Gravitational lensing by the Sun of non-relativistic penetrating particles

The flux of weakly interacting particles from celestial sources, moving with a velocity v≈0.2c, can be temporarily amplified at the site of the Earth, due to gravitational lensing effects by the Sun. The effective amplification factor can be as much as ∼10³ to ∼10⁴, for a velocity bin-width of ∼0.1%. The theoretically motivated solar Kaluza-Klein axions provide a generic example of particles with a wide velocity spectrum, filling the gap between v≈c (e.g. neutrinos) and v≈10^-3c (e.g. dark matter (DM) candidates). If the putative particles come from a direction along the projected path of the Sun in the Sky, within a strip of ∼0.1° along the ecliptic, then, time windows of possible enhanced flows can be predicted. This suggestion can be implemented in the (re)-analysis of data from DM-experiments, and, it does not need any major experimental modification. In particular, performing a cross-correlation of data taken over a period more than 1 year, from the same or even also from other experiments, this can result to (un)predictable time windows of interest. Because, if burst-like events re-appear in following years in fixed dates, this will be an unambiguous identification of the cosmic origin of underground events, which were ignored before. Thus, thanks to solar gravitational effects, DM-experiments can be transformed to telescopes of penetrating non-relativistic particles with a field-of-view of ∼0.1°, or even more, along the ecliptic. The missing access to DM-data does not allow us to test this technique. We therefore suggest to the astroparticle physics community to release its data.