polarimeter.html

Soft X-ray Polarimeter Concepts

A Narrow-band Approach

The PLEXAS design was proposed to NASA as a small explorer in 1998. A paper on this approach was presented at the 2002 SPIE meeting.

A Broad-band Approach

The basic concept was outlined in Paper 1 (pdf), presented at the SPIE meeting in 2007. This approach could be used to measure X-ray polarization across the band from 0.2 to 0.8 keV.

Paper 2 (pdf) was presented at the SPIE meeting in 2008, this paper was presented at the Rome X-ray Polarimetry meeting held in April, 2009, and Paper 3 (pdf) was presented at the SPIE meeting in 2010. This approach could be implemented as a small mission or used on a large X-ray astronomy mission such as AXSIO (pdf).

Examples of targets for both instruments:

BL Lac Objects with relativistic, magnetized jets which should be polarized up to 60 %
Isolated pulsars such as PSR 0656+14, which have a strong magnetic field which will polarize the surface emission at the 20-50% level
Quasars and Active Galactic Nuclei (AGN) whose disks will show polarized emission due to electron scattering up to 12%

Recent Work:

A laboratory for demonstrating critical components of this design is also described in Paper 3. A small scale version of the laboratory work was started in the summer of 2009 with MIT Kavli internal funding and now has NASA APRA funding. See this pdf for a presentation at the 2013 SPIE meeting in San Diego and see this pdf for the submitted paper with more details.

A successful polarization test. The polarization source is 100% polarized and its orientation was rotated through 150 degrees to demonstrate that the system can produce, rotate, and measure polarized X-rays.

For more information, see Herman Marshall, or send e-mail to hermanm -at- space.mit.edu.

Updated: September 16, 2013