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The EWOCS view of supermassive stellar clusters

Sede A. Riccò Via Santa Sofia 78, Catania

Star formation in our Galaxy typically occurs in environments less massive than 10^4 solar masses. However, a few more extreme star forming environments on the Milky Way exist, where hundreds of thousands to millions of stars form in dense regions. Often called “supermassive star clusters”, they are rare in our Galaxy today, while they are common in galaxies experiencing epochs of starburst. The international project EWOCS (Extendend Westerlund 1 and 2 Open Clusters Survey) is targeting the two closest superstar clusters in the Milky Way with a multi-wavelengtht survey which is based on an extensive set of data from radio to X-rays, with the main objective of studying the formation and early evolution of stars over the whole mass spectrum in a starburst environment.
In this talk, I will discuss the motivations and objectives of the project, the published results, ongoing studies and the future developments.

The Nature of Polarized Sources in the MIGHTEE XMM-LSS Deep Field

Sede A. Riccò Via Santa Sofia 78, Catania

This study explores the polarized emission of the faint extragalactic radio sources in the MIGHTEE (MeerKAT International Giga-Hertz Tiered Extragalactic Exploration, Jarvis et al., 2016) survey in order to systematically study cosmic magnetic fields in galaxies to high redshift. Reaching a sensitivity of 1.5 µJy/beam at a resolution of 5 arcseconds, MIGHTEE is providing an opportunity to chart the evolution of polarized emission from distant galaxies over cosmic time.
The MIGHTEE survey detects polarized emission for a large number of radio sources down to total intensity flux densities of the order of 100 µJy. At these flux densities the source population is increasingly dominated by star-forming galaxies (SFGs) as opposed to active galactic nuclei (AGNs). While polarized emission of AGN can be traced to very distant galaxies, polarized emission of SFGs at moderate distance has been detected only once.
I use multi-wavelength criteria to classify MIGHTEE radio objects as either SFG or AGN. I perform Rotation Measure Synthesis (RMSY) on the spectro-polarimetric data cubes and use the polarization and RMSY spectra to search for polarized emission. A comparative analysis of the polarization properties of SFGs and AGNs is performed. The analysis is extended to the lowest possible flux densities using stacking techniques. I will show preliminary results of the MeerKAT polarization studies of radio sources down to a sensitivity at the micro-Jansky level.