Line derived infrared extinction towards the Galactic Center
Abstract
We derive the extinction curve towards the Galactic Center from 1 to 19 micron. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction free flux reference is the 2 cm continuum emission observed by the VLA. Towards the inner 14" * 20" we find an extinction of A(2.166 micron)=2.62 +/- 0.11, with a power-law slope of alpha=-2.11 +/- 0.06 shortward of 2.8 micron, consistent with the average near infrared slope from the recent literature. At longer wavelengths, however, we find that the extinction is grayer than shortward of 2.8 micron. We find it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only, and the addition of composite particles, including ices, is needed to explain the observations. Combining a distance dependent extinction with our distance independent extinction we derive the distance to the GC to be R_0=7.94 +/- 0.65 kpc. Towards Sgr A* (r<0.5") we obtain A_H=4.21 +/- 0.10, A_Ks=2.42 +/- 0.10 and A_L'=1.09 +/- 0.13.
Cite
@article{arxiv.1105.2822,
title = {Line derived infrared extinction towards the Galactic Center},
author = {Tobias K. Fritz and Stefan Gillessen and Katie Dodds-Eden and Dieter Lutz and Reinhard Genzel and Walfried Raab and Thomas Ott and Oliver Pfuhl and Frank Eisenhauer and Farhad Yusef-Zadeh},
journal= {arXiv preprint arXiv:1105.2822},
year = {2015}
}
Comments
23 pages, 12 figures, 9 tables, ApJ accepted