  We explore the Gravitational Waves (GW) phenomenology of a simple class of
supergravity models that can explain and unify inflation and Primordial Black
Holes (PBH) as Dark Matter (DM). Our (modified) supergravity models naturally
lead to a two-field attractor-type double inflation, whose first stage is
driven by Starobinsky scalaron and the second stage is driven by another scalar
belonging to a supergravity multiplet. The PBHs formation in our supergravity
models is efficient, compatible with all observational constraints, and
predicts a stochastic GW background. We compute the PBH-induced GW power
spectrum and show that GW signals can be detected within the sensitivity curves
of the future space-based GW interferometers such as LISA, DECIGO, TAIJI and
TianQin projects, thus showing predictive power of supergravity in GW physics
and their compatibility.
