A Slippery Slope: Systematic Uncertainties in the Line Width Baryonic Tully-Fisher Relation

Understand

The baryonic Tully-Fisher relation (BTFR) is a valuable observational tool and a critical test of galaxy formation theory.

• We explore the systematic uncertainty in the slope and the scatter of the observed line width BTFR utilizing homogeneously measured, unresolved HI observations for 930 isolated galaxies.
• We measure a fiducial relation of $\log_{10}{M_{\rm baryon}} = 3.24\log_{10}{V_{\rm rot}}+3.21$ with observed scatter of 0.25 dex with $10^{7.4} < M_{\rm baryon} < 10^{11.3}M_{\odot}$ where $V_{\rm rot}$ is measured from 20\% HI line widths.
• We vary the definitions of $M_{\rm baryon}$ and $V_{\rm rot}$, the sample selection, and the linear fitting algorithm.