We investigate the dependence of the galaxy luminosity function on geometric environment within the Galaxy And Mass Assembly (GAMA) survey. The tidal tensor prescription, based on the Hessian of the pseudo-gravitational potential, is used to classify the cosmic web and define the geometric environments: for a given smoothing scale, we classify every position of the surveyed region, 0.04<z<0.26, as either a void, a sheet, a filament or a knot. We consider how to choose appropriate thresholds in the eigenvalues of the Hessian in order to partition the galaxies approximately evenly between environments. We find a significant variation in the luminosity function of galaxies between different geometric environments; the normalisation, characterised by ϕ∗ in a Schechter function fit, increases by an order of magnitude from voids to knots. The turnover magnitude, characterised by M∗, brightens by approximately 0.5 mag from voids to knots. However, we show that the observed modulation can be entirely attributed to the indirect local-density dependence. We therefore find no evidence of a direct influence of the cosmic web on the galaxy luminosity function.
@article{arxiv.1412.2141,
title = {Galaxy And Mass Assembly (GAMA): The galaxy luminosity function within the cosmic web},
author = {E. Eardley and J. A. Peacock and T. McNaught-Roberts and C. Heymans and P. Norberg and M. Alpaslan and I. Baldry and J. Bland-Hawthorn and S. Brough and M. E. Cluver and S. P. Driver and D. J. Farrow and J. Liske and J. Loveday and A. S. G. Robotham},
journal= {arXiv preprint arXiv:1412.2141},
year = {2015}
}