Testing the Axion-Conversion Hypothesis of 3.5 keV Emission with Polarization

Yan Gong, Xuelei Chen, and Hua Feng
Phys. Rev. Lett. 118, 061101 – Published 10 February 2017

Abstract

The recently measured 3.5 keV line in a number of galaxy clusters, the Andromeda galaxy (M31), and the Milky Way (MW) center can be well accounted for by a scenario in which dark matter decays to axionlike particles (ALPs) and subsequently convert to 3.5 keV photons in magnetic fields of galaxy clusters or galaxies. We propose to test this hypothesis by performing x-ray polarization measurements. Since ALPs can only couple to photons with a polarization orientation parallel to the magnetic field, we can confirm or reject this model by measuring the polarization of the 3.5 keV line and compare it to the orientation of the magnetic field. We discuss luminosity and polarization measurements for both a galaxy cluster and spiral galaxy, and provide a general relation between the polarization and galaxy inclination angle. This effect is marginally detectable with x-ray polarimetry detectors currently under development, such as the enhanced X-ray Timing and Polarization satellite, the Imaging X-ray Polarimetry Explorer and the X-ray Imaging Polarimetry Explorer. The sensitivity can be further improved in the future with detectors of a larger effective area or better energy resolutions.

  • Figure
  • Figure
  • Figure
  • Received 1 June 2016

DOI:https://doi.org/10.1103/PhysRevLett.118.061101

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Yan Gong1, Xuelei Chen1,2,3,*, and Hua Feng4

  • 1Key Laboratory of Computational Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Center of High Energy Physics, Peking University, Beijing 100871, China
  • 4Department of Engineering Physics and Center for Astrophysics, Tsinghua University, Beijing 100084, China

  • *Corresponding author. xuelei@cosmology.bao.ac.cn

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 118, Iss. 6 — 10 February 2017

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Letters

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×