ALMA 0.1-0.2 arcsec RESOLUTION IMAGING OF THE NGC 1068 NUCLEUS: COMPACT DENSE MOLECULAR GAS EMISSION AT THE PUTATIVE AGN LOCATION

作者：Imanishi Masatoshi^*; Nakanishi Kouichiro; Izumi Takuma

来源：Astrophysical Journal Letters, 2016, 822(1): L10.

DOI：10.3847/2041-8205/822/1/L10

• galaxies: active
• galaxies: nuclei
• galaxies: Seyfert
• galaxies: starburst
• radio lines: galaxies

We present the results of our ALMA Cycle 2 high angular resolution (0 ''.1-0 ''.2) observations of the nuclear region of the nearby well-studied type-2 active galactic nucleus (AGN), NGC 1068, at HCN J = 3-2 and HCO+ J = 3-2 emission lines. For the first time, due to a higher angular resolution than previous studies, we clearly detected dense molecular gas emission at the putative AGN location, identified as a similar to 1.1 mm (similar to 266 GHz) continuum emission peak, by separating this emission from brighter emission located at 0 ''.5-2 ''.0 on the eastern and western sides of the AGN. The estimated intrinsic molecular emission size and dense molecular mass, which are thought to be associated with the putative dusty molecular torus around an AGN, were similar to 10 pc and similar to several x 10(5)M(circle dot), respectively. HCN-to-HCO+ J = 3-2 flux ratios substantially higher than unity were found throughout the nuclear region of NGC 1068. The continuum emission displayed an elongated morphology along the direction of the radio jet located at the northern side of the AGN, as well as a weak spatially-resolved component at similar to 2 ''.0 on the southwestern side of the AGN. The latter component most likely originated from star formation, with the estimated luminosity more than one order of magnitude lower than the luminosity of the central AGN. No vibrationally excited (v(2) = 1f) J = 3-2 emission lines were detected for HCN and HCO+ across the field of view.

• 出版日期2016-5-1
• 单位中国科学院国家天文台