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Gamma-Ray Observations of the Youngest Known Pulsar

Submitter: Maura Pilia
Description: PSR J1846-0258, located in the supernova remnant Kes 75, is a
relatively slowly rotating pulsar (P = 324ms) with a relatively high spin-down rate. If standard dipole magnetic braking is assumed, its spin-down age of 723 years is in agreement with the estimated age of Kes 75, making it the youngest pulsar known.

Pulsed gamma-ray emission from PSR J1846-0258 is only observed up to 150 MeV, making it the "softest" gamma-ray pulsar known. Given its high inferred surface magnetic field B = 4.9 x 10^13 G, which is higher than the so-called "quantum critical limit", we interpret the soft spectral cutoff as due to photon splitting in the inner magnetosphere (Pilia et al. 2012, submitted to ApJ). Given that PSR J1846-0258 has recently shown magnetar-like behavior, we further propose that its spectral properties in gamma-rays could constitute an indication that PSR J1846-0258 might be evolving into a magnetar.

From top to bottom: background subtracted gamma-ray light curves for PSR J1846-0258 in the standard energy ranges (below and above 100 MeV) and in the energy range 30-150 MeV corresponding to the highest detection significance, as observed from the Italian satellite AGILE. This constitutes the first ever detection of this pulsar in this energy range. At the bottom, the RXTE X-ray light curve in the 2-20 keV energy range.
Copyright: Maura Pilia
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