The Virasoro symmetries of the bigraded modified Toda hierarchy

Abstract: Modified Toda hierarchy is a two-component generalization of the 1st modified KP hierarchy, which has been widely applied to analyze constraints of the Toda hierarchy, including the B--Toda and C--Toda hierarchies. In this paper, we construct additional symmetries for the modified Toda hierarchy and derive the corresponding Adler-Shiota-van Moerbeke formula. In addition, we also show that $(N,M)$--bigraded modified Toda hierarchy(BMTH), which is a special reduction for modified Toda, possess additional symmetries that form a subalgebra of the Virasoro algebra.