Speaker: Eric Faustino Jimenez-Andrade
Title: Hot vs cold mode of star formation: New insights from radio continuum emission of galaxies over 0.35<z<2.25
Most star-forming galaxies (SFGs) follow a tight correlation in the SFR-stellar mas plane; i.e. the “main-sequence” (MS) of SFGs. While the steady accretion of cold gas from the cosmic web (cold mode) is thought to fuel the star formation in MS galaxies, gas-rich mergers (hot mode) trigger intense and short-lived starbursts that appear above the MS. To validate this picture of galaxy evolution, we have carried out the first systematic study of the radio continuum size evolution of SFGs over 0.35<z<2.25. A mass-complete sample of ~3500 SFGs was assembled from the VLA COSMOS 3GHz map (2sq degrees, 0.75 arcsec resolution, 2.3muJy/beam), which allow us to statistically analyze the size and SFR surface density of galaxies in and out the MS. We found that the bulk of the SFG population follows a linear relation (in log space) between the SFR surface density and distance to the MS, yet a fraction of MS galaxies harbor enhanced and compact star formation activity. I will discuss these results in the context of gas accretion and merger-driven star formation throughout cosmic time.
Speaker: Anne-Kathrin Baczko
Title: AGN Jet Formation and Evolution – The case of NGC1052
Active Galactic Nuclei (AGN) are among the most studied extragalactic sources. A large fraction appear to have bipolar outflows of relativistic plasma, so called jets. However, due to differential Doppler boosting most sources reveal only a one-sided jet. To understand the origin and observed characteristics of jets many experimental and theoretical studies have been conducted during the last decades. Still, there is a lack of understanding the main features. How are jets formed, accelerated, and collimated? Do they evolve symmetrically? Being nearby and revealing a twin-jet system, our target sources NGC1052 is the ideal target to study these properties. We conducted multi-wavelength Very Long Baseline Interferometry (VLBI) observations from 1.5GHz up to 230GHz using VLBI Arrays spread not only over the whole earth, but reaching up to space. These are capable to reach resolutions down to 50 micro arc seconds, giving us access to unknown regions in which we expect the formation of the twin-jet system.