Exploration of Fermi GBM TTE data

Abstract

During this bachelor research I did an exploration of Fermi GBM TTE data in studying energetic fast pulsars. The Fermi Gamma-ray Burst Monitor (GBM) operates in a new default data taking mode since 26 November 2012. In this mode events are time-tagged with a 2 micro s precision for 128 different energy channels in the 8 keV-30 MeV regime. Data from this mode is used to analyse the pulsars PSR B0531+21 (the Crab pulsar), PSR B1509-58 and 1RXS J170849.0-400910 with spin periods of approximately 33 ms, 150 ms and 11 s, respectively. The 2 micro s precision provides for each of the three pulsars a more than sufficient time resolution. However, since this was not required for the pulsars PSR B1509-58 and 1RXS J170849.0-400910 I reduced the sampling time to enhance the computation speed. Based on this work I conclude that Fermi GBM TTE data can be used to produce pulse profiles, which show clear resemblance with profiles from earlier observations by other high-energy instruments, for all three pulsars. I produced phase folded pulse profiles for PSR B0531+21with significances well above 36sigma analysing 0.42 Ms exposure time per detector, and for PSR B1509-58 significances ∼ 36.0sigma analysing 15.66 Ms exposure time per detector. Although I was able to produce phase folded pulse profiles for 1RXS J170849.0-400910 the data consist of unexpectedly strong signals for certain time intervals. More research has to be done to find the origin of this. These signals are likely caused by erratic strong flares of high-mass X-ray binary 4U1700-377 which is located at only 3degrees from 1RXS J170849.0-400910 and thus always in the selected data sample.