Abstract
We present the first physically motivated background model for the Gamma-ray Burst Monitor (GBM) on board the Fermi satellite. Such a physically motivated background model has the potential to significantly improve the scientific output of Fermi/GBM, as it can be used to improve the background estimate for spectral analysis and localization of gamma-ray bursts (GRBs) and other sources. Additionally, this model can also lead to detections of new transient events, since long and weak, or slowly rising, events do not activate one of the existing trigger algorithms. In this paper we show the derivation of such a physically motivated background model, which includes the modeling of the different background sources and the correct handling of the response of GBM. While the goal of the paper is to introduce the model rather than developing a transient search algorithm, we demonstrate the ability of the model to fit the background seen by GBM by showing the following four applications for (1) a canonical GRB, (2) the ultra-long GRB 091024, (3) the V404 Cygni outburst in June 2015, and (4) the ultra-long GRB 130925A.
Highlights
The background seen by astrophysical instruments can be very hard to model, as it normally contains a plethora of unmodeled sources, instrumental background, and general unknowns
In this paper we show the derivation of such a physically motivated background model, which includes the modeling of the different background sources and the correct handling of the response of Gamma-ray Burst Monitor (GBM)
While the goal of the paper is to introduce the model rather than developing a transient search algorithm, we demonstrate the ability of the model to fit the background seen by GBM by showing the following four applications for (1) a canonical gamma-ray bursts (GRBs), (2) the ultra-long GRB 091024, (3) the V404 Cygni outburst in June 2015, and (4) the ultra-long GRB 130925A
Summary
The background seen by astrophysical instruments can be very hard to model, as it normally contains a plethora of unmodeled sources, instrumental background, and general unknowns. The GBM is one of two instruments that are part of the Fermi Gamma-ray Space Telescope, which was launched in 2008 into a low-Earth orbit This instrument consists of 12 sodium iodide (NaI) and 2 bismuth germanate (BGO) detectors, pointing in different directions (see Fig. 1). When building a physically motivated background model for GBM, for instance, to detect new sources, it is reasonable to start by fitting for the sharply peaked and rapidly decaying signal that occurs after the exits of the SAA. This is our first extension to the constant background model. We see the GRB as clear deviation from the background fits even without excluding the time, which means that this GRB could have been found with the background model without prior knowledge of the time of the GRB event
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
