Abstract
We derive spectral line shapes of the expected signal for a haloscope experiment searching for axionlike dark matter. The knowledge of these line shapes is needed to optimize an experimental design and data analysis procedure. We extend the previously known results for the axion-photon and axion-gluon couplings to the case of gradient (axion-fermion) coupling. A unique feature of the gradient interaction is its dependence not only on magnitudes but also on directions of velocities of galactic halo particles, which leads to the directional sensitivity of the corresponding haloscope. We also discuss the daily and annual modulations of the gradient signal caused by the Earth's rotational and orbital motions. In the case of detection, these periodic modulations will be an important confirmation that the signal is sourced by axionlike particles in the halo of our Galaxy.
Highlights
According to diverse astronomical observations, about 85% of the total mass of the Universe can be attributed to dark matter (DM), whose origin and composition remain unknown [1–3]
We have considered spectral line shapes and power spectra of the expected signal for a haloscope experiment searching for axionlike DM in our Galaxy
Assuming the standard halo model, we have rederived the spectral line shape (12) that has been previously obtained for the nongradient couplings in Refs. [12,21,35,39]
Summary
According to diverse astronomical observations, about 85% of the total mass of the Universe can be attributed to dark matter (DM), whose origin and composition remain unknown [1–3]. Among the best-motivated DM candidates are the quantum chromodynamics axion and other light pseudoscalar bosons, which are collectively referred to as axionlike particles (ALPs) [6–8]. Their characteristic feature is low mass (ma ≪ 1 eV=c2) that leads to high number density. This feature distinguishes ALPs from other popular DM candidates, such as weakly interacting massive particles (WIMPs), which are much heavier. The first two couplings, which are proportional to aðtÞ, are referred to as the ALP field couplings. The third one is proportional to the spatial gradient of aðtÞ and is referred to as the gradient coupling. We discuss the daily and annual modulations of the gradient line shape, which, if detected, will be an important confirmation that the signal is sourced by ALPs in the halo of our Galaxy
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
