Colloq Abstract - Schinzel
Feb 12
12:00noon Mountain
Frank Schinzel (NRAO)
Revealing the extreme universe through radio observations
Abstract
The radio and high energy skies share a tight physical connection primarily through non-thermal emission, i.e. synchrotron and inverse Compton processes. Over half of the known gamma-ray sources are active galaxies of the blazar class (AGN), all of which are prominent emitters at radio wavelengths. The second largest known class of gamma-ray emitter are pulsars, almost all of which are detected at radio wavelengths. Besides AGN and pulsars, about one third of detected gamma-ray sources are objects that have no known electromagnetic counterpart and are classified as "unassociated". The physical origin of these objects is unknown, which makes the gamma-ray sky one of the least explored in astronomy. Taking the example of NASA's Fermi Large Area Telescope detected point sources I will illustrate how radio observations enabled the discovery of over 200 new gamma-ray loud AGN among these unassociated sources, improved astrometric positions of radio counterparts to known gamma-ray objects, and facilitated obtaining redshifts for a significant number of objects. I will also provide a summary of ongoing efforts that aid the discovery of new gamma-ray pulsars, specifically highlighting our recent discovery of a cannonball pulsar. During this new decade, with the continued operation of the Fermi satellite, existing ground-based facilities like HAWC, VERITAS, HESS, or MAGIC, and the expected start of operation of the Cherenkov Telescope Array, radio observations will continue to play an essential role to study extreme physical processes in the universe at both ends of the electromagnetic spectrum.
