We present a method for determining the background of Fermi GBM GRBs using the satellite positional information and a physical model. Since the polynomial fitting method typically used for GRBs is generally only indicative of the background over relatively short timescales, this method is particularly useful in the cases of long GRBs or those which have Autonomous Repoint Request (ARR) and a background with much variability on short timescales. We give a Direction Dependent Background Fitting (DDBF) method for separating the motion effects from the real data and calculate the duration (T90 and T50, as well as confidence intervals) of the nine example bursts, from which two resulted an ARR. We also summarize the features of our method and compare it qualitatively with the official GBM Catalogue. Our background filtering method uses a model based on the physical information of the satellite position. Therefore, it has many advantages compared to previous methods. It can fit long background intervals, remove all the features caused by the rocking behaviour of the satellite, and search for long emissions or not-triggered events. Furthermore, many part of the fitting have now been automatised, and the method have been shown to work for both Sky Survey mode and ARR mode data. Future work will provide a burst catalogue with DDBF.
A recent work has found a tight global relation between the GRB prompt fluence, peak flux (based on the optimum time scale determined from the Bayesian Blocks-based analysis) and duration using data from the Fermi Gamma-Ray burst monitor, which they have dubbed as "Fundamental Plane". We quantitatively characterize the tightness of this Fundamental Plane relation by calculating the scatter in dex. We also check for a fundamental plane using the peak flux over time scales of 64 ms, 256 ms and 1024 ms. For our analysis, we incorporate the uncertainties in the above observables and carried out bo…
A Multi-Mission Detection Framework for High-Energy Transients: Application to a 13-year Fermi/GBM and Swift/BAT Sample
Weizmann Institute of Science（魏茨曼科学研究所）；University of California at Santa Barbara（加州大学圣塔芭芭拉分校）；International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（塔塔基础研究院国际理论科学中心）
In the era of time-domain, multi-messenger astronomy, the detection of transient events on the high-energy electromagnetic sky has become more important than ever. Previous attempts to systematically search for onboard-untriggered events in the data of Fermi-GBM have been limited to short-duration signals with variability time scales smaller than ~1 min due to the dominance of background variations on longer timescales. In this study, we aim at the detection of slowly rising or long-duration transient events with high sensitivity and full coverage of the GBM spectrum. We make use of our earlie…
Muon excess at sea level from solar flares in association with the Fermi GBM spacecraft detector
本文介绍了一个正在进行的调查结果之间的关联在地面水平的μ介子过剩登记的Tupi望远镜和瞬态太阳事件，两个太阳耀斑的伽马射线和X射线的排放分别报告，费米GBM和GOES 14。我们表明，小规模的太阳耀斑，那些与即时的X射线发射分类为GOES的C类（功率$10^{-6}$，以$10^{-5}$ W m $^2$在1 AU）可能会引起μ子过剩可能与太阳质子和离子发射的耀斑和到达地球作为一个相干粒子脉冲。图皮望远镜位于南大西洋异常（SAA）的中心区域，这使得粒子探测器能够对初级和次级带电粒子（$\geq 0.1$ GV）实现低刚性响应。在这里，我们认为一个“无标度”的能量分布粒子加速的太阳耀斑的可能性。大尺度耀斑和小尺度耀斑在能量超过π介子产生之前具有相同的能谱，它们之间的区别只是强度。如果这一假设是正确的，图皮望远镜正在记录质子（离子）产生的μ子，其能量对应于光谱的尾部。因此，所发射的质子的能量分布必须是幂律谱，因为幂律分布被表征为无标度分布。图皮事件支持了这一猜想。
