The hidden beauty of Arp220; star birth and death in an extreme environment
by
John Conway(Onsala Space observatory / Chalmers)
→
Europe/Stockholm
FD41
FD41
Description
Arp220 is the nearest of the Ultraluminous Infra-Red Galaxies (ULIRGs), defined
as galaxies with IR luminosity > 10^12 L_sol; it is therefore a key local object to study to understand
the intense star formation processes common at high redshift. Although the nucleus is
highly obscured in the optical/IR, observations at radio and millimetre
wavelengths can pierce through the dust to reveal its inner structures.
In particular global radio VLBI observations can detect, image and monitor radio
supernovae and supernova remnants (SNR) tracing the deaths of massive stars. These
observations can constrain the stellar Initial Mass Function (IMF) to check whether the standard
form applies in the extreme environment of Arp220. This a question of great importance in calibrating
methods to determine the star-formation history of the universe and testing IMF theories.
Furthermore the observed radio SNRs can be used as
in-situ probes of the extreme ISM of Arp220 constraining its pressure, magnetic field and distribution of
densities. As the acceleration sites of the relativistic electrons (and protons) that power
star-formation induced radio emission the energetics of these SNRs are also vital to understand in order to
explain the IR-radio correlation. This correlation is one of the tightest in astronomy and a vital tool
planned to be used extensively by the next generation of radio telescopes to trace
cosmic star-formation. Finally we can search for candidate exotic objects, illuminating
proposed AGN-startburst connections, the frequency of occurrence of
hypernovae/GRBs and possible new classes of source.