2018/02/27 by Nickolas Pingel, Min-Young Lee, Blakesley Burkhart +1 · 2 citations
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aab34b
Accepted for publication in The Astrophysical Journal
arxiv created 2018/02/27 · arxiv updated 2018/04/18
We derive two-dimensional spatial power spectra of four distinct interstellar medium tracers, HI, 12CO(J=1--0), 13CO(J=1--0), and dust, in the Perseus molecular cloud, covering linear scales ranging from ∼0.1 pc to ∼90 pc. Among the four tracers, we find the steepest slopes of -3.23±0.05 and -3.22±0.05 for the uncorrected and opacity-corrected HI column density images. This result suggests that the HI in and around Perseus traces a non-gravitating, transonic medium on average, with a negligible effect from opacity. On the other hand, we measure the shallowest slope of -2.72±0.12 for the 2MASS dust extinction data and interpret this as the signature of a self-gravitating, supersonic medium. Possible variations in the dust-to-gas ratio likely do not change our conclusion. Finally, we derive slopes of -3.08±0.08 and -2.88±0.07 for the 12CO(1--0) and 13CO(1--0) integrated intensity images. Based on theoretical predictions for an optically thick medium, we interpret these slopes of roughly -3 as implying that both CO lines are susceptible to the opacity effect. While simple tests for the impact of CO formation and depletion indicate that the measured slopes of 12CO(1--0) and 13CO(1--0) are not likely affected by these chemical effects, our results generally suggest that chemically more complex and/or fully optically thick media may not be a reliable observational tracer for characterizing turbulence.