2023/05/04 by Mitchell T Dennis, Jeremy Sakstein, Dennis, Mitchell T +1 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Phenomenology (hep-ph) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2305.03113
openalex publication_date 2023/05/04 · openalex created_date 2023/05/10 · openalex updated_date 2026/07/28
We present a novel method for incorporating the effects of stellar modeling uncertainties into constraints on the axion-electron coupling constant found using the observed calibration of the tip of the red giant branch (TRGB) I band magnitude MI.~We simulate grids of models with varying initial stellar mass, helium abundance, metallicity, and axion-electron coupling α26= 1026 g2ae/4π but different (fixed) mixing lengths and mass loss efficiencies.~We then train separate machine learning emulators to predict MI as a function of the varying parameters for each grid.~Our emulators enable the use of Markov Chain Monte Carlo simulations where α26 is varied simultaneously with the stellar parameters.~One of our grids yields a bound α26≤ 0.75 at the 95% confidence limit, a factor of ∼3.7 weaker than previous bounds;~while the other grid yields α26≤1.58 at the 95% confidence limit, a factor ∼7.8 weaker than previous bounds.~We demonstrate that the different values we find are due to covariances between stellar and axion physics that are not accounted for by single parameter variations.~Our results suggest that the bound on α26 derived using empirical calibrations of the TRGB I band magnitude need to be reevaluated using simultaneous parameter variation.~Alternative methods that use the bolometric luminosity instead of MI are more robust because they are not reliant upon theoretical predictions of the effective temperature.