Complex small-scale structure in the infrared extinction towards the Galactic Centre

Abstract

A high level of complex structure, or ``granularity'', has been observed in the distribution of infrared-obscuring material towards the Galactic Centre (GC), with a characteristic scale of 5arcsec - 15arcsec, corresponding to 0.2 - 0.6pc at a GC distance of 8.5kpc. This structure has been observed in ISAAC images which have a resolution of 0.6arcsec, significantly higher than that of previous studies of the GC. We have discovered granularity throughout the GC survey region, which covers an area of 1.6deg x 0.8deg in longitude and latitude respectively (300pc x 120pc at 8.5kpc) centred on Sgr A*. This granularity is variable over the whole region, with some areas exhibiting highly structured extinction in one or more wavebands and other areas displaying no structure and a uniform stellar distribution in all wavebands. The granularity does not appear to correspond to longitude, latitude or radial distance from Sgr A*. We find that regions exhibiting high granularity are strongly associated with high stellar reddening.

5 pages, 3 figures, accepted for publication in ApJL

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• Interstellar Extinction Law in the J, H, and Ks Bands toward the Galactic Center
• A $\lambda$20cm Survey of the Galactic Center Region I: Detection of Numerous Linear Filaments
• Infrared stellar populations in the central parts of the Milky Way galaxy
• JHKL Photometry and the K-band Luminosity Function at the Galactic Center
• ISOGAL: A deep survey of the obscured inner Milky Way with ISO at 7 and 15 micron and with DENIS in the near-infrared
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• GALACTICNUCLEUS: A high-angular-resolution $JH{K}_s$ imaging survey of the Galactic centre. IV. Extinction maps and de-reddened photometry
• GRO J1744-28, search for the counterpart: infrared photometry and spectroscopy
• A Search for the Near-Infrared Counterpart to GCRT J1745-3009
• The Mid-Infrared Colors of the ISM and Extended Sources at the Galactic Center
• The efficiency and wavelength dependence of near-infrared interstellar polarization toward the Galactic center
• Mapping the aliphatic hydrocarbon content of interstellar dust in the Galactic plane
• Infrared observations of the candidate double neutron star system PSR J1811-1736