In this work, we study the optical properties of 58 CSS/GPS radio sources selected from the literature in order to determine the impact of the radio-jet in the circumnuclear environment of these objects. We obtained optical spectra for all sources from SDSS-DR12 and performed a stellar population synthesis using the Starlight code. Our results indicate that the sample is dominated by intermediate to old stellar populations and there is no strong correlation between optical and radio properties of these sources.

The inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey in its final year and is mapping out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4″ (0.2 pc) and good image fidelity up to large spatial scales.

We present GASP, an ongoing ESO Large Program with MUSE aiming to study gas removal processes from galaxies at low redshift. GASP targets 100 galaxies with tails, tentacles and one-sided debris. MUSE data allows a detailed investigation of the ionized stripped gas, as well as of the gas and stars within the galaxy out to large distances from the galaxy center. We show the first results for two of the GASP galaxies that are striking cluster jellyfish galaxies of stellar masses ~ 1011M⊙.

How is gas converted into stars across cosmic time? Observations of star-forming galaxies at high redshift indicate that the conditions of the interstellar medium (ISM) were remarkably distinct from typical spirals in the local universe. Nevertheless, these observations are biased towards objects brighter than L*, due to the large luminosity distances involved. Here I present a survey targeting the molecular gas in galaxies at low redshift (z ~ 0.2) with ISM conditions remarkably similar to those observed at earlier epochs, including high star formation rates and lower metallicities. CO observations performed with CARMA indicate that these galaxies follow the same star-formation law as local spirals and other galaxies at the same redshift, albeit at much higher densities. We also present recent results from our ALMA program studying galaxies down to 12 + log(O/H) ~ 8, and discuss the implications of these data to our understanding of the molecular gas reservoir and the conversion factor between CO luminosity and gas mass in environments that are simultaneously low in metal content and extremely dense.

Galaxy nuclei are a unique laboratory to study gas flows. Their high-resolution imaging in galactic nuclei are instrumental in the study of the fueling and feedback of star formation and nuclear activity in nearby galaxies. Several fueling mechanisms can now be confronted in detail with observations done with state-of-the-art interferometers. Furthermore, the study of gas flows in galactic nuclei can probe the feedback of activity on the interstellar medium of galaxies. Feedback action from star formation and AGN activity is invoked to prevent galaxies from becoming overly massive, but also to explain scaling laws like black hole (BH)-bulge mass correlations and the bimodal color distribution of galaxies. This close relationship between galaxies and their central supermassive BH can be described as co-evolution. There is mounting observational evidence for the existence of gas outflows in different populations of starbursts and active galaxies, a manifestation of the feedback of activity. We summarize the main results recently obtained from the observation of galactic inflows and outflows in a variety of active galaxies with current millimeter interferometers such as ALMA or the IRAM array.

Three different types of evidence are presented in favour of the hypothesis that the HII regions in disk galaxies with Hα luminosities greater than a critical value of 1038·6 erg s−1 are density-bounded, and that the escaping Lyman continuum photons from these are the principal ionising agents for the diffuse ISM in disk galaxies. This has important implications for the ionisation of the intergalactic medium, and for computed star formation rates in spirals.

Most early-type galaxies are not devoid of cold and warm gas. The origin and ionization of this gas reveal the intriguing ongoing evolution of these galaxies. In most cases, the warm ionized gas shows emission-line spectra similar to low-ionization nuclear emission-line regions (LINERs). Their ionization mechanism has been hotly debated. We will present evidence from line ratio gradient that rules out AGN and shocks as the dominant ionization mechanism, and suggests the ionizing sources follow the stellar density profile. Hot evolved stars are the favorite candidates but bring new puzzles.

This finding allows us to obtain a gas-phase metallicity calibration in these early-type galaxies, using the line emission. We will show how the metallicity of the warm gas depends on stellar mass and stellar age, and what it tells us about the origin of the warm gas in these galaxies.

The evolution of galaxies is greatly influenced by their interactions. As part of a program to study interacting galaxies, we have measured and modeled the spectral energy distributions (SEDs) from the ultraviolet (UV) to the far-infrared (FIR). We describe the constraints imposed on star formation histories by these SEDs, and the variations therein seen across the interaction sequence, and we compare the results of different star formation rate prescriptions applied to the data. The sample itself is based on the Spitzer Interacting Galaxy Survey (SIGS) of 111 galaxies in 50 systems, a project designed to probe a range of galaxy interaction parameters in the infrared. Our SEDs combine the Spitzer results with multiwavelength data from other missions, in particular GALEX and Herschel. The subset presented here is the sample for which FIR Herschel observations are currently publicly available.

The efficiency of star formation governs many observable properties of the cosmological galaxy population, yet many current models of galaxy formation largely ignore the important physics of star formation and the interstellar medium (ISM). Using hydrodynamical simulations of disk galaxies that include a treatment of the molecular ISM and star formation in molecular clouds (Robertson & Kravtsov 2008), we study the influence of star formation efficiency and molecular hydrogen abundance on the properties of high-redshift galaxy populations. In this work, we focus on a model of low-mass, star forming galaxies at 1 ≲ z ≲ 2 that may host long duration gamma-ray bursts (GRBs). Observations of GRB hosts have revealed a population of faint systems with star formation properties that often differ from Lyman-break galaxies (LBGs) and more luminous high-redshift field galaxies. Observed GRB sightlines are deficient in molecular hydrogen, but it is unclear to what degree this deficiency owes to intrinsic properties of the galaxy or the impact the GRB has on its environment. We find that hydrodynamical simulations of low-stellar mass systems at high-redshifts can reproduce the observed star formation rates and efficiencies of GRB host galaxies at redshifts 1 ≲ z ≲ 2. We show that the compact structure of low-mass high-redshift GRB hosts may lead to a molecular ISM fraction of a few tenths, well above that observed in individual GRB sightlines. However, the star formation rates of observed GRB host galaxies imply molecular gas masses of 108 – 109M⊙ similar to those produced in the simulations, and may therefore imply fairly large average H2 fractions in their ISM.

Masers in starburst galaxies are outstanding probes of a range of phenomena related to galaxy and black hole evolution, and offer unique high brightness temperature illumination that can be used to probe small scales in the host galaxy and in our own. But we require a deeper understanding of the galaxy-scale maser phenomenon if we wish to employ starburst galaxy masers as probes using the next generation of radio telescopes. This review summarizes what is known about the different flavors of masers in starburst galaxies and the setting and structure of OH megamasers. The question of which galaxies produce megamasers and which do not is critical to our understanding of the megamaser phenomenon, and recent studies of HCN and H2CO are particularly instructive. Constraints on the lifetime of OH megamasers and the predictability of OH megamaser line properties are critical issues to address in the near future. It is also time to begin the next wave of OH megamaser surveys at higher redshifts and to finally employ them as probes of starbursts, massive black holes, galaxy evolution, and intervening media.