New Method for the Astrometric Direct Detection of Ultralight Dark Matter

Area of Science:

• Cosmology and astrophysics
• Particle physics
• Gravitational wave astronomy

Background:

• Dark matter constitutes a significant portion of the universe's mass-energy content.
• The nature of dark matter, particularly ultralight scalar fields, remains largely unknown.
• Direct detection of dark matter is crucial for understanding its fundamental properties.

Purpose of the Study:

• To propose and investigate astrometry as a novel method for the direct detection of ultralight dark matter.
• To analyze the influence of dark matter-induced spacetime perturbations on the apparent motion of astrophysical bodies.
• To determine the sensitivity of current and future astrometric surveys to ultralight dark matter candidates.

Main Methods:

• Reviewing the calculation of the spacetime metric in the presence of scalar dark matter.
• Studying the effects of metric perturbations on the apparent angular positions of distant celestial objects.
• Applying the theoretical framework to quasar astrometry and simulating the capabilities of Very Long Baseline Interferometry (VLBI) and optical surveys.

Main Results:

• Ultralight dark matter induces detectable time-dependent perturbations in the spacetime metric.
• Astrometric measurements of quasars can potentially detect dark matter with masses as low as 10^{-33} eV.
• Current astrometric surveys could detect ultralight dark matter with energy densities as low as 3×10^{-11} GeV/cm³.

Conclusions:

• Astrometry offers a promising new avenue for the direct gravitational detection of ultralight dark matter.
• The proposed method is sensitive to a wide range of ultralight dark matter masses and densities.
• Future astrometric missions hold significant potential for discovering these elusive cosmic relics.