@article {2012A\&A...546A..68A, title = {{Winds of change - a molecular outflow in NGC 1377?. The anatomy of an extreme FIR-excess galaxy}}, journal = {Astronomy and Astrophysics}, volume = {546}, year = {2012}, month = {oct}, pages = {A68}, abstract = {
Aims: Our goal was to investigate the molecular gas distribution and kinematics in the extreme far-infrared (FIR) excess galaxy NGC 1377 and to address the nature and evolutionary status of the buried source.
Methods: We used high- (0{\textquoteright}{\textquoteright}65 {\times} 0{\textquoteright}{\textquoteright}52, (65 {\times} 52 pc)) and low- (4{\textquoteright}{\textquoteright}88 {\times} 2{\textquoteright}{\textquoteright}93) resolution SubMillimeter Array (SMA) observations to image the $^{12}$CO and $^{13}$CO 2-1 line emission.
Results: We find bright, complex $^{12}$CO 2-1 line emission in the inner 400 pc of NGC 1377. The $^{12}$CO 2-1 line has wings that are tracing a kinematical component that appears to be perpendicular to the component traced by the line core. Together with an intriguing X-shape of the integrated intensity and dispersion maps, this suggests that the molecular emission of NGC 1377 consists of a disk-outflow system. Lower limits to the molecular mass and outflow rate are M$_{out}$(H$_{2}$) {\gt} 1 {\times} 10$^{7}$ M$_{\&sun;}$ and {\.M} {\gt} 8 M$_{\&sun;}$ yr$^{-1}$. The age of the proposed outflow is estimated to be 1.4 Myr, the extent to be 200 pc and the outflow speed to be V$_{out}$ = 140 km s$^{-1}$. The total molecular mass in the SMA map is estimated to M$_{tot}$(H$_{2}$) = 1.5 {\times} 10$^{8}$ M$_{\&sun;}$ (on a scale of 400 pc) while in the inner r = 29 pc the molecular mass is M$_{core}$(H$_{2}$) = 1.7 {\times} 10$^{7}$ M$_{\&sun;}$ with a corresponding H$_{2}$ column density of N(H$_{2}$) = 3.4 {\times} 10$^{23}$ cm$^{-2}$ and an average $^{12}$CO 2-1 brightness temperature of 19 K. $^{13}$CO 2-1 emission is found at a factor 10 fainter than $^{12}$CO in the low-resolution map while C$^{18}$O 2-1 remains undetected. We find weak 1 mm continuum emission of 2.4 mJy with spatial extent less than 400 pc.
Conclusions: Observing the molecular properties of the FIR-excess galaxy NGC 1377 allows us to probe the early stages of nuclear activity and the onset of feedback in active galaxies. The age of the outflow supports the notion that the current nuclear activity is young - a few Myr. The outflow may be powered by radiation pressure from a compact, dust enshrouded nucleus, but other driving mechanisms are possible. The buried source may be an active galactic nucleus (AGN) or an extremely young (1 Myr) compact starburst. Limitations on size and mass lead us to favor the AGN scenario, but additional studies are required to settle this question. In either case, the wind with its implied mass outflow rate will quench the nuclear power source within the very short time of 5-25 Myr. It is possible, however, that the gas is unable to escape the galaxy and may eventually fall back onto NGC 1377 again.}, keywords = {galaxies: active, galaxies: evolution, galaxies: individual: NGC 1377, galaxies: starburst, ISM: molecules, radio lines: ISM}, doi = {10.1051/0004-6361/201118052}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...546A..68A}, author = {Aalto, S. and Muller, S. and Sakamoto, K. and Gallagher, J.~S. and Mart{\'\i}n, S. and F. Costagliola} } @article {2011A\&A...528A..30C, title = {{Molecules as tracers of galaxy evolution: an EMIR survey. I. Presentation of the data and first results}}, journal = {Astronomy and Astrophysics}, volume = {528}, year = {2011}, month = {apr}, pages = {A30}, abstract = {
Aims: We investigate the molecular gas properties of a sample of 23 galaxies in order to find and test chemical signatures of galaxy evolution and to compare them to IR evolutionary tracers.
Methods: Observation at 3 mm wavelengths were obtained with the EMIR broadband receiver, mounted on the IRAM 30 m telescope on Pico Veleta, Spain. We compare the emission of the main molecular species with existing models of chemical evolution by means of line intensity ratios diagrams and principal component analysis.
Results: We detect molecular emission in 19 galaxies in two 8 GHz-wide bands centred at 88 and 112 GHz. The main detected molecules are CO, $^{13}$CO, HCN, HNC, HCO$^{+}$, CN, and C$_{2}$H. We also detect HC$_{3}$N J = 10-9 in the galaxies IRAS 17208, IC 860, NGC 4418, NGC 7771, and NGC 1068. The only HC$_{3}$N detections are in objects with HCO$^{+}$/HCN {\l}t} 1. Galaxies with the highest HC$_{3}$N/HCN ratios have warm IRAS colours (60/100 {$μ$}m {\gt} 0.8). The brightest HC$_{3}$N emission is found in IC 860, where we also detect the molecule in its vibrationally excited state. We find low HNC/HCN line ratios ({\l}t}0.5), that cannot be explained by existing PDR or XDR chemical models. The intensities of HCO+ and HNC appear anti-correlated. No correlation is found between the HNC/HCN line ratio and dust temperature. All HNC-bright objects are either luminous IR galaxies (LIRG) or Seyferts. Galaxies with bright polycyclic aromatic hydrocarbons (PAH) emission show low HNC/HCO$^{+}$ ratios. The CO/$^{13}$CO ratio is positively correlated with the dust temperature and is generally higher than in our galaxy. The emission of CN and C$^{18}$O is correlated.
Conclusions: Bright HC$_{3}$N emission in HCO$^{+}$-faint objects may imply that these are not dominated by X-ray chemistry. Thus the HCN/HCO$^{+}$ line ratio is not, by itself, a reliable tracer of XDRs. Bright HC$_{3}$N and faint HCO$^{+}$ could be signatures of embedded star-formation, instead of AGN activity. Mechanical heating caused by supernova explosions may be responsible for the low HNC/HCN and high HCO$^{+}$/HCN ratios in some starbursts. We cannot exclude, however, that the discussed trends are largely caused by optical depth effects or excitation. Chemical models alone cannot explain all properties of the observed molecular emission. Better constraints to the gas spacial distribution and excitation are needed to distinguish abundance and excitation effects. Appendices are only available in electronic form http://www.aanda.org}, keywords = {evolution, galaxies: active, galaxies: evolution, galaxies: ISM, ISM: molecules}, doi = {10.1051/0004-6361/201015628}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...528A..30C}, author = {F. Costagliola and Aalto, S. and M. Rodr{\'\i}guez and Muller, S. and Spoon, H.~W.~W. and Mart{\'\i}n, S. and M. A. P{\'e}rez-Torres and Alberdi, A. and Lindberg, J.~E. and Batejat, F. and J{\"u}tte, E. and van der Werf, P. and Lahuis, F.} }