Structures in circumbinary disks: Prospects for observability

TL;DR

This study explores the observability of large-scale structures in circumbinary disks caused by binary-disk interactions, using simulations to predict how these features can be detected with ALMA depending on system orientation and parameters.

Contribution

It provides a detailed analysis of how binary parameters influence observable disk structures and demonstrates ALMA's potential to detect these features.

Findings

ALMA can trace inner disk asymmetries and resolve spiral arms in face-on disks.

ALMA can detect density perturbations through brightness asymmetries in edge-on disks.

Perturbed disks exhibit regions with temperatures 2.6 times higher than unperturbed disks.

Abstract

During the past decade circumbinary disks have been discovered around various young binary stars. Hydrodynamical calculations indicate that the gravitational interaction between the central binary star and the surrounding disk results in global perturbations of the disk density profile. We study the observability of characteristic large-scale disk structures resulting from the binary-disk interaction in the case of close binary systems. We derived the structure of circumbinary disks from smoothed-particle hydrodynamic simulations. Subsequently, we performed radiative transfer simulations to obtain scattered light and thermal reemission maps. We investigated the influence of the binary mass ratio, the inclination of the binary orbit relative to the disk midplane, and the eccentricity of the binary orbit on observational quantities. We find that ALMA will allow tracing asymmetries of the inner edge of the disk and potentially resolving spiral arms if the disk is seen face-on. For an edge-on orientation, ALMA will allow detecting perturbations in the disk density distribution through asymmetries in the radial brightness profile. Through the asymmetric structure of the disks, areas are formed with a temperature $2.6$ times higher than at the same location in equivalent unperturbed disks. The time-dependent appearance of the density waves and spiral arms in the disk affects the total re-emission flux of the object by a few percent.