The power spectrum of turbulence in NGC 1333: Outflows or large-scale driving?

Abstract

Is the turbulence in cluster-forming regions internally driven by stellar outflows or the consequence of a large-scale turbulent cascade? We address this question by studying the turbulent energy spectrum in NGC 1333. Using synthetic 13CO maps computed with a snapshot of a supersonic turbulence simulation, we show that the velocity coordinate spectrum method of Lazarian & Pogosyan provides an accurate estimate of the turbulent energy spectrum. We then apply this method to the 13CO map of NGC 1333 from the COMPLETE database. We find that the turbulent energy spectrum is a power law, E(k) k -β, in the range of scales 0.06 pc ≤ ℓ ≤ 1.5 pc, with slope β = 1.85 ± 0.04. The estimated energy injection scale of stellar outflows in NGC 1333 is ℓinj 0.3 pc, well resolved by the observations. There is no evidence of the flattening of the energy spectrum above the scale ℓ inj predicted by outflow-driven simulations and analytical models. The power spectrum of integrated intensity is also a nearly perfect power law in the range of scales 0.16 pc < 7.9 pc, with no feature above ℓinj. We conclude that the observed turbulence in NGC 1333 does not appear to be driven primarily by stellar outflows. © 2009. The American Astronomical Society. All rights reserved.