In braneworld cosmology the brane accelerates in the bulk, and hence it
perceives Unruh radiations in the bulk. We discuss the Unruh effect for a
Dvali-Gabadadze-Porrati (DGP) brane. We find that the Unruh temperature is
proportional to the acceleration of the brane, but chemical potential appears
in the distribution function for massless modes. The Unruh temperature does not
vanish even at the limit rcβββ, which means the gravitational effect
of the 5th dimension vanishes. The Unruh temperature equals the geometric
temperature when the the density of matter on the brane goes to zero for branch
Ο΅=1, no matter what the value of the cross radius rcβ and the
spatial curvature of the brane take. And if the state equation of the matter on
the brane satisfies p=βΟ, the Unruh temperature always equals the
geometric temperature of the brane for both the two branches, which is also
independent of the cross radius and the spatial curvature. The Unruh
temperature is always higher than geometric temperature for a dust dominated
brane.Comment: 11 pages, 2 eps figures, the Green function for DGP brane is
correcte