Modelling spin evolution of magnetars
arXiv:2109.07484 · doi:10.1093/mnras/stab2677
Abstract
The origin and fate of magnetars (young, extremely magnetized neutron stars, NSs) remain unsolved. Probing their evolution is therefore crucial for investigating possible links to other species of isolated NSs, such as the X-ray dim NSs (XDINSs) and rotating radio transients (RRATs). Here we investigate the spin evolution of magnetars. Two avenues of evolution are considered: one with exponentially decaying B-fields, the other with sub- and super-exponential decay. Using Monte Carlo methods, we synthesize magnetar populations using different input distributions and physical parameters, such as for the initial spin period, its time derivative and the B-field decay timescale. Additionally, we introduce a fade-away procedure that can account for the fading of old magnetars, and we briefly discuss the effect of alignment of the B-field and spin axes. Imposing the Galactic core-collapse supernova rate of ~20 kyr^-1 as a strict upper limit on the magnetar birthrate and comparing the synthetic populations to the observed one using both manual and automatic optimization algorithms for our input parameter study, we find that the B-field must decay exponentially or super-exponentially with a characteristic decay timescale of 0.5-10 kyr (with a best value of ~4 kyr). In addition, the initial spin period must be less than 2 sec. If these constraints are kept, we conclude that there are multiple choices of input physics that can reproduce the observed magnetar population reasonably well. We also conclude that magnetars may well be evolutionary linked to the population of XDINSs, whereas they are in general unlikely to evolve into RRATs.
18 pages, 11 figures, +appendices, accepted for publication in MNRAS
References in corpus (15)
- The ATNF Pulsar Catalogue
- A periodically active pulsar giving insight into magnetospheric physics
- Detection of 16 Gamma-Ray Pulsars Through Blind Frequency Searches Using the Fermi LAT
- Magnetar-like Emission from the Young Pulsar in Kes 75
- Formation of millisecond pulsars with CO white dwarf companions - II. Accretion, spin-up, true ages and comparison to MSPs with He white dwarf companions
- On the birthrates of Galactic neutron stars
- Formation Rates and Evolution Histories of Magnetars
- Pulsar braking and the P-Pdot diagram
- Magnetic, thermal and rotational evolution of isolated neutron stars
- Population synthesis of isolated Neutron Stars with magneto--rotational evolution
- Radio and X-ray observations of the intermittent pulsar J1832+0029
- Weighted Kolmogorov-Smirnov test: Accounting for the tails
- The new magnetar SGR J1830-0645 in outburst
- Reactivation of the high-magnetic field pulsar PSR J1846--0258 with magnetar-like bursts
- Neutron stars: Observational diversity and evolution