Published in Journal of Cosmology and Astroparticle Physics
We revisit the evidence for CMB birefringence in the context of a rich Axiverse. Using probability density functions (PDFs) for various axion parameters, such as the mass and axion decay constant, we construct the PDF for the cosmic birefringence angle and investigate its properties. By relating the observed value of the birefringence angle to the ...
Published in Journal of Cosmology and Astroparticle Physics
In this work, we show that the Cold New Early Dark Energy (Cold NEDE) model in its original form can solve both the Hubble tension and the S 8 tension without adding any new ingredients at the fundamental level. So far, it was assumed that the trigger field in the Cold NEDE model is completely subdominant. However, relaxing this assumption and lett...
Published in Journal of Cosmology and Astroparticle Physics
We propose a novel explanation for the 18 TeV gamma ray from GRB 221009A observed by LHAASO. High-energy neutrinos are converted into axion-like particles (ALPs) via their interaction with the cosmic neutrino background. Subsequently, ALPs are converted into high-energy photons in the magnetic field of our galaxy. We compute the fluxes of neutrinos...
Published in Journal of Cosmology and Astroparticle Physics
We investigate how the resonant conversion at a temperature T̅ = 25–65 keV of a fraction of the CMB photons into an axion-like majoron affects BBN. The scenario, that assumes the presence of a primordial magnetic field and the subsequent decay of the majorons into neutrinos at T ≈ 1 eV, has been proposed to solve the H 0 tension. We find two main e...
Published in Journal of Cosmology and Astroparticle Physics
We compute the detailed energy spectra of axions with two-photon coupling produced in stellar cores over a wide range of stellar masses. We focus on main sequence stars and base our calculations on the stellar interior profiles from MESA, for which we provide simple fits in an appendix. The obtained stellar axion spectra, combined with recent model...
Published in Journal of Cosmology and Astroparticle Physics
In this study, we examine the phenomenon of photon axion conversion occurring in the spacetime surrounding a black hole. Specifically, we focus on the potential existence of a magnetic field around the supermassive black hole M87*, which could facilitate the conversion of photons into axions in close proximity to the photon sphere. While photons tr...
Published in Journal of Cosmology and Astroparticle Physics
Oscillating scalar field condensates induce small amplitude oscillations of the Hubble parameter which can induce a decay of the condensate due to a parametric resonance instability [1]. We show that this instability can lead to the decay of the coherence of the condensate of axion-like particle (ALP) fields during the radiation phase of standard c...
Published in Journal of Cosmology and Astroparticle Physics
Axion-like particles (ALPs) are leading candidates to explain the dark matter in the universe. Their production via the misalignment mechanism has been extensively studied for cosine potentials characteristic of pseudo-Nambu-Goldstone bosons. In this work we investigate ALPs with non-periodic potentials, which allow for large misalignment of the fi...
Published in Journal of Cosmology and Astroparticle Physics
Axions, if discovered, could serve as a powerful new messenger for studying astrophysical objects. In this study we show how the Sun's spatial and spectral “axion image” can be inverted to infer the radial dependence of solar properties in a model-independent way. In particular, the future helioscope IAXO may allow us to accurately reconstruct the ...
Published in Journal of Cosmology and Astroparticle Physics
Axion-like particles (ALPs) are a broad class of pseudo-scalar bosons that generically arise from broken symmetries in extensions of the standard model. In many scenarios, ALPs can mix with photons in regions with high magnetic fields. Photons from distant sources can mix with ALPs, which then travel unattenuated through the Universe, before they m...
