Landing page for project GV028

Arp 220 is one of the most nearby examples of extreme star formation (SF) environments thought to dominate in the early universe. Understanding the origin of radio emission in these environments is crucial for e.g. SKA projects using the IR-radio correlation to probe the SF-history of the early universe. Global VLBI observations spanning 20 years have revealed 97 compact sources in Arp 220, most consistent with being radio supernovae (SNe) or supernova remnants (SNRs) which are responsible for SF-induced radio emission and feedback. However, many lack sufficient data for robust classification. The observed source luminosity function also suggests thousands of weaker sources below our current detection threshold. New, high-sensitivity multi-frequency global VLBI observations is the only way to constrain the nature and evolution of these obscured sources. Surprisingly, we find that only 20% of the flux density measured on VLA/MERLIN scales is recovered at VLBI scales. This suggests significant activity on intermediate scales, possibly due to buried-AGN activity, which can only be probed by joint eMERLIN+VLBI observations. Together with existing data, the proposed observations also allow us to search for unknown events like the Tidal Disruption Event observed in Arp299.

This data is part of the archive of VLBI data maintained by JIVE on behalf of the EVN, a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa. The EVN archive itself has the DOI https://doi.org/10.17616/R3Z197