Calibrated Tully-Fisher relations for improved estimates of disc rotation velocities

Abstract

In this paper, we derive scaling relations between photometric observable quantities and disc galaxy rotation velocity Vrot or Tully–Fisher relations (TFRs). Our methodology is dictated by our purpose of obtaining purely photometric, minimal‐scatter estimators of Vrot applicable to large galaxy samples from imaging surveys. To achieve this goal, we have constructed a sample of 189 disc galaxies at redshifts z < 0.1 with long‐slit Hα spectroscopy from Pizagno et al. and new observations. By construction, this sample is a fair subsample of a large, well‐defined parent disc sample of ∼170 000 galaxies selected from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7). The optimal photometric estimator of Vrot we find is stellar mass M★ from Bell et al., based on the linear combination of a luminosity and a colour. Assuming a Kroupa initial mass function (IMF), we find: log [V80/(km s−1)] = (2.142 ± 0.004) + (0.278 ± 0.010)[log (M★/M⊙) − 10.10], where V80 is the rotation velocity measured at the radius R80 containing 80 per cent of the i‐band galaxy light. This relation has an intrinsic Gaussian scatter dex and a measured scatter σmeas= 0.056 dex in log V80. For a fixed IMF, we find that the dynamical‐to‐stellar mass ratios within R80, (Mdyn/M★)(R80), decrease from approximately 10 to 3, as stellar mass increases from M★≈ 109 to 1011 M⊙. At a fixed stellar mass, (Mdyn/M★)(R80) increases with disc size, so that it correlates more tightly with stellar surface density than with stellar mass or disc size alone. We interpret the observed variation in (Mdyn/M★)(R80) with disc size as a reflection of the fact that disc size dictates the radius at which Mdyn/M★ is measured, and consequently, the fraction of the dark matter ‘seen’ by the gas at that radius. For the lowest M★ galaxies, we find a positive correlation between TFR residuals and disc sizes, indicating that the total density profile is dominated by dark matter on these scales. For the highest M★ galaxies, we find instead a weak negative correlation, indicating a larger contribution of stars to the total density profile. This change in the sense of the correlation (from positive to negative) is consistent with the decreasing trend in (Mdyn/M★)(R80) with stellar mass. In future work, we will use these results to study disc galaxy formation and evolution and perform a fair, statistical analysis of the dynamics and masses of a photometrically selected sample of disc galaxies.

The new semi-analytic code GalICS 2.0 – reproducing the galaxy stellar mass function and the Tully–Fisher relation simultaneously

“…The measurements by Papastergis et al (2016) at low masses provide the main observational hint for a concave stellar TFR when combined with those by Bradford et al (2016) and Reyes et al (2011) at higher masses, but the same data are perfectly consistent with a single power-law if taken in conjunction with those by Rhee et al (2004), instead. This stresses the danger of combining different data sets without fully understanding their systematics.…”

“…The data points correspond to observed galaxies. Those for the stellar TFR (left) are from Bradford et al (2016), Papastergis et al (2016), Reyes et al (2011), Pizagno et al (2005 and Rhee et al (2004).…”

“…To quantify the evolution of the TFR from z ∼ 0 to z ∼ 1, Tiley et al fitted the local data by Pizagno et al (2005), Rhee et al (2004) and Reyes et al (2011) with a slope 3.68, which they then used to fit their z ∼ 1 data and measure the change in normalization. Any conclusion from this comparison should be tempered by the scatter in the observations.…”

The Dawes Review 1: Kinematic Studies of Star-Forming Galaxies Across Cosmic Time

“…Fast evolution at z > 2 could be possible, however deeper surveys are needed to also verify the z > 2 IFS results. The local relation is that of Reyes et al (2011) which is based on that of Pizagno et al (2007). Credit: from Figure 7 of Miller et al (2012), reproduced by permission of the AAS.…”

A Testable Conspiracy: Simulating Baryonic Effects on Self-interacting Dark Matter Halos

“…=´ galaxies (Reyes et al 2011). In particular, the compact disk is extremely dense and was chosen to investigate whether or not core collapse occurs.…”