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Title:Electromagnetic emission of white dwarf binary mergers
Authors:Rueda, Jorge Armando (Author)
Ruffini, Remo (Author)
Wang, Yu (Author)
Bianco, Carlo Luciano (Author)
Blanco-Iglesias, J.M. (Author)
Karlica, Mile (Author)
Lorén-Aguilar, P. (Author)
Moradi, Rahim (Author)
Sahakyan, Narek (Author)
Files:This document has no files. This document may have a phisical copy in the library of the organization, check the status via COBISS. Link is opened in a new window
Language:English
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:UNG - University of Nova Gorica
Abstract:It has been recently proposed that the ejected matter from white dwarf (WD) binary mergers can produce transient, optical and infrared emission similar to the "kilonovae" of neutron star (NS) binary mergers. To confirm this we calculate the electromagnetic emission from WD-WD mergers and compare with kilonova observations. We simulate WD-WD mergers leading to a massive, fast rotating, highly magnetized WD with an adapted version of the smoothed-particle-hydrodynamics (SPH) code Phantom. We thus obtain initial conditions for the ejecta such as escape velocity, mass and initial position and distribution. The subsequent thermal and dynamical evolution of the ejecta is obtained by integrating the energy-conservation equation accounting for expansion cooling and a heating source given by the fallback accretion onto the newly-formed WD and its magneto-dipole radiation. We show that magnetospheric processes in the merger can lead to a prompt, short gamma-ray emission of up to ≈ 1046 erg in a timescale of 0.1-1 s. The bulk of the ejecta initially expands non-relativistically with velocity 0.01 c and then it accelerates to 0.1 c due to the injection of fallback accretion energy. The ejecta become transparent at optical wavelengths around ~ 7 days post-merger with a luminosity 1041-1042 erg s-1. The X-ray emission from the fallback accretion becomes visible around ~ 150-200 day post-merger with a luminosity of 1039 erg s-1. We also predict the post-merger time at which the central WD should appear as a pulsar depending on the value of the magnetic field and rotation period.
Keywords:Astrophysics - High Energy Astrophysical Phenomena
Year of publishing:2019
Number of pages:13
Numbering:03, 2019
COBISS_ID:23022339 Link is opened in a new window
URN:URN:SI:UNG:REP:LPWEN8YL
DOI:https://doi.org/10.1088/1475-7516/2019/03/044 Link is opened in a new window
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Record is a part of a journal

Title:Journal of Cosmology and Astroparticle Physics
Shortened title:JCAP
Publisher:IOP Publishing Ltd and SISSA Medialab
Year of publishing:2019

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