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This is the second paper in a series on a new luminous z ~ 5 quasar surveyusing optical and near-infrared colors. Here we present a new determination ofthe bright end of the quasar luminosity function (QLF) at z ~ 5. Combined our45 new quasars with previously known quasars that satisfy our selections, weconstruct the largest uniform luminous z ~ 5 quasar sample to date, with 99quasars in the range 4.7 <= z < 5.4 and -29 < M1450 <= -26.8, within the SloanDigital Sky Survey (SDSS) footprint. We use a modified 1/Va method includingflux limit correction to derive a binned QLF, and we model the parametric QLFusing maximum likelihood estimation. With the faint-end slope of the QLF fixedas alpha = -2.03 from previous deeper samples, the best fit of our QLF gives aflatter bright end slope beta = -3.58+/-0.24 and a fainter break magnitudeM*1450 = -26.98+/-0.23 than previous studies at similar redshift. Combined withprevious work at lower and higher redshifts, our result is consistent with aluminosity evolution and density evolution (LEDE) model. Using the best fitQLF, the contribution of quasars to the ionizing background at z ~ 5 is foundto be 18% - 45% with a clumping factor C of 2 - 5. Our sample suggests anevolution of radio loud fraction with optical luminosity but no obviousevolution with redshift.

A survey of luminous high-redshift quasars with SDSS and WISE II. the bright end of the quasar luminosity function at z ~ 5