Galactic Axions Research Articles

Supernova Axions Convert to Gamma Rays in Magnetic Fields of Progenitor Stars

It has long been established that axions could have been produced within the nascent proto-neutron star formed following the type II supernova SN1987A, escaped the star due to their weak interactions, and then converted to gamma rays in the Galactic magnetic fields; the nonobservation of a gamma-ray flash coincident with the neutrino burst leads to strong constraints on the axion-photon coupling for axion masses ma≲10−10 eV. In this Letter, we use SN1987A to constrain higher mass axions, all the way to ma∼10−3 eV, by accounting for axion production from the Primakoff process, nucleon bremsstrahlung, and pion conversion along with axion-photon conversion on the still-intact magnetic fields of the progenitor star. Moreover, we show that gamma-ray observations of the next Galactic supernova, leveraging the magnetic fields of the progenitor star, could detect quantum chromodynamics axions for masses above roughly 50 μeV, depending on the supernova. We propose a new full-sky gamma-ray satellite constellation that we call the GALactic AXion Instrument for Supernova (GALAXIS) to search for such future signals along with related signals from extragalactic neutron star mergers. Published by the American Physical Society 2024

Superconducting Qubit Network as a Single Microwave Photon Detector for Galactic Axion Search

Superconducting Qubit Network as a Single Microwave Photon Detector for Galactic Axion Search

Erratum: Hunting galactic axion dark matter with gravitationally lensed fast radio bursts [Phys. Rev. D 109 , L021303 (2024)

Erratum: Hunting galactic axion dark matter with gravitationally lensed fast radio bursts [Phys. Rev. D <b>109</b> , L021303 (2024)

A Forecast of the Sensitivity of the DALI Experiment to Galactic Axion Dark Matter

The axion is a long-postulated boson that can simultaneously solve two fundamental problems of modern physics: the charge–parity symmetry problem in the strong interaction and the enigma of dark matter. In this work, we estimate, by means of Monte Carlo simulations, the sensitivity of the Dark-photons &amp; Axion-Like particles Interferometer (DALI), a new-generation Fabry–Pérot haloscope proposed to probe axion dark matter in the 25–250 μeV band.

Hunting galactic axion dark matter with gravitationally lensed fast radio bursts

Hunting galactic axion dark matter with gravitationally lensed fast radio bursts

Coherent Quantum Network of Superconducting Qubits as a Highly Sensitive Detector of Microwave Photons for Searching of Galactic Axions

We propose a novel approach to detect a low power microwave signal with a frequency of the order of several GHz based on a coherent collective response of quantum states occurring in a superconducting qubits network (SQN). An SQN composes of a large number of superconducting qubits embedded in a low-dissipative superconducting resonator. Our theory predicts that an SQN interacting with the off-resonance microwave radiation, demonstrates the collective alternating current Stark effect that can be measured even in the limit of single photon counting. A design of the layout of three terminals SQN detectors containing 10 flux qubits weakly coupled to a low-dissipative R-resonator and T-transmission line was developed. The samples were fabricated by Al-based technology with Nb resonator. The SQN detector was tested in terms of microwave measurements of scattering parameters and two-tone spectroscopy. A substantial shift of the frequency position of the transmission coefficient drop induced by a second tone pump signal was observed, and this effect clearly manifests a nonlinear multiphoton interaction between the second-tone microwave pump signal and an array of qubits.

Search for Dark Matter Axions with CAST-CAPP

The CAST-CAPP axion haloscope, operating at CERN inside the CAST dipole magnet, has searched for axions in the 19.74 μeV to 22.47 μeV mass range. The detection concept follows the Sikivie haloscope principle, where Dark Matter axions convert into photons within a resonator immersed in a magnetic field. The CAST-CAPP resonator is an array of four individual rectangular cavities inserted in a strong dipole magnet, phase-matched to maximize the detection sensitivity. Here we report on the data acquired for 4124 h from 2019 to 2021. Each cavity is equipped with a fast frequency tuning mechanism of 10 MHz/ min between 4.774 GHz and 5.434 GHz. In the present work, we exclude axion-photon couplings for virialized galactic axions down to gaγγ = 8 × 10−14 GeV−1 at the 90% confidence level. The here implemented phase-matching technique also allows for future large-scale upgrades.

Search for Galactic axions with a high- Q dielectric cavity

A haloscope of the QUAX--$a\gamma$ experiment, composed of an high-Q resonant cavity immersed in a 8 T magnet and cooled to $\sim 4.5$~K is operated to search for galactic axion with mass $m_a\simeq42.8~\mu\text{eV}$. The design of the cavity with hollow dielectric cylinders concentrically inserted in a OFHC Cu cavity, allowed us to maintain a loaded quality-factor Q $\sim 300000$ during the measurements in presence of magnetic field. Through the cavity tuning mechanism it was possible to modulate the resonance frequency of the haloscope in the region $10.35337-10.35345$~GHz and thus acquire different dataset at different resonance frequencies. Acquiring each dataset for about 50 minutes, combining them and correcting for the axion's signal estimation-efficiency we set a limit on the axion-photon coupling $g_{a\gamma\gamma}< 0.731\times10^{-13}$ GeV$^{-1}$ with the confidence level set at $90\%$.

Single-Photon Detection with a Josephson Junction Coupled to a Resonator

We use semiclassical formalism to optimize a microwave single photon detector based on switching events of a current biased Josephson junction coupled to a resonator. In order to detect very rare events, the average time between dark counts $\tau_{\rm dark}$ should be maximized taking into account that the switching time $\tau_{\rm sw}$ should be sufficiently small. We demonstrate that these times can be tuned in the wide range by changing the junction parameters, and the ratios $\tau_{\rm dark}/\tau_{\rm sw} \sim 10^9$ can be achieved. Therefore, a junction-resonator arrangement can be used for detecting extremely low photon fluxes, for instance for searching galactic axions.

Decoherence from general relativity

It is of great interest to explore matter in nontrivial quantum arrangements, including Schrodinger cat-like states. Such states are sensitive to decoherence from their environment. Recently, in Ref. [1] we computed the rate of decoherence of a piece of superposed matter that primarily only interacts gravitationally, a dark-matter-Schrodinger-cat-state (DMSCS), within the nonrelativistic approximation. In this work we improve this to a general relativistic analysis. We firstly derive a single particle relativistic Schrodinger equation for a probe particle that passes through the DMSCS; the interaction is provided by the weak field metric of general relativity from the source. For a static DMSCS we find a neat generalization of our previous results. We then turn to the interesting new case of a time dependent DMSCS, which can be provided by a coherently oscillating axion field leading to superposed time dependent oscillations in the metric; a truly quantum-general relativistic phenomenon. We use scattering theory to derive the decoherence rate in all these cases. When the DMSCS is in a superposition of distinct density profiles, we find that the decoherence rate can be appreciable. We then consider the novel special case in which the density is not in a superposition, but the phase of its field oscillation is; this is a property that cannot be decohered within the nonrelativistic framework. We find that if the probe particle and/or the DMSCS's velocity dispersion is slow, then the rate of decoherence of the phase is exponentially suppressed. However, if both the probe and the DMSCS's velocity dispersion are relativistic, then the phase can decohere more rapidly. As applications, we find that diffuse galactic axions with superposed phases are robust against decoherence, while dense boson stars and regions near black hole horizons are not, and we discuss implications for experiment.

Search for invisible axion dark matter of mass ma=43 μeV with the QUAX– aγ experiment

A haloscope of the QUAX--$a\gamma$ experiment composed of an oxygen-free high thermal conductivity-Cu cavity inside an 8.1 T magnet and cooled to $\sim200$ mK is put in operation for the search of galactic axion with mass $m_a\simeq43~\mu\text{eV}$. The power emitted by the resonant cavity is amplified with a Josephson parametric amplifier whose noise fluctuations are at the standard quantum limit. With the data collected in about 1 h at the cavity frequency $\nu_c=10.40176$ GHz, the experiment reaches the sensitivity necessary for the detection of galactic QCD-axion, setting the $90\%$ confidence level limit to the axion-photon coupling $g_{a\gamma\gamma}<0.639\times10^{-13}$ GeV$^{-1}$.

Development of a Josephson junction based single photon microwave detector for axion detection experiments

Josephson junctions, in appropriate configurations, can be excellent candidates for detection of single photons in the microwave frequency band. Such possibility has been recently addressed in the framework of galactic axion detection. Here are reported recent developments in the modelling and simulation of dynamic behaviour of a Josephson junction single microwave photon detector. For a Josephson junction to be enough sensitive, small critical currents and operating temperatures of the order of ten of mK are necessary. Thermal and quantum tunnelling out of the zero-voltage state can also mask the detection process. Axion detection would require dark count rates in the order of 0.001 Hz. It is, therefore, is of paramount importance to identify proper device fabrication parameters and junction operation point.

A first proof of principle booster setup for the MADMAX dielectric haloscope

Axions and axion-like particles are excellent low-mass dark matter candidates. The MADMAX experiment aims to directly detect galactic axions with masses between 40 and 400,upmu mathrm{eV} by using the axion-induced emission of electromagnetic waves from boundaries between materials of different dielectric constants under a strong magnetic field. Combining many such surfaces, this emission can be significantly enhanced (boosted) using constructive interference and resonances. We present a first proof of principle realization of such a booster system consisting of a copper mirror and up to five sapphire disks. The electromagnetic response of the system is investigated by reflectivity measurements. The mechanical accuracy, calibration process of unwanted reflections and the repeatability of a basic tuning algorithm to place the disks are investigated. We find that for the presented cases the electromagnetic response in terms of the group delay predicted by one-dimensional calculations is sufficiently realized in our setup. The repeatability of the tuning is at the percent level, and would have small impact on the sensitivity of such a booster.

Detecting axionlike dark matter with linearly polarized pulsar light

Non-relativistic QCD axions or axion-like particles are among the most popular candidates for cold Dark Matter (DM) in the universe. We proposed to detect axion-like DM, using linearly polarized pulsar light as a probe. Because of birefringence effect potentially caused by an oscillating galactic axion DM background, when pulsar light travels across the galaxy, its linear polarization angle may vary with time. With a soliton+NFW galactic DM density profile, we show that this strategy can potentially probe an axion-photon coupling as small as $\sim 10^{-13}$ GeV$^{-1}$ for axion mass $m_a \sim 10^{-22}-10^{-20}$ eV, given the current measurement accuracy. An exclusion limit stronger than CAST ($ \sim 10^{-10}$ GeV$^{-1}$) and SN1987A ($ \sim 10^{-11}$ GeV$^{-1}$) could be extended up to $m_a \sim 10^{-18}$ eV and $\sim 10^{-19}$ eV, respectively.

Axion quark nuggets and how a global network can discover them

We advocate an idea that the presence of the daily and annual modulations of the axion flux on the Earth surface may dramatically change the strategy of the axion searches. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model which was originally put forward to explain the similarity of the dark and visible cosmological matter densities $\Omega_{\rm dark}\sim \Omega_{\rm visible}$. In our framework, the population of galactic axions with mass $ 10^{-6} {\rm eV}\lesssim m_a\lesssim 10^{-3}{\rm eV}$ and velocity $< v_a>\sim 10^{-3} c$ will be always accompanied by the axions with typical velocities $<v_a>\sim 0.6 c$ emitted by AQNs. We formulate the broadband detection strategy to search for such relativistic axions by studying the daily and annual modulations. We describe several tests which could effectively discriminate a true signal from noise. These AQN-originated axions can be observed as correlated events which could be recorded by synchronized stations in the global network. The correlations can be effectively studied if the detectors are positioned at distances shorter than a few hundred kilometres.

MADMAX: A new way of probing QCD Axion Dark Matter with a Dielectric Haloscope – Foundations

In contrast to WIMPs, light Dark Matter candidates have increasingly come under the focus of scientific interest. In particular the QCD axion is also able to solve other fundamental problems such as CP-conservation in strong interactions. Galactic axions, axion-like particles and hidden photons can be converted to photons at boundaries between materials of different dielectric constants under a strong magnetic field. Combining many such surfaces, one can enhance this conversion significantly using constructive interference and resonances. The proposed MADMAX setup containing 80 high dielectric disks in a 10 T magnetic field would probe the well-motivated mass range of 40–400 μeV, a range which is at present inaccessible by existing cavity searches. We present the foundations of this approach and its expected sensitivity.

Microwave Losses in a DC Magnetic Field in Superconducting Cavities for Axion Studies

The hypothetical axion particle is an excellent cold dark matter candidate. Models predict an axion mass of tens of μeV (GHz frequency range). In principle, it is possible to convert galactic axions into a monochromatic microwave signal or to detect them with an electron-spin flip. In both cases, to measure the resulting vanishing signal (P ≈ 10 -23 W), a high-Q cavity is needed, with Q ~ 10 6 . Superconducting RF technology can satisfy the requirement of operation in moderate-to-high dc magnetic fields. In this paper, we present an experimental study of the behavior of superconducting cavities in the vortex state. This study has been realized using 14 GHz Cu-NbTi and Cu-NbTiNx film cavities. A new cavity geometry is presented. We measured the magnetic field dependence of the Q-factor and Δf res /f res , where f res is the resonant frequency in the range B = 0-6 T at 4.2 K. Also, Q versus temperature at fixed B in zero-field-cooling and field-cooling setups has been considered. A comparison was made with Cu and Nb cylindrical bulk cavities. The data for Q(B) were analyzed in terms of the elastic and dissipative motion of flux lines, thus including flux flow and flux pinning. We discuss whether the field-induced quasiparticle contribution is relevant in our field and temperature range.

Galactic axions search with a superconducting resonant cavity

To account for the dark matter content in our Universe, post-inflationary scenarios predict for the QCD axion a mass in the range $(10-10^3)\,\mu\mbox{eV}$. Searches with haloscope experiments in this mass range require the monitoring of resonant cavity modes with frequency above 5\,GHz, where several experimental limitations occur due to linear amplifiers, small volumes, and low quality factors of Cu resonant cavities. In this paper we deal with the last issue, presenting the result of a search for galactic axions using a haloscope based on a $36\,\mbox{cm}^3$ NbTi superconducting cavity. The cavity worked at $T=4\,\mbox{K}$ in a 2\,T magnetic field and exhibited a quality factor $Q_0= 4.5\times10^5$ for the TM010 mode at 9\,GHz. With such values of $Q$ the axion signal is significantly increased with respect to copper cavity haloscopes. Operating this setup we set the limit $g_{a\gamma\gamma}<1.03\times10^{-12}\,\mbox{GeV}^{-1}$ on the axion photon coupling for a mass of about 37\,$\mu$eV. A comprehensive study of the NbTi cavity at different magnetic fields, temperatures, and frequencies is also presented.

New method of galactic axion search

An appealing candidate of the galactic dark matter is the axion, which was postulated to solve the strong CP (Charge-conjugation Parity) violation problem in the standard particle theory. A new experimental method is proposed to determine the axion mass. The method uses collectively and coherently excited atoms or molecules, the trigger laser inducing galactic axion absorption along with signal photon emission to be detected.

Single Photon Counter Based on a Josephson Junction at 14 GHz for Searching Galactic Axions

Axions and axion-like particles appear in well-motivated extensions of the standard model of particle physics and may be the solution to the long-standing puzzle of the dark matter in our Universe. Several new experiments are foreseen in the next decade searching them in a wide range of the parameter space. In the mass region from few to several tens of microelectronvolt, detector sensitivity will be limited by the standard quantum limit of linear amplifiers and a new class of single microwave-photon detector will be needed. We have developed a single photon counter based on the voltage switching of an underdamped Josephson junction that is coupled to a coplanar waveguide. By measuring the switching voltage, we can register single photons at 14 GHz with the rate less than 1 photon per 3000 s.