http://arxiv.org/abs/2303.11314
The radial acceleration relation (RAR) of late-type galaxies relates their dynamical acceleration, $g_\text{obs}$, to that sourced by baryons alone, $g_\text{bar}$, across their rotation curves. Literature fits to the RAR have fixed the galaxy parameters on which the relation depends — distance, inclination, luminosity and mass-to-light ratios — to their maximum a priori values with an uncorrelated Gaussian contribution to the uncertainties on $g_\text{bar}$ and $g_\text{obs}$. In reality these are free parameters of the fit, contributing systematic rather than statistical error. Assuming a range of possible functional forms for the relation with or without intrinsic scatter (motivated by Modified Newtonian Dynamics with or without the external field effect), I use Hamiltonian Monte Carlo to perform the full joint inference of RAR and galaxy parameters for the SPARC dataset. This reveals the intrinsic RAR underlying that observed. I find an acceleration scale $a_0=(1.19 \pm 0.04 \, \text{(stat)} \pm 0.09 \, \text{(sys)}) : \times : 10^{-10}$ m s$^{-2}$, an intrinsic scatter $\sigma_\text{int}=(0.034 \pm 0.01 \, \text{(stat)} \pm 0.01 \, \text{(sys)})$ dex (assuming the SPARC error model is reliable) and weak evidence for the external field effect. I make summary statistics of all my analyses publicly available for future SPARC studies or applications of a calibrated RAR, for example redshift-independent distance measurement.
H. Desmond
Tue, 21 Mar 23
31/68
Comments: 10 pages, 4 figures; MNRAS submitted
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