Chameleon-photon mixing in a primordial magnetic field

Abstract

The existence of a sizable, O 10 −10 -10 −9 G , cosmological magnetic field in the early Universe has been postulated as a necessary step in certain formation scenarios for the large scale O(µG) magnetic fields found in galaxies and galaxy clusters. If this field exists then it may induce significant mixing between photons and axion-like particles (ALPs) in the early Universe. The resonant conversion of photons into ALPs in a primordial magnetic field has been studied elsewhere by Mirizzi, Redondo and Sigl (2009). Here we consider the non-resonant mixing between photons and scalar ALPs with masses much less than the plasma frequency along the path, with specific reference to the chameleon scalar field model. The mixing would alter the intensity and polarization state of the cosmic microwave background (CMB) radiation. We find that the average modification to the CMB polarization modes is negligible. However the average modification to the CMB intensity spectrum is more significant and we compare this to high precision measurements of the CMB monopole made by the far infrared absolute spectrophotometer (FIRAS) on board the COBE satellite. The resulting 95% confidence limit on the scalar-photon conversion probability in the primordial field (at 100 GHz) isP γ↔φ < 2.6 × 10 −2 . This corresponds to a degenerate constraint on the photonscalar coupling strength, g eff , and the magnitude of the primordial magnetic field. Taking the upper bound on the strength of the primordial magnetic field derived from the CMB power spectra, B λ ≤ 5.0 × 10 −9 G, this would imply an upper bound on the photon-scalar coupling strength in the range g eff 7.14 × 10 −13 GeV −1 to g eff 9.20 × 10 −14 GeV −1 , depending on the power spectrum of the primordial magnetic field.

Standard electroweak interactions in gravitational theory with chameleon field and torsion

“…8 can make new constraints on the photon-chameleon oscillations in the magnetic field of the laboratory search for the chameleon field [67][68][69].…”

Chameleons in the early Universe: Kicks, rebounds, and particle production

“…To analyze the excitation of perturbations during the chameleon field's rebound off its bare potential, we first write the chameleon field as ϕðτ; ⃗xÞ ¼φðτÞ þ δϕðτ; ⃗xÞ; (40) whereφðτÞ is the spatial average of the field. We insert this expression into the chameleon's equation of motion and Taylor expand V 0 ðϕÞ aroundφ to obtain…”

“…We can search for strongly coupled chameleons in high-precision low-energy photon experiments [19][20][21][22][23][24], with ultra-cold neutrons [25][26][27], in precision atomic measurements [28], in Casimir force experiments [29,30], with dark matter direct detection experiments [31], and in particle colliders [32,33]. It has also been suggested to look for strongly coupled chameleons produced in the Sun [34,35] and to seek chameleon signatures in observations of stars and galaxies [34][35][36][37][38][39], the cosmic microwave background [40][41][42], and the 21-cm power spectrum [43]. These experiments exploit the fact that strongly coupled chameleons interact strongly with matter particles and photons in vacuum, so if an experiment or an astrophysical observation is targeted at a diffuse environment, it has the potential to see a chameleon signal.…”

Cosmic magnetization in curved and Lorentz violating space–times

“…The aforementioned strength problem is confronted by several proposed amplification mechanisms, operating within or beyond the framework of conventional electromagnetism (see for example [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]). The vector nature of the electromagnetic field guarantees that it couples to the curvature of space-time through the Ricci identities [46][47][48].…”