Publications by Peter Hatfield

The environment and host haloes of the brightest z~6 Lyman-break galaxies


PW Hatfield, RAA Bowler, MJ Jarvis, CL Hale

By studying the large-scale structure of the bright high-redshift Lyman-break galaxy (LBG) population it is possible to gain an insight into the role of environment in galaxy formation physics in the early Universe. We measure the clustering of a sample of bright ($-22.7<M_{UV}<-21.125$) LBGs at $z\sim6$ and use a halo occupation distribution (HOD) model to measure their typical halo masses. We find that the clustering amplitude and corresponding HOD fits suggests that these sources are highly biased ($b\sim10$) objects in the densest regions of the high-redshift Universe. Coupled with the observed rapid evolution of the number density of these objects, our results suggest that the shape of high luminosity end of the luminosity function is related to feedback processes or the onset of dust obscuration - as opposed to a scenario where these sources are predominantly rare instances of the much more numerous $M_{UV} \sim -19$ population of galaxies caught in a particularly vigorous period of star formation. Despite investigating several variations on the model, we struggle to simultaneously fit both the number densities and clustering measurements. We interpret this as a signal that a refinement of the model halo bias relation at high redshifts or the incorporation of quasi-linear effects may be needed for future attempts at modelling the clustering and number counts. Finally, the difference in number density between the fields (UltraVISTA has a surface density$\sim 1.8$ times greater than UDS) is shown to be consistent with the cosmic variance implied by the clustering measurements.

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