Scientific Colloquium
December 13, 2013
NOTE: Building 34, Room W150

"Attack of the Gamma-Ray Spiders from Space!"

The Fermi Gamma-ray Space Telescope has been surveying the sky in the gamma-ray band (photon energies of 100 MeV and greater) since August 2008. The Large Area Telescope, Fermi's prime instrument, has revealed a large population of gamma-ray sources associated with active galactic nuclei, pulsars, and a few other source classes. However, about a third of the gamma-ray sources are unassociated with any known gamma-ray emitting source. I will describe a worldwide effort to search for pulsars powering these sources. We have been extremely successful, discovering 56 new millisecond pulsars (MSPs), over 1/4 of all known MSPs in the Galaxy! A striking feature of these new MSPs is that many of them are so-called `black widow' systems that are eating away their companion with powerful beams of particles and high energy radiation. Another class being found are the `redbacks', named after the Australian cousin of the black widow spider. These systems are proving to be the missing link between accreting X-ray binaries and millisecond pulsars. I will describe the Fermi mission, our radio searches and some of the surprising systems we have discovered. This work is supported by the Fermi Guest Observer Program administered by NASA.

About the speaker:

Paul Ray is an Astrophysicist at the Naval Research Laboratory. He is an active member of the Fermi Large Area Telescope collaboration and the leader of the Fermi Pulsar Search Consortium. He has been studying neutron stars, predominately pulsars, at radio, X-ray, and gamma-ray wavelengths for over twenty years. He did his undergraduate work in physics at Berkeley and then went on to a Ph.D. in physics at Caltech. He started at NRL in 1995 as an NRC postdoc and has been a civil servant scientist since 1997.

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