Axion Quark Nugget Dark Matter Research Articles

The glow of axion quark nugget dark matter. Part I. Large scale structures

Axion quark nuggets (AQN) are hypothetical, macroscopically large objects with a mass greater than a few grams and sub-micrometer size, formed during the quark-hadrontransition. Originating from the axion field, they offer a possible resolution of the similarity between visible and dark components of the Universe, i.e. ΩDM ∼ Ωvisible and observed matter-antimatter asymmetry. These composite objects behave as cold dark matter, interacting with ordinary matter and resulting in pervasive electromagnetic radiation throughout the Universe. This work aims to predict the electromagnetic signature in large-scale structures from this AQN-baryon interaction, accounting for thermal and non-thermal radiations.We use Magneticum hydrodynamical simulations to describe the realistic distribution and dynamics of gas and dark matter at cosmological scales. We construct a light cone encompassing a 1.4 square degree area on the sky, extending up to redshift z = 5.4, and we calculate the electromagnetic signature across a wide range of frequencies from radio, starting at ν ∼ 1 GHz, up to a few keV X-ray energies. We find that the AQNs electromagnetic signature is characterized by global (monopole) and fluctuation signals. The amplitude of both signals strongly depends on the average nugget mass and the ionization level of the baryonic environment, allowing us to identify a most optimistic scenario and a minimal configuration. The signal of our most optimistic scenario is often near the sensitivity limit of existing instruments, such as FIRAS in the ν = [100-500] GHz range and the South Pole Telescope for high-resolution ℓ > 4000 at ν = 95 GHz. Fluctuations in the Extra-galactic Background Light caused by the axion quark nuggets in the most optimistic scenario can also be tested with space-based imagers Euclid and James Webb Space Telescope. In general, our minimal configuration is still out of reach of existing instruments, but future experiments might be able to pose some constraints.We conclude that the axion quark nuggets model represents a viable model for dark matter, which does not violate the canons of cosmology nor existing observations. A reanalysis of existing data sets could provide some evidence of axion quark nuggets if our most optimistic configuration is correct. The best chances for testing the model reside in 1) ultra-deep infrared and optical surveys, 2) future experiments to probe the frequency spectrum of the cosmic microwave background, and 3) low-frequency (1 GHz < ν < 100 GHz) and high-resolution (ℓ ≳ 104) observations.

Structure formation paradigm and axion quark nugget dark matter model

We advocate an idea that ``non-baryonic" dark matter in form of nuggets made of standard model quarks and gluons (similar to the old idea of the Witten's strangelets) could play a crucial role in structure formation. The corresponding macroscopically large objects, which are called the axion quark nuggets (AQN) behave as {\it chameleons}: they do not interact with the surrounding material in dilute environment, but they become strongly interacting objects in sufficiently dense environment. The AQN model was invented long ago with a single motivation to explain the observed similarity $\Omega_{\rm DM}\sim \Omega_{\rm visible}$ between visible and DM components. This relation represents a very generic feature of this framework, not sensitive to any parameters of the construction. We argue that the strong visible-DM interaction may dramatically modify the conventional structure formation pattern at small scales to contribute to a resolution of a variety of interconnected problems (such as Core-Cusp problem, etc) which have been a matter of active research and debates in recent years. We also argue that the same visible-DM interaction at small scales is always accompanied by a broad band diffuse radiation. We speculate that the recently observed excesses of the UV emission by JWST at high redshifts and by GALEX in our own galaxy might be a direct manifestation of this AQN-induced radiation. We also speculate that the very same source of energy injection could contribute to the resolution of another long standing problem related to the Extragalactic Background Light (EBL) with known discrepancies in many frequency bands (from UV to optical, IR light and radio emissions).

X-ray annual modulation observed by XMM-Newton and Axion Quark Nugget dark matter

The XMM- Newton observatory shows evidence, with a 11 σ confidence level, for seasonal variation of the X-ray background in the near-Earth environment in the 2–6 keV energy range Fraser et al. (2014). The authors argue that the observed seasonal variation suggests a possible link with dark matter. We propose an explanation which involves the Axion Quark Nugget (AQN) dark matter model. In our proposal, AQNs can cross the Earth and emit high energy photons at their exit. We show that the emitted spectrum is consistent with Fraser et al. (2014), and that our calculation is not sensitive to the specific details of the model. Our proposal predicts a large seasonal variation, on the level of 20%–25%, much larger than conventional dark matter models (1%–10%). Since the AQN emission spectrum extends up to ∼ 100 keV, well beyond the keV sensitivity of XMM- Newton , we predict the AQN contribution to the hard X-ray and γ -ray backgrounds in the Earth’s environment. The Gamma-Ray Burst Monitor (GBM) instrument, aboard the FERMI telescope, is sensitive to the 8 keV–40 MeV energy band. The NuSTAR (Nuclear Spectroscopic Telescope Array) is a NASA space based X ray telescope which operates in the range 3 to 79 keV is also sensitive to higher energy bands. We suggest that the multi-year archival data from the GBM or NuSTAR could be used to search for a seasonal variation in the near-Earth environment up to 100 keV as a future test of the AQN framework.

The mysterious diffuse UV radiation and axion quark nugget dark matter model

It has been recently argued [1–3] that there is a strong component of the diffuse far-ultraviolet (FUV) background which is hard to explain by conventional physics in terms of the dust-scattered starlight. We propose that this excess in FUV radiation might be result of the dark matter annihilation events within the so-called axion quark nugget (AQN) dark matter model, which was originally invented for completely different purpose to explain the observed similarity between the dark and the visible components in the Universe, i.e. ΩDM∼Ωvisible. We support this proposal by demonstrating that intensity and the spectral features of the AQN induced emissions are consistent with the corresponding characteristics of the observed excess of the FUV radiation. If the future studies confirm the puzzling characteristics observed in [1–3] it might unlock a much more deeper and fundamental problem of modern cosmology– it may reveal the nature of the dark matter.

X-Ray Annual Modulation Observed by Xmm-Newton and Axion Quark Nugget Dark Matter

The XMM-Newton observatory shows evidence with an $11 \sigma$ confidence level for seasonal variation of the X-ray background in the near-Earth environment in the 2-6 keV energy range (Fraser et al. 2014). The interpretation of the seasonal variation given in Fraser et al. 2014 was based on the assumption that solar axions convert to X-rays in the Earth's magnetic field. There are many problems with this interpretation, since the axion-photon conversion must preserve the directionality of the incoming solar axion. At the same time, this direction is avoided by the observations because the XMM-Newton's operations exclude pointing at the Sun and at the Earth. The observed seasonal variation suggests that the signal could have a dark matter origin, since it is very difficult to explain with conventional astrophysical sources. We propose an alternative explanation which involves the so-called Axion Quark Nugget (AQN) dark matter model. In our proposal, dark matter is made of AQNs, which can cross the Earth and emit high energy photons at their exit. We show that the emitted intensity and spectrum is consistent with Fraser et al. 2014, and that our calculation is not sensitive to the specific details of the model. We also find that our proposal predicts a large seasonal variation, on the level of 20-25%, much larger than conventional dark matter models (1-10%). Since the AQN emission spectrum extends up to $\sim$100 keV, well beyond the keV sensitivity of XMM-Newton, we predict the AQN contribution to the hard X-ray and $\gamma$-ray backgrounds in the Earth's environment. The Gamma-Ray Burst Monitor instrument (GBM), aboard the Fermi telescope, is sensitive to the 8 keV-40 MeV energy band. We suggest that the multi-year archival data from the GBM could be used to search for a seasonal variation in the near-Earth environment up to 100 keV as a future test of the AQN framework.

Proposed network to detect axion quark nugget dark matter

A network of synchronized detectors can increase the likelihood of discovering the QCD axion within the axion quark nugget (AQN) dark matter model. A similar network can also discriminate the x rays emitted by the AQNs from the background signal. These networks can provide information on the directionality of the dark matter flux (if any), as well as its velocity distribution, and can therefore test the Standard Halo Model. We show that the optimal configuration to detect AQN-induced axions is a triangular network of stations 100 km apart. For x rays, the optimal network is an array of tetrahedral units.

Impulsive radio events in quiet solar corona and axion quark nugget dark matter

The Murchison Widefield Array (MWA) recorded \cite{Mondal-2020} impulsive radio events in the quiet solar corona at frequencies 98, 120, 132, and 160 MHz. We propose that these radio events are the direct manifestation of dark matter annihilation events within the axion quark nugget (AQN) framework. It has been argued \cite{Zhitnitsky:2017rop,Raza:2018gpb} that the AQN annihilation events in the quiet solar corona can be identified with the nanoflares conjectured by Parker \cite{Parker-1983}. We further support this claim by demonstrating that observed impulsive radio events \cite{Mondal-2020}, including their rate of appearance, their temporal and spatial distributions and their energetics, are matching the generic consequences of AQN annihilations in the quiet corona. We propose to test this idea by analyzing the correlated clustering of impulsive radio events in different frequency bands. These correlations are expressed in terms of the time delays between radio events in different frequency bands, measured in seconds. We also make generic predictions for low (80 and 89 MHz) and high (179, 196, 217 and 240 MHz) frequency bands, that have been recorded, but not published, by \cite{Mondal-2020}. We finally suggest to test our proposal by studying possible cross-correlation between MWA radio signals and Solar Orbiter recording of extreme UV photons (a.k.a. "campfires").

Axion quark nugget dark matter model: Size distribution and survival pattern

We consider the formation and evolution of Axion Quark Nugget dark matter particles in the early universe. The goal of this work is to estimate the mass distribution of these objects and assess their ability to form and survive to the present day. We argue that this model allows a broad range of parameter space in which the AQN may account for the observed dark matter mass density, naturally explains a similarity between the "dark" and "visible" components, i.e. $\Omega_{\rm dark}\sim \Omega_{\rm visible}$, and also offer an explanation for a number of other long standing puzzles such as "Primordial Lithium Puzzle" and "the Solar Corona Mystery" among many other cosmological puzzles.

The 21 cm absorption line and the axion quark nugget dark matter model

We argue that dark matter in the form of macroscopically large nuggets of standard model quarks and antiquarks can help to alleviate the tension between standard model cosmology and the recent EDGES observation of a stronger than anticipated 21 cm absorption feature. The effect occurs as a result of the thermal emission from quark nugget dark matter at early times and at energies well below the peak of the CMB. Similar radiation at early times may also contribute a fraction of the GHz range excess observed by ARCADE2.

Fast radio bursts and the axion quark nugget dark matter model

We explore the possibility that the Fast Radio Bursts (FRBs) are powered by magnetic reconnection in magnetars, triggered by Axion Quark Nugget (AQN) dark matter. In this model, the magnetic reconnection is ignited by the shock wave which develops when the nuggets' Mach number $M \gg 1$. These shock waves generate very strong and very short impulses expressed in terms of pressure $\Delta p/p\sim M^2$ and temperature $\Delta T/T\sim M^2$ in the vicinity of (would be) magnetic reconnection area. We find that the proposed mechanism produces a coherent emission which is consistent with current data, in particular the FRB energy requirements, the observed energy distribution, the frequency range and the burst duration. Our model allows us to propose additional tests which future data will be able to challenge.

Solar corona heating by axion quark nugget dark matter

In this work we advocate for the idea that two seemingly unrelated 80-year-old mysteries - the nature of dark matter and the high temperature of the million degree solar corona - may have resolutions that lie within the same physical framework. The current paradigm is that the corona is heated by nanoflares, which were originally proposed as miniature versions of the observed solar flares. It was recently suggested that the nanoflares could be identified as annihilation events of the nuggets from the Axion Quark Nugget (AQN) dark matter model. This model was invented as an explanation of the observed ratio $\Omega_{\rm dark} \sim \Omega_{\rm visible}$, based only on cosmological and particle physics considerations. In this new paradigm, the AQN particles moving through the coronal plasma and annihilating with normal matter can lead to the drastic change of temperatures seen in the Sun's Transition Region (TR), and significantly contribute to the extreme ultraviolet (EUV) excess of $10^{27}~{\rm erg~s^{-1}}$. To test this proposal, we perform numerical simulations with a realistically modeled AQN particle distribution and explore how the nuggets interact with the coronal plasma. Remarkably, our simulations predict the correct energy budget for the solar corona, and show that the energy injection mostly occurs at an altitude of around 2000 km, which is where the TR lies. Therefore, we propose that these long unresolved mysteries could be two sides of the same coin. We make several predictions based on this proposal, some of which could be tested by the recently launched NASA mission, the Parker Solar Probe.