Probing magnetar formation channels with high-precision astrometry: The progress of VLBA astrometry of the fastest-spinning magnetar Swift J1818.0-1607

TL;DR

This paper reports high-precision VLBA astrometry of the fastest-spinning magnetar Swift J1818.0-1607, aiming to test magnetar formation theories by analyzing its space velocity and distribution, and exploring links to fast radio bursts.

Contribution

It provides the first high-precision astrometric measurements of Swift J1818.0-1607, including proper motion and tentative parallax, to probe magnetar formation channels.

Findings

Measured proper motion of Swift J1818.0-1607

Tentative parallax measurement obtained

Results can distinguish between formation models

Abstract

Boasting supreme magnetic strengths, magnetars are among the prime candidates to generate fast radio bursts. Several theories have been proposed for the formation mechanism of magnetars, but have not yet been fully tested. As different magnetar formation theories expect distinct magnetar space velocity distributions, high-precision astrometry of Galactic magnetars can serve as a probe for the formation theories. In addition, magnetar astrometry can refine the understanding of the distribution of Galactic magnetars. This distribution can be compared against fast radio bursts (FRBs) localized in spiral galaxies, in order to test the link between FRBs and magnetars. Swift J1818.0-1607 is the hitherto fastest-spinning magnetar and the fifth discovered radio magnetar. In an ongoing astrometric campaign, we have observed Swift J1818.0-1607 for one year using the Very Long Baseline Array, and have determined a precise proper motion as well as a tentative parallax for the magnetar.