Gravity And Extreme Magnetism SMEX - GEMS
Abstract
The Gravity and Extreme Magnetism Small explorer (GEMS) will make a sensitive survey of the polarization of the 2-10 keV X-ray flux from most of the categories of bright (> 1 mCrab) astrophysical X-ray sources. The baseline mission will measure the polarization degree and angle for stellar and supermassive black holes to test models for black hole spin and the emission source geometry. GEMS will determine the emission regions for neutron stars that are magnetars as well as those that are accretion-powered and rotation-powered. It will observe selected shock regions of shell supernova remnants to constrain the magnetic field characteristics. It will determine average field direction of selected pulsar wind nebulae. GEMS uses the polarization sensitivity of the photoelectric effect in gas polarimeters that are Time Projection Chambers at the focus of X-ray foil mirrors. The observatory rotates at about 0.1 rpm so that systematic errors can be seen and much reduced. A small Bragg reflection soft X-ray experiment makes use of the rotation to extend the sensitivity to 0.5 keV. Over the last year requirements were developed. The resource margins can accommodate two telescopes, which can provide the survey within a baseline mission of 9 months. A Preliminary Design Review at the end of September 2011 will show the results of engineering test units of the polarimeters and the extendable boom needed to deploy the telescopes.
GEMS is a SMEX mission proposed in response to NASA's AO NNH07ZDA0030 and selected to launch in 2014.- Publication:
-
AAS/High Energy Astrophysics Division #12
- Pub Date:
- September 2011
- Bibcode:
- 2011HEAD...12.2901H