Speaker
Description
The accreting pulsar 4U1907-09 is one of ~35 high-mass X-ray binaries with known high
magnetic field strengths. A detected cyclotron resonance scattering feature (CRSF) at ~19 keV leads
to a field strength of ~$\sim 2\times10^{12}$ G. The system consists of a slowly-rotating (~440 s) X-ray
pulsar accreting from the stellar wind of an O8/9 supergiant. The X-ray pulsar is in a close
(~8.37 d) elliptical orbit (e $\sim$ 0.28) around its donor.
We conducted an analysis of four High Energy Transmission Grating observations with the
Chandra X-ray Observatory for a total of ~140 ks and one NuSTAR observation for 78 ks, at
different orbital phases, to probe the variation of the absorbing column around the orbit.
We measure line fluorescence at Fe K and possibly Si K and other lower Z elements to study
dense clumps in the wind of the pulsar's companion star. The details of the NuSTAR
observation are used to determine the higher energy continuum beyond 10 keV.
