Radio Transients from Accretion Induced Collapse and Neutron Star Mergers
Abstract
It has long been expected that in some scenarios when a white dwarf (WD) grows to the Chandrasekhar limit, it can undergo accretion induced collapse (AIC) to form a neutron star (NS). Nevertheless, the detection of such events have so far evaded discovery, likely because the supernova-like emission associated with AIC is rather dim. Here we propose a novel observational signature of AIC, namely a transient radio burst. Rapid rotation along with flux freezing or dynamo action can grow the WD's magnetic field to magnetar strengths during collapse. The spindown of this newly born magnetar generates a pulsar wind nebula (PWN) within the ~10^{-3}-10^{-1} Msun of ejecta surrounding it. The synchrotron emission in the radio is absorbed by synchrotron self-absorption (SSA) due to the large magnetic fields of the PWN until it expands sufficiently and becomes optical thin to SSA on a few month timescale. Our estimates show that such events will be detectable even if the magnetar has a rather modest magnetic field of ~10^{14} G and initial spin period of ~10 ms. A survey with a detection limit of 1 mJy at 1.4 GHz would roughly see ~35(f/10^{-2}) above threshold at any given time, where f is the ratio of the AIC rate to the Type Ia supernova rate. A similar scenario may also apply to NS binary mergers if some are able to survive as massive NSs rather than make black holes.
- Publication:
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American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22121402P