Very Fine Time-Resolved Spectral Studies of the Vela Pulsar

T. J. Johnson, Ö. Çelik, M. Kerr, A. K. Harding, G. A. Caliandro

Published 2009-12-18Version 1

The Vela pulsar is one of the most exciting gamma-ray sources and has been at the forefront of high-energy pulsar science since the detection of gamma-ray pulsations at the radio period by SAS-2 in 1975. With the unprecedented angular resolution, effective area, field of view, and timing resolution, in the GeV band, of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope, the light curve of the Vela pulsar can be studied in greater detail than ever before. Using a timing solution derived solely from the LAT data, phase aligned with the radio emission, the spectrum of the Vela pulsar has been fit in intervals as small as 0.0016 in phase. Significant variation is seen in the cutoff energy and photon index across the light curve, strongly supporting curvature radiation as the source of the high-energy gamma-rays from the Vela pulsar.