X-Ray Polarimetry of Accreting White Dwarfs: A Case Study of EX Hydrae
Abstract We present the first first X-ray polarization measurements of a white dwarf (WD), the intermediate polar EX Hya. We measured significant polarization only in the 2–3 keV energy band with a polarization degree of 8% at a 3 σ significance. No significant polarization was detected above 3 keV, which we attribute to the higher energy bands having lower signal to noise. We found that the scattering surface detected by the Imaging X-ray Polarimetry Explorer appears to be nearly perpendicular to the optical scattering plane, showing that the X-ray scattering surface is the WD and close to the base of the accretion column. Finally, we show how the polarization can be used to estimate the height of the accretion shock above the WD’s surface.
Authors
- Yaël Nazé (ORCID: https://orcid.org/0000-0003-4071-9346)
- Pragati Pradhan (ORCID: https://orcid.org/0000-0002-1131-3059)
- Sean J. Gunderson (ORCID: https://orcid.org/0000-0003-2602-6703)
- Herman L. Marshall (ORCID: https://orcid.org/0000-0002-6492-1293)
- Dustin K. Swarm (ORCID: https://orcid.org/0000-0003-1898-4223)
- Richard Ignace (ORCID: https://orcid.org/0000-0002-7204-5502)
- David P. Huenemoerder (ORCID: https://orcid.org/0000-0002-3860-6230)
- Swati Ravi (ORCID: https://orcid.org/0000-0002-2381-4184)
Institutions
- East Tennessee State University (US)
- University of Iowa (US)
- University of Liège (BE)
- Massachusetts Institute of Technology (US)
- Embry–Riddle Aeronautical University (US)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-11-10
- DOI
- https://doi.org/10.3847/1538-4357/ae11b5
- Citations
- 1
- Primary Topic
- Astrophysical Phenomena and Observations
- Type
- article
- Field-Weighted Citation Impact
- 1.15