We present the results of a study of a large sample of luminous ( z _ { AB } ^ { \prime } < 26 ) Lyman break galaxies ( LBGs ) in the redshift interval 4.7 < z < 6.3 , selected from a contiguous 0.63 square degree area covered by the UKIDSS Ultra Deep Survey ( UDS ) and the Subaru XMM-Newton Survey ( SXDS ) .
Utilising the large area coverage and the excellent available optical+nearIR data , we use a photometric redshift analysis to derive a new , robust , measurement of the bright end ( L \geq L ^ { \star } ) of the UV-selected luminosity function at high redshift .
When combined with literature studies of the fainter LBG population , our new sample provides improved constraints on the luminosity function of redshift 5 < z < 6 LBGs over the luminosity range 0.1L ^ { \star } \stackrel { < } { { \scriptstyle \sim } } L \mbox { { \raisebox { -1.72 pt } { $ \stackrel { < } { { \scriptstyle \sim } } $ } } } 10 L ^ { \star } .
A maximum likelihood analysis returns best-fitting Schechter function parameters of M _ { 1500 } ^ { \star } = -20.73 \pm 0.11 , \phi ^ { \star } = 0.0009 \pm 0.0002 { Mpc } ^ { -3 } and \alpha = -1.66 \pm 0.06 for the luminosity function at z = 5 , and M _ { 1500 } ^ { \star } = -20.04 \pm 0.12 , \phi ^ { \star } = 0.0018 \pm 0.0005 { Mpc } ^ { -3 } and \alpha = -1.71 \pm 0.11 at z = 6 .
In addition , an analysis of the angular clustering properties of our LBG sample demonstrates that luminous 5 < z < 6 LBGs are strongly clustered ( r _ { 0 } = 8.1 ^ { +2.1 } _ { -1.5 } h _ { 70 } ^ { -1 } Mpc ) , and are consistent with the occupation of dark matter halos with masses of \simeq 10 ^ { 11.5 - 12.0 } \mbox { $ M _ { \odot } $ } .
Moreover , by stacking the available multi-wavelength imaging data for the high-redshift LBGs it is possible to place useful constraints on their typical stellar mass .
The results of this analysis suggest that luminous LBGs at 5 < z < 6 have an average stellar mass of \log _ { 10 } ( { M / \mbox { $ M _ { \odot } $ } } ) = 10.0 ^ { +0.2 } _ { -0.4 } , consistent with the results of the clustering analysis assuming plausible values for the ratio of stellar to dark matter .
Finally , by combining our luminosity function results with those of the stacking analysis we derive estimates of \simeq 1 \times 10 ^ { 7 } \mbox { $ M _ { \odot } $ } Mpc ^ { -3 } and \simeq 4 \times 10 ^ { 6 } \mbox { $ M _ { \odot } $ } Mpc ^ { -3 } for the stellar mass density at z \simeq 5 and z \simeq 6 respectively .