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Post Info TOPIC: NGC 1266
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RE: NGC 1266
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Title: NGC 1266: Characterisation of the Nuclear Molecular Gas in an Unusual SB0 Galaxy
Author: Jason Glenn, Naseem Rangwala, Philip R. Maloney, Julia R. Kamenetzky

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 AGN. 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-J 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 modelling 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 (Tnuclear=6+10-2 K and Toutflow~30 K), comprising bulk of the mass (Log Mnuclear/solar masses=8.3+0.5-0.4 and Log Moutflow/solar masses=7.6+0.3-0.3), and the minority of the luminosity (Log Lnuclear/L_{\odot}=5.44+0.22-0.18 and Log Loutflow/L_{\odot}~6.5) and warm (Tnuclear=74+130-26 K and Toutflow>100 K), comprising a minority of the mass (Log Mnuclear/solar masses=7.3+0.5-0.5 and Log Moutflow/solar masses~6.3) but the majority of the luminosity (Log Lnuclear/L_{\odot}=6.90+0.16-0.16 and Log Loutflow/L_{\odot}~7.2). The outflow has an anomalously high LCO/LFIR of 1.7 x 10^-3 and is almost certainly shock excited.

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Title: Suppression of Star Formation in NGC1266
Author: K. Alatalo (1), M. Lacy (2), L. Lanz (1), T. Bitsakis (3), P. N. Appleton (1), K. Nyland (4,5,6), S. L. Cales (7,8), P. Chang (9), T. A. Davis (10,11), P. T. de Zeeuw (11,12), C. J. Lonsdale (2), S. Martín (13), D. S. Meier (5,6), P. M. Ogle (1) ((1) IPAC, (2) NRAO Charlottesville, (3) UNAM, (4) New Mexico Tech, (5) NRAO Socorro, (6) ASTRON, (7) U. Concepción, (8) Yale, (9) UW - Milwaukee, (10) Hertfordshire, (11) ESO Garching, (12) Leiden, (13) IRAM)

NGC1266 is a nearby lenticular galaxy that harbours a massive outflow of molecular gas powered by the mechanical energy of an active galactic nucleus (AGN). It has been speculated that such outflows hinder star formation (SF) in their host galaxies, providing a form of feedback to the process of galaxy formation. Previous studies, however, indicated that only jets from extremely rare, high power quasars or radio galaxies could impart significant feedback on their hosts. Here we present detailed observations of the gas and dust continuum of NGC1266 at millimetre wavelengths. Our observations show that molecular gas is being driven out of the nuclear region at M_out=~110 solar masses yr-1, of which the vast majority cannot escape the nucleus. Only 2 solar masses yr-1 is actually capable of escaping the galaxy. Most of the molecular gas that remains is very inefficient at forming stars. The far-infrared emission is dominated by an ultra-compact (<~50pc) source that could either be powered by an AGN or by an ultra-compact starburst. The ratio of the SF surface density (Sigma_SFR) to the gas surface density (Sigma_H2) indicates that SF is suppressed by a factor of about =50 compared to normal star-forming galaxies if all gas is forming stars, and about =150 for the outskirt (98%) dense molecular gas if the central region is is powered by an ultra-compact starburst. The AGN-driven bulk outflow could account for this extreme suppression by hindering the fragmentation and gravitational collapse necessary to form stars through a process of turbulent injection. This result suggests that even relatively common, low-power AGNs are able to alter the evolution of their host galaxies as their black holes grow onto the M-sigma relation.

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Title: AGN Feedback Driven Molecular Outflow in NGC 1266
Authors: K. Alatalo, K. E. Nyland, G. Graves, S. Deustua, J. Wrobel, L. M. Young, T. A. Davis, M. Bureau, E. Bayet, L. Blitz, M. Bois, F. Bournaud, M. Cappellari, R. L. Davies, P. T. de Zeeuw, E. Emsellem, S. Khochfar, D. Krajnovic, H. Kuntschner, S. Martin, R. M. McDermid, R. Morganti, T. Naab, T. Oosterloo, M. Sarzi, N. Scott, P. Serra, A. Weijmans

NGC 1266 is a nearby field galaxy observed as part of the ATLAS3D survey (Cappellari et al. 2011). NGC 1266 has been shown to host a compact (< 200 pc) molecular disk and a mass-loaded molecular outflow driven by the AGN (Alatalo et al. 2011). Very Long Basline Array (VLBA) observations at 1.65 GHz revealed a compact (diameter < 1.2 pc), high bright- ness temperature continuum source most consistent with a low-level AGN origin. The VLBA continuum source is positioned at the center of the molecular disk and may be responsible for the expulsion of molecular gas in NGC 1266. Thus, the candidate AGN-driven molecular outflow in NGC 1266 supports the picture in which AGNs do play a significant role in the quenching of star formation and ultimately the evolution of the red sequence of galaxies.

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Possible missing link between young and old galaxies

University of California, Berkeley, astronomers may have found the missing link between gas-filled, star-forming galaxies and older, gas-depleted galaxies typically characterized as "red and dead."
In a poster to be presented this week at the American Astronomical Society meeting in Seattle, UC Berkeley astronomers report that a long-known "early-type" galaxy, NGC 1266, is expelling molecular gas, mostly hydrogen, from its core.
Astronomers have long recognised the distinction between early-type red and dead galaxies, thought to be largely devoid of gas and dust and thus not forming stars, and galaxies that are currently forming stars from the raw material molecular hydrogen. One of the outstanding problems in astronomy is how galaxies evolve from being star-forming spirals to red and dead.
With such a rapid outflow - about 13 solar masses per year travelling at up to 400 kilometres per second - the galaxy NGC 1266 could easily shed all of its molecular gas in less than 100 million years, equivalent to about one percent the age of the Milky Way, according to the researchers.
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