DIBs in Magellanic Clouds and Milky Way

Here we present a dedicated, high signal-to-noise spectroscopic survey of two of the strongest DIBs, at 5780 and 5797{AA}, in optical spectra of 666 early-type stars in the Small and Large Magellanic Clouds, along with measurements of the atomic NaI D and CaII K lines. The resulting maps show for the first time the distribution of DIB carriers across large swathes of galaxies, as well as the foreground Milky Way ISM.

We confirm the association of the 5797{AA} DIB with neutral gas, and the 5780{AA} DIB with more translucent gas, generally tracing the star-forming regions within the Magellanic Clouds. Likewise, the NaI D line traces the denser ISM whereas the CaII K line traces the more diffuse, warmer gas. The CaII K line has an additional component at ~200-220km/s seen towards both Magellanic Clouds; this may be associated with a pan-Magellanic halo.