GW170817 Most Likely Made a Black Hole

Understand

There are two outstanding issues regarding the neutron-star merger event GW170817: the nature of the compact remnant and the interstellar shock.

• The mass of the remnant of GW170817, $\sim$2.7 $M_\odot$, implies the remnant could be either a massive, rotating, neutron star, or a black hole.
• We report Chandra Director's Discretionary Time observations made in 2017 December and 2018 January, and we reanalyze earlier observations from 2017 August and 2017 September, in order to address these unresolved issues.
• We estimate the X-ray flux from a neutron star remnant and compare that to the measured X-ray flux.