble view of the Galactic system of stellar streams’s properties, its current observational biases, and results inspired by recent discoveries made possible by the Gaia mission.

Resumen:

Currently it is known that galaxies like ours have formed gradually, progressively assimilating smaller galaxies. These accretion events have left fossil records that can be discovered by studying the most ancient populations such as the Galactic halo.\\ An important part of this fossil record are the globular clusters and stellar streams present in the halo. Studies have revealed that a large number of globular clusters fell into the Milky Way along with their respective host galaxies. But, these are only the “surviving” clusters. During the accretion process, clusters and dwarf galaxies can be disrupted in the halo thanks to tidal forces, generating stellar streams. Almost one hundred streams are known in the Galaxy today, most of them produced by globular clusters.\\ Our general aim is to search for RR Lyrae associated to all known stellar streams. The RR Lyrae are horizontal branch pulsating stars known for being standard candles, in this way we can obtain precise distances of the stars being able to determine the distance gradient of the stellar stream. This will be needed to determine its dynamic properties.\\ In a first exploration for the Pal5 stellar stream 10 RR Lyrae were found in the cluster and 17 in the tails; in the M68-Fjorm stream the opposite is found, while there are over 40 RR Lyrae in the cluster, only less than a handful are found in the tails. Furthermore, in the case of Pal5 the RR Lyrae are segregated: The majority of the RRc (8/12) are in the cluster while the majority of the RRab (13/15) are in the tails. In this talk we will present the first results of a systematic census of RR Lyrae in the cluster vs. the tails of the streams with an associated cluster.

Resumen:

The Nuclear Bulge is a unique region of the Milky Way, located in the innermost ~220 pc of our Galaxy. Here, both gas structures -i.e. Central Molecular Zone, CMZ- and stellar components -i.e. Nuclear Stellar Disc, NSD- coexist. While the CMZ has been extensively studied in radio/sub-mm, the NSD lacks comprehensive observational studies. This is due to a combination of severe extinction and crowding when observing stars. In this context, Red Clump stars (RC) studies in near infrared (NIR) are the ideal structure tracers. In this talk, I will review the importance of the Nuclear Bulge for the entire Galaxy, and present the HAWK-I@VLT deep NIR high-quality photometry study of RC stars. Given the degeneracy of distance and extinction, we employ the shape of the RC to constrain the line-of-sight (LOS) distribution and the extinction law simultaneously. We obtained a set of feasible extinction laws in this particular region, along with different LOS distributions of RC stars. These results are key for further computation of the star formation history of the Nuclear Bulge, and to improve our understanding of the interaction of all structures lying here.

Resumen:

Gravitational interactions between the Large Magellanic Cloud (LMC) and the outer halo of the Milky Way are expected to generate a large-scale asymmetry that spans the northern Galactic hemisphere (collective response), along with a localized wake that trails the LMC's orbit. These predicted phenomena present opportunities to gain insights into the Milky Way's mass and the distribution of dark matter within its outer halo. A previous study using Gaia Early Data Release 3 and WISE surveys reported the detection of both the collective response and the wake. However, the low number statistics of the wake detection hampered an in-depth characterization of the densities involved. In our study, we leverage deep near-infrared and optical photometry from the VISTA and DECam instruments allowing for a clean sample of halo stars that reach the oldest main sequence turnoffs at 100 kpc. Preliminary results using near-main sequence turn-off photometric distances show that the Magellanic Wake is present in our data with enough stars in the outer halo (~ 600 sources further than 60 kpc) for the detection to be considered statistically significant. This research provides us with the required data to characterize the density and position of the wake which will provide a point of comparison and constraints to simulations.