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C M Hui

Publications and source records attributed to C M Hui.

3 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2025

ACROSS: Enabling Time Domain and Multi-Messenger Astrophysics

The U.S. Astro2020 Decadal Survey recommended an investment in Time Domain and Multi-Messenger Astrophysics (TDAMM) as the top-priority sustaining activity in space for the coming decade. One aspect of NASA’s response to this rec-ommendation is a pilot project, the Astrophysics Cross-Observatory Science Support (ACROSS) Initiative, designed to provide support to both missions and observers as they pursue TDAMM science. In this talk, we present our observations of needs in the community and initial plans for ACROSS activities, including services to facilitate and improve cross-mission follow-up planning and execution; a multi-messenger web portal with links to existing mission resources, community tools, and information tar-geted for TDAMM General Observers; development of "Smart Target of Opportunity submission page" proof-of-concepts; and ongoing development of a potential TDAMM general observing competitive grant solicitation. While the initial focus has been to en-hance coordination between NASA missions, we are eager to work with ground-based and international partners as well. We invite discussion with both missions and ob-servers to better understand their needs and concerns as ACROSS progresses. Here we present our efforts on the web-portal and API, along with our development to support NASA’s BurstCube mission.

T B Humensky↗
NASA NTRS2021

Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin

Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar giant flares (MGFs). Three have been observed from the Milky Way and its satellite galaxies, and they have long been suspected to constitute a third class of extragalactic GRBs. We report the unambiguous identification of a distinct population of four local (<5 Mpc) short GRBs, adding GRB 070222 to previously discussed events. While identified solely based on alignment with nearby star-forming galaxies, their rise time and isotropic energy release are independently inconsistent with the larger short GRB population at >99.9% confidence. These properties, the host galaxies, and non-detection in gravitational waves all point to an extragalactic MGF origin. Despite the small sample, the inferred volumetric rates for events above 4 × 10(exp 44) erg of R(sub MGF) =3.8(sup +4.0)(sub -3.1) ×10(exp 5) Gpc(exp -3) yr(exp -1) make MGFs the dominant gamma-ray transient detected from extragalactic sources. As previously suggested, these rates imply that some magnetars produce multiple MGFs, providing a source of repeating GRBs. The rates and host galaxies favor common CCSN as key progenitors of magnetars.

Gamma-ray bursts↗