is much larger than the massive–halo prediction. These results are consistent with a picture which leaves some of the most–massive haloes available for occupation by other populations which do not meet the LBG selection criteria. Our new dynamical mass limit is a factor three larger than our earlier estimate which neglected the effects of seeing and slit width. The median halo mass recently estimated by Adelberger et al. from the measured clustering of LBGs is $10^{11.86\pm0.3}$[${\mathrm M_{\odot}\thinspace}$]{}. Our dynamical analysis appears to favour lower masses and to be more in line with the median mass predicted by the collisional starburst model of Somerville et al., which is $10^{11.3}$[${\mathrm M_{\odot}\thinspace}$]{}.
author:
- |
    Stephen J. Weatherley[^1] and Stephen J. Warren\
    Astrophysics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW, UK
date: 'Accepted 0000 January 00. Received 0000 January 00; in original form 0000 January 00'
title: 'Dynamical virial masses of Lyman–break galaxy haloes at [$z=3$]{}'
---

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galaxies: kinematics and dynamics – galaxies: formation – galaxies: high redshift

Introduction
============

The development of the Lyman–break selection technique (Steidel & Hamilton, 1993) led to the first substantial samples of galaxies at high redshifts. There is now a wealth 