Searching for Dark Photon Dark Matter with Terrestrial Magnetic Fields Improves Limits up to 100Hz and 1eV eV

The search for dark matter receives a novel approach as Kimihiro Nomura from Kyoto University, Atsushi Nishizawa from Hiroshima University, and Atsushi Taruya et al. investigate the potential of terrestrial magnetic field measurements to detect these elusive particles. Their work explores the idea that coherently oscillating dark matter can generate a detectable magnetic field through interactions with ordinary matter, and importantly, that this signal becomes amplified by the Earth’s natural resonant cavity formed between the surface and the ionosphere. By modelling the expected signal and accounting for atmospheric effects, the team derives new constraints on the interaction strength between dark and ordinary matter, significantly improving upon existing limits for dark matter masses within a specific energy range. This research opens a new avenue for dark matter detection, utilising naturally occurring phenomena to search for these fundamental particles.

Dark Photon Detection Via Atmospheric Magnetic Fields

This research investigates the possibility of detecting dark photons, hypothetical particles that could constitute dark matter, by examining their interaction with the Earth’s atmosphere. Scientists are searching for extremely faint magnetic fields potentially induced by these particles as they pass through the atmosphere, refining theoretical models and analyzing existing data to narrow down possible dark photon properties. Dark photons interact very weakly with ordinary matter, quantified by a kinetic mixing parameter indicating the strength of the connection between dark photons and ordinary light. The team developed a sophisticated model to predict the strength of the induced magnetic field, carefully considering atmospheric electrical conductivity at different altitudes and times of day.

Researchers also accounted for the possibility of resonance, where the induced magnetic field could be amplified at specific frequencies. By analyzing geomagnetic data, the team aimed to identify these faint signals and set limits on the kinetic mixing parameter, refining our understanding of dark photon properties. The analysis of existing data revealed that four previously reported signal candidates were likely not caused by dark photons. The team also established new upper limits on the kinetic mixing parameter for certain frequencies, demonstrating the sensitivity of the approach and its potential for detecting or excluding dark photon candidates. This research highlights the importance of accurately modeling atmospheric effects when searching for these faint signals, contributing to the ongoing effort to unravel the mysteries of dark matter.

Terrestrial Magnetic Fields Constrain Light Dark Matter

Scientists conducted a novel search for dark matter using precise measurements of terrestrial magnetic fields at frequencies below 100Hz. The research explores the possibility that coherently oscillating dark matter particles can induce magnetic fields through kinetic mixing with ordinary photons. The study leverages the theoretical prediction that this signal can be amplified within a resonant cavity formed by the Earth’s surface and the ionosphere, particularly for dark matter particles with masses around 1eV. The methodology centers on detecting a monochromatic magnetic field induced by dark photons, a compelling dark matter candidate.

The team modeled the interaction between dark photons and ordinary photons using a kinetic mixing parameter and the dark photon mass to predict the expected signal strength. They calculated the frequency of the dark photon, directly relating it to the dark photon mass, allowing for precise frequency targeting in the geomagnetic data analysis. Scientists analyzed long-term geomagnetic data from the Eskdalemuir Observatory, searching for the predicted monochromatic signals and establishing stringent upper limits on the kinetic mixing parameter, improving upon existing constraints in the mass range of 1 × 10−15 eV ≲mA′ ≲2 ×10−13 eV. This innovative approach to dark matter detection demonstrates the power of carefully modeling the dark photon’s interaction with the Earth’s magnetic field and accounting for atmospheric effects.

Geomagnetic Data Constrains Light Dark Matter

Scientists conducted a novel search for dark matter using measurements of terrestrial magnetic fields at frequencies below 100Hz. The research centers on the premise that coherently oscillating dark matter can induce a magnetic field through kinetic mixing with ordinary photons. Notably, for dark matter masses around electronvolts, this signal can be amplified within a resonant cavity formed by the Earth’s surface and the ionosphere. The team developed a detailed prediction of the expected signal, incorporating the effects of atmospheric conductivity, and used this to derive new upper limits on the kinetic mixing parameter from long-term geomagnetic data.

These limits represent a significant improvement over previous ground-based constraints, specifically in the mass range of 1 × 10−15 eV to 2 × 10−13 eV. The research demonstrates that no significant signals were detected across most frequencies, leading to stringent upper limits on the mixing parameter. The team’s calculations show that the induced magnetic field strength is roughly estimated as 3 × 10−2 picotesla, scaled by the mixing parameter and the dark matter mass, and would manifest as a sharp, persistent spectral line distinguishable from random noise. The adopted atmospheric conductivity profile gradually increases from 10−14 Siemens per meter at lower altitudes to 10−3 S/m at 99km, providing a realistic representation of the Earth’s atmosphere. The analysis reveals that the induced magnetic field contains primarily the l=1 mode, and the team calculated the expected amplitude of this field as a function of dark matter mass, demonstrating a clear relationship between the dark matter mass and the predicted magnetic field strength.

Earth-Ionosphere Cavity Constrains Light Dark Matter

Scientists have conducted a search for dark matter using measurements of terrestrial magnetic fields at frequencies below 100Hz. Their work centres on the prediction that coherently oscillating dark matter can generate a magnetic field through interaction with ordinary matter. Notably, the research demonstrates that for certain dark matter masses around electronvolt levels, this induced magnetic field can be amplified within a cavity created by the Earth’s surface and the ionosphere. The team incorporated the effect of atmospheric conductivity into their models and, using long-term geomagnetic data, established new upper limits on the strength of the interaction between dark and ordinary matter. These limits improve upon existing constraints from ground-based experiments for dark matter masses ranging from approximately 1x 10⁻¹⁵ eV.