Searching for axion-like time-dependent cosmic birefringence with data from SPT-3G

TL;DR

This paper uses cosmic microwave background data from SPT-3G to set new upper limits on axion-like particles' coupling to photons, constraining their properties as dark matter candidates within specific mass and oscillation period ranges.

Contribution

First to analyze CMB polarization data for time-dependent cosmic birefringence caused by axion-like particles, improving existing limits on axion-photon coupling by a factor of 3.8.

Findings

Set upper limits on axion-photon coupling for masses 10^{-22} to 10^{-19} eV.

Achieved a median 95% C.L. upper limit on polarization rotation amplitude of 0.071 degrees.

Improved previous limits on axion-like particles by a factor of approximately 3.8.

Abstract

Ultralight axionlike particles (ALPs) are compelling dark matter candidates because of their potential to resolve small-scale discrepancies between $\Lambda$CDM predictions and cosmological observations. Axion-photon coupling induces a polarization rotation in linearly polarized photons traveling through an ALP field; thus, as the local ALP dark matter field oscillates in time, distant static polarized sources will appear to oscillate with a frequency proportional to the ALP mass. We use observations of the cosmic microwave background from SPT-3G, the current receiver on the South Pole Telescope, to set upper limits on the value of the axion-photon coupling constant $g_{\phi\gamma}$ over the approximate mass range $10^{-22} - 10^{-19}$ eV, corresponding to oscillation periods from 12 hours to 100 days. For periods between 1 and 100 days ($4.7 \times 10^{-22} \text{ eV} \leq m_\phi \leq 4.7 \times 10^{-20} \text{ eV}$), where the limit is approximately constant, we set a median 95% C.L. upper limit on the amplitude of on-sky polarization rotation of 0.071 deg. Assuming that dark matter comprises a single ALP species with a local dark matter density of $0.3\text{ GeV/cm}^3$, this corresponds to $g_{\phi\gamma} < 1.18 \times 10^{-12}\text{ GeV}^{-1} \times \left( \frac{m_{\phi}}{1.0 \times 10^{-21} \text{ eV}} \right)$. These new limits represent an improvement over the previous strongest limits set using the same effect by a factor of ~3.8.