2021ApJ...917L..11K -
Astrophys. J., 917, L11-L11 (2021/August-2)
Dynamical formation channels for fast radio bursts in globular clusters.
KREMER K., PIRO A.L. and LI D.
Abstract (from CDS):
The repeating fast radio burst (FRB) localized to a globular cluster (GC) in M81 challenges our understanding of FRB models. In this Letter, we explore dynamical formation scenarios for objects in old GCs that may plausibly power FRBs. Using N-body simulations, we demonstrate that young neutron stars (NSs) may form in GCs at a rate of up to ∼50 Gpc–3 yr–1 through a combination of binary white dwarf (WD) mergers, WD-NS mergers, binary NS mergers, and accretion-induced collapse of massive WDs in binary systems. We consider two FRB emission mechanisms: First, we show that a magnetically powered source (e.g., a magnetar with field strength >=1014 G) is viable for radio emission efficiencies >=10–4. This would require magnetic activity lifetimes longer than the associated spin-down timescales and longer than empirically constrained lifetimes of Galactic magnetars. Alternatively, if these dynamical formation channels produce young rotation-powered NSs with spin periods of ∼10 ms and magnetic fields of ∼1011 G (corresponding to spin-down lifetimes of >=105 yr), the inferred event rate and energetics can be reasonably reproduced for order unity duty cycles. Additionally, we show that recycled millisecond pulsars or low-mass X-ray binaries similar to those well-observed in Galactic GCs may also be plausible channels, but only if their duty cycle for producing bursts similar to the M81 FRB is small.
Abstract Copyright:
© 2021. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Globular star clusters - Radio transient sources - Neutron stars - N-body simulations - Magnetars
Simbad objects:
5
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