The Baryonic Tully-Fisher Relation of Gas Rich Galaxies as a Test of LCDM and MOND

TL;DR

The paper examines the Baryonic Tully-Fisher Relation in gas-rich galaxies to test predictions of LCDM and MOND, finding data consistent with MOND's relation and exploring feedback effects in galaxy formation.

Contribution

It provides new observational constraints on the BTFR using gas-rich galaxies and introduces a feedback parameter linking halo properties to galaxy characteristics.

Findings

Data supports the MOND prediction of Mb = AVf^4.

Scatter in the data is mainly due to observational uncertainties.

Feedback effects correlate with star formation and gas fraction.

Abstract

The Baryonic Tully-Fisher Relation (BTFR) is an empirical relation between baryonic mass and rotation velocity in disk galaxies. It provides tests of galaxy formation models in LCDM and of alternative theories like MOND. Observations of gas rich galaxies provide a measure of the slope and normalization of the BTFR that is more accurate (if less precise) than that provided by star dominated spirals, as their masses are insensitive to the details of stellar population modeling. Recent independent data for such galaxies are consistent with Mb = AVf^4 with A = 47+/-6 Msun (km/s)^-4. This is equivalent to MOND with $a_0 = 1.3 +/- 0.3 A/s/s. The scatter in the data is consistent with being due entirely to observational uncertainties. It is unclear why the physics of galaxy formation in LCDM happens to pick out the relation predicted by MOND. We introduce a feedback efficacy parameter E to relate halo properties to those of the galaxies they host. E correlates with star formation rate and gas fraction in the sense that galaxies that have experienced the least star formation have been most impacted by feedback.