The Fourth Fermi-GBM Gamma-Ray Burst Catalog: A Decade of Data

Abstract: We present the fourth in a series of catalogs of gamma-ray bursts (GRBs) observed with Fermi's Gamma-Ray Burst Monitor (Fermi-GBM). It extends the six year catalog by four more years, now covering the ten year time period from trigger enabling on 2008 July 12 to 2018 July 11. During this time period GBM triggered almost twice a day on transient events of which we identifyied 2356 as cosmic GRBs. Additional trigger events were due to solar are events, magnetar burst activities, and terrestrial gamma-ray flashes. The intention of the GBM GRB catalog series is to provide updated information to the community on the most important observables of the GBM-detected GRBs. For each GRB the location and main characteristics of the prompt emission, the duration, peak flux, and fluence are derived. The latter two quantities are calculated for the 50-300 keV energy band, where the maximum energy release of GRBs in the instrument reference system is observed and also for a broader energy band from 10-1000 keV, exploiting the full energy range of GBM's low-energy detectors. Furthermore, information is given on the settings of the triggering criteria and exceptional operational conditions during years 7 to 10 in the mission. This fourth catalog is an official product of the Fermi-GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).

The Fourth Fermi-GBM Gamma-Ray Burst Catalog: A Decade of Data

The paper presents the fourth catalog of gamma-ray bursts (GRBs) observed via the Fermi Gamma-Ray Burst Monitor (Fermi-GBM), covering a time frame of a decade—from July 12, 2008, to July 11, 2018. This catalog extends the previous six-year catalog by an additional four years, thus encapsulating a significant volume of observational data on GRBs, totaling 2,356 cosmic GRBs identified within this period.

Key Features of the Catalog

• Quantity and Frequency of Detection: Over the ten-year period, GBM triggered on average almost twice daily on transient events, leading to the identification of 2,356 cosmic GRBs. This rate of detection emphasizes the effectiveness of GBM despite its lower sensitivity compared to the Burst and Transient Source Experiment (BATSE).

• Energy Band Analysis: The catalog offers detailed analyses of GRB emissions over two energy bands—50-300 keV and 10-1000 keV. This approach utilizes GBM’s broad spectral range to provide insights into the peak energy release of GRBs.

• Localization and Duration: The fourth catalog presents detailed localizations of GRBs along with characteristic data: duration, peak flux, and fluence, derived for each GRB. Information about the operational state during the last four years is also included.

• Systematic Updates: The fourth catalog updates ongoing observations and supplementations with more precise spectral analyses, empowering the research community with current data critical for follow-up studies.

Implications and Observational Insights

• Multi-Messenger Astrophysics: The catalog underscores the growing significance of GRB data for multi-messenger astrophysics, notably exemplified by GRBs detected in conjunction with gravitational waves from neutron star mergers.

• Spatial Distribution Analysis: Analysis indicates that GRB emissions are isotropic, a crucial point that assists in understanding their spatial origins and confirming theories regarding their distribution in the universe.

• Statistical Analysis of GRB Classes: Significant statistical analyses of GRB durations and hardness ratios suggest bimodal distributions, identifying short-hard and long-soft GRB classes. This reaffirmation aids in refining classification schemes within GRB studies.

Future Directions in Research

The fourth Fermi-GBM GRB catalog acts as a comprehensive dataset aiding theoretical and observational pursuits in gamma-ray astrophysics. It provides essential groundwork for future analyses, including the intriguing realm of time-resolved spectroscopy and the exploration of high-energy phenomena linked to GRBs. With ongoing advancements in satellite technology and collaborative multi-modal research pursuits, future catalogs are likely to uncover further intricacies in GRB behavior, potentially linking these massive cosmic events with broader astrophysical mechanisms observed throughout the universe.

In summary, this catalog not only provides essential GRB data but also serves as a pivotal reference aiding continuous progress in gamma-ray burst research, bridging the gap between observational data and theoretical understanding.