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GW170817/GRB Neutron Star Collision may have Created the Smallest Known Black Hole

posted by martyb on Thursday June 07 2018, @11:31PM   
from the how-big-is-that-in-Libraries-of-Congress? dept.

takyon writes:

Okay, Last Year's Kilonova Did Probably Create a Black Hole

In August of 2017 [open, DOI: 10.1103/PhysRevLett.119.161101] [DX], another major breakthrough occurred when the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected waves that were believed to be caused by a neutron star merger. Shortly thereafter, scientists at LIGO, Advanced Virgo, and the Fermi Gamma-ray Space Telescope were able to determine where in the sky this event (known as a kilonova) occurred.

This source, known as GW170817/GRB, has been the target of many follow-up surveys since it was believed that the merge could have led to the formation of a black hole. According to a new study by a team that analyzed data from NASA's Chandra X-ray Observatory since the event, scientists can now say with greater confidence that the merger created a new black hole in our galaxy.

[...] While the LIGO data provided astronomers with a good estimate of the resulting object's mass after the neutron stars merged (2.7 Solar Masses), this was not enough to determine what it had become. Essentially, this amount of mass meant that it was either the most massive neutron star ever found or the lowest-mass black hole ever found (the previous record holders being four or five Solar Masses).

Previously: "Kilonova" Observed Using Gravitational Waves, Sparking Era of "Multimessenger Astrophysics"
Neutron-Star Merger Grows Brighter

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Original Submission

• Re:Kilonova came first (Score: 1, Informative) by Anonymous Coward on Friday June 08 2018, @01:05AM

  by Anonymous Coward on Friday June 08 2018, @01:05AM (#690141)

  On 2017 August 17 12:41:06 UTC the Fermi Gamma-ray Burst Monitor (GBM; Meegan et al. 2009) onboard flight software triggered on, classified, and localized a GRB. A Gamma-ray Coordinates Network (GCN) Notice (Fermi-GBM 2017) was issued at 12:41:20 UTC announcing the detection of the GRB, which was later designated GRB 170817A (von Kienlin et al. 2017). Approximately 6 minutes later, a gravitational-wave candidate (later designated GW170817) was registered in low latency (Cannon et al. 2012; Messick et al. 2017) based on a single-detector analysis of the Laser Interferometer Gravitational-wave Observatory (LIGO) Hanford data. The signal was consistent with a BNS coalescence with merger time, tc, 12:41:04 UTC, less than $2\,{\rm{s}}$ before GRB 170817A. A GCN Notice was issued at 13:08:16 UTC. Single-detector gravitational-wave triggers had never been disseminated before in low latency. Given the temporal coincidence with the Fermi-GBM GRB, however, a GCN Circular was issued at 13:21:42 UTC (LIGO Scientific Collaboration & Virgo Collaboration et al. 2017a) reporting that a highly significant candidate event consistent with a BNS coalescence was associated with the time of the GRB959 .

  http://iopscience.iop.org/article/10.3847/2041-8213/aa91c9/meta [iop.org]

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