Could an X-ray Flare after GRB 170817A Originate from a Post-merger Slim Accretion Disc?

Abstract

GRB 170817A, detected by Fermi-GBM 1.7\,s after the merger of a neutron star (NS) binary, provides the first direct evidence for a link between such a merger and a short-duration gamma-ray burst. The X-ray observations after GRB 170817A indicate a possible X-ray flare with a peak luminosity $L_{\mathrm{peak}}\sim 2\times 10^{39}{\mathrm{erg}\mathrm{s}}^{-1}$ near day 156. Here we show that this X-ray flare may be understood based on a slim disc around a compact object. On the one hand, there exists the maximal accretion rate ${\dot{M}}_{\max }$ for the slim disc, above which an optically thick outflow is significant and radiation from the disc is obscured. Based on the energy balance analysis, we find that ${\dot{M}}_{\max }$ is in the range of $\sim 4{\dot{M}}_{\mathrm{Edd}}$ and $\sim 21{\dot{M}}_{\mathrm{Edd}}$ when the angular velocity of the slim disc is between $(1/5{)}^{1/2}{\mathrm{\Omega }}_{\mathrm{K}}$ and ${\mathrm{\Omega }}_{\mathrm{K}}$ (where ${\dot{M}}_{\mathrm{Edd}}$ is the Eddington accretion rate and ${\Omega }_K$ is the Keplerian angular velocity). With ${\dot{M}}_{\max }$, the slim disc can provide a luminosity $\sim L_{\mathrm{peak}}$ for a compact object of $2.5 M_{\sun}$. On the other hand, if the merger of two NSs forms a typical neutrino-dominated accretion disc whose accretion rate $\dot{M}$ follows a power-law decline with an index $-1.8$ , then the system must pass through the outflow regime and enter the slim disc in $\sim 11-355$ days. These results imply that a post-merger slim accretion disc could account for the observed late-time $L_{\mathrm{peak}}$.

arXiv comment5 pages, 2 figures,accepted for publication in MNRAS

References in corpus (47)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A
• Physical processes shaping GRB X-ray afterglow lightcurves: theoretical implications from the Swift XRT observations
• Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data
• Illuminating Gravitational Waves: A Concordant Picture of Photons from a Neutron Star Merger
• Optical emission from a kilonova following a gravitational-wave-detected neutron-star merger
• Thermal Equilibria of Accretion Disks
• Bright X-ray Flares in Gamma-Ray Burst Afterglows
• X-Ray Flares from Postmerger Millisecond Pulsars
• Global Structure of Three Distinct Accretion Flows and Outflows around Black Holes through Two-Dimensional Radiation-Magnetohydrodynamic Simulations
• Neutrino-Cooled Accretion Disks around Spinning Black Hole
• Long-term GRMHD Simulations of Neutron Star Merger Accretion Disks: Implications for Electromagnetic Counterparts
• Flares in long and short Gamma-Ray Bursts: a common origin in a hyperaccreting accretion disk
• The First Survey of X-ray Flares from Gamma Ray Bursts Observed by Swift: Temporal Properties and Morphology
• Testing the Curvature Effect and Internal Origin of Gamma-Ray Burst Prompt Emissions and X-ray Flares with Swift Data
• Three-dimensional simulations of super-critical black hole accretion disks --- luminosities, photon trapping and variability
• Three-dimensional GRMHD simulations of neutrino-cooled accretion disks from neutron star mergers
• A cocoon shock breakout as the origin of the $\gamma$-ray emission in GW170817
• The First Survey of X-ray Flares from Gamma Ray Bursts Observed by Swift: Spectral Properties and Energetics
• The late time evolution of Gamma-Ray Bursts: ending hyperaccretion and producing flares
• Fallback accretion in the aftermath of a compact binary merger
• Unveiling the origin of X-ray flares in Gamma-Ray Bursts
• The Giant X-ray Flare of GRB 050502B: Evidence for Late-Time Internal Engine Activity
• A long-lived neutron star merger remnant in GW170817: constraints and clues from X-ray observations
• Synchrotron radiation from the fast tail of dynamical ejecta of neutron star mergers
• X-ray flare in XRF 050406: evidence for prolonged engine activity
• The X-ray afterglow of the short gamma ray burst 050724
• Giant X-ray Bump in GRB 121027A: Evidence for Fall-back Disk Accretion
• The interplay of disk wind and dynamical ejecta in the aftermath of neutron star - black hole mergers
• From $\gamma$ to Radio - The Electromagnetic Counterpart of GW 170817
• The effects of r-process heating on fall-back accretion in compact object mergers
• Implications of the radio and X-ray emission that followed GW170817
• On the average Gamma-Ray Burst X-ray flaring activity
• Flares in GRB afterglows from delayed magnetic dissipation
• Gamma-Ray Burst long lasting X-ray flaring activity
• Mechanism of Outflows in Accretion System: Advective Cooling Cannot Balance Viscous Heating?
• Collisions of neutron stars with primordial black holes as fast radio bursts engines
• Constraints on the emitting region of the gamma-rays observed in GW170817
• A Note on the Slim Accretion Disk Model
• HEROIC: 3D General Relativistic Radiative Postprocessor with Comptonization for Black Hole Accretion Discs
• Is the macronova in GW170817 powered by the central engine?
• Constraints on the Bulk Lorentz Factors of GRB X-Ray Flares
• Isotropic Detectable X-ray Counterparts to Gravitational Waves from Neutron Star Binary Mergers
• Central Engine of Late-Time X-ray Flares with Internal Origin
• Limits on luminosity and mass accretion rate of a radiation pressure dominated accretion disc
• Global Slim Accretion Disk Solutions Revisited
• Central Engine-Powered Bright X-ray Flares in Short Gamma-Ray Bursts: A Hint of Black Hole-Neutron Star Merger?

Cited by in corpus (2)

• The evolution of binary neutron star post-merger remnants: a review
• Diagnosing the remnants of binary neutron star merger from GW170817/GRB170817A event