Galaxy and Mass Assembly (GAMA): Small-scale anisotropic galaxy clustering and the pairwise velocity dispersion of galaxies

The galaxy pairwise velocity dispersion (PVD) can provide important tests of non-standard gravity and galaxy formation models. We describe measurements of the PVD of galaxies in the Galaxy and Mass Assembly (GAMA) survey as a function of projected separation and galaxy luminosity. Due to the faint magnitude limit ($r<19.8$) and highly-complete spectroscopic sampling of the GAMA survey, we are able to reliably measure the PVD to smaller scales ($r_{\mathrm{\perp }}=0.01$ Mpc/h) than previous work. The measured PVD at projected separations $r_{\mathrm{\perp }}<1$ Mpc/h increases near-monotonically with increasing luminosity from $\sigma \approx 200$km\mathrm{/}sat$M_r = -17$magto$\sigma \approx 600$km\mathrm{/}sat$M_r \approx -22$ mag. Analysis of the Gonzalez-Perez (2014) GALFORM semi-analytic model yields no such trend of PVD with luminosity: the model over-predicts the PVD for faint galaxies. This is most likely a result of the model placing too many low-luminosity galaxies in massive halos.