Black hole in the West Nucleus of Arp 220 - AstrophysicsReportar como inadecuado

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Abstract: We present new observations with the IRAM Interferometer, in itslongest-baseline configuration, of the CO2-1 line and the 1.3mm dustradiation from the Arp 220 nuclear region. The dust source in the West nucleushas a size of 0.19 x 0.13 arcsec and a 1.3mm brightness temperature of 90K.This implies that the dust ring in the West nucleus has a high opacity, withtau = 1 at 1.1mm. Not only is the dust ring itself optically thick in the submmand far-IR, but it is surrounded by the previously-known, rapidly rotatingmolecular disk of size 0.5 arcsec that is also optically thick in the mid-IR.The molecular ring is cooler than the hot dust disk because the CO2-1 line isseen in absorption against the dust disk. The dust ring is massive 1E9 solarmasses, compact radius 35pc, and hot true dust temperature 170K. Itresembles rather strikingly the dust ring detected around the quasar APM08279+52, and is most unlike the warm, extended dust sources in starburstgalaxies. Because there is a strong temperature gradient from the hot dust ringto the cooler molecular disk, the heating must come from a concentrated source,an AGN accretion disk that is completely invisible at optical wavelengths, andheavily obscured in hard X-rays.

Autor: D. Downes, A. Eckart


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