Published online by Cambridge University Press: 11 January 2016
Let L be a divergence form elliptic operator with complex bounded measurable coefficients, let ω be a positive Musielak-Orlicz function on (0, ∞) of uniformly strictly critical lower-type pω ∈ (0, 1], and let ρ(x,t) = t−1/ω−1 (x,t−1 ) for x ∈ ℝn, t ∊ (0, ∞). In this paper, we study the Musielak-Orlicz Hardy space Hω,L (ℝn ) and its dual space BMOρ,L * (ℝ n ), where L* denotes the adjoint operator of L in L 2 (ℝ n ). The ρ-Carleson measure characterization and the John-Nirenberg inequality for the space BMOρ,L (ℝn ) are also established. Finally, as applications, we show that the Riesz transform ∇L −1/2 and the Littlewood–Paley g-function gL map Hω,L (ℝn ) continuously into L(ω).