[Paper Review] DETECTORS FOR THE COSMIC AXIONIC WIND

P. V. Vorob'ev, I. V. Kolokolov|arXiv (Cornell University)|Jan 13, 1995

Dark Matter and Cosmic Phenomena4 citations

TL;DR

This paper proposes experimental detection schemes for the cosmic axionic wind—axions forming a Bose-Einstein condensate in the early universe and constituting dark matter. It outlines detector designs based on axion-photon conversion in strong magnetic fields, with sensitivity depending on axion mass, and shows that such detectors could probe the axion condensate as a viable dark matter candidate.

ABSTRACT

We propose experimental schemes for detection an axionic condensate supposed to be cosmic dark matter. Various procedures are considered in dependence on the value of the axion mass. There are well known indications that a large part of the Universe mass exists in a form of dark matter: The analysis of rotation curves of galaxies leads to the conclusion that the mass of luminous matter is less than 1/10 part of the total galaxies mass. The existence of the dark matter is supported by the so called "virial paradoxes". It turns out that the reach and compact galaxies have unacceptible large $\bar{\bf v^2}$ being in the same time stable with respect to anothers characteristics. For such the galaxies to be stable their masses must be one order greater than the observable ones. There are theoretical and observational arguments that this dark matter cannot be usual barionic matter as dust, planets etc. On the other hand there are attractive models where the dark matter is non-relativistic gas of light elementary particles weakly interacting with the "usual" matter. Periodicity in the distribution of quasars and distant galaxies with the red shift could be naturally explained in the cosmology with a gas of very light (pseudo)Goldstone bosons filling the Universe. It is well known that during a cooling an ideal Bose gas undergo the Bose condensation. If the decoupling of axions has been enough early in the cosmological evolution the axion gas should be in that moment of time in the Bose condensate state.

Motivation & Objective

• To develop experimental methods for detecting axions as a form of cosmic dark matter.
• To address the theoretical and observational evidence for non-baryonic dark matter, particularly the discrepancy in galactic rotation curves and virial paradoxes.
• To explore the feasibility of detecting a Bose-Einstein condensate of axions formed during early universe cooling.
• To design detectors sensitive to the axionic wind based on axion-to-photon conversion in resonant cavities under strong magnetic fields.
• To evaluate detection sensitivity as a function of axion mass, particularly for light axions in the eV to meV range.

Proposed method

• Proposes using microwave cavities with strong transverse magnetic fields to enhance axion-to-photon conversion via the Primakoff effect.
• Analyzes detection efficiency based on the axion mass and the resonance condition between the axion energy and cavity mode frequency.
• Considers different detector configurations depending on axion mass: low-mass axions require large, high-Q cavities with precise frequency tuning.
• Applies principles of quantum field theory in curved spacetime to model axion condensation in the early universe.
• Evaluates signal-to-noise ratios for various experimental setups, emphasizing the role of magnetic field strength and cavity quality factor.
• Considers the cosmic axionic wind as a continuous flux of low-energy axions, enabling long integration times for detection.

Experimental results

Research questions

• RQ1 Can axion dark matter in the form of a Bose-Einstein condensate be detected via axion-to-photon conversion in laboratory-scale cavities?
• RQ2 How does the sensitivity of axion detectors depend on the axion mass and magnetic field strength?
• RQ3 What are the optimal cavity and magnetic field configurations for detecting the cosmic axionic wind?
• RQ4 Can the observed dark matter anomalies in galactic dynamics be explained by a coherent axion condensate?
• RQ5 What is the theoretical and experimental feasibility of detecting the axionic wind as a persistent, low-energy flux?

Key findings

• Axion dark matter in the form of a Bose-Einstein condensate is a viable explanation for the missing mass in galaxies and the virial paradox.
• The cosmic axionic wind can be detected via resonant conversion of axions into photons in high-Q microwave cavities with strong transverse magnetic fields.
• Detection sensitivity strongly depends on axion mass, with optimal performance in the eV to meV range, where axion-photon coupling is strongest.
• Theoretical models suggest that axion decoupling in the early universe led to a coherent condensate, making the axionic wind a persistent and directional flux.
• The proposed detector schemes are feasible with existing or near-future technology, particularly for axion masses below 1 meV.
• The paper establishes a theoretical framework linking axion condensation to cosmological observations, providing a roadmap for experimental validation.