Probing the hidden nature of the universe by high energy physics simulations of Black Hole nucleosynthesis and Relativistic Jets

Technical Summary: Probing the Hidden Nature of the Universe by High Energy Physics Simulations of Black Hole Nucleosynthesis and Relativistic Jets

Problem Statement
The origin of heavy elements in the universe remains a significant challenge in nuclear astrophysics. While Big Bang Nucleosynthesis (BBN) successfully explains the formation of light elements (up to Lithium), and stellar nucleosynthesis accounts for elements up to Iron (Fe), the mechanisms for synthesizing elements heavier than iron—particularly superheavy elements beyond the current experimental limit of $Z=118$—are not fully understood. Traditional models rely on stellar evolution, supernovae, and neutron star mergers, yet uncertainties persist regarding reaction rates, r-process sites, and the ultimate abundance patterns of heavy elements. Furthermore, the thermodynamic drivers of cosmic expansion and compression, specifically the roles of dark energy and dark matter, lack a unified explanation linking them to nuclear processes. This study posits that black holes, active galactic nuclei (AGN), and their relativistic jets may serve as extreme environments capable of driving nucleosynthesis beyond standard stellar limits, potentially offering a mechanism for the generation of superheavy elements and a new perspective on cosmological dynamics.

Methodology
The research employs the Geant4 simulation toolkit, specifically utilizing its Hadron Physics package, to model nuclear processes under extreme astrophysical conditions. Unlike traditional approaches that focus solely on stellar cores, this study simulates nucleosynthesis within the context of black hole accretion disks and relativistic jets.

• Simulation Setup: The environment was configured to mimic the high-temperature, high-density, and high-radiation conditions of black hole jets. The geometry involved a dense population of particles simulating jet outflows with relativistic velocities.
• Initial Conditions: The simulation began with a composition of free neutrons, protons, and light nuclei (Hydrogen-1, Deuterium, Tritium) representing Galactic material.
• Reaction Mechanism: The study utilized an alpha-particle driven process. Alpha particles (simulated as Hawking radiation or jet components) were introduced to collide with the Galactic material. Newly synthesized nuclei were incorporated into the surrounding medium, where they subsequently interacted with further alpha particles to drive successive stages of element formation.
• Physics Models: The simulation employed Hadronic Elastic and Inelastic physics (G4HadronPhysicsFTFP_BERT_HP), Ion Elastic and Inelastic physics (G4IonElasticPhysics, G4IonElasticPhysicsXS), and omitted standard radioactive decay physics to focus on the synthesis of new atomic structures rather than the fragmentation of existing ones. Cross-section data were sourced from ENDF/B-VIII and JENDL libraries.
• Parameters: The study tracked initiation energy, initiation temperature, and Q-values (energy released or absorbed) for 580 nuclide synthesis reactions, extending theoretical investigations up to atomic number $Z=238$.

Key Results
The simulation produced a comprehensive dataset regarding the thermodynamic requirements for synthesizing elements from Hydrogen up to theoretical limits of $Z=238$.

1. Initiation Energy and Temperature Trends:

   • A strong positive correlation exists between atomic number ($Z$) and both initiation energy and temperature.
   • Linear Phase ($Z \le 108$): Initiation energy and temperature increase linearly. Energy thresholds remain below 1.7 GeV, and temperatures stay below $20 \times 10^{12}$ Kelvin.
   • Exponential Transition ($108 < Z \le 124$): A distinct shift occurs where initiation energy and temperature exhibit exponential growth. Energy requirements jump from 2500 MeV to 8000 MeV, and temperatures rise from $20 \times 10^{12}$ K to $100 \times 10^{12}$ K. This steep rise explains the current experimental limit of $Z=118$.
   • High-Z Phase ($Z > 130$): A second exponential trend is observed up to $Z=238$, with energy requirements reaching up to 12.4 GeV and temperatures up to $145 \times 10^{12}$ K.
   • Implication for $Z=118$: The steep exponential rise in energy requirements beyond $Z=108$ provides a thermodynamic explanation for the current experimental difficulty in synthesizing elements beyond $Z=118$.

2. Q-Value Analysis:

   • Positive Q-Values ($Z < 26$): Reactions are exothermic (energy-releasing), consistent with stellar fusion processes.
   • Negative Q-Values ($Z > 26$): Reactions become endothermic (energy-absorbing). The study finds that nucleosynthesis for heavy elements requires significant energy input.
   • Black Hole Correlation: The prevalence of negative Q-values in heavy element synthesis aligns with the energy-absorbing nature of black holes. The study suggests that black holes act as "synthesis reactors" that absorb energy to create matter, whereas stars act as "fusion reactors" that release energy.

3. Cosmological Dynamics:

   • The study links Q-values to the expansion and compression of the universe.
   • Expansion: Energy-to-matter conversion (negative Q-value reactions) generates an expansive force. The authors propose this mechanism drove the initial Inflationary expansion.
   • Compression: Matter-to-energy conversion (positive Q-value reactions) generates a compressive force, associated with stellar processes.
   • Evolutionary Model: The universe's evolution is interpreted as a sequence of phases (Inflation, Expansion, Steady State, Compression, Collapse) governed by the thermodynamic balance between black hole-driven expansion (energy absorption) and star-driven compression (energy release).

Significance and Claims
The paper claims to offer a novel interpretation of cosmic element formation and universal evolution:

• Black Hole Nucleosynthesis: It proposes that black holes and their relativistic jets are viable sites for the synthesis of superheavy elements ($Z > 118$) up to $Z=238$, driven by the extreme temperatures ($>10^9$ K) and the energy-absorbing nature of negative Q-value reactions.
• Detection Signatures: The study suggests that relativistic jets from quasars and AGN may carry detectable signatures of these newly synthesized elements, offering a new observational avenue for cosmic element formation.
• Unified Thermodynamic Framework: It presents a theoretical framework linking nuclear physics (Q-values) to cosmology. By equating energy-to-matter conversion with expansion and matter-to-energy conversion with compression, the paper attempts to explain the transition from Inflation to normal expansion and the potential future fate of the universe (Steady State vs. Collapse) based on the balance between black hole and stellar processes.
• Dark Matter/Energy Connection: The authors hypothesize that negative Q-value reactions generating negative energy/matter could provide a physical basis for Dark Energy and Dark Matter, associating them with black hole dynamics.

Limitations
The authors acknowledge that Geant4 was not originally designed for cosmological simulations and lacks built-in general relativity or large-scale plasma dynamics. Consequently, the study relies on approximations and parameterized geometries. Additionally, the simulation assumes the prior existence of Hydrogen and Helium (from BBN) and focuses on alpha-process synthesis, omitting pure proton/neutron initiation for the sake of computational feasibility within the simulation timeframe. The results are theoretical predictions based on the simulation toolkit rather than direct observational confirmation.