The Circumnuclear Environment of IRAS 20551-4250: A Case Study of AGN/Starburst Connection for JWST
Figure 5
Dust extinction laws obtained by assuming a single power-law form () to reproduce the intrinsic AGN hot-dust emission over the 3–8 μm band. The solid lines correspond to different choices of the spectral index: blue for , and red for . The dashed lines are standard Galactic extinction curves for comparison: cyan for [18], orange for Chiar and Tielens [28], and green for Nishiyama et al. [29, 30]. The relation with the extinction in visual magnitudes plotted on the vertical axis is based on the latter works, and all the curves are normalized in order to have the same value at 3 μm. While the exact extinction shape is not so important in the L-band, at 5–8 μm (and most likely beyond, with the presence of the silicate absorption feature) the difference in terms of optical depth in the different cases can be as large as a factor of 3. However, it seems quite hard to obtain such a large dust extinction around 6 μm to be consistent with the gas column density of nearly ~1024 cm−2 measured in the X-rays.
