STANFORD UNIVERSITY
EE 350 RADIOSCIENCE SEMINAR
Professor Umran S. Inan

Winter 1998-99

Date: Wednesday, March 10, 1999
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: GESB 124


The Gamma-ray Large Area Space Telescope: Understanding the Most Powerful Energy Sources in the Universe

Dr. Scott Wiliams
W.W. Hansen Experimental Physics Laboratory

Abstract

The Gamma-ray Large Area Space Telescope (GLAST) begins a new epoch in space-based physics investigation. Using the most powerful particle accelerators in the universe as cosmic laboratories, GLAST will explore the extreme environments of supermassive black holes, neutron stars, and gamma-ray bursts. On cosmological scales, GLAST will explore the era of star formation in the universe, the physics of dark matter and the creation and evolution of galaxies.

GLAST is a next generation high-energy gamma-ray observatory designed for making observations of celestial gamma-ray sources in the energy band extending from 10 MeV to more than 100 GeV. It follows in the footsteps of the Energetic Gamma-ray Experiment Telescope (EGRET) on the Compton Gamma-ray Observatory (CGRO), and is a top priority mission in the Structure and Evolution of the Universe theme area in the NASA Office of Space Science.

The GLAST mission will:

1. Identify and study nature's highest-energy particle accelerators through observations of active galactic nuclei, pulsars, stellar-mass black holes, supernova remnants, gamma-ray bursts, and the diffuse galactic and extragalactic high-energy radiation.

2. Use high-energy gamma-ray observations to try to address important cosmological and physical questions that are not easily answered at longer wavelengths. Examples include GLAST's ability to search for the origins of cosmic rays by mapping supernova remnants and the possibility that GLAST could detect the first "light" from certain types of "dark matter".

GLAST has a field of view about twice as wide (greater than 2.5 steradians), and sensitivity about 30 times that of EGRET at 100 MeV and even more at higher energies. Its one year limit for source detection in an all-sky survey is 5 x 10-9 photons cm-2 s-1 (at 100 MeV). It will be able to locate sources to positional accuracies of 30 arc seconds to 5 arc minutes. Yet, it is a relatively small and inexpensive mission, which will be able to be launched on a Delta II rocket. The GLAST Mission is presently in the formulation phase with a launch date of June 2005. Stanford University, through Prof. Peter Michelson, Physics and Prof. Elliott Bloom, Stanford Linear Accelerator Center (SLAC), is leading a consortium of 30 institutions in developing technology for the GLAST Large Area Telescope (LAT) instrument and will be responding to the upcoming Announcement of Opportunity for the GLAST flight instrument.