| Autor: |
Kameno, Seiji, Sawada-Satoh, Satoko, Impellizzeri, C. M. Violette, Espada, Daniel, Nakai, Naomasa, Sugai, Hajime, Terashima, Yuichi, Kohno, Kotaro, Lee, Minju, Martín, Sergio |
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| Zdroj: |
Astrophysical Journal; 05/20/2020, Vol. 895 Issue 1, p1-20, 20p |
| Abstrakt: |
We report ALMA observations of NGC 1052 to search for mass accretion in a gas-poor active galactic nucleus. We detected CO emission representing a rotating ring-like circumnuclear disk (CND) seen edge-on with a gas mass of 5.3 × 105M⊙. The CND has smaller gas mass than that in typical Seyfert galaxies with circumnuclear star formation and is too gas-poor to drive mass accretion onto the central engine. The continuum emission casts molecular absorption features of CO, HCN, HCO+, SO, SO2, CS, CN, and H2O, with H13CN and HC15N and vibrationally excited (v2 = 1) HCN and HCO+. Broader absorption line widths than CND emission-line widths imply the presence of a geometrically thick molecular torus with a radius of 2.4 ± 1.3 pc and a thickness ratio of 0.7 ± 0.3. We obtain an H2 column density of (3.3 ± 0.7) × 1025 cm−2 using H12CN, H13CN, and HCO+ absorption features and adopting abundance ratios of 12C to 13C and HCO+ to H2, and we derived a torus gas mass of (1.3 ± 0.3) × 107M⊙, which is ∼9% of the central black hole mass. The molecular gas in the torus is clumpy, with an estimated covering factor of. The gas density of the clumps inside the torus is inferred to be (6.4 ± 1.3) × 107 cm−3, which meets the excitation conditions for an H2O maser. The specific angular momentum in the torus exceeds the flat rotation curve extrapolated from that of the CND, indicating a Keplerian rotation inside a 14.4 pc sphere of influence. [ABSTRACT FROM AUTHOR] |
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