The baryonic Tully-Fisher relation as an independent direct probe of cosmology and of the nature of dark matter

Abstract

The baryonic Tully-Fisher relation (BTFR), a well-established galaxy scaling relation linking the dynamical mass of rotation-supported galaxies through their maximum circular velocity to the baryonic luminous mass, has emerged over the decades as a fundamental scaling relation and as a robust calibrated distance indicator, thereby providing a robust benchmark to test galaxy formation and evolution theories as well as an independent probe of the expansion of the Universe. In this paper, we show for the first time that the BTFR is also simultaneously directly sensitive to the cosmological parameters $Ω_m$ and $σ_8$, the astrophysical feedback from supernovae (SNe) and active galactic nuclei (AGN), and the mass of warm dark matter particles $M_{\rm wdm}$, and can therefore be used as novel, direct probe of cosmology and fundamental physics. We perform simulation-based inference on the large DREAMS cosmological magneto-hydrodynamic simulations suite and train deep neural networks in the form of normalizing flows to estimate the posterior distributions of $Ω_m$, $σ_8$, $M_{\rm wdm}$ and the three astrophysical free parameters, given a BTFR measurement. Our framework is able to recover unbiased values for $Ω_m$ and $σ_8$, with subpercent deviations accuracy and a $\sim 2.6\%$ and $\sim 3.9\%$ median precision, respectively, to capture the warm dark matter particle mass $M_{\rm wdm}$ within a $\sim 30-35\%$ precision, as well as to constrain the SN feedback parameters (but not the one regulating AGN feedback). We conclude that, beyond its usage as a distance indicator and to constrain the baryon cycle and the feedback mechanisms shaping galaxy formation and evolution, the BTFR constitutes a direct independent probe of cosmology and fundamental physics and opens new promising avenues, to be explored with the future Square Kilometer Array.