Nonlinear evolution of streaming instabilities in accreting protoplanetary disks

TL;DR

This paper presents the first nonlinear simulations of the azimuthal drift streaming instability (AdSI) in accreting protoplanetary disks, revealing its potential to generate dense dust structures even without radial pressure gradients, impacting planetesimal formation.

Contribution

It introduces the nonlinear behavior of the previously identified AdSI, demonstrating its ability to produce turbulence and dense dust filaments in realistic accreting disks.

Findings

AdSI can destabilize accreting dusty disks without radial pressure gradients.

AdSI drives turbulence and forms vertically-extended dust filaments.

Dust-to-gas ratios can exceed 100 in dust-rich disks due to AdSI.

Abstract

The streaming instability (SI) is one of the most promising candidates for triggering planetesimal formation by producing dense dust clumps that undergo gravitational collapse. Understanding how the SI operates in realistic protoplanetary disks (PPDs) is therefore crucial to assess the efficiency of planetesimal formation. Modern models of PPDs show that large-scale magnetic torques or winds can drive laminar gas accretion near the disk midplane. In a previous study, we identified a new linear dust-gas instability, the azimuthal drift SI (AdSI), applicable to such accreting disks and is powered by the relative azimuthal motion between dust and gas that results from the gas being torqued. In this work, we present the first nonlinear simulations of the AdSI. We show that it can destabilize an accreting, dusty disk even in the absence of a global radial pressure gradient, which is unlike the classic SI. We find the AdSI drives turbulence and the formation of vertically-extended dust filaments that undergo merging. In dust-rich disks, merged AdSI filaments reach maximum dust-to-gas ratios exceeding 100. Moreover, we find that even in dust-poor disks the AdSI can increase local dust densities by two orders of magnitude. We discuss the possible role of the AdSI in planetesimal formation, especially in regions of an accreting PPD with vanishing radial pressure gradients.