Probing the evolution of galaxies since z ~ 1 with the Tully-Fisher relation

Thesis

In this thesis we use the Tully-Fisher relation (TFR), the correlation between a galaxy's luminosity and its rotation velocity, to probe the luminous and dark matter in galaxies over the last ≈ 8 Gyr. First, we use samples of galaxies spatially resolved in Hα emission with integral field unit observations from the K-band Multi-Object Spectrograph (KMOS) Redshift One Spectroscopic Survey (KROSS) at z ≈ 1 and the Sydney-Australian-Astronomical-Observatory Multi- object Integral-Field Spectrograph (SAMI) Galaxy Survey at z ≈ 0. We match the data quality, analysis methods and sample selection between the two surveys to conduct a direct comparison of the absolute K-band magnitude (MK) and stellar mass (M_*) TFRs at z ≈ 1 and z ≈ 0, free of any difference in biases between them. We measure no evolution of the MK TFR zero-point for star- forming disk-like galaxies since z ≈ 1, but an increase by 0.2 ± 0.2 dex of the M_* TFR zero-point for the same galaxies over the same period. This implies the total mass-to-stellar mass ratio of those galaxies has decreased by a factor of ≈ 0.4 since z ≈ 1 at fixed rotation velocity, whilst their K-band stellar mass-to- light ratio has increased by a factor of ≈ 1.6. Moderate rates of star formation in galaxies and continued gas accretion since z ≈ 1 can explain these changes. Second, we take a step toward an independent measure of the TFR evolution over the same period using carbon monoxide (CO) emission from galaxies as an alternative kinematic tracer. We present the M_* and Wide-Field Infrared Survey Explorer absolute Band 1 magnitude (MW1) TFRs for galaxies from the CO Legacy Database for the Galex Arecibo SDSS Survey (COLD GASS) as z ≈ 0 benchmarks that are pre-requisites to extend the CO TFR to z ≳ 1. We find no significant offsets between the COLD GASS TFR zero-points and those of similar z ≈ 0 studies. The slope of the M_* COLD GASS TFR agrees with those of similar z ≈ 0 studies, but the MW1 TFR slope is slightly shallower than previous studies at a similar redshift. 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.

Authors: Tiley, A

• DOI: 10.5287/ora-oznkbg7zy
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: galaxies; galaxy kinematics; galaxy evolution
• Subjects: Astronomy