Gamma-Ray Transient Network Science Analysis Group Report

Abstract

The Interplanetary Network (IPN) is a detection, localization and alert system that utilizes the arrival time of transient signals in gamma-ray detectors on spacecraft separated by planetary baselines to geometrically locate the origin of these transients. Due to the changing astrophysical landscape and the new emphasis on time domain and multimessenger astrophysics (TDAMM) from the Pathways to Discovery in Astronomy and Astrophysics for the 2020s, this Gamma-ray Transient Network Science Analysis Group was tasked to understand the role of the IPN and high-energy monitors in this new era. The charge includes describing the science made possible with these facilities, tracing the corresponding requirements and capabilities, and highlighting where improved operations of existing instruments and the IPN would enhance TDAMM science. While this study considers the full multiwavelength and multimessenger context, the findings are specific to space-based high-energy monitors. These facilities are important both for full characterization of these transients as well as facilitating follow-up observations through discovery and localization. The full document reports the history of this field in Section 1, followed by our detailed analyses and findings in some 68 pages, providing a holistic overview of the role of the IPN and high-energy monitors in the coming decades.We here summarize our core conclusions. Scientific breakthroughs which require capable high-energy monitors are fully detailed in Section 2. Specific questions of interest include: unique example of NASA's Transform to Open Science initiative. Adding the numerous gamma-ray smallsats to the collaboration would allow for greater inclusion of the international community, ensure maximum gain of their data, act to facilitate inclusion of private data towards productive TDAMM results, and allow the United States to support the developing space capabilities in other countries.We identify a number of specific actions that could be taken by NASA to increase the TDAMM return of current, forthcoming, and future facilities, discussed in Section 4. These include:• Enhanced space-based communications: Providing additional communication contacts for gamma-ray burst monitors will lead to faster retrieval of data and data of higher quality (e.g. high resolution time-tagged event data). The immediate allocation of additional contacts for the Neil Gehrels Swift Observatory is important to discovery in the on-going gravitational-wave observing run (the capability was requested in the latest Senior Review round but not mentioned in the report). Similar improvements can be made to forthcoming Astrophysics missions like StarBurst and the Compton Spectrometer and Imager (COSI). This finding also applies to assets in NASA Planetary and Heliophysics, as well as missions led by other space agencies, where additional or more frequent contacts would boost the scientific return of the IPN and other TDAMM facilities. This provides an avenue for a TDAMM program built with international partn...

How do nuclear isomers influence the gamma-ray bursts in binary neutron star mergers?

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