The Globe Orbiting Soft X-ray (GOSoX) polarimeter concept study

We describe an implementation of a broad-band soft X-ray polarimeter, substantially based on previous designs. The Globe-Orbiting Soft X-ray Polarimeter (GOSoX) is a SmallSat. As in a related mission concept the PiSoX Polarimeter, the grating arrangement is designed optimally for the purpose of polarimetry matching the dispersion of a spectrometer to a laterally graded multilayer (LGML). For GOSoX, the optics are lightweight Si mirrors in a one-bounce parabolic configuration. The instrument covers the wavelength range from 31 A to 75 A (165 - 400 eV). Upon satellite rotation, the intensities of the dispersed spectra, after reflection and polarizing by the LGMLs, give the three Stokes parameters needed to determine a source's linear polarization fraction and orientation. The design can be extended to higher energies as LGMLs are developed further. We describe the potential scientific return and the proposed mission concept following the results of a JPL Team X concept study.