Mondal, T (2021) The life cycle of magnetars: A novel approach to estimate their ages. In: Astrophysical Journal Letters, 913 (1).
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Abstract
Anomalous X-ray pulsars and soft gamma repeaters are slowly rotating, young, and isolated neutron stars exhibiting sporadic outbursts and high X-ray quiescent luminosities. They are believed to be powered by ultrastrong magnetic fields, B � 1014�1015 G, associated with �magnetars.� In the peculiar case of SGR 0418 +5729, timing parameters imply a dipolar B-field of 6.1 � 1012 G. This discovery has challenged the traditional picture of magnetars in terms of B-field strengths, evolutionary stages, and ages. Here we provide a novel approach to estimate a magnetar�s age by considering the self-consistent time evolution of a plasma-filled oblique pulsar with the state-of-the-art magnetospheric particle acceleration gaps. The rotational period of magnetars increases over time due to angular momentum extraction by gravitational-wave radiations, magnetic dipole radiations, and particle winds. These torques also change the obliquity angle between the magnetic and rotation axes. For SGR 0418+5729, we obtain a dipolar B-field of 1.0 � 1014 G, and a realistic age of �18 kyr, consistent within the magnetar paradigm. © 2021. The American Astronomical Society. All rights reserved.
| Item Type: | Journal Article |
|---|---|
| Publication: | Astrophysical Journal Letters |
| Publisher: | American Astronomical Society |
| Additional Information: | The copyright for this article belongs to Authors |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 25 Aug 2021 10:50 |
| Last Modified: | 25 Aug 2021 10:50 |
| URI: | http://eprints.iisc.ac.in/id/eprint/69337 |
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