Searching for undetected Gamma Ray Bursts in Fermi GBM Data

Speaker: Ariel Perera (Weizmann Institute) In Person and zoom 

Zoom info: https://stanford.zoom.us/j/98604058568

The recent discovery of simultaneous gravitational wave (GW) emission and short gamma-ray burst from a binary neutron star (BNS) merger has opened a new window to study such compact binary systems. The joint detection rate from this event is estimated at approximately 0.1 to 1.4 per year, with no other confirmed sources identified yet. In my research, I develop a GRB detection pipeline with rigorous statistical analysis to scan the Fermi GBM data, with the aim of increasing the search sensitivity. This will result in a larger number of known GRBs, and hence increased probability of another joint GRB-GW detection. This expectation is supported by a comparison of the detection probability of the pipeline and the significance of GBM triggering algorithm; our pipeline shows between 2 to 15 times higher signal-to-noise ratio, depending on source direction and intrinsic spectrum. Another feature of this pipeline is a statistical estimation of the location of the burst and discrimination between cosmological, terrestrial, and stellar origins. This allows for a robust classification of the signal, lowering the contamination of the sample. Our analysis includes operating the pipeline on ”time-slided” copies of the data, which allows exact significance assessment and p_{astro} computation, akin to the state-of-the-art GW data analysis pipelines. This, along with a sky-map for the direction to the GRB, will facilitate a rigorous joint GW-GRB search on O3 and O4 LVK data.