Bright X-ray and Radio Pulses from a Recently Reactivated Magnetar

Abstract

Magnetars are young, rotating neutron stars that possess larger magnetic fields ($B$ $\approx$ $10^{13}$-$10^{15}$ G) and longer rotational periods ($P$ $\approx$ 1-12 s) than ordinary pulsars. In contrast to rotation-powered pulsars, magnetar emission is thought to be fueled by the evolution and decay of their powerful magnetic fields. They display highly variable radio and X-ray emission, but the processes responsible for this behavior remain a mystery. We report the discovery of bright, persistent individual X-ray pulses from XTE J1810-197, a transient radio magnetar, using the Neutron star Interior Composition Explorer (NICER) following its recent radio reactivation. Similar behavior has only been previously observed from a magnetar during short time periods following a giant flare. However, the X-ray pulses presented here were detected outside of a flaring state. They are less energetic and display temporal structure that differs from the impulsive X-ray events previously observed from the magnetar class, such as giant flares and short X-ray bursts. Our high frequency radio observations of the magnetar, carried out simultaneously with the X-ray observations, demonstrate that the relative alignment between the X-ray and radio pulses varies on rotational timescales. No correlation was found between the amplitudes or temporal structure of the X-ray and radio pulses. The magnetar's 8.3 GHz radio pulses displayed frequency structure, which was not observed in the pulses detected simultaneously at 31.9 GHz. Many of the radio pulses were also not detected simultaneously at both frequencies, which indicates that the underlying emission mechanism producing these pulses is not broadband. We find that the radio pulses from XTE J1810-197 share similar characteristics to radio bursts detected from fast radio burst (FRB) sources, some of which are now thought to be produced by active magnetars.

54 pages, 8 figures, Submitted for publication in Nature Astronomy

References in corpus (12)

• TEMPO2, a new pulsar timing package. I: Overview
• The direct localization of a fast radio burst and its host
• Transient pulsed radio emission from a magnetar
• A repeating fast radio burst source localised to a nearby spiral galaxy
• A single fast radio burst localized to a massive galaxy at cosmological distance
• 1E 1547.0-5408: a radio-emitting magnetar with a rotation period of 2 seconds
• Wideband polarized radio emission from the newly revived magnetar XTE J1810$-$197
• Simultaneous multi-frequency single-pulse properties of AXP XTE J1810-197
• Magnetar-like X-ray bursts suppress pulsar radio emission
• Neutral Hydrogen Absorption Toward XTE J1810-197: the Distance to a Radio-Emitting Magnetar
• Fast Radio Bursts from reconnection events in magnetar magnetospheres
• Detecting Fast Radio Bursts in the Milky Way

Cited by in corpus (5)

• What does FRB light-curve variability tell us about the emission mechanism?
• A 62-minute orbital period black widow binary in a wide hierarchical triple
• The X-ray evolution and geometry of the 2018 outburst of XTE J1810-197
• Multiwavelength Constraints on the Origin of a Nearby Repeating Fast Radio Burst Source in a Globular Cluster
• Multi-frequency radio observations of the radio-loud magnetar XTE J1810-197