NGC 1266: Characterization of the Nuclear Molecular Gas in an Unusual SB0 Galaxy

Abstract

With a substantial nuclear molecular gas reservoir and broad, high-velocity CO molecular line wings previously interpreted as an outflow, NGC 1266 is a rare SB$0$ galaxy. Previous analyses of interferometry, spectrally resolved low-$J$ CO emission lines, and unresolved high-$J$ emission lines have established basic properties of the molecular gas and the likely presence of an AGN. Here, new spectrally resolved CO $J=5-4$ to $J=8-7$ lines from {\it Herschel Space Observatory} HIFI observations are combined with ground-based observations and high-$J$ {\it Herschel} SPIRE observations to decompose the nuclear and putative outflow velocity components and to model the molecular gas to quantify its properties. Details of the modeling and results are described, with comparisons to previous results and exploration of the implications for the gas excitation mechanisms. Among the findings, like for other galaxies, the nuclear and putative outflow molecular gas are well represented by components that are cool ($T_{nuclear}=6_{-2}^{+10}$ K and $T_{outflow}\sim 30$ K), comprising bulk of the mass (Log $M_{nuclear}/M_{\odot }=8.3_{-0.4}^{+0.5}$ and Log $M_{outflow}/M_{\odot }=7.6_{-0.3}^{+0.3}$), and the minority of the luminosity (Log $L_{nuclear}/L_{\odot }=5.44_{-0.18}^{+0.22}$ and Log $L_{outflow}/L_{\odot }\sim 6.5$) and warm ($T_{nuclear}=74_{-26}^{+130}$ K and $T_{outflow}>100$ K), comprising a minority of the mass (Log $M_{nuclear}/M_{\odot }=7.3_{-0.5}^{+0.5}$ and Log $M_{outflow}/M_{\odot }\sim 6.3$) but the majority of the luminosity (Log $L_{nuclear}/L_{\odot }=6.90_{-0.16}^{+0.16}$ and Log $L_{outflow}/L_{\odot }\sim 7.2$). The outflow has an anomalously high $L_{\mathrm{CO}}/L_{\mathrm{FIR}}$ of $1.7\times 10^{-3}$ and is almost certainly shock excited.

References in corpus (4)

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• A Compendium of Far-Infrared Line and Continuum Emission for 227 Galaxies Observed by the Infrared Space Observatory
• Suppression of Star Formation in NGC 1266
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Cited by in corpus (6)

• The origin of fast molecular outflows in quasars: molecule formation in AGN-driven galactic winds
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• PHANGS-JWST First Results: Stellar Feedback-Driven Excitation and Dissociation of Molecular Gas in the Starburst Ring of NGC 1365?
• SPIRE Spectroscopy of Early Type Galaxies
• The Unusual AGN Host NGC 1266: Evidence for Shocks in a Molecular Gas Rich S0 Galaxy with a Low Luminosity Nucleus
• Multiwavelength characterisation of an ACT-selected, lensed dusty star-forming galaxy at z=2.64