Existence of solutions of an integral equation of chandrasekhar type in the theory of radiative transfer

We give an existence theorem for some functional-integral equa- tions which includes many key integral and functional equations that arise in nonlinear analysis and its applications. In particular, we extend the class of characteristic functions appearing in Chandrasekhar's classical integral equa- tion from astrophysics and retain existence of its solutions. Extensive use is made of measures of noncompactness and abstract fixed point theorems such as Darbo's theorem.