paper

Accretion Outbursts in Self-gravitating Protoplanetary Disks

arXiv:1409.3891 · doi:10.1088/0004-637X/795/1/61

Abstract

We improve on our previous treatments of long-term evolution of protostellar disks by explicitly solving disk self-gravity in two dimensions. The current model is an extension of the one-dimensional layered accretion disk model of Bae et al. We find that gravitational instability (GI)-induced spiral density waves heat disks via compressional heating (i.e. work), and can trigger accretion outbursts by activating the magnetorotational instability (MRI) in the magnetically inert disk dead-zone. The GI-induced spiral waves propagate well inside of gravitationally unstable region before they trigger outbursts at AU where GI cannot be sustained. This long-range propagation of waves cannot be reproduced with the previously used local treatments for GI. In our standard model where zero dead-zone residual viscosity () is assumed, the GI-induced stress measured at the onset of outbursts is locally as large as in terms of the generic parameter. However, as suggested in our previous one-dimensional calculations, we confirm that the presence of a small but finite triggers thermally-driven bursts of accretion instead of the GI + MRI-driven outbursts that are observed when . The inclusion of non-zero residual viscosity in the dead-zone decreases the importance of GI soon after mass feeding from the envelope cloud ceases. During the infall phase while the central protostar is still embedded, our models stay in a quiescent accretion phase with over of the time and spend less than of the infall phase in accretion outbursts.

arXiv comment16 pages, 17 figures, 1 table, Accepted for publication in ApJ

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