Constraints on the polarization angle oscillations of the Crab Nebula with the Simons Array and its applications to the search for axion-like particles

TL;DR

This study uses the Simons Array to search for polarization oscillations in the Crab Nebula, aiming to validate its stability as a calibration source and to constrain axion-like particles, finding no significant signals but setting upper bounds.

Contribution

First to use the Simons Array for polarization oscillation search in Tau A, providing new constraints on axion-like particles and polarization stability at millimeter wavelengths.

Findings

No detection of polarization oscillation signals.

Set upper bounds on ALP-photon coupling.

No confirmation of previously hinted signals.

Abstract

We present a search for polarization oscillation of the Crab Nebula, also known as Tau A, at millimeter wavelengths using observations with the Simons Array, the successor experiment to POLARBEAR. We follow up on previous work by POLARBEAR using 90 GHz band data of the 2023 observing season of the Simons Array to evaluate the variability of Tau A's polarization angle. Tau A is widely used as a polarization angle calibration source in millimeter-wave astronomy, and thus it is necessary to validate the stability. Additionally, an interesting application of the time-resolved polarimetry of Tau A is to search for axion-like particles (ALPs). We do not detect a global signal across the frequencies considered in this analysis and place a median 95% upper bound of polarization oscillation amplitude $A<0.12^{\circ}$ over oscillation frequencies from 3.39 year$^{-1}$ to 1.50 day$^{-1}$. This constrains the ALP-photon coupling at a median 95% upper bound of $g_{a\gamma\gamma}< 3.84\times 10^{-12}\times\left(m_a/10^{-21}\,\mathrm{eV}\right)$ in the mass range from $4.4\times10^{-22}$ to $7.2\times10^{-20}$ eV, assuming the ALP constitutes all of dark matter, its field is a stochastic Gaussian field, and it is the sole source of Tau A's polarization angle oscillation. Additionally, we do not detect signal at the frequencies where 2.5$\sigma$ hints were previously reported by POLARBEAR, but we do not exclude these signals at the 95% confidence level.