Scaling Relations of Spiral Galaxies

Abstract

We construct a large data set of global structural parameters for 1300 field and cluster spiral galaxies and explore the joint distribution of luminosity L, optical rotation velocity V, and disk size R at I- and 2MASS K-bands. The I- and K-band velocity-luminosity (VL) relations have log-slopes of 0.29 and 0.27, respectively with sigma_ln(VL)~0.13, and show a small dependence on color and morphological type in the sense that redder, early-type disk galaxies rotate faster than bluer, later-type disk galaxies for most luminosities. The VL relation at I- and K-bands is independent of surface brightness, size and light concentration. The log-slope of the I- and K-band RL relations is a strong function of morphology and varies from 0.25 to 0.5. The average dispersion sigma_ln(RL) decreases from 0.33 at I-band to 0.29 at K, likely due to the 2MASS selection bias against lower surface brightness galaxies. Measurement uncertainties are sigma_ln(V)~0.09, sigma_ln(L)~0.14 and somewhat larger and harder to estimate for ln(R). The color dependence of the VL relation is consistent with expectations from stellar population synthesis models. The VL and RL residuals are largely uncorrelated with each other; the RV-RL residuals show only a weak positive correlation. These correlations suggest that scatter in luminosity is not a significant source of the scatter in the VL and RL relations. The observed scaling relations can be understood in the context of a model of disk galaxies embedded in dark matter halos that invokes low mean spin parameters and dark halo expansion, as we describe in our companion paper (Dutton et al. 2007). We discuss in two appendices various pitfalls of standard analytical derivations of galaxy scaling relations, including the Tully-Fisher relation with different slopes. (Abridged).Comment: Accepted for publication at ApJ. The full document, with high-resolution B&W and colour figures, is available at http://www.astro.queensu.ca/~courteau/papers/VRL2007ApJ.pdf . Our data base for 1303 spiral galaxies is also available at http://www.astro.queensu.ca/~courteau/data/VRL2007.da

The variation of rotation curve shapes as a signature of the effects of baryons on dark matter density profiles

“…Scatter in disc scale length comes from the empirical scatter of 0.23 dex in the luminostydisc scale length relation, determined using 144 observed galaxies (Hunter & Elmegreen 2006, Oh et al 2015, as shown in Figure 1. This is lower than the scatter of ∼0.3 dex found in Courteau et al (2007) for a larger sample of late type galaxies, but a sample which is of generally higher mass galaxies than used in this study. Fathi et al (2010) explored the relation between scale-length and stellar mass down to 10 6.6 M , and found similar scatter to Courteau et al (2007), but with lower scatter for low mass galaxies.…”

“…This is lower than the scatter of ∼0.3 dex found in Courteau et al (2007) for a larger sample of late type galaxies, but a sample which is of generally higher mass galaxies than used in this study. Fathi et al (2010) explored the relation between scale-length and stellar mass down to 10 6.6 M , and found similar scatter to Courteau et al (2007), but with lower scatter for low mass galaxies. We tested our results using a scatter of 0.3 dex and found relatively insignificant effects that do not alter our conclusions.…”

“…Galaxy stellar masses are matched to dark matter halos using the empirical abundance matching relation (Guo et al 2010). We include the universal dark matter fraction of mass (ΩDM/Ωm=0.83) in dark matter halos, and add a stellar disc with scale-lengths (hs) taken from the observed Mhs relation, log10(hs)=−2.8+0.35log10(M ), (Dutton 07 gives log10(hs)=−2.46+0.281log10(M )) coming from a fit to galaxies from Hunter & Elmegreen (2006), which is similar to the relation found previously in larger studies of generally more massive galaxies (Courteau et al 2007;Fathi et al 2010). We also add a gas disk with mass Mgas=1.3MHI, with log10(MHI/M )=−0.43log10(M ) + 3.75 (Papastergis et al 2012) and disc scale length hg=3hs.…”

“…This Letter examines the scatter in the Vrot(1kpc)-Vmax plane in a model population of galaxies that incorporates the empirical scatter in disc scale-lengths (Courteau et al 2007;Swaters et al 2009;Fathi et al 2010), scatter in the concentration-halo mass relation , and scatter in the M -M halo relation (Reddick et al 2013;Behroozi et al 2013). Different forms of the underlying dark matter halo are assumed.…”

From distances to galaxy evolution and the dark matter problem

“…The scaling law is fundamental to a better understanding of the processes of galaxy formation (e.g. Courteau et al 2007) and has been continuously used for many peculiar classes of galaxies, unlike the normal ones (e.g. Iodice et al 2003), or as a function of environment (Biviano et al 1990).…”