$v$-adic Chowla-Selberg formula over function fields

Abstract

Let $v$ be a finite place of a rational function field with finite constant field. We establish an Ogus-type $v$-adic Chowla-Selberg formula for $t$-motives with "complex multiplication" by subfields of Carlitz cyclotomic function fields. For this purpose, we first introduce the $v$-adic crystalline action of the Weil group on the de Rham spaces of $t$-motives via the de Rham-crystalline comparison isomorphism of Hartl-Kim, and use it to give a "$v$-isocrystal" period interpretation of special values of Thakur's $v$-adic geometric gamma function. Our Ogus-type formula is then based on the isogeny theorem for CM $t$-motives, together with a recipe for constructing "abelian CM types" given in the $\infty$-adic setting over function fields.