A magnetar-powered X-ray transient as the aftermath of a binary neutron-star merger

Understand

Neutron star-neutron star mergers are known to be associated with short gamma-ray bursts.

• If the neutron star equation of state is sufficiently stiff, at least some of such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field (i.e., a magnetar).
• Such a magnetar signature may have been observed as the X-ray plateau following a good fraction (up to 50%) of short gamma-ray bursts, and it has been expected that one may observe short gamma-ray burst-less X-ray transients powered by double neutron star mergers.
• A fast X-ray transient (CDF-S XT1) was recently found to be associated with a faint host galaxy whose redshift is unknown.