ALMA 0.1–0.2 arcsec resolution imaging of the NGC 1068 Nucleus: compact dense molecular gas emission at the putative AGN location

Journal Article · Sun May 01 04:00:00 EDT 2016 · Astrophysical Journal Letters

DOI:https://doi.org/10.3847/2041-8205/822/1/L10· OSTI ID:22654256

Imanishi, Masatoshi ^[1]; Nakanishi, Kouichiro ^[2]; Izumi, Takuma ^[3]

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1. Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States)
2. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
3. Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

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{sup +} 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 ∼1.1 mm (∼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 ∼10 pc and ∼several × 10{sup 5} M {sub ⊙}, respectively. HCN-to-HCO{sup +} 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 ∼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 {sub 2} = 1f) J = 3–2 emission lines were detected for HCN and HCO{sup +} across the field of view.

• OSTI ID: 22654256
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 822; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
EMISSION
GALAXY NUCLEI
GASES
GHZ RANGE
LUMINOSITY
MASS
MOLECULES
RESOLUTION
STARS