Related papers: Pulse and Polarization Structures in Axion-Convert…
Neutron stars provide ideal astrophysical laboratories for probing new physics beyond the Standard Model. If axions exist, photons can develop linear polarization during photon-axion conversion in the magnetic field of a neutron star. We…
The intense magnetic fields of neutron stars naturally lead to strong anisotropy and polarization of radiation emanating from their surfaces, both being sensitive to the hot spot position on the surface. Accordingly, pulse phase-resolved…
Axion-like particles can be abundantly produced through scattering processes in the cores of neutron stars (NSs). If they are ultralight ($m_a \lesssim 10^{-4}$ eV), then they can efficiently convert to detectable photons in the external NS…
Recent investigations by Noordhuis et al. [1, 2] and others have demonstrated the occurrence of strong local inhomogeneous axion regions in the polar cap regions of neutron stars. These regions are characterized by static magnetic fields…
We review the polarization properties of X-ray emission from highly magnetized neutron stars, focusing on emission from the stellar surfaces. We discuss how x-ray polarization can be used to constrain neutron star magnetic field and…
Axions can be copiously produced in localized regions of neutron star magnetospheres where the ambient plasma is unable to efficiently screen the induced electric field. As these axions stream away from the neutron star they can resonantly…
We present an analysis of polarized X-ray pulses based on simulated data for accreting millisecond pulsars (AMPs). We used the open-source X-ray Pulse Simulation and Inference code (previously applied to NICER observations), which we…
Conversion of photons into axions under the presence of a strong magnetic field can dim the radiation from magnetized astrophysical objects. Here we perform a detailed calculation aimed at quantifying the signatures of photon-axion…
Since the opacity of a magnetized plasma depends on polarization of radiation, the radiation emergent from atmospheres of neutron stars with strong magnetic fields is expected to be strongly polarized. The degree of linear polarization,…
Recent work has shown that axions can be efficiently produced via non-stationary pair plasma discharges in the polar cap region of pulsars. Here, we point out that for axion masses $10^{-9} \, {\rm eV} \lesssim m_a \lesssim 10^{-4} \, \rm…
Recent experiments suggest that polarized photons may couple significantly to pseudoscalar particles such as axions. We study the possible observational signatures of axion-photon coupling for radiation from magnetic stars, with particular…
The surfaces of neutron stars are sources of strongly polarized soft X rays due to the presence of strong magnetic fields. Radiative transfer mediated by electron scattering and free-free absorption is central to defining local surface…
Axion-like particles lead to a plethora of new phenomena relating to compact astrophysical objects including stellar and black hole superradiance, axion stars and axion clusters. In this work, we investigate a new scenario in which…
The axion is well motivated in physics. It solves the strong charge conjugation-parity reversal problem CP in fundamental physics and the dark matter problem in astronomy. Its interaction with the electromagnetic field has been expected but…
Axion-like particles (ALPs) can couple to photons in strong magnetic fields, producing characteristic fluctuations in X-ray spectra. Using data from NASA's Neutron Star Interior Composition Explorer (NICER), we analyzed three pulsars: PSR…
Hypothetical oscillations of probe photons into axion-like particles might be revealed by exploiting the strong fields of high-intensity laser pulses. Considering an arbitrary plane-wave background, we determine the polarization tensor…
Axions are hypothetical particles related to the violation of the charge-parity symmetry, being the most prone candidates for dark matter. Multiple attempts to prove their existence are currently performed in different physical systems.…
The pulsations of X-ray pulsars carry information about the accretion and magnetic field geometry. Here we present a study and classification of energy resolved pulse profiles of a sample of X-ray pulsars, focusing on high-mass X-ray…
Ultraluminous X-ray sources (ULXs) are enigmatic sources first discovered in the 1980s in external galaxies. They are characterized by their extraordinarily high X-ray luminosity, which often exceeds $10^{40}\, \rm{erg \; s^{-1}}$. Our…
The surfaces of neutron stars are likely sources of strongly polarized soft X rays due to the presence of strong magnetic fields. Scattering transport in the surface layers is critical to the determination of the emergent anisotropy of…