No Evidence for Axions from Chandra Observation of the Magnetic White Dwarf RE J0317-853

Area of Science:

• Particle Physics
• Astrophysics
• Cosmology

Background:

• Axions are hypothetical particles proposed to solve various astrophysical anomalies.
• These anomalies include unexpected TeV transparency, anomalous stellar cooling, and X-ray excesses from neutron stars.

Purpose of the Study:

• To investigate the constraints on axion properties, specifically the axion-photon coupling (g_{aγγ}), using observations of magnetic white dwarfs.
• To test if axions with couplings capable of resolving astrophysical anomalies are compatible with observational data.

Main Methods:

• Utilizing approximately 40 ks of data from the Chandra X-ray Observatory targeting the magnetic white dwarf RE J0317-853.
• Analyzing the non-observation of X-rays, which are predicted to be produced by axion-photon conversion in the white dwarf's magnetosphere.

Main Results:

• The non-observation of X-rays constrains the axion-photon coupling to g_{aγγ}≲5.5×10^{-13}sqrt[C_{aγγ}/C_{aee}] GeV^{-1} at 95% confidence for axion masses m_{a}≲5×10^{-6} eV.
• These results robustly disfavor axion-photon couplings g_{aγγ}≳4.4×10^{-11} GeV^{-1}, even for models without ultraviolet contributions to the electron coupling constant (C_{aee}).

Conclusions:

• Observations of magnetic white dwarfs provide stringent constraints on axion properties.
• The studied axion models, while potentially explaining astrophysical anomalies, are significantly disfavored by current observational limits.