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Sekatchev, Michael

University of British Columbia

Observations of background radiation in the Milky Way have revealed a puzzling excess of far-ultraviolet (FUV) emission (1350–1750 Å), confirmed by the GALEX space telescope and the New Horizons mission. The origin of this excess remains unexplained by conventional astrophysical sources. This thesis investigates the potential role of the Axion Quark Nugget (AQN) dark matter model in accounting for this mysterious emission. The model proposes that dark matter is dominated by macroscopic composite objects of nuclear density, in the form of matter and antimatter nuggets. Matter (antimatter) AQNs contain quarks (antiquarks) surrounded by an electrosphere (positron-sphere). When antimatter AQNs collide with baryonic matter in the Milky Way, the baryons annihilate leading the AQN to emit a broadband electromagnetic radiation, which includes FUV photons. By simulating these annihilation events within a high-resolution cosmological hydrodynamic model of a Milky Way-like galaxy (the FIRE-2 Latte suite), we estimate the AQN-induced FUV signal. Our analysis reveals that the predicted AQN signal is consistent with the observed FUV excess within the same order of magnitude. More specifically, AQN annihilations can produce an FUV signal of 100–200 photon cm⁻² s⁻¹ sr⁻¹ Å⁻¹ for nugget masses m_AQN ~ 0.1–1 kg, consistent with the excess from GALEX. These findings suggest that AQN-baryon annihilations could provide a viable explanation for the diffuse FUV background and shed light on the nature of dark matter and its interaction with visible matter. We motivate future studies of the broadband AQN emission to probe other Galactic excesses (e.g., X-ray, radio) and cosmological tensions (e.g. reionization).

Text

2025-04-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90744

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/