Asymptotic behavior for twisted traces of self-dual and conjugate self-dual representations of $\mathrm{GL}_n$

Abstract: In this paper, we study the asymptotic behavior of the sum of twisted traces of self-dual or conjugate self-dual discrete automorphic representations of $\mathrm{GL}_n$ for the level aspect of principal congruence subgroups under some conditions. Our asymptotic formula is derived from the Arthur twisted trace formula, and it is regarded as a twisted version of limit multiplicity formula on Lie groups. We determine the main terms for the asymptotic behavior under different conditions, and also obtain explicit forms of their Fourier transforms, which correspond to endoscopic lifts from classical groups. Its main application is the self-dual (resp. conjugate self-dual) globalization of local self-dual (resp. conjugate self-dual) representations of $\mathrm{GL}_n$. We further derive an automorphic density theorem for conjugate self-dual representations of $\mathrm{GL}_n$.