This is a pure radiation field with energy density M ( v ) , v 4 π π r 2 , and once again it follows from the null energy condition Eq(11) that M ( v ) , v > 0 , so the central object is absorbing null dusts. As calculated in Box C, the nonzero Weyl-NP and Ricci-NP components of the "advanced/ingoing" Vaidya metric Eq(7) are