Searching for WISPy Cold Dark Matter with a Dish Antenna

TL;DR

This work proposes a broadband dish-antenna approach to search for cold dark matter composed of axion-like particles and hidden photons, leveraging WISP-to-photon conversion at reflective surfaces. A spherical dish concentrates the emitted radiation from the dish boundary into the centre, enabling scanning-free coverage across a wide mass range with sensitivity set by detectable power or photon rate. The authors derive the HP case and the ALP case (in a magnetic field), provide order-of-magnitude sensitivity estimates, and compare the method to resonant cavities, highlighting advantages at higher masses and robustness to non-idealities. They also analyze boundary and medium effects, showing the scheme remains viable under realistic conditions and across a broad frequency spectrum.

Abstract

The cold dark matter of the Universe may be comprised of very light and very weakly interacting particles, so-called WISPs. Two prominent examples are hidden photons and axion-like particles. In this note we propose a new technique to sensitively search for this type of dark matter with dish antennas. The technique is broadband and allows to explore a whole range of masses in a single measurement.

Figures (3)

• Figure 1: The allowed parameter space for hidden photon cold dark matter (HP CDM) is shown in red (for details see Ref. Arias:2012az). The regions in various colours are excluded by experiments and astrophysical observations that do not require HP dark matter (for reviews see Ringwald:2012hrJaeckel:2010ni). The lines correspond to the sensitivity of a dish antenna ($1\,{\rm m}^{2}$) search with a detector sensitive to $10^{-21}$, $10^{-23}$ and $10^{-25}$ W (green, from top to bottom) and $1$, $0.01$ and $10^{-4}$ photons per second (blue, from top to bottom).
• Figure 2: Sketch of our WISPy cold dark matter experiment. Non relativistic HPs or ALPs mixing with photons are converted into monochromatic photons (black) emitted from the surface of an spherical dish antenna and focused in the centre, where a broadband detector is placed. Photons emitted from other boundaries or from far away sources (red) are typically not focused there.
• Figure 3: The allowed parameter space for axion-like particle dark matter (ALP CDM) is shown in various shades of red (for details see Ref. Arias:2012az). The various colored regions are excluded by experiments and astrophysical observations that do not require HP dark matter (for reviews see Ringwald:2012hrJaeckel:2010ni). The lines correspond to the sensitivity of a dish antenna ($1\,{\rm m}^{2}$ dish in a 5 T magnetic field) with a detector sensitive to $10^{-21}$, $10^{-23}$ and $10^{-25}$ W (green, from top to bottom) and $1$, $0.01$ and $10^{-4}$ photons per second (blue, from top to bottom).