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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 SB0 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 active galactic nucleus. Here, new spectrally resolved CO J = 5-4 to J = 8-7 lines from Herschel Space Observatory HIFI observations are combined with ground-based observations and high-JHerschel 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 ( K and Toutflow ∼ 30 K), comprising bulk of the mass (log and log ), and the minority of the luminosity (log and log Loutflow/L☼ ∼ 6.5) and warm ( K and Toutflow > 100 K), comprising a minority of the mass (log and log Moutflow/M☼ ∼ 6.3) but the majority of the luminosity (log and log Loutflow/L☼ ∼ 7.2). The outflow has an anomalously high LCO/LFIR of 1.7 × 10–3 and is almost certainly shock excited. [ABSTRACT FROM AUTHOR]

The 12CO J = 4 → 3 to J = 13 → 12 lines of the interstellar medium from nearby galaxies, newly observable with the Herschel SPIRE Fourier transform spectrometer, offer an opportunity to study warmer, more luminous molecular gas than that traced by 12CO J = 1 → 0. Here we present a survey of 17 nearby infrared-luminous galaxy systems (21 pointings). In addition to photometric modeling of dust, we modeled full 12CO spectral line energy distributions from J = 1 → 0 to J = 13 → 12 with two components of warm and cool CO gas, and included LTE analysis of [C I], [C II], [N II], and H2 lines. CO is emitted from a low-pressure/high-mass component traced by the low-J lines and a high-pressure/low-mass component that dominates the luminosity. We found that, on average, the ratios of the warm/cool pressure, mass, and 12CO luminosity are 60 ± 30, 0.11 ± 0.02, and 15.6 ± 2.7. The gas-to-dust-mass ratios are <120 throughout the sample. The 12CO luminosity is dominated by the high-J lines and is 4 × 10–4LFIR on average. We discuss systematic effects of single-component and multi-component CO modeling (e.g., single-component J ⩽ 3 models overestimate gas pressure by ∼0.5 dex), as well as compare to Galactic star-forming regions. With this comparison, we show the molecular interstellar medium of starburst galaxies is not simply an ensemble of Galactic-type giant molecular clouds. The warm gas emission is likely dominated by regions resembling the warm extended cloud of Sgr B2. [ABSTRACT FROM AUTHOR]

We present new Herschel-SPIRE imaging spectroscopy (194-671 μm) of the bright starburst galaxy M82. Covering the CO ladder from J = 4 → 3 to J = 13 → 12, spectra were obtained at multiple positions for a fully sampled ∼3 × 3 arcmin map, including a longer exposure at the central position. We present measurements of 12CO, 13CO, [C I], [N II], HCN, and HCO+ in emission, along with OH+, H2O+, and HF in absorption and H2O in both emission and absorption, with discussion. We use a radiative transfer code and Bayesian likelihood analysis to model the temperature, density, column density, and filling factor of multiple components of molecular gas traced by 12CO and 13CO, adding further evidence to the high-J lines tracing a much warmer (∼500 K), less massive component than the low-J lines. The addition of 13CO (and [C I]) is new and indicates that [C I] may be tracing different gas than 12CO. No temperature/density gradients can be inferred from the map, indicating that the single-pointing spectrum is descriptive of the bulk properties of the galaxy. At such a high temperature, cooling is dominated by molecular hydrogen. Photon-dominated region (PDR) models require higher densities than those indicated by our Bayesian likelihood analysis in order to explain the high-J CO line ratios, though cosmic-ray-enhanced PDR models can do a better job reproducing the emission at lower densities. Shocks and turbulent heating are likely required to explain the bright high-J emission. [ABSTRACT FROM AUTHOR]