Astronomers from the Open University in Milton Keynes, UK and elsewhere report the detection of a new Be/X-ray binary. The newfound system, designated 4XMM J182531.5–144036, exhibits persistent X-ray emission. The finding was detailed in a paper published January 4 on the pre-print server arXiv.
Be/X-ray binaries (Be/XRBs) are the largest subgroup of HMXBs. These systems consist of Be stars and, usually, neutron stars, including pulsars. Observations have found that most of these systems showcase weak persistent X-ray emission that is interrupted by outbursts lasting several weeks.
4XMM J182531.5–144036 was initially detected as a hard X-ray source in April 2008 with ESA’s XMM-Newton satellite. Given that its nature remains undisclosed, a team of astronomers led by Open University’s Andrew Mason Jr. has analyzed the available data from XMM-Newton, NASA’s Chadra spacecraft, Very Large Telescope (VLT) and UKIDSS (UKIRT Infrared Deep Sky Survey) Galactic Plane Survey, in order to investigate this source.
The study found that the position of 4XMM J182531.5–144036 is coincident with an infrared object exhibiting a near-infrared excess when compared to the spectra of early B-type dwarf or giant stars. This object also displays a strong hydrogen emission line. The researchers noted that these properties are characteristic for Be stars.
Furthermore, coherent X-ray pulsation of 4XMM J182531.5–144036 was detected, with a period of 781 seconds. The presence of such a pulsation is typical for BeXRB pulsars. The astronomers added that the X-ray pulse profile is asymmetric, which is seen in X-ray pulsars and it can provide information about the magnetic field structure of the neutron star.
2024-01-16 08:41:03
Article from phys.org rnrn
