J. A. Rueda (Author), Remo Ruffini (Author), Y. Wang (Author), C. L. Bianco (Author), J. M. Blanco-Iglesias (Author), Mile Karlica (Author), P. Lorén-Aguilar (Author), Rahim Moradi (Author), N. Sahakyan (Author)

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

gamma ray bursts theory;white dwarfs;brown dwarfs;accretion;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UNG - University of Nova Gorica
UDC: 52
COBISS: 23022339 Link will open in a new window
ISSN: 1475-7516
Views: 1928
Downloads: 0
Average score: 0 (0 votes)
Metadata: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Other data

URN: URN:SI:UNG
Type (COBISS): Not categorized
Pages: str. 1-13
Volume: ǂVol. ǂ2019
Issue: ǂno. ǂ3
Chronology: Mar. 2019
DOI: 10.1088/1475-7516/2019/03/044
ID: 11908595
Recommended works:
, no subtitle data available
, lecture at University of Science and Technology, Hefei China, 21. June, 2016
, no subtitle data available
, no subtitle data available
, no subtitle data available