2011MNRAS.415.1590O -
Mon. Not. R. Astron. Soc., 415, 1590-1596 (2011/August-1)
SGR 0418+5729 as an evolved quark-nova compact remnant.
OUYED R., LEAHY D. and NIEBERGAL B.
Abstract (from CDS):
Soft γ-ray repeaters (SGRs) and anomalous X-ray pulsars are believed to be magnetars, i.e. neutron stars powered by extreme magnetic fields, B∼ 1014-1015 G. The recent discovery of an SGR with low magnetic field (<7.5 {x} 1012 G), SGR 0418+5729, which shows bursts similar to those of SGRs, implies that a high surface dipolar magnetic field might not be necessary for magnetar-like activity. We show that the quiescent and bursting properties of SGR 0418+5729 find natural explanations in the context of low magnetic field Quark-Nova (detonative transition from a neutron star to a quark star) remnants, i.e. an old quark star surrounded by degenerate (iron-rich) Keplerian ring/debris ejected during the Quark-Nova explosion. We find that a 16 Myr old quark star surrounded by an ∼10–10 M☉ring, extending in radius from ∼30 to 60 km, reproduces many observed properties of SGR 0418+5729. The SGR-like burst is caused by magnetic penetration of the inner part of the ring and subsequent accretion. Radiation feedback results in months long accretion from the ring's non-degenerate atmosphere which matches well the observed decay phase. We make specific predictions (such as an accretion glitch of ΔP/P∼-2 {x} 10–11 during burst and a sub-keV proton cyclotron line from the ring) that can be tested by sensitive observations.
Abstract Copyright:
2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS
Journal keyword(s):
stars: neutron - stars: magnetic fields
Simbad objects:
4
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