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Papers by Shahriar Siddiqui
SSRN Electronic Journal, 2022
The XMM-Newton observatory shows evidence with an 11σ confidence level for seasonal variation of ... more The XMM-Newton observatory shows evidence with an 11σ 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 ∼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. 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.
We advocate for the idea that there is a fundamentally new mechanism for axion production on Eart... more We advocate for the idea that there is a fundamentally new mechanism for axion production on Earth, as recently suggested in Fischer et al. (2018) and Liang & Zhitnitsky (2018). We specifically focus on production of axions within Earth, with low velocities such that they will be trapped in the gravitational field. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. This occurs in the model irrespective of the axion mass m_a or initial misalignment angle θ_0. Annihilation of antimatter AQNs with visible matter inevitably produce axions when AQNs hit Earth. The emission rate of axions with velocities below escape velocity is very tiny compared to the overall emission, however these axions will be accumulated over the 4.5 billion year life time of the Earth, which greatly enhances the discovery potential. We perform numerical simulations wi...
The Murchison Widefield Array (MWA) has recorded <cit.> impulsive radio events in the quiet... more The Murchison Widefield Array (MWA) has recorded <cit.> impulsive radio events in the quiet solar corona at frequencies 98, 120, 132, and 160 MHz. We propose that these radio events represent the direct manifestation of the dark matter annihilation events within the so-called axion quark nugget (AQN) framework. It has been previously argued that the AQN annihilation events in the quiet solar corona <cit.> can be identified with nanoflares originally conjectured by Parker long ago <cit.>. In the present work we further support this claim by demonstrating that the radio observations <cit.>, including the frequency of appearance, temporal and spatial distributions, energetics, and other related observables are nicely matching the generic consequences of the AQN annihilation events in the quiet corona. We propose to test these ideas by analyzing the correlated clustering radio impulsive events in the different frequency bands. We also make generic predictions for...
Physical Review D, 2020
The Murchison Widefield Array (MWA) has recorded [1] impulsive radio events in the quiet solar co... more The Murchison Widefield Array (MWA) has recorded [1] impulsive radio events in the quiet solar corona at frequencies 98, 120, 132, and 160 MHz. We propose that these radio events represent the direct manifestation of the dark matter annihilation events within the so-called axion quark nugget (AQN) framework. It has been previously argued that the AQN annihilation events in the quiet solar corona [2, 3] can be identified with nanoflares originally conjectured by Parker long ago [4]. In the present work we further support this claim by demonstrating that the radio observations [1], including the frequency of appearance, temporal and spatial distributions, energetics, and other related observables are nicely matching the generic consequences of the AQN annihilation events in the quiet corona. We propose to test these ideas by analyzing the correlated clustering radio impulsive events in the different frequency bands. We also make generic predictions for low (80 and 89) MHz and high (179, 196, 217 and 240) MHz frequency bands which had been already recorded but not published by [1] yet. We also suggest to test this proposal by studying possible cross-correlation between MWA radio signals and Solar Orbiter recording of the extreme ultraviolet photons (coined as the "campfires") to support or refute this proposal.
arXiv: Cosmology and Nongalactic Astrophysics, 2019
We advocate the idea that the study of time variation in the axion dark matter searches can great... more We advocate the idea that the study of time variation in the axion dark matter searches can greatly enhance its discovery potential. We specifically focus on a new mechanism of the axion production suggested recently in [1,2]. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. We perform numerical simulations to evaluate the axion flux on the surface of Earth based on realistic models of AQN velocity and mass distributions. We examine several potential flux modulations such as annual or daily modulation, which have been studied previously and are known to occur for any type of dark matter. We also discuss a novel type of short time enhancements which are unique to the AQN model: the statistical fluctuations and local flashes, both of which can drastically amplify the axion signal, up to a factor 10210^2102-$10^3$ for a short period of time. ...
We study the new mechanism of the axion production suggested recently in [1,2]. This mechanism is... more We study the new mechanism of the axion production suggested recently in [1,2]. This mechanism is based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. We perform numerical simulations to evaluate the axion flux on the Earth's surface. We examine annual and daily modulations, which have been studied previously and are known to occur for any type of dark matter. We also discuss a novel type of short time enhancements which are unique to the AQN model: the statistical fluctuations and burst-like amplification, both of which can drastically amplify the axion signal, up to a factor ∼10^2-10^3 for a very short period of time. The present work studies the AQN-induced axions within the mass window 10^-6 eV≲ m_a≲10^-3 eV with typical velocities 〈 v_a〉∼0.6c. We also comment on the broadband detection strategy to search for such relativistic axions by studying the da...
SSRN Electronic Journal, 2022
The XMM-Newton observatory shows evidence with an 11σ confidence level for seasonal variation of ... more The XMM-Newton observatory shows evidence with an 11σ 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 ∼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. 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.
We advocate for the idea that there is a fundamentally new mechanism for axion production on Eart... more We advocate for the idea that there is a fundamentally new mechanism for axion production on Earth, as recently suggested in Fischer et al. (2018) and Liang & Zhitnitsky (2018). We specifically focus on production of axions within Earth, with low velocities such that they will be trapped in the gravitational field. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. This occurs in the model irrespective of the axion mass m_a or initial misalignment angle θ_0. Annihilation of antimatter AQNs with visible matter inevitably produce axions when AQNs hit Earth. The emission rate of axions with velocities below escape velocity is very tiny compared to the overall emission, however these axions will be accumulated over the 4.5 billion year life time of the Earth, which greatly enhances the discovery potential. We perform numerical simulations wi...
The Murchison Widefield Array (MWA) has recorded <cit.> impulsive radio events in the quiet... more The Murchison Widefield Array (MWA) has recorded <cit.> impulsive radio events in the quiet solar corona at frequencies 98, 120, 132, and 160 MHz. We propose that these radio events represent the direct manifestation of the dark matter annihilation events within the so-called axion quark nugget (AQN) framework. It has been previously argued that the AQN annihilation events in the quiet solar corona <cit.> can be identified with nanoflares originally conjectured by Parker long ago <cit.>. In the present work we further support this claim by demonstrating that the radio observations <cit.>, including the frequency of appearance, temporal and spatial distributions, energetics, and other related observables are nicely matching the generic consequences of the AQN annihilation events in the quiet corona. We propose to test these ideas by analyzing the correlated clustering radio impulsive events in the different frequency bands. We also make generic predictions for...
Physical Review D, 2020
The Murchison Widefield Array (MWA) has recorded [1] impulsive radio events in the quiet solar co... more The Murchison Widefield Array (MWA) has recorded [1] impulsive radio events in the quiet solar corona at frequencies 98, 120, 132, and 160 MHz. We propose that these radio events represent the direct manifestation of the dark matter annihilation events within the so-called axion quark nugget (AQN) framework. It has been previously argued that the AQN annihilation events in the quiet solar corona [2, 3] can be identified with nanoflares originally conjectured by Parker long ago [4]. In the present work we further support this claim by demonstrating that the radio observations [1], including the frequency of appearance, temporal and spatial distributions, energetics, and other related observables are nicely matching the generic consequences of the AQN annihilation events in the quiet corona. We propose to test these ideas by analyzing the correlated clustering radio impulsive events in the different frequency bands. We also make generic predictions for low (80 and 89) MHz and high (179, 196, 217 and 240) MHz frequency bands which had been already recorded but not published by [1] yet. We also suggest to test this proposal by studying possible cross-correlation between MWA radio signals and Solar Orbiter recording of the extreme ultraviolet photons (coined as the "campfires") to support or refute this proposal.
arXiv: Cosmology and Nongalactic Astrophysics, 2019
We advocate the idea that the study of time variation in the axion dark matter searches can great... more We advocate the idea that the study of time variation in the axion dark matter searches can greatly enhance its discovery potential. We specifically focus on a new mechanism of the axion production suggested recently in [1,2]. Our computations are based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. We perform numerical simulations to evaluate the axion flux on the surface of Earth based on realistic models of AQN velocity and mass distributions. We examine several potential flux modulations such as annual or daily modulation, which have been studied previously and are known to occur for any type of dark matter. We also discuss a novel type of short time enhancements which are unique to the AQN model: the statistical fluctuations and local flashes, both of which can drastically amplify the axion signal, up to a factor 10210^2102-$10^3$ for a short period of time. ...
We study the new mechanism of the axion production suggested recently in [1,2]. This mechanism is... more We study the new mechanism of the axion production suggested recently in [1,2]. This mechanism is based on the so-called Axion Quark Nugget (AQN) dark matter model, which was originally invented to explain the similarity of the dark and visible cosmological matter densities. We perform numerical simulations to evaluate the axion flux on the Earth's surface. We examine annual and daily modulations, which have been studied previously and are known to occur for any type of dark matter. We also discuss a novel type of short time enhancements which are unique to the AQN model: the statistical fluctuations and burst-like amplification, both of which can drastically amplify the axion signal, up to a factor ∼10^2-10^3 for a very short period of time. The present work studies the AQN-induced axions within the mass window 10^-6 eV≲ m_a≲10^-3 eV with typical velocities 〈 v_a〉∼0.6c. We also comment on the broadband detection strategy to search for such relativistic axions by studying the da...