The fundamental plane for radio magnetars

TL;DR

This paper suggests that radio emission in magnetars may be powered by rotational energy, similar to normal pulsars, and proposes a predictive model based on rotational period, its derivative, and X-ray luminosity.

Contribution

It introduces a new perspective that magnetar radio activity can be explained by rotational energy, challenging previous beliefs about their emission mechanisms.

Findings

Radio emission in magnetars may be powered by rotation.

Magnetar radio activity can be predicted from rotational parameters and X-ray luminosity.

Magnetar magnetic geometry influences radio emission characteristics.

Abstract

High magnetic fields are a distinguishing feature of neutron stars and the existence of sources (the soft gamma repeaters and the anomalous X-ray pulsars) hosting an ultra-magnetized neutron star (or magnetar) has been recognized in the past few decades. Magnetars are believed to be powered by magnetic energy and not by rotation, as with normal radio pulsars. Until recently, the radio quietness and magnetic fields typically above the quantum critical value (Bq~4.4x10^{13} G), were among the characterizing properties of magnetars. The recent discovery of radio pulsed emission from a few of them, and of a low dipolar magnetic field soft gamma repeater, weakened further the idea of a clean separation between normal pulsars and magnetars. In this Letter we show that radio emission from magnetars might be powered by rotational energy, similarly to what occurs in normal radio pulsars. The peculiar characteristics of magnetars radio emission should be traced in the complex magnetic geometry of these sources. Furthermore, we propose that magnetar radio activity or inactivity can be predicted from the knowledge of the star's rotational period, its time derivative and the quiescent X-ray luminosity.