Optimising the detection of soft-spectrum gamma-ray sources with day & night observations

Titel: Optimising the detection of soft-spectrum gamma-ray sources with day & night observations (halvtidsseminarium i forskarutbildningen)
Föreläsare: Mohanraj Senniappan, doktorand i fysik i forskargruppen Data Intensive Astroparticle Physics vid Linnéuniversitetet

Abstract

The study of physical processes involving origin, propagation, interaction and detection of extra-terrestrial electromagnetic radiation in the energy range of 0.1 to 100 TeV is called Very High Energy (VHE) gamma-ray astrophysics. The extra-galactic VHE gamma-ray sources like Gamma-Ray Bursts (GRBs), Active Galactic Nuclei (AGN) have a soft spectrum, meaning that their gamma-ray emission concentrates in the low energy region (100 GeV - 1 TeV).

In addition, the gamma-ray emission from GRBs can last only a few milliseconds to tenths of hours. Existing Imaging Atmospheric Cherenkov Technique (IACT) telescopes can observe the sky only at night with good weather conditions and with a small field of view (3 to 5 degrees). Due to these limitations, short-lived gamma-ray sources, like GRBs, can be detected 'first' only by chance.

The Astroparticle group at Linnaeus University focuses on optimizing the technique for the detection of such sources through the ALTO/COMET project.
The proposed ALTO technique is based on water Cherenkov detection and scintillators. ALTO is expected to provide regular observations of soft-spectrum gamma-ray sources in a wide field-of-view of 30 degrees. This will allow the observation of short-lived as well as spatially extended gamma-ray sources.

In order to have a good detection capability on soft-spectrum sources, we have developed an analysis technique called SEMLA (Signal Extraction using Machine Learning for ALTO). I will present the technique, its performance in terms of angular and energy resolution, effective detection area and final point-source sensitivity.