Spectral enclosures for a class of block operator matrices

Juan Giribet, Matthias Langer, Francisco Martínez Pería, Friedrich Philipp, Carsten Trunk

Research output: Contribution to journalArticle

Abstract

We prove new spectral enclosures for the non-real spectrum of a class of 2×2 block operator matrices with self-adjoint operators A and D on the diagonal and operators B and -B* as off-diagonal entries. One of our main results resembles Gershgorin's circle theorem. The enclosures are applied to J-frame operators.
Original languageEnglish
Article number108455
Number of pages24
JournalJournal of Functional Analysis
Volume278
Issue number10
Early online date2 Jan 2020
DOIs
Publication statusPublished - 1 Jun 2020

Keywords

  • block operator matrix
  • quadratic numerical range
  • spectral enclosure
  • Gershgorin's circle

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