Evidence for gravitational-wave dominated emission in the central engine of short GRB 200219A

Abstract

GRB 200219A is a short gamma-ray burst (GRB) with an extended emission (EE) lasting $\sim 90$s. By analyzing data observed with the {\em Swift}/BAT and {\em Fermi}/GBM, we find that a cutoff power-law model can adequately fit the spectra of the initial short pulse with ${\mathrm{E}}_{\mathrm{p}}=1387_{-134}^{+232}$ keV. More interestingly, together with the EE component and early X-ray data, it exhibits plateau emission smoothly connected with a $\sim t^{-1}$ segment and followed by an extremely steep decay. The short GRB composed of those three segments is unique in the {\em Swift} era and is very difficult to explain with the standard internal/external shock model of a black hole central engine, but could be consistent with the prediction of a magnetar central engine from the merger of an NS binary. We suggest that the plateau emission followed by a $\sim t^{-1}$ decay phase is powered by the spin-down of a millisecond magnetar, which loses its rotation energy via GW quadrupole radiation. Then, the abrupt drop decay is caused by the magnetar collapsing into a black hole before switching to EM-dominated emission. This is the first short GRB for which the X-ray emission has such an intriguing feature powered by a magnetar via GW-dominated radiation. If this is the case, one can estimate the physical parameters of a magnetar, the GW signal powered by a magnetar and the merger-nova emission are also discussed.

21 pages, 2 Tables, 7 figures, ApJL in press, two more references added, matched the published version

References in corpus (17)

• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A
• The Physics of Gamma-Ray Bursts and Relativistic Jets
• INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational Wave Event GW170817
• Discerning the physical origins of cosmological Gamma-ray bursts based on multiple observational criteria: the cases of z=6.7 GRB 080913, z=8.3 GRB 090423, and some short/hard GRBs
• X-Ray Flares from Postmerger Millisecond Pulsars
• Search for post-merger gravitational waves from the remnant of the binary neutron star merger GW170817
• A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. I. Spectral Components and Their Possible Physical Origins of LAT/GBM GRBs
• The Millisecond Magnetar Central Engine in short GRBs
• A Comprehensive Analysis of Swift/XRT Data: III. Jet Break Candidates in X-ray and Optical Afterglow Lightcurves
• The First Swift BAT Gamma-Ray Burst Catalog
• GRB afterglow plateaus and Gravitational Waves: multi-messenger signature of a millisecond magnetar?
• A comprehensive analysis of Swift/XRT data: I. Apparent spectral evolution of GRB X-ray tails
• Magnetically Torqued Neutrino-Dominated Accretion Flows for Gamma-ray Bursts
• Magnetar central engine and possible gravitational wave emission of nearby short GRB 160821B
• Signature of a New-Born Black Hole from the Collapse of a Supra-massive Millisecond Magnetar
• X-ray afterglows of Short gamma-ray bursts: Magnetar or Fireball?

Cited by in corpus (2)

• Constraining the ellipticity and frequency of binary neutron star remnant via its gravitational-wave and electromagnetic radiations
• Gravitational-wave evolution of newborn magnetars with different deformed structure