1 A Role for Bose-Einstein Condensation in Astrophysics B. W. Ninham1,*, I. Brevik2,*, O. I. Malyi3,*, and M. Boström3,* 1Department of Materials Physics, Research School of Physics, Australian National University, Canberra, Australia, 0200. 2Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway 3Centre of Excellence ENSEMBLE3 Sp. z o. o., Wolczynska Str. 133, 01-919, Warsaw, Poland. * E-mail addresses: Barry.Ninham@anu.edu.au; iver.h.brevik@gmail.com; oleksandr.malyi@ensemble3.eu; Mathias.Bostrom@ensemble3.eu Received: Mar 21, 2023 Revised: May 23, 2023 Just Accepted Online: Jun 06, 2023 Published: Xxx This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as: B. W. Ninham, I. Brevik, O. I. Malyi, and M. Boström, (2023) A Role for Bose-Einstein Condensation in Astrophysics. Substantia. Just Accepted. DOI: 10.36253/Substantia-2091 Abstract We revive a 60-year-old idea that might explain a remarkable new observation of a periodic low-frequency radio emission from a source at galactic distances (GLEAM-X J162759.5- mailto:Barry.Ninham@anu.edu.au mailto:iver.h.brevik@gmail.com mailto:oleksandr.malyi@ensemble3.eu 2 523504.3). It derives from the observation that a high-density high-temperature charged boson plasma is a superconducting superfluid with a Meissner effect. Keywords: Bose-Einstein condensate, Charged Bose gas, Astrophysical Chemistry Introduction Sporadic forays over the years have explored the possibility that the physics of Bose- Einstein condensation ought to play some role in Astrophysics, e.g. [1,2]. Many of the particles involved in stellar evolution are bosons, i.e. have zero or integer spin. Bose-Einstein condensation is a fundamental macroscopic manifestation of quantum physics. It would seem remiss of the Creator not to have employed the phenomenon somewhere in building the Universe. Especially is this so since Fermi-Dirac and Classical Statistical Mechanics do figure largely. A suggestion of a role for Bose-Einstein condensation was made 60 years ago when quasars were first observed [1], and forgotten. Later attempts failed because they considered superconductivity and Bose condensation as classical low-temperature phenomena like that which occurs for electrons in metals. But the phenomena are not limited and exist for very high-temperature high-density charged particles [1]. We here revive that 60-year-old idea and suggest it might explain a recent extraordinary observation. The Phenomenon Hurley-Walker et al. [3] recently reported an unusually slow periodic low-frequency radio emission from a source at galactic distances (GLEAM-X J162759.5-523504.3) with a pulse 3 period of 18.18 minutes. One clue to its origin is that high linear polarization has been shown to be characteristic of a source with strongly ordered magnetic fields [4-6]. The observations are unlike emissions characteristic of stars, white dwarfs, white binaries, or exoplanets. Furthermore, the 0.5-light-second upper limit on the object’s size and estimated brightness temperature of 1016 K led Hurley-Walker et al. [3] to propose that a radiation source is a compact object with a rotational origin. The Idea With that in mind, we give reasons to consider if Bose-Einstein condensation [1] might have something to do the phenomenon: (i) Stable nuclei in stellar interiors have zero or integer spin. Nuclei of higher and higher atomic numbers built up during the evolution of stars. They are charged bosons. (ii) A dense charged high-temperature boson plasma becomes nearly perfect as density increases (i.e., the Coulomb collective interactions become so weak that they can be ignored, and we can work with the perfect gas approximation). (iii) It can undergo Bose-Einstein condensation to a superfluid state. (iv) A conducting superfluid is a superconductor. A rotating superconducting superfluid has a Meissner effect. That is, it expels the magnetic field generated by rotation. (v) Such a magnetic field would be trapped in the lower-density surface region. This process continues as the star collapses and its rotation speeds up. 4 (vi) Massive synchrotron radiation follows that dissipates this increasing build-up of energy. The assumptions i-vi were originally made 60 years ago to explain the newly discovered quasars. Schafroth [8], Blatt [9], and Butler [10] had shown earlier that an ideal charged Bose gas below the critical point for superfluidity is a superconductor (see also Refs. [7,8-17]). These theories [7-17] call on electron pairing to generate charged bosons that then lead to Bose condensation and superconductivity at very low temperatures. Our situation is quite different. The stellar objects involve real boson nuclei of even spin. The high-density, high-temperature plasmas are close to ideal. We recall the process of nucleosynthesis in stellar interiors [18-21]. The theory explains how nuclear reactions convert lighter elements into heavier ones through the fusion of atomic nuclei. As the star evolves, the fuel elements involve successive steps, with H, He, C, O, Ne, Si, Fe, and U providing increasingly heavier energy sources that drive the stellar evolution to completion [18]. We need to estimate the critical temperatures and core densities for Bose condensation for stars with different fuel elements to check that they can have a Boson core region. Calculations Consider an assembly of ions of even spin, mass M and charge Ze, in a background electron gas. Under extreme high-density and high-temperature conditions, the system is expected to behave like a mixture of ideal gases. That can be achieved by ensuring that the average energy of Coulomb interactions between two ions is small compared to their kinetic energy. At densities approaching the critical value for Bose-Einstein condensation of ions, i.e., when their 5 chemical potential approaches zero, the mean energy, per particle of the ideal Bose gas is approximately equal to kT. The average distance between the particles is then [1] r ≈ 2 √3M/[4πρ] 3 ≈  λ = ℎ/(𝑀𝑣) = ℎ/√2  M kT, (1) where 𝜆 is the de Broglie wave length of an ion of mass M and kinetic energy ~𝑘𝑇 (taken in Eq (1) equal to Mv2/2). The condition that the actual gas be nearly ideal is [1] 2𝑍2𝑒2 𝑟 ≪ 𝑘𝑇. (2) Hence, taking the requirement Eq. (2) with Eq. (1), the critical expressions for temperatures, density, and particle separation can be estimated to be of the order 𝑇𝐶~ 8𝑀𝑍4𝑒4 ℎ2𝑘 (3) ρ𝐶~ 384 𝜋 𝑀4𝑍6𝑒6 ℎ6 ~ 6 8𝜋 𝑀𝑘3 𝑍6𝑒6 𝑇𝐶 3, (4) r𝐶~ ℎ2 4𝑀𝑍2𝑒2 ~ 2𝑍2𝑒2 𝑘𝑇𝐶 . (5) The numerical values are summarized in Table 1. We expect that highly charged nuclei will be “dressed” by an inhomogeneous adsorbed relativistic electron cloud (mesons in another guise): just as for charged micelles or highly charged ions in electrolyte solutions. In that case, “bound” counterions are typically 80-90% of the bare charge. The effective charge is 10-20% of the actual charge. Without recognising such screening, estimated critical parameters for the separation of heavy ions become unphysical and ridiculous. In Table 1, we take two 6 extreme estimates to bound these uncertainties: the unscreened Z and Z=1. To illustrate our point, we present also the critical temperatures with 10% and 20% effective charges in Table 2. For Uranium, from Table 2, the estimated critical temperatures are 1014 K