Fermi/GBM detection of renewed activity from the transient Be/X-ray binary 4U 0115+634
ATel #16353; C. Malacaria (ISSI), P. Jenke (UAH), C. A. Wilson-Hodge (NASA/MSFC)
on 29 Nov 2023; 15:24 UT
Credential Certification: Christian Malacaria (cmalacaria.astro@gmail.com)
Subjects: X-ray, Neutron Star, Transient, Pulsar
We report on recent detections with Fermi/GBM of the transient Be/X-ray binary system 4U 0115+634 with the GBM Accreting Pulsar Program (GAPP, Malacaria et al. 2020, ApJ, 896, 90).
GBM detected pulsations from the source starting on Nov. 24, 2023 (MJD 60272) with an orbit-corrected spin frequency of 276.6825(3) mHz and on Nov. 27, 2023 (MJD 60274) with a spin frequency of 276.6841(4) mHz, thus showing local spin-up. The source pulsed flux in the 12-50 keV band during the latest detection is 0.186 +/- 0.017 erg/cm^2/s.
Earlier GBM detection of this source was in Oct. 7, 2023 (MJD 60224) when transient pulsations were detected at a spin frequency of 276.6841(3) mHz.
GBM will keep monitoring the source. The GBM pulse history of this source can be found at:
https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/4u0115.html
We encourage further observations with X-ray observatories and multi-wavelength facilities.
