Soft Gravitons in the BFSS Matrix Model

TL;DR

This paper explores how soft gravitons are represented in the BFSS matrix model, revealing their connection to submatrix excitations and large N expansions, and linking soft theorems to asymptotic gauge symmetries in quantum gravity.

Contribution

It demonstrates that soft gravitons correspond to fixed-rank submatrices in the BFSS model and relates soft theorems to Ward identities of asymptotic gauge symmetries.

Findings

Soft gravitons are realized by fixed-rank submatrices.

Soft theorem corresponds to a Ward identity of asymptotic gauge symmetry.

Large N expansion encodes soft graviton effects.

Abstract

BFSS proposed that asymptotically flat M-theory is dual to a large $N$ limit of the matrix quantum mechanics describing $N$ nonrelativistic D0-branes. Recent insights on the soft symmetries of any quantum theory of gravity in asymptotically flat space are applied to the BFSS matrix model. It is shown that soft gravitons are realized by submatrices whose rank is held fixed in the large $N$ M-theory limit, rather than the usual linear scaling with $N$ for hard gravitons. The soft expansion is identified with the large $N$ expansion and the soft theorem becomes a universal formula for the quantum mechanical scattering of such submatrix excitations. This formula is shown to be the Ward identity of large type IIA $U(1)_{RR}$ asymptotic gauge symmetry in the matrix model, whose asymptotic boundaries are at future and past timelike infinity.