Three-dimensional interstellar extinction map toward the Galactic bulge

Abstract

Context. Studies of the properties of the inner Galactic bulge strongly depend on the assumptions made about interstellar extinction. Most of the extinction maps available in the literature lack the information about the distance. Aims. We combine observations with the Besançon model of the Galaxy to investigate the variations of extinction along different lines of sight toward the inner Galactic bulge as a function of distance. In addition we study the variations in the extinction law in the bulge. Methods. We constructed color-magnitude diagrams with the following sets of colors: H-Ks and J-Ks from the VVV catalog and Ks- [3.6], , from GLIMPSE-II catalog matched with 2MASS. Using the newly derived temperature−color relation for M giants that match the observed color-magnitude diagrams better we then used the distance−color relations to derive the extinction as a function of distance. The observed colors were shifted to match the intrinsic colors in the Besançon model as a function of distance, thereby iteratively creating an extinction map with three dimensions: two spatial and one distance dimension along each line of sight toward the bulge. Results. Color excess maps are presented at a resolution of 15 × 15 for six different combinations of colors in distance bins of 1 kpc. The high resolution and depth of the photometry allows us to derive extinction maps to 10 kpc distance and up to 35 mag of extinction in A V (3.5 mag in A Ks ). Integrated maps show the same dust features and consistent values with the other 2D maps. Starting from the color excess between the observations and the model, we investigate the extinction law in near-infrared and its variation along different lines of sight.

The long bar as seen by the VVV Survey

“…We have not used this last one in our comparison since, as pointed out by Chen et al (2013), the results for the region of present study are in good agreement with ones obtained by .…”

“…The maps of and Nidever et al (2012) were available during the referee process, as well as the 3D extinction model provided by Chen et al (2013). We have not used this last one in our comparison since, as pointed out by Chen et al (2013), the results for the region of present study are in good agreement with ones obtained by .…”

“…Even though this work was not devoted to the study of interstellar extinction, our results highlight the potential use of the VVV survey for modeling the dust distribution for both 2D and 3D maps/models as presented by and Chen et al (2013). This type of analysis also has the potential for studying interstellar extinction in the Galactic disk with the use of NIR and MIR colors using combined VVV and GLIMPSE data.…”

“…A detailed analysis of the interstellar extinction toward VVV fields is beyond the scope of this present paper, and it is presented in others papers of the VVV collaboration: e.g., and Chen et al (2013).…”

Mapping the Milky Way bulge at high resolution: the 3D dust extinction, CO, and X factor maps

“…The VVV data processing, photometric catalogues construction, and a comparison between VVV and 2MASS is presented in detail in Gonzalez et al (2011b). Gonzalez et al (2012) used these catalogues to construct the complete high spatial resolution 2D extinction map of the Bulge using the red clump star technique, while Chen et al (2013) based on the VVV and 2MASS low-resolution 3D extinction maps of the inner Bulge.…”