Spectral mapping theorems for essential spectra and regularized functional calculi

Abstract

Gramsch and Lay [8] gave spectral mapping theorems for the Dunford-Taylor calculus of a closed linear operator $T$ , \[ \widetilde{\sigma}_i(f(T)) = f(\widetilde{\sigma}_i(T)), \] for several extended essential spectra $\widetilde {\sigma }_i$ . In this work, we extend such theorems for the regularized functional calculus introduced by Haase [10, 11] assuming suitable conditions on $f$ . At the same time, we answer in the positive a question made by Haase [11, Remark 5.4] regarding the conditions on $f$ which are sufficient to obtain the spectral mapping theorem for the usual extended spectrum $\widetilde \sigma$ . We use the model case of bisectorial-like operators, although the proofs presented here are generic, and are valid for similar functional calculi.