A Comparison of the Baryonic Tully-Fisher Relation in MaNGA and IllustrisTNG

TL;DR

This study compares the observed Baryonic Tully-Fisher Relation from galaxy surveys with a simulated version from IllustrisTNG, showing they agree within uncertainties when mock observations are used for a fair comparison.

Contribution

It demonstrates that the IllustrisTNG simulation accurately reproduces the observed BTFR when mock observational effects are properly incorporated.

Findings

MaNGA and IllustrisTNG BTFRs agree within uncertainties

Mock observations are essential for fair comparison

IllustrisTNG galaxy population matches observed mass-rotation relation

Abstract

We compare an observed Baryonic Tully-Fisher Relation (BTFR) from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) and HI-MaNGA surveys to a simulated BTFR from the cosmological magnetohydrodynamical simulation IllustrisTNG. To do so, we calibrate the BTFR of the local universe using 377 galaxies from the MaNGA and HI-MaNGA surveys, and perform mock 21 cm observations of matching galaxies from IllustrisTNG. The mock observations are used to ensure that the comparison with the observed galaxies is fair since it has identical measurement algorithms, observational limitations, biases and uncertainties. For comparison, we also calculate the BTFR for the simulation without mock observations, and demonstrate how mock observations are necessary to fairly and consistently compare between observational and theoretical data. We report a MaNGA BTFR of log$_{10} (M_{ \rm Bary}/M_\odot)= (2.97 \pm 0.18)$ log$_{10} V_{ \rm Rot} + (4.04 \pm 0.41)\,\log_{10}{M_{\odot}}$ and an IllustrisTNG BTFR of log$_{10} (M_{ \rm Bary}/M_\odot) = (2.94 \pm 0.23$) log$_{10} V_{ \rm Rot} + (4.15 \pm 0.44)\,\log_{10}{M_{\odot}}$. Thus, MaNGA and IllustrisTNG produce BTFRs that agree within uncertainties, demonstrating that IllustrisTNG has created a galaxy population that obeys the observed relationship between mass and rotation velocity in the observed universe.