WD2 - Origin and physics of Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars |
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Speaker |
Mukhopadhyay, Banibrata |
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Coauthors |
Bhattacharya, Mukul; Rao, AR; Mukerjee, Subroto; Das, Upasana |
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Possible formation of lowly luminous highly magnetized white dwarfs by accretion leading to SGRs/AXPs |
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Abstract |
We sketch a possible evolutionary scenario by which a highly magnetized super-Chandrasekhar white dwarf could be formed by accretion on to a commonly observed magnetized white dwarf. This is an exploratory study, when the physics in CVs is very rich and complex. Based on this, we also explore the possibility that the white dwarf pulsar AR Sco acquired its high spin and magnetic field due to repeated episodes of accretion and spin-down. We show that strong magnetic field dramatically decreases the luminosity of these highly magnetized white dwarf (B-WD), letting them below the current detection limit. The repetition of this cycle can eventually lead to a B-WD, recently postulated to be the reason for over-luminous type Ia supernovae. This evolution leading to a spinning B-WD could also be an ideal source for soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs). SGRs/AXPs are generally believed to be highly magnetized, but observationally not confirmed yet, neutron stars. Invoking B-WDs to explain them does not require the magnetic field to be as high as for neutron star based model, however reproducing other observed properties intact. |
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