October 4 - 4:00pm Phys 223
(Coffee at 3:30p.m. in room 242)
Purdue University
Physics Department
One of the highlights and most significant discoveries in astrophysics during the 1990's was the detection of a class of Active Galactic Nuclei (AGN) that produce most of their power in the TeV energy band. The Whipple collaboration, utilizing a 10m atmospheric Cherenkov telescope in southern Arizona, was the critical player in this discovery and during the decade revealed many stunning features of these active galaxies that are powered by super-massive black holes. One of the exciting possibilities that the observations at TeV energies of these AGN affords is the measurement of the intergalactic infrared background through attenuation of the TeV beam as it traverses the space between the source and the detector. Information on this background directly addresses the epoch of galaxy formation during the evolution of the universe and will constrain cosmological models where scant data exists from direct observation. This talk will briefly describe the manner in which observations at TeV energies are carried out and describe some very recent measurements that are revealing both the promise of measuring the infrared background density and the inherent difficulties in that measurement. The next generation instruments in the field of TeV astronomy will be arrays of telescopes that will significantly increase the sensitivity and reduce the energy threshold. The US array, VERITAS, of which the Purdue high energy astrophysics group is a collaborating member will also be described.