Search for Ultralight Dark Matter
Overview
The Search for Ultralight Dark Matter project explores possible interactions between dark matter and the Standard Model using high-precision magnetometry in environments with extremely low magnetic noise.
We target ultralight bosonic dark matter candidates such as dark photons and axion-like particles (ALPs), whose wave-like nature can produce coherent, oscillating magnetic signatures measurable by sensitive magnetometers.
These experiments open up the sub-eV mass range, complementing collider and astrophysical searches by exploiting terrestrial precision instrumentation.
Scientific Motivation
In ultralight dark matter models, new bosonic fields can couple weakly to electromagnetism or to nucleon spins:
- Dark photons interact via kinetic mixing with the ordinary photon, inducing oscillating effective magnetic fields.
- Axion-like particles (ALPs) couple to the electromagnetic field through the axion–photon term gaγγaE⋅B , leading to pseudo-magnetic modulations.
Both cases result in narrow-band magnetic signals at frequencies corresponding to the dark matter mass, typically in the mHz–Hz range.
These signatures are expected to be coherent across large spatial scales and to exhibit daily modulation from the Earth’s rotation with respect to the galactic dark matter wind.
Detecting such faint, structured signals requires long-term stability and sensitivity well below the picotesla level — achievable with state-of-the-art magnetometers operated in magnetically shielded or remote environments.
Experimental Approach
Our setup combines scalar optically pumped magnetometers (Twinleaf PPMs) and a spatially distributed fluxgate array at a low-noise alpine test site.
Together, these systems form a hybrid detector network sensitive to both scalar and vector magnetic field components.
Key features:
- Location:
- The structure is located in Austria on a quiet alpine pasture, far away from human-made sources of electromagnetic disturbances.
- Optically Pumped Magnetometers (OPM):
- Detect absolute field magnitude with sub-picotesla precision.
- Provide narrow-band spectral sensitivity for dark photon and ALP signals below 10 Hz.
- Fluxgate magnetometer array:
- Consists of multiple 3-axis fluxgate sensors arranged over several meters.
- Records the vector magnetic field in the surrounding volume, enabling spatial correlation analysis and rejection of local noise sources.
- Offers continuous monitoring of ambient and instrumental magnetic fluctuations.
- Data acquisition and analysis:
- All channels can be synchronized with test pulses.
- Spectral analysis employs a discrete-time Fourier transform (DTFT) at the exact signal frequencies, optimized for narrow-band searches.
- The combined data enable cross-correlation between OPM and fluxgate channels, improving sensitivity and robustness against false positives.
This dual-instrument approach leverages both absolute-field and gradient sensitivity, maximizing the experiment’s discovery potential for ultralight dark matter signatures.
Contact
For collaboration, thesis opportunities, or further inquiries, please contact:
Prof. Dr.sc.nat. Peter Fierlinger
- Tel.: +49 (89) 289 - 51324, 53711
- Raum: 5117.02.306
- peter.fierlinger@tum.de
Publications and finished Theses
- Maria Georgia Benning, Towards Dark Matter Limits with High Precision Magnetometers in a Low Ambient Noise Environment. 2024, Bachelors Thesis
Involved Persons and Former Members
Currently Involved persons: Peisen Zhao, Maximilian Huber, Philipp Wunderl, Dr. Florian Kuchler
Former members: Maria Georgia Benning,