A new probe of axion-like particles: CMB polarization distortions due to cluster magnetic fields

Abstract

We propose using the upcoming Cosmic Microwave Background (CMB) ground based experiments to detect the signal of ALPs (Axion like particles) interacting with magnetic fields in galaxy clusters. The conversion between CMB photons and ALPs in the presence of the cluster magnetic field can cause a polarized spectral distortion in the CMB around a galaxy cluster. The strength of the signal depends upon the redshift of the galaxy cluster and will exhibit a distinctive spatial profile around it depending upon the structure of electron density and magnetic field. This distortion produces a different shape from the other known spectral distortions like y-type and µ-type and hence are separable from the multi-frequency CMB observation. The spectrum is close to Kinetic Sunyaev-Zeldovich (kSZ) signal but can be separated from it using the polarization information. For the future ground-based CMB experiments such as Simons Observatory and CMB-S4, we estimate the measurability of this signal in the presence of foreground contamination, instrument noise and CMB anisotropies. This new avenue can probe the photon-ALP coupling over the ALP mass range from a few ×10 −14 eV to 10 −12 eV with two orders of magnitude better accuracy from CMB-S4 than the current existing bounds.

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

“…Along with the spectral distortions on the CMB monopole, spatially fluctuating polarised CMB spectral distortion can also arise due to conversion of photons to axions (or axion like particles (ALPs)) in the presence of external magnetic field as proposed in Refs. [1887,1888]. The measurement of the polarised axion distortion will provide a new way to detect the coupling of photons with ALPs in the mass range 10 −11 -10 −14 eV.…”

“…The complementary between CMB anisotropies and SDs mentioned at the beginning of this section can also be applied to models requiring, for example, primordial magnetic fields (PMFs) [658,1889,1890], DM with non-standard characteristics, such as decays [1811,1871] or interactions [1223,1891], Axion-Like Particles [1887,1888] and dark photons, or primordial black holes [1811,[1892][1893][1894][1895]. Many of this scenarios have also been shown to solve either the Hubble tension, such as for PMFs [651], the EDGES anomaly, such as for DM-b interactions [1896], or the σ 8 tension, such as for DM-photon interactions [1236,1238].…”

New horizons in cosmology with spectral distortions of the cosmic microwave background

“…The northsouth asymmetry of the signal stems from the structure of the galactic magnetic field and electron density distortion signal requires both wide frequency-and sky-coverage, which is possible only with space-based CMB missions. The same physical effect also arises in galaxy clusters [254] and produces polarized spectral distortions that can be measured using high-resolution CMB experiments with an imaging telescope [59,255].…”

A space mission to map the entire observable universe using the CMB as a backlight

“…It is to be noted that our survey of Backlight science is not exhaustive and there remain further possibilities to probe the interaction of CMB photons with intervening matter. For example, CMB as a backlight can be used to measure the coupling strength between photon and axion/Axion Like Particles (ALPs) by exploiting a new kind of spectral distortions originating in the presence of magnetic field in galaxy clusters [15] 3.1 The dark sector: dark energy, dark matter and gravity…”