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

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 $T_{\omega }^{\ast }$ 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 $T_{\omega }^{\ast }$ is symmetric and when $T_{\omega }^{\ast }$ 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 $T_{\omega }^{\ast }$ coincides with the unbounded Toeplitz operator defined by Sarason in [10].