The First Magnetar in a Binary System?

In March 2016, Swift found a new magnetar candidate designated SGR 0755-2933. Coincident to this target on the sky, we found a Be star: CPD-29 2176. We obtained 17 spectroscopic observations from CTIO and the Chiron spectrograph for this target. These spectra showed that the star has a He II 4686 Å line in absorption, consistent with a spectral type of B0Ve. From measurements of the radial velocity, we find a single-lined orbit which is consistent with the reflex motion from a magnetar companion in a 60-day orbit. Photometric data shows no evidence of eclipses but does show long-term variations similar to Be-X-ray binaries. We are continuing to analyze the spectroscopic observations to investigate possible disk variability related to the orbit or long-term behavior.

This research was partially supported through Embry-Riddle Aeronautical University’s Faculty Innovative Research in Science and Technology (FIRST) Program.