MUSE stares into the shadows: the high-resolution dust attenuation curve of NGC 5626

TL;DR

This study uses high-resolution integral field spectroscopy from MUSE to map and analyze the dust attenuation properties in NGC 5626, revealing complex variations and emphasizing the importance of realistic dust models.

Contribution

It provides the first detailed spatially resolved dust attenuation curve of NGC 5626 using MUSE, highlighting the degeneracy between dust distribution and intrinsic extinction law.

Findings

Attenuation curve is slightly steeper than Milky Way and SMC curves.

No correlation between sodium line strength and dust reddening.

Dust resides in a well-settled, regular disk.

Abstract

The newest generation of integral field unit spectrographs brings three-dimensional mapping of nearby galaxies one step closer. While the focus up to this point was mostly on stars and ionised gas, it is also possible to look at dust in a new, more complete way. Using MUSE science verification observations of NGC 5626, we map the interstellar matter in this dusty lenticular. We use the resolving power of MUSE to measure the optical attenuation with a spectral resolution of 6.25 \AA, at physical scales of 0.1-1 kpc. The integrated attenuation curve of NGC 5626 shows a smooth, slightly steeper than Milky Way and SMC attenuation curves. Several sharp features are superimposed: we measure lower attenuation at spectral emission lines and higher attenuation for the sodium line doublet. No correlation was observed between sodium line strength and reddening by dust on spatially resolved scales. Additionally, the continuum attenuation was found to be independent from the Balmer decrement (tracing ionised gas attenuation). We model and interpret the variations in the attenuation curves of each spatial resolution element of NGC 5626. We find that the amount and distribution of dust along the line-of-sight is highly degenerate with any variation in the intrinsic extinction law. Our analysis shows that the interstellar matter in NGC 5626 resides in a regular and well-settled disk. Our results preach caution in the application of simple recipes to de-redden global galaxy spectra and underlines the need for more realistic dust geometries when constructing such correction formulas.