Detection of the Crab Pulsar with VERITAS above 100 GeV

Дата и время публикации : 2011-10-19T19:03:41Z

Авторы публикации и институты :
Andrew McCann
for the VERITAS Collaboration

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 4 pages, 4 figures, to appear in the proceedings of the 32nd ICRC, Beijing, China
Первичная категория: astro-ph.HE

Все категории : astro-ph.HE

Краткий обзор статьи: We discuss the recent detection of pulsed gamma-ray emission from the Crab Pulsar above 100 GeV with the VERITAS array of atmospheric Cherenkov telescopes. Gamma-ray emission at theses energies is not expected in present pulsar models. We find that the photon spectrum of pulsed emission between 100 MeV and 400 GeV can be described by a broken power law, and that it is statistically preferred over a power law with an exponential cut-off. In the VERITAS energy range the spectrum can be described with a simple power law with a spectral index of -3.8 and a flux normalization at 150 GeV that is equivalent to 1% of the Crab Nebula gamma-ray flux. The detection of pulsed emission above 100 GeV and the absence of an exponential cutoff rules out curvature radiation as the primary gamma-ray-producing mechanism. The pulse profile exhibits the characteristic two pulses of the Crab Pulsar at phases 0.0 and 0.4, albeit 2-3 times narrower than below 10 GeV. The narrowing can be interpreted as a tapered particle acceleration region in the magnetosphere. Our findings require that the emission region of the observed gamma rays be beyond 10 stellar radii from the neutron star.

Category: Physics