Cobordisms of global quotient orbifolds and an equivariant Pontrjagin-Thom construction

Abstract

We introduce an equivariant Pontrjagin-Thom construction which identifies equivariant cohomotopy classes with certain fixed point bordism classes. This provides a concrete geometric model for equivariant cohomotopy which works for any compact Lie group G. In the special case when G is finite or a torus, we show that our construction recovers the construction of Wasserman, providing a new perspective on equivariant bordism. We connect the results with bordisms of global quotient orbifolds, utilizing the machinery of Gepner-Henriques to describe bordisms of framed orbifolds in terms of equivariant cohomotopy. We also illustrate the utility of the theory by applying our results to M-theory, thus connecting with recent work of Huerta, Sati and Schreiber.