The Tully-Fisher Relation of COLD GASS Galaxies

TL;DR

This study establishes the Tully-Fisher relations for COLD GASS galaxies using CO line widths, providing a comparison with previous relations and highlighting the effects of galaxy morphology on these relations.

Contribution

It introduces new CO-based Tully-Fisher relations for COLD GASS galaxies and compares them with existing optical and infrared relations, considering galaxy morphology effects.

Findings

The M_W1 TFR slope is shallower than previous studies due to galaxy morphology diversity.

No significant offset between COLD GASS TFRs and similar redshift/morphology samples.

The Gaussian Double Peak function is preferred for fitting CO line widths.

Abstract

We present the stellar mass (M_*) and Wide-Field Infrared Survey Explorer (WISE) absolute Band 1 magnitude (M_W1) Tully-Fisher relations (TFRs) of subsets of galaxies from the CO Legacy Database for the Galex Arecibo SDSS Survey (COLD GASS). We examine the benefits and drawbacks of several commonly used fitting functions in the context of measuring CO(1-0) line widths (and thus rotation velocities), favouring the Gaussian Double Peak function. We find the M_W1 and M_* TFR, for a carefully selected sub-sample, to be M_W1 = (-7.1 +/- 0.6) [log(W_50/sin i) - 2.58] - 23.83 +/- 0.09 and log(M_*/M_Sun) = (3.3 +/- 0.3) [log(W_50/sin i) - 2.58] + 10.51 +/- 0.04, respectively, where W_50 is the width of a galaxy's CO(1-0) integrated profile at 50% of its maximum and the inclination i is derived from the galaxy axial ratio measured on the SDSS r-band image. We find no evidence for any significant offset between the TFRs of COLD GASS galaxies and those of comparison samples of similar redshifts and morphologies. The slope of the COLD GASS M_* TFR agrees with the relation of Pizagno et al. (2005). However, we measure a comparatively shallower slope for the COLD GASS M_W1 TFR as compared to the relation of Tully & Pierce (2000). We attribute this to the fact that the COLD GASS sample comprises galaxies of various (late-type) morphologies. Nevertheless, our work provides a robust reference point with which to compare future CO TFR studies.