Insight-HXMT Discovery of the Highest-energy CRSF from the First Galactic Ultraluminous X-Ray Pulsar Swift J0243.6+6124
The Swift J0243.6+6124 is one of my favorite sources, linking normal pulsars with PULXs and one where we found solid evidence for presence of radiatively-pressure-dominated accretion disk normally reserved for BH systems. Now with the help of Insight-HXMT it was possible to detect also the highest-energy-to-date cyclotron line in spectrunm of the source!
The results are reported in Chinese-led paper where we also discuss implications of the discovery. Basically, it does not simply imply that the field is strong, it also means that the field is strongly non-dipolar!