GW170817 Most Likely Made a Black Hole
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Date
2018-05-14
Authors
Pooley, David
Kumar, Pawan
Wheeler, J. Craig
Grossan, Bruce
Journal Title
Journal ISSN
Volume Title
Publisher
NURIS; Energetic Cosmos Laboratory
Abstract
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, ∼2.7 M⊙, 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. If we assume that the spin-down luminosity of any putative neutron star is converted to pulsar wind nebula X-ray emission in the 0.5-8 keV band with an efficiency of 10−3, for a dipole magnetic field with 3×1011 G < B < 1014 G, a rising X-ray signal would result and would be brighter than that observed by day 107, we therefore conclude that the remnant of GW170817 is most likely a black hole. Independent of any assumptions of X-ray efficiency, however, if the remnant is a rapidly-rotating, magnetized, neutron star, the total energy in the external shock should rise by a factor ∼102 (to ∼1052 erg) after a few years, therefore, Chandra observations over the next year or two that do not show substantial brightening will rule out such a remnant. The same observations can distinguish between two different models for the relativistic outflow, either an angular or radially varying structure.
Description
Energetic Cosmos Laboratory. ECL Publication, 2019
Keywords
The 2nd international conference of the Energetic Cosmos Laboratory (ECL), Energetic Cosmos Laboratory (ECL), ECL19
Citation
Pooley, D., Kumar, P., Wheeler, C. & Grossan, B. (2018). GW170817 Most Likely Made a Black Hole. 2nd international conference of the Energetic Cosmos Laboratory (ECL) at Nazarbayev University. Retrieved from https://arxiv.org/pdf/1712.03240.pdf