[Paper Review] Nano meter Size Dirty Dark Matter Pearls, electron-signal, IMP or SIDM, not WIMP

C.D. Froggatt, H. B. Nielsen|arXiv (Cornell University)|May 18, 2022

Dark Matter and Cosmic Phenomena4 citations

TL;DR

This paper proposes a nanometer-sized, dusty dark matter pearl model where dark matter consists of high-pressure vacuum bubbles (with a 3.5 keV electronic homolumo gap) embedded in interstellar dust grains. The model explains the DAMA-LIBRA annual modulation and the 3.5 keV X-ray line via electron de-excitation, predicting electron-only signals—making it an interacting massive particle (IMP) or self-interacting dark matter (SIDM) model, not a WIMP.

ABSTRACT

Through several articles we have developed a model for dark matter as consisting of bubbles of a new (speculated) type of vacuum, starting from cm-sized pearls or balls down to atomic size ones and now we believe they have nanometer sizes. In the latest development of our model we have the bubbles of the new vacuum imbedded in dust grains very similar to the grains present in interstellar and intergalactic space anyway, although the presence of the bubble with a very large homolumo gap in its single electron spectrum influences the dust grain material so as to become denser and harder. We have earlier explained how our dark matter particles get stopped in the shielding, so that normally expected nucleonic collisions are not observable. The signal of the dark matter in the underground experiments rather becomes decays of excited particles actually with the energy of the homolumo gap, which is also equal to the photon energy of the X-ray line presumably observed astronomically from galaxy clusters etc. A new calculation here is a fitting of the velocity dependence of the dark matter self-interaction as estimated by Correa [15], using deviations from the only gravitationally interacting dark matter in dwarf galaxies. Let us stress that apart from the speculated new vacuum we have no new physics, and if the couplings in the Standard Model were adjusted to make degenerate vacua as speculated according to our Multiple Point Principle (MPP) we would only need the Standard Model, so dark matter would not require new physics.

Motivation & Objective

• To resolve the discrepancy between DAMA-LIBRA’s observed annual modulation and null results from xenon-based experiments.
• To explain the persistent 3.5 keV X-ray line observed in galaxy clusters and supernova remnants as a signature of dark matter de-excitation.
• To propose a dark matter model based on vacuum bubbles with a homolumo gap, avoiding new physics beyond the Standard Model via the Multiple Point Principle.
• To account for the velocity-dependent dark matter self-interaction cross-section ratio σ/M observed in dwarf galaxies via a dense, dusty pearl structure.
• To show that electron-only signals—due to excitation and decay of electrons across the homolumo gap—can explain why only electron-sensitive experiments detect dark matter.

Proposed method

• Model dark matter as nanoscale vacuum bubbles (R ≈ 10⁻⁹ m) filled with high-pressure matter (e.g., carbon), embedded in interstellar dust grains.
• Use the homolumo gap energy (3.5 keV) as the primary emission energy for X-ray and electron signals, derived from the electron spectrum of the pearl.
• Apply dimensional arguments to estimate suppression of kinetic energy transfer to underground detectors, based on excitation lifetime vs. passage time through Earth.
• Fit the velocity-dependent σ/M ratio from dwarf galaxy observations to the model’s predicted interaction cross-section, assuming the pearl behaves as a dense, hard object.
• Use the observed 3.5 keV X-ray intensity from galaxy clusters and Tycho’s supernova remnant to constrain the model’s parameters, particularly the ratio ξ_fS^{1/4}/ΔV.
• Treat the 3.5 keV energy as a theoretical parameter in the model, calibrated against astrophysical observations to derive mass and radius bounds.

Experimental results

Research questions

• RQ1 Why do electron-only experiments like DAMA-LIBRA detect dark matter while nuclear-recoil experiments like Xenon1T do not?
• RQ2 What physical mechanism could produce a 3.5 keV X-ray line in galaxy clusters and supernova remnants, consistent with dark matter decay?
• RQ3 How can the observed velocity-dependent dark matter self-interaction cross-section (σ/M) be explained without invoking new fundamental interactions?
• RQ4 Can the observed annual modulation in DAMA-LIBRA be explained by long-lived excited states of dark matter pearls with 3.5 keV transitions?
• RQ5 What are the mass and size constraints on dark matter pearls that reproduce both the 3.5 keV signal and the σ/M velocity dependence?

Key findings

• The model predicts a 3.5 keV electron transition energy from the homolumo gap in nanoscale vacuum bubbles, matching the energy of the observed 3.5 keV X-ray line in galaxy clusters.
• The DAMA-LIBRA annual modulation rate of 0.041 cpd/kg is reproduced via a crude dimensional estimate of energy transfer, with suppression factors of ~6×10⁻¹⁰ (air) and ~6×10⁻¹⁴ (stone).
• The observed σ/M ratio in dwarf galaxies (15 m²/kg at v→0) is consistent with the model’s prediction for a 10⁻⁹ m radius pearl with mass ~3×10⁻¹⁵ kg.
• The model explains the 3.5 keV X-ray line from Tycho’s supernova remnant as due to cosmic-ray-induced excitation of dark matter pearls, with ~1% of cosmic ray energy converted to X-rays.
• The 3.5 keV energy appears consistently across three independent observations: DAMA-LIBRA (electron events), Xenon1T (electron recoil excess), and astrophysical X-ray lines.
• Mass and radius estimates range from R ≈ 10⁻⁹ m (1.2×10⁻⁹ m uncertainty) and M ≈ 3×10⁻¹⁵ kg (200% uncertainty), with larger values possible under different assumptions, all consistent with nanoscale, dusty vacuum bubbles.