Very fast optical flaring from a possible new Galactic magnetar

TL;DR

This paper reports the first observation of extremely bright, rapid optical flares from a galactic transient, suggesting a possible new class of magnetar with optical activity similar to high-energy phenomena.

Contribution

The discovery of unprecedented fast optical flaring in a galactic transient, indicating potential new magnetar behavior with optical emissions comparable to high-energy counterparts.

Findings

First detection of rapid optical flaring in a galactic transient

Optical flares resemble high-energy magnetar emissions

Suggests a new class of magnetars with optical activity

Abstract

Highly luminous rapid flares are characteristic of processes around compact objects like white dwarfs, neutron stars or black holes. In the high energy regime of X- and gamma-rays, outbursts with variability time-scales of seconds and faster are routinely observed, e.g. in gamma-ray bursts or Soft Gamma Repeaters. In the optical, flaring activity on such time-scales has never been observed outside the prompt phase of GRBs. This is mostly due to the fact that outbursts with strong, fast flaring usually are discovered in the high-energy regime. Most optical follow-up observations of such transients employ instruments with integration times exceeding tens of seconds, which are therefore unable to resolve fast variability. Here we show the observation of extremely bright and rapid optical flaring in the galactic transient SWIFT J195509.6+261406. Flaring of this kind has never previously been reported. Our optical light-curves are phenomenologically similar to high energy light-curves of Soft Gamma Repeaters and Anomalous X-ray Pulsars, which are thought to be neutron stars with extremely high magnetic fields (magnetars). This suggests similar emission processes may be at work, but in contrast to the other known magnetars with strong emission in the optical.