The detection of PSR J1846-0258 at high-energy gamma-rays

Abstract

PSR J1846-0258 is a 324 ms pulsar discovered in 1999 at X-ray energies. It is the youngest rotation-powered pulsar known and is located at the centre of SN-remnant Kes 75. The magnetic field strength has a value of ~4.9x10^13 G, which is just above the quantum critical field strength of 4.413x10^13 G. In June 2006 a magnetar-like outburst occurred: a dramatic brightening with spectral softening. It recovered to pre-outburst flux levels at 1/e-time scale of ~55 days. During its outburst, five short magnetar-like bursts (less than ~100 ms) were discovered as well as a large timing glitch making phase-coherent timing impossible for a couple of months. Since then, PSR J1846-0258 has been behaving again as a stable rotation-powered pulsar. Deep INTEGRAL and RXTE HEXTE observations showed the detection of pulsed emission up to ~150 keV. Its pulsed spectrum mimics that of the canonical soft gamma-ray pulsar PSR B1509-58, but the flux level is about ~10 times lower. Therefore, PSR J1846-0258 is an excellent candidate to be detected as a high-energy gamma-ray pulsar (greater than ~30 MeV) given the detection of pulsed gamma-rays from PSR B1509-58 up to ~300 MeV. For this bachelor thesis I analysed all available Fermi LAT (>30 MeV) and GBM (8 keV - 2 MeV) data on this pulsar collected over a ~7.6 year time period. In this work I discovered for the first time pulsed emission at high-energy gamma-rays in the 30-100 MeV band, while the simultaneously obtained Fermi GBM data made the detection of pulsed soft gamma-ray emission possible up to ~300 keV.