Earth as a Lens for Searching Dark Matter ⚡ экспресс
We propose a telescope concept based on Earth's gravitational lensing, optimized for detecting distant sources of axion-like particles (ALPs). The method combines ALP flux concentration in the focal region with stimulated back-reflection — the induced decay of ALPs by sending a coherent electromagnetic beam toward the focal point. We performed a numerical analysis of the focal region structure: for an average ALP speed of 520 km/s, consistent with the S1 stellar stream, the focus lies between 9×10⁹ and 1.4×10¹⁰ m, with a density peak near 9.6×10⁹ m. For a point source at ~8 kpc, the sensitivity to the ALP-photon coupling constant in the eV mass range is g/M ~ 10⁻²² GeV⁻¹. Thus, this method opens the prospect for a general-purpose space-based ALP observatory capable of detecting sources far beyond ~10 kpc, provided that M is much smaller than the Planck mass.
Dark matter is the invisible backbone of the universe. Vera Rubin proved its existence by the motion of stars, yet the particles themselves have never been captured. A new method turns Earth into a giant gravitational lens: a massive body, as shown by Einstein, curves spacetime and focuses passing dark matter particles into a point beyond Pluto's orbit. That spot is about the size of a football field.
A powerful laser is aimed at the focus. If dark matter consists of axions – ultralight particles outside the Standard Model – the beam makes them momentarily turn into photons and reflect light back. Like a match igniting invisible gunpowder, the laser triggers a flash that can be registered.
Calculations show: at speeds around 520 km/s, the focus lies 9–14 billion meters away. The sensitivity is such that a signal can be picked up even from the opposite edge of the Galaxy. This approach paves the way for a space observatory to directly detect dark matter.
🎯 The distance to Earth's gravitational focus is roughly the distance light travels in half a minute — farther than Pluto, but still within our solar system.