What do you mean by 'void' ?
Is it some region of space , where there is no force-field and no energy-field ?
An are that appears to be empty, of stars and other observable objects. An area of the sky, far away where nothing seems to be observable. This is likely in the visible or near visible spectrum, not microwave... I don't have a link off hand.
Just a hole in what otherwise seems to be, something no matter where you look.
I don't think the idea of force fields in space has much support and when talking about energy, in terms of vacuum energy, the cosmological constant, dark energy and such, the term is mostly a place holder for something about space and the interaction of objects, we can observe.., that we have no clear explanation and/or definition for.
Energy at intergalactic scales is the same as saying some undescribed substance. It is not the same as the classical meaning of the word energy. Nor is it the same as saying matter or mass. Mathematically it makes sense in our models and theories, but we have no real macrocosmic or classical understanding of exactly what or why it is.