Volume 603, July 2017
|Number of page(s)||7|
|Published online||30 June 2017|
Evolution of newborn rapidly rotating magnetars: Effects of R-mode and fall-back accretion
1 School of Astronomy and Space Science, Nanjing University, 210093 Nanjing, PR China
2 Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, 210093 Nanjing, PR China
3 Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
Received: 30 August 2016
Accepted: 24 April 2017
In this paper we investigate effects of the r-mode instability on a newborn rapidly-rotating magnetar with fall-back accretion. Such a magnetar could usually occur in core-collapse supernovae and gamma-ray bursts. We find that the magnetar’s spin and r-mode evolution are influenced by accretion. If the magnetar is sufficiently spun up to a few milliseconds, gravitational radiation leads to the growth of the r-mode amplitude significantly. The maximum r-mode amplitude reaches an order of ~0.001 when the damping due to the growth of a toroidal magnetic field balances the growth of the r-mode amplitude. If such a sufficiently spun-up magnetar was located at a distance less than 1 Mpc, then gravitational waves would be detectable by the Einstein Telescope but would have an extremely low event rate. However, if the spin-up is insufficient, the growth of the r-mode amplitude is mainly due to the accretion torque. In this case, the maximum r-mode amplitude is of the order of ~10-6−10-5.
Key words: stars: neutron / gravitational waves / stars: rotation / stars: magnetars / stars: oscillations / accretion, accretion disks
© ESO, 2017
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