Fermi/GBM Detection of 9.80s Pulsation from XTE J1859+083
ATel #7045; Mark H. Finger (USRA), Peter A. Jenke (UAH) and Colleen Wilson-Hodge (NASA/MSFC)
on 10 Feb 2015; 19:34 UT
Credential Certification: Dr. Mark H. Finger (mark.h.finger@nasa.gov)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
Referred to by ATel #: 7067
Using Fermi/GBM data we have measured 9.80 s pulsations from the direction of XTE J1859+083, which has recently been reported as being active (ATel #7034, ATel #7037), confirming the identity of the source.
In our daily FFT based pulse search we had two weak detections on February 7 and 8 that were consistent with a source with a pulse period near 9.80s in the general direction of XTE J1859+083. In response we have made pulse searches using the Fermi/GBM NaI detectors in the 12-50 keV band. These searches where in 5 day intervals beginning 2014 November 27, and were optimized for the direction of XTE J1859+083. The searches included barycentric frequencies in the range 0.10175-0.10211 Hz and barycentric frequency rates in the range of +/- 1.0 E-10 Hz/s. Significant pulsations were found in the intervals January 26.0-31.0, January 31.0-February 5.0, and February 5.0-10.0. The frequencies at the middle of these intervals were 0.1019513(1) 0.1019590(1) , and 0.1019832(1) Hz. The frequency rates in these intervals were -7(2)E-12, 4.2(2)E-11, and 6.7(2)E-11 Hz/s. The frequency and frequency rate in the 3 intervals is consistent with a continuous evolution in pulse frequency.
The changes in frequency are likely caused by a combination of orbital motion and accretion induced spin-up and are of the magnitude observed by R. H. D. Corbet et al., ApJ 695:30-35, 2009.
GBM Pulsar Project
