Spin frequency evolution and pulse profile variations of the recently re-activated radio magnetar XTE J1810-197

Understand

After spending almost a decade in a radio-quiet state, the Anomalous X-ray Pulsar XTE J1810-197 turned back on in early December 2018.

• We have observed this radio magnetar at 1.5 GHz with ~daily cadence since the first detection of radio re-activation on 8 December 2018.
• In this paper, we report on the current timing properties of XTE J1810-197 and find that the magnitude of the spin frequency derivative has increased by a factor of 2.6 over our 48-day data set.
• We compare our results with the spin-down evolution reported during its previous active phase in the radio band.