Speaker
Description
The Exploring the X-ray Transient and variable Sky (EXTraS) project represents the most thorough living search for new X-ray pulsators in the XMM-Newton archive, having led to the discovery of about 60 new pulsators and still counting. In 2022, we discovered an X-ray pulsator on the outskirts of the Large Magellanic Cloud (LMC). The source (J0456 from now on) shows a coherent signal with a period of $P\sim7.25\,\mathrm{s}$, which allows us to classify J0456 as a spinning neutron star, a scenario also supported by spectral analysis. Furthermore, J0456 is a highly variable source, with only one detection out of five XMM-Newton and eROSITA observations. In this talk, I will report the results of our Swift monitoring programme and show that, regardless of its classification, this new pulsar represents a peculiar object. The only optical object within the XMM-Newton uncertainty region is a low-mass star. Should the star be the optical counterpart of J0456, this system would be the first of its kind in the LMC and a real puzzle for the current evolutionary models. Alternatively, the object is unrelated, and J0456 is isolated. In this case, the combination of high pulsed fraction ($\sim86\%$) and low luminosity ($\sim2.7\times10^{34}\,\mathrm{erg}\,\mathrm{s}^{-1}$ in the 0.3-10 keV band) suggests that J0456 is a candidate magnetar, the third known outside our Galaxy.
