Related papers: Stellar Evolution confronts Axion Models
Relativistic axions are good candidates for the dark radiation for which there are mounting observational hints. The primordial decays of heavy fields produce axions which are ultra-energetic compared to thermalised matter and inelastic…
In this chapter I give an overall description of the structure and evolution of stars of different masses, and review the main ingredients included in state-of-the-art calculations aiming at reproducing observational features. I give…
Axions, if realized in nature, can be copiously produced in the early universe via thermal processes, contributing to the mass-energy density of thermal hot relics. In light of the most recent cosmological observations, we analyze two…
There has been remarkable progress recently in both observational and theoretical studies of galaxy formation and evolution. Largely due to a combination of deep Hubble Space Telescope imaging, Keck spectroscopy, and COBE far-IR background…
Understanding the origins and distribution of matter in the Universe is one of the most important quests in physics and astronomy. Themes range from astro-particle physics to chemical evolution in the Galaxy to cosmic nucleosynthesis and…
We derive a strong bound on the axion-photon coupling $g_{a\gamma}$ from the analysis of a sample of 39 Galactic Globular Clusters. As recognized long ago, the R parameter, i.e. the number ratio of stars in horizontal over red giant branch…
The modelling of massive star evolution is a complex task, and is very sensitive to the way physical processes (such as convection, rotation, mass loss, etc.) are included in stellar evolution code. Moreover, the very high observed fraction…
We explore the dynamics of boson stars in the presence of axionic couplings through nonlinear evolutions of Einstein's field equations. We show that, for large axionic couplings, isolated boson stars become unstable, and decay via a large…
The Peccei-Quinn mechanism proposed to solve the CP problem of Quantum Chromodynamics has as consequence the existence of axions, hypothetical weakly interacting particles whose mass is constrained to be on the sub-eV range. If these…
Recently we have proposed a simple hadronic axion model within gauge-mediated supersymmetry breaking. In this paper we discuss various cosmological consequences of the model in great detail. A particular attention is paid to a saxion, a…
We review current cosmological constraints on the axion. We describe the basic mechanisms by which axions are created in the early universe, focussing on the standard thermal scenario where the dominant process is through axion radiation by…
1. Introduction 2. Models: the QCD axion; the strong CP problem; PQWW, KSVZ, DFSZ; anomalies, instantons and the potential; couplings; axions in string theory 3. Production and I.C.'s: SSB and non-perturbative physics; the axion field…
The origin of various celestial phenomena have remained mysterious for conventional astrophysics. Therefore, alternative solutions should be considered, taking into account the involvement of unstable dark-matter particle candidates, such…
Stellar energy loss arguments lead to strong constraints on the coupling $\phi \gamma \gamma$ of a light axion-like particle to two photons. Helioscopes, like CAST, are able to put competitive bounds. The PVLAS experiment has recently…
Rotation has a number of important effects on the evolution of stars. Apart from structural changes because of the centrifugal force, turbulent mixing and meridional circulation caused by rotation can dramatically affect a star's chemical…
Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core $|\theta_0| \equiv…
High precision photometry and spectroscopy of low-mass stars reveal a variety of properties standard stellar evolution cannot predict. Rotation, an essential ingredient of stellar evolution, is a step towards resolving the discrepancy…
We discuss how recent advances in observations, theory and numerical simulations have allowed the stellar community to progress in its understanding of stellar convection, rotation and magnetism and to assess the degree to which the Sun and…
We have searched for solar axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup with improved conditions in all detectors. From the absence of excess X-rays when the magnet was pointing…
The observable characteristics and subsequent evolution of young stellar populations is dominated by their massive stars. As our understanding of those massive stars and the factors affecting their evolution improves, so our interpretation…