“…Since the introduction of the Bost-Connes system in the mid '90s, [1], a very rich interplay between number theory and quantum statistical mechanics developed, involving the Galois theory of abelian and non-abelian extensions of number fields ( [6], [7], [11], [13], [21], [27]), Shimura varieties ( [4], [11], [14]), L-series and zeta functions ( [3], [8]), etc. On the other hand, the work of Manin and Marcolli, [19], and the subsequent work [12], [20], [22], developed a theory of limiting modular symbols, and a related noncommutative geometry model of the boundary of modular curves.…”