Related papers: Axion Clouds around Neutron Stars
A finite axion-nucleon coupling enables the production of axions in stellar environments via the thermal excitation and subsequent de-excitation of the $^{57}$Fe isotope. Given its low-lying excited state at 14.4 keV, $^{57}$Fe can be…
New particles coupled to the Standard Model can equilibrate in stellar cores if they are sufficiently heavy and strongly coupled. In this work, we investigate the astrophysical consequences of such a scenario for massive stars by…
An effective Lagrangian for the interaction between a pseudo-scalar (axion-like) field and massive fermions is considered. At high density and non-zero temperature axions can be produced through bremsstrahlung. If the axion-neutron…
Axion-photon conversion is a prime mechanism to detect axion-like particles that share a coupling to the photon. We point out that in the vicinity of neutron stars with strong magnetic fields, magnetars, the effective photon mass receives…
For the first time, we predict the axion spectra and their associated luminosities for several low-mass stars -- one and two solar masses stars in the main sequence and post-main sequence stages of evolution. Equally, we also compute the…
We investigate solar X-ray observations as a probe of axions and axion-like particles. These particles can be produced in the interior of the Sun via the conversion of thermal photons, as well as through processes involving axion-electron…
Axion is one of the most popular candidates of the cosmological dark matter. Recent studies considering the misalignment production of axions suggest some benchmark axion mass ranges near $m_a \sim 20$ $\mu$eV. For such axion mass, the…
Axions with masses of order keV can be produced in great abundance within the Solar core. The majority of Sun-produced axions escape to infinity, but a small fraction of the flux is produced with speeds below the escape velocity. Over time,…
If dark matter is composed of axions, then axion stars form in the cores of dark matter halos. These stars are unstable above a critical mass, decaying to radio photons that heat the intergalactic medium, offering a new channel for axion…
As a cold dark matter candidate, the QCD axion may form Bose-Einstein condensates, called axion stars, with masses around $10^{-11}\,M_{\odot}$. In this paper, we point out that a brand new astrophysical object, a Hydrogen Axion Star (HAS),…
Axions are expected to be produced in the sun via the Primakoff process. They may be detected through the inverse process in the laboratory, under the influence of a strong magnetic field, giving rise to X-rays of energies in the range of a…
The nature of dark matter is one of the longest-standing puzzles in science. Axions or axion-like particles are a key possibility, and arise in mechanisms to solve the strong CP problem but also in low-energy limits of string theory.…
Light QCD axions, introduced to solve the strong CP problem, may form condensates inside neutron stars, giving rise to a novel ground state of dense matter. We investigate how such axion condensates modify the equilibrium structure and…
It is a well-known fact that compact gravitating objects admit bound state configurations for massive bosonic fields. In this work we describe a new class of superradiant instabilities of axion bound states in neutron star magnetospheres.…
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…
Electromagnetic fields surrounding pulsars may source coherent ultralight axion signals at the known rotational frequencies of the neutron stars, which can be detected by laboratory experiments (e.g., pulsarscopes). As a promising case…
We investigate the distribution of an interacting axion-like massive field within a magnetized Neutron Star. For this we consider the effect of an intense density-dependent axially symmetric stellar magnetic field ${\bf B}(r,\theta)$ adding…
Axion physics is briefly reviewed. Constraints from laboratory searches, astrophysics and cosmology require the axion mass to be in the range $10^{-6} \lesssim m_a < 3\cdot 10^{-3}$eV. Near the lower end of this range, axions are all or a…
The hot interiors of massive stars in the later stages of their evolution provide an ideal place for the production of heavy axion-like particles (ALPs) with mass up to O(100 keV) range. We show that a fraction of these ALPs could stream…
If dark matter is mainly composed of axions, the density distribution can be nonuniformly distributed, being clumpy instead. By solving the Einstein-Klein-Gordon system of a scalar field with the potential energy density of an axionlike…