December 13, 2013
NOTE: Building 34, Room W150
NAVAL RESEARCH LABORATORY
"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.