GRB afterglow plateaus and Gravitational Waves: multi-messenger signature of a millisecond magnetar?

摘要

The existence of a shallow decay phase in the early X-ray afterglows ofgamma-ray bursts is a common feature. Here we investigate the possibility thatthis is connected to the formation of a highly magnetized millisecond pulsar,pumping energy into the fireball on timescales longer than the prompt emission.In this scenario the nascent neutron star could undergo a secular bar-modeinstability, leading to gravitational wave losses which would affect theneutron star spin-down. In this case, nearby gamma-ray bursts with isotropicenergies of the order of 1e50 ergs would produce a detectable gravitationalwave signal emitted in association with an observed X-ray light-curve plateau,over relatively long timescales of minutes to about an hour. The peak amplitudeof the gravitational wave signal would be delayed with respect to the gamma-rayburst trigger, offering gravitational wave interferometers such as the advancedLIGO and Virgo the challenging possibility of catching its signature on thefly.