Let (
X, d, μ) be a metric measure space endowed with a distance
d and a nonnegative Borel doubling measure μ. Let
L be a non-negative self-adjoint operator on
L2(
X). Assume that the semigroup
e-tL generated by
L satisfies the Davies-Gaffney estimates. Let
HpL(
X) be the Hardy space associated with
L. We prove a Hörmander-type spectral multiplier theorem for
L on
HpL(
X) for 0 <
p < ∞: the operator
m(
L) is bounded from
HpL(
X) to
HpL(
X) if the function
m possesses
s derivatives with suitable bounds and
s >
n (1/
p-1/2) where
n is the “dimension” of
X. By interpolation,
m(
L) is bounded on
HpL(
X) for all 0 <
p < ∞ if
m is infinitely differentiable with suitable bounds on its derivatives. We also obtain a spectral multiplier theorem on
Lp spaces with appropriate weights in the reverse Hölder class.
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