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

Loveday, J, Christodoulou, L, Norberg, P, Peacock, JA, Baldry, IK, Bland-Hawthorn, J, Brown, MJI, Colless, M, Driver, SP, Holwerda, BW, Hopkins, AM, Kafle, PR, Liske, J, Lopez-Sanchez, AR and Taylor, EN (2017) Galaxy and Mass Assembly (GAMA): Small-scale anisotropic galaxy clustering and the pairwise velocity dispersion of galaxies. Monthly Notices of the Royal Astronomical Society, 474 (3). pp. 3435-3450. ISSN 0035-8711

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Galaxy and Mass Assembly (GAMA) Small-scale anisotropic galaxy clustering and the pairwise velocity dispersion of galaxies.pdf - Published Version

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 ($r_\bot = 0.01$ Mpc/h) than previous work. The measured PVD at projected separations $r_\bot <~ 1$ Mpc/h increases near-monotonically with increasing luminosity from $\sigma \approx 200$ km/s at $M_r = -17$ mag to $\sigma \approx 600$ km/s at $M_r \approx -22$ 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.