Absolute continuity in families of parametrised non-homogeneous self-similar measures

Abstract

Let $\mu$ be a planar self-similar measure with similarity dimension exceeding $1$, satisfying a mild separation condition, and such that the fixed points of the associated similitudes do not share a common line. Then, we prove that the orthogonal projections ${\pi }_{e♯}(\mu )$ are absolutely continuous for all $e\in S^1\setminus E$, where the exceptional set $E$ has zero Hausdorff dimension. The result is obtained from a more general framework which applies to certain parametrised families of self-similar measures on the real line. Our results extend previous work of Shmerkin and Solomyak from 2016, where it was assumed that the similitudes associated with $\mu$ have a common contraction ratio.

31 pages; downgraded Theorem 1.5 a bit in v2; the main application to projections remains unchanged