A new approach for probing circumbinary disks

TL;DR

This paper investigates oscillation modes in circumbinary disks around binary systems, proposing a new method to detect such disks through variability in emission lines and light curves caused by wave precession.

Contribution

It introduces a novel approach to identify circumbinary disks by analyzing prograde wave-induced variabilities in emission profiles and light curves.

Findings

Prograde, nonaxisymmetric waves are induced in circumbinary disks.

Wave precession causes periodic variability in emission lines and light curves.

The method offers a new way to detect circumbinary disks in diverse systems.

Abstract

Circumbinary disks are considered to exist in a wide variety of astrophysical objects, e.g., young binary stars, protoplanetary systems, and massive binary black hole systems in active galactic nuclei (AGNs). However, there is no definite evidence for the circumbinary disk except for some in a few young binary star systems. In this Letter, we study possible oscillation modes in circumbinary disks around eccentric and circular binaries. We find that progarde, nonaxisymmetric waves are induced in the inner part of the circumbinary disk by the tidal potential of the binary. Such waves would cause variabilities in emission line profiles from circumbinary disks. Because of prograde precession of the waves, the distance between each component of the binary and the inner edge of the circumbinary disk varies with the beat period between the precession period of the wave and the binary orbital period. As a result, light curves from the circumbinary disks are also expected to vary with the same period. The current study thus provides a new method to detect circumbinary disks in various astrophysical systems.