The life cycle of magnetars: a novel approach to estimate their ages

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, $B\sim 10^{14}-10^{15}$ G, associated with `magnetars'. In the peculiar case of SGR 0418+5729, timing parameters imply a dipolar $B$-field of $6.1\times 10^{12}$ 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 $1.0\times 10^{14}$ G, and a realistic age of $\sim 18$ kyr, consistent within the magnetar paradigm.

8 pages, 3 figures. Accepted for publication in ApJ Letters

References in corpus (8)

• The strongest cosmic magnets: Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• Modelling magnetically deformed neutron stars
• Magnetic field dissipation in neutron star crusts: from magnetars to isolated neutron stars
• Ab-initio pulsar magnetosphere: three-dimensional particle-in-cell simulations of oblique pulsars
• Supernova remnant energetics and magnetars: no evidence in favour of millisecond proto-neutron stars
• 2D Cooling of Magnetized Neutron Stars
• Possible Evidence for Free Precession of a Strongly Magnetized Neutron Star in the Magnetar 4U 0142+61
• Timescales for detection of super-Chandrasekhar white dwarfs by gravitational wave astronomy

Cited by in corpus (18)

• Searching for Time-Dependent Axion Dark Matter Signals in Pulsars
• Where are the magnetar binary companions? Candidates from a comparison with binary population synthesis predictions
• Modelling spin evolution of magnetars
• The Early Evolution of Magnetar Rotation I: Slowly Rotating "Normal" Magnetars
• Detection possibility of continuous gravitational waves from rotating magnetized neutron stars
• Searching for Magnetar Binaries Disrupted by Core-Collapse Supernovae
• Representation Learning for Time-Domain High-Energy Astrophysics: Discovery of Extragalactic Fast X-ray Transient XRT 200515
• Multipolar Electromagnetic Emission of Newborn Magnetar
• Searching for continuous gravitational waves from slowly spinning neutron stars with DECIGO, Big Bang Observer, Einstein Telescope and Cosmic Explorer
• Resolving dichotomy in compact objects through continuous gravitational waves observation
• The infrared counterpart and proper motion of magnetar SGR0501+4516
• Quantum Effects on Dynamic Structure Factors in Dense Magnetized Plasmas
• Detectability of the gravitational-wave background produced by magnetar giant flares
• Angular Dependence of Coherent Radio Emission from Magnetars with Multipolar Magnetic Fields
• Periodic Activities of Fast Radio Burst Repeaters from Precessing Magnetars with Evolving Obliquity
• 4XMM J175136.8-275858: A New Magnetar Candidate?
• Correlation of Burst Behaviour with Magnetar Age
• Continuous Gravitational Waves from Supersoft X-ray Sources: Promising Targets for deci-Hz Detectors