Resumen:

At high redshifts, when intermediate to massive galaxies were gas-rich and formed stars at high rates, most of them were probably in a regime of strong dust-obscured star formation (SF); they were dusty-star forming galaxies. How did these galaxies subsequently evolve as a function of mass and environment? Which galaxies underwent SF quenching and morphological transformation? And how did the dust-obscured SF fraction of those galaxies that remained as disk-dominated change with mass and time? We study these questions using EMPIRE, a sophisticated semi-empirical model for the evolution of the galaxy-halo connection within LCDM cosmology, and also using a statistical approach that combines the observed FUV and IR rest-frame luminosity functions with the galaxy stellar mass functions (GSMFs) at different redshifts. We find that 1) there is no inconsistency between the observed evolution of the FUV/IR LFs and the evolution of the SFR-$M_*$ relation and the GSMF of SF main sequence galaxies; 2)  the dust-obscured SF fraction strongly increases with mass, while at $z\lesssim0.75$ massive galaxies become more transparent; and 3) the SF quenching is related to the increase in the inner stellar surface density. Finally, with our model we generate light cones in the sky and predict the number counts of submillimeter galaxies to compare with the results of deep FIR/submillimeter extragalactic surveys such as the forthcoming TolTEC-LMT survey.

Resumen:

In dense regions like clusters, groups, and filaments, galaxies may experience a process called ram-pressure stripping (RPS). This occurs when the surrounding gas exerts pressure on the galaxy's interstellar material (ISM), causing it to be stripped away. The most extreme cases of RPS result in "jellyfish galaxies," where the stripped material forms asymmetric tentacle-like structures, giving rise to multiple star-forming regions. RPS plays a crucial role in the theory of galaxy formation and evolution, as it is considered one of the main mechanisms leading to the suppression of star formation in galaxies within dense regions. This happens because RPS removes a significant portion of their gas reservoir. However, interestingly, jellyfish galaxies tend to exhibit higher star formation rates (SFR) compared to other star-forming galaxies in the same environments. This suggests that RPS actually triggers star formation in these galaxies. In our study, we aim to identify potential jellyfish galaxies in the Deep fields of HSC (ELAIS-N1, COSMOS, XMM-LSS, and Deep2-3) using a combination of Hyper Supreme-CAM (HSC) photometry and Dark Energy Spectroscopic Instrument (DESI) spectrometry. The candidates are visually selected at a redshift of z~0.24, making use of the 5 broad band filters of HSC and the narrow band NB0816, which captures the $H\alpha$+[NII] lines. The $H\alpha$ emission is particularly useful for highlighting jellyfish features due to their high star formation activity. By employing specific combinations of HSC filters, we can better observe the morphology of these objects and also measure various properties such as colors, spectral emission-line fluxes, ionizing source diagrams, and spectral energy distribution (SED) fitting. In this presentation, we will present our methodology and show our first results for 4 clusters in the ELAIS-N1 field.

Resumen:

Galaxies can be classified according to their star formation activity as either star forming or quiescent. Star forming galaxies are rich in gas and vigorously form new stars. Quiescent galaxies have low star formation activity and old, metal-rich stellar populations. The quiescent galaxies observed at $z \sim 2-3$ are very different from their local counterparts. Particularly, they are extremely compact, with sizes a factor of $\sim 3-5$ smaller than quiescent galaxies at $z \sim 0$. Due to their small sizes and faint stellar continua spectroscopic studies of large samples are extremely challenging with current facilities. As an alternative, massive compact galaxies (MCGs) at low-redshifts can be explored as local analogues. We studied the stellar population properties of a large sample of $1858$ MCGs from the Sloan Digital Sky Survey. To assess if MCGs differ from typical quiescent galaxies in their stellar population properties, we build a control sample of average-sized quiescent (CSGs). Considering that the stellar population properties of quiescent galaxies correlate better with velocity dispersion ($\sigma_e$) than with parameters such as stellar mass, we compare MCGs and CSGs at fixed $\sigma_e$, finding that MCGs are older, have higher [$\alpha$/Fe] and lower metallicities, except for $\sigma_e \gtrsim 230$ km/s where MCGs and CSGs have similar ages. These differences are driven by variations in the stellar mass of galaxies at $\sigma_e$, CSGs are, on average, $ \sim 0.7$ dex more massive than MCGs of similar $\sigma_e$. We argue that the differences in stellar population properties and stellar mass point to MCGs and CSGs descending from different subgroups of the high-redshift quiescent population. Lastly, we found that the metallicity of MCGs shows a dependence on stellar mass at fixed $\sigma_e$, while the age and [$\alpha$/Fe] do not. We suggest that this is a possibly signature of different quenching pathways followed by MCGs.

Resumen:

Galaxy mergers are often mentioned in the literature as ideal places to study diverse starbursts triggered during fusion events. In that sense, the intermediate-age merger remnant NGC 1316, constitutes a perfect merger scenario to study complex large-scale star formation events in the Local Universe. This colossal galaxy, which dominates an important sub-group of the Fornax galaxy cluster, still shows the scars of its violent near past. In a series of previous works, we confirmed the existence of a complex globular cluster system associated with NGC 1316. Using photometric and spectroscopic GEMINI/GMOS data, we found that the globular cluster system is dominated by the presence of an unusual young and metal-rich subpopulation. In addition, several objects in our sample seem to show similarities with some nuclei of early-type dwarf galaxies. Some of these objects could actually be stripped nuclei, possibly accreted during minor merger events. We will present an exhaustive study of the most outstanding stellar systems associated with this galaxy. Indeed, some of them appear to be composed of more than one stellar population. We will show the analysis of its most relevant physical properties and its star formation history, which we have obtained through the full spectral fitting technique. In this new approach, we propose to obtain a more detailed picture of the recent past of this galaxy, and its different fusion events, which have given rise to a complex family of stellar systems.

Resumen:

Dwarf galaxies have a variety of sizes (stellar half-mass radii), at given stellar mass, in the present-day Universe. This suggests different scenarios of evolution according to their final size. In this work, we compare the evolution of compact and normal dwarf galaxies in the Illustris TNG50 cosmological hydrodynamical simulation. We denote \textit{Compact} those dwarf galaxies ($\log (M / M_\odot)$ between 8.3 and 9.3) that end up in the low-size ($r_{1/2} < 450$ pc) branch at $z$=0. We then compare the median evolution of relevant physical parameters and radial profiles to understand the different evolution of the \textit{Compact} population. In TNG50, \textit{Compact} galaxies are rounder at $z=0$ and their current environments are fairly similar. However, at $z \sim 1$, the sizes (half-mass radii of the stellar component) of their most massive progenitors begin to decrease relative to those of normals, while their gas half-mass-radii and stellar masses evolve similarly to those of normal galaxies. This is related to star formation concentrated (suppressed) in the inner (outer) region of the galaxy, which is due to efficient gas infall associated with the lower density environment and fewer interactions for the \textit{Compact} galaxies that otherwise pump angular momentum into normal galaxies. Their low merger rate also leads to lower black hole occupation fractions and mass, and AGN activity, but these effects appear to be secondary compared to the lack of interactions and mergers. In TNG50, the formation of \textit{Compact} galaxies is driven by the lack of mergers and interactions, in contrast with the popular idea of merger-driven compaction at high redshift for more massive compact star-forming galaxies.

Resumen:

Super Massive Clusters (SSCs) are thought to be the progenitors of Globular Clusters (GCs) due to their similar masses and densities. One way to test such a link is via the Cluster Mass Function (CMF), related to the Cluster Luminosity Function (CLF) via the mass-to-light ratio. In particular, the Cluster Initial Mass Function (CIMF) can be established from studies of young clusters (age$\sim$ 1—10 Myr). Several studies have reported a power-law CIMF with an index of 2. However, the GCs CLF has been found to follow a log-normal function. Since, the CLF is a proxy of the CMF, a change from power-law to log-normal is expected to occur due to evolution to support the link between SSCs and GCs. Hence, a large population of SSCs is required to study whether SSCs follow power-law or log-normal functions. The prototype starburst galaxy M82 harbors $\sim$400 almost coeval SSCs (100-300 Myr) in the disk, offering an opportunity to characterize the CIMF of the observed present-day CMF. We carry out the dynamical and photometric evolution of the CMF assuming the clusters move in circular orbits under the gravitational potential of M82 using the semi-analytical simulation code EMACSS. We explore power-law and log-normal functions for the CIMFs and populate the clusters in the disk assuming uniform, power-law, and exponential radial distribution functions. We find that the observed CMF is best produced by a CIMF that is power-law in form with an index of 1.8, for a power-law radial distribution function. We establish that the observed turn-over in the present-day CMF is the result of observational incompleteness rather than due to dynamically induced effects, or an intrinsically log-normal CIMF, as was proposed for the fossil starburst region B of this galaxy. Our simulations naturally reproduce the mass-radius relation observed for a sub-sample of M82 SSCs.