A Toeplitz-like operator with rational symbol having poles on the unit circle III: the adjoint

G. J. Groenewald, S. Ter Horst, J. Jaftha, A. C. M. Ran

Published 2018-12-18Version 1

This paper contains a further analysis of the Toeplitz-like operators $T_\omega$ on $H^p$ with rational symbol $\omega$ having poles on the unit circle that were previously studied in [5.6]. Here the adjoint operator $T_\omega^*$ is described. In the case where $p=2$ and $\omega$ has poles only on the unit circle $\mathbb{T}$, a description is given for when $T_\omega^*$ is symmetric and when $T_\omega^*$ admits a selfadjoint extension. Also in the case where $p=2$, $\omega$ has only poles on $\mathbb{T}$ and in addition $\omega$ is proper, it is shown that $T_\omega^*$ coincides with the unbounded Toeplitz operator defined by Sarason in [10].