The Unusual AGN Host NGC 1266: Evidence for Shocks in a Molecular Gas Rich S0 Galaxy with a Low Luminosity Nucleus

Abstract

NGC 1266 is a lenticular galaxy (S0) hosting an active galactic nucleus (AGN), and known to contain a large amount of shocked gas. We compare the luminosity ratio of mid-\emph{J} CO lines to IR continuum with star-forming galaxies (SFGs), and then model the CO spectral line energy distribution (SLED). We confirm that in the mid- and high-\emph{J} regions ($J_{\mathrm{up}}$ = 4--13), the C-type shock ($v_{\mathrm{s}}$ = 25 km s${}^{-1}$, $n_{\mathrm{H}}$ = $5\times 10^4$ cm${}^{-3}$) can reproduce the CO observations well. The galaxy spectral energy distribution (SED) is constructed and modeled by the code {\tt X-CIGALE} and obtains a set of physical parameters including the star formation rate (SFR, 1.17 $\pm$ 0.47 \emph{M${}_{\odot }$}yr${}^{-1}$). Also, our work provides SFR derivation of [C\,{\sc ii}] from the neutral hydrogen regions only (1.38 $\pm$ 0.14 $M_{\odot }$yr${}^{-1}$). Previous studies have illusive conclusions on the AGN or starburst nature of the NGC 1266 nucleus. Our SED model shows that the hidden AGN in the system is intrinsically low-luminosity, consequently the infrared luminosity of the AGN does not reach the expected level. Archival data from \emph{NuSTAR} hard X-ray observations in the 3--79 keV band shows a marginal detection, disfavoring presence of an obscured luminous AGN and implying that a compact starburst is more likely dominant for the NGC 1266 nucleus.

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Cited by in corpus (3)

• A possible relation between global CO excitation and massive molecular outflows in local ULIRGs
• Properties of Interstellar Medium in the S0 Galaxy NGC 1222: Evidence for Shocked-enhanced Line Emission
• Toward Understanding the Evolutionary Role of Star-forming Lenticular Galaxies: New HI Detections and Comparison with Quiescent S0s and Red Spirals