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Galaxies with nuclear bars are believed to efficiently drive gas inward, generating a nuclear starburst and possibly an active galactic nucleus. We confirm this scenario for the isolated, double-barred, luminous infrared galaxy ESO 320-G030 based on an analysis of Herschel and ALMA spectroscopic observations. Herschel/PACS and SPIRE observations of ESO 320-G030 show absorption or emission in 18 lines of H2O, which we combine with the ALMA H2O 4(23)-3(30) 448 GHz line (E-upper similar to 400 K) and continuum images to study the physical properties of the nuclear region. Radiative transfer models indicate that three nuclear components are required to account for the multi-transition H2O and continuum data. An envelope, with radius R similar to 130-150 pc, dust temperature T-dust approximate to 50 K, and N-H2 similar to 2x10(23) cm(-2), surrounds a nuclear disk with R similar to 40 pc that is optically thick in the far-infrared (tau (100 mu m)similar to 1.5-3, N-H2 similar to 2x10(24) cm(-2)). In addition, an extremely compact (R similar to 12 pc), warm (approximate to 100 K), and buried (tau (100 mu m)> 5, N-H2 greater than or similar to 5x10(24) cm(-2)) core component is required to account for the very high-lying H2O absorption lines. The three nuclear components account for 70% of the galaxy luminosity (SFR similar to 16-18 M-circle dot yr(-1)). The nucleus is fed by a molecular inflow observed in CO 2-1 with ALMA, which is associated with the nuclear bar. With decreasing radius (r=450-225 pc), the mass inflow rate increases up to M-inf similar to 20 M yr(-1), which is similar to the nuclear star formation rate (SFR), indicating that the starburst is sustained by the inflow. At lower r, similar to 100-150 pc, the inflow is best probed by the far-infrared OH ground-state doublets, with an estimated M-inf similar to 30 M yr(-1). The inferred short timescale of similar to 20 Myr for nuclear gas replenishment indicates quick secular evolution, and indicates that we are witnessing an intermediate stage (< 100 Myr) proto-pseudobulge fed by a massive inflow that is driven by a strong nuclear bar. We also apply the H2O model to the Herschel far-infrared spectroscopic observations of H218O, OH, 18OH, OH+, H2O+, H3O+, NH, NH2, NH3, CH, CH+, 13CH+, HF, SH, and C3, and we estimate their abundances. © ESO 2021., EG-A is grateful for the warm hospitality of the Harvard-Smithsonian Center for Astrophysics, where part of the present study was carried out, and thanks Javier Goicoechea for useful conversations on the far-IR spectrum of Sgr B2, Alex Crespo Gomez for sharing preliminary results on the stellar kinematics in ESO 320-G030, and Juan Rafael Martinez-Galarza for useful conversations on the Bayesian analysis. We thank the anonymous referee for constructive and helpful comments on the manuscript. PACS was developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAFIFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). SPIRE was developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ.Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00263.S and ADS/JAO.ALMA#2013.1.00271.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 086.B-0901(A). EG-A is a Research Associate at the Harvard-Smithsonian Center for Astrophysics. EG-A, JM-P, and FR-V thank the Spanish Ministerio de Economia y Competitividad for support under projects ESP2017-86582-C4-1-R and PID2019-105552RB-C41. EG-A and HAS thank NASA grant ADAP NNX15AE56G. MP-S acknowledges support from the Comunidad de Madrid, Spain, through Atraccion de Talento Investigador Grant 2018-T1/TIC-11035 and PID2019-105423GA-I00 (MCIU/AEI/FEDER,UE). AA-H and SG-B acknowledge support through grant PGC2018-094671-B-I00 (MCIU/AEI/FEDER,UE). LC, AA-H, MP-S, and JM-P acknowledge support under project No. MDM-2017-0737 Unidad de Excelencia "Maria de Maeztu" - Centro de Astrobiologia (INTA-CSIC). SG-B acknowledges support from the Spanish MINECO and FEDER funding grant AYA2016-76682-C3-2-P. C.Y. acknowledges support from an ESO Fellowship. LC acknowledges support from the Spanish Ministerio de Economia y Competitividad for support under project ESP2017-83197. SC acknowledges financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709). This research has made use of NASA's Astrophysics Data System (ADS) and of GILDAS software.

We analyze new high-resolution (400 pc) ∼220 GHz continuum and CO(2–1) Atacama Large Millimeter Array (ALMA) observations of a representative sample of 23 local (z 1 for 70% of the sample. Therefore, this favors the presence of an obscured active galactic nucleus (AGN) in these objects that could dominate the LIR. We also classify the ULIRG nuclei in two groups: (a) compact nuclei (rcont

Tidal dwarf galaxies (TDGs) are gravitationally bound condensations of gas and stars that formed during galaxy interactions. Here we present multi-configuration ALMA observations of J1023+1952, a TDG in the interacting system Arp 94, where we resolved CO(2–1) emission down to giant molecular clouds (GMCs) at 0.6400 ∼ 45 pc resolution. We find a remarkably high fraction of extended molecular emission (∼80−90%), which is filtered out by the interferometer and likely traces diffuse gas. We detect 111 GMCs that give a similar mass spectrum as those in the Milky Way and other nearby galaxies (a truncated power law with a slope of −1.76±0.13). We also study Larson’s laws over the available dynamic range of GMC properties (∼2 dex in mass and ∼1 dex in size): GMCs follow the sizemass relation of the Milky Way, but their velocity dispersion is higher such that the size-linewidth and virial relations appear superlinear, deviating from the canonical values. The global molecular-to-atomic gas ratio is very high (∼1) while the CO(2–1)/CO(1–0) ratio is quite low (∼0.5), and both quantities vary from north to south. Star formation predominantly takes place in the south of the TDG, where we observe projected offsets between GMCs and young stellar clusters ranging from ∼50 pc to ∼200 pc; the largest offsets correspond to the oldest knots, as seen in other galaxies. In the quiescent north, we find more molecular clouds and a higher molecular-to-atomic gas ratio (∼1.5); atomic and diffuse molecular gas also have a higher velocity dispersion there. Overall, the organisation of the molecular interstellar medium in this TDG is quite different from other types of galaxies on large scales, but the properties of GMCs seem fairly similar, pointing to near universality of the star-formation process on small scales., Instituto de Salud Carlos III Spanish Government PID2019-106027GA-C44, Spanish Ministerio de Economia y Competitividad AYA2017-84897-P, European Commission, Junta de Andalucia European Commission FQM108, European Research Council (ERC) 726384/EMPIRE 714907, MCIU/AEI/FEDER,UE PGC2018-094671-B-I00 AYA2016-76682-C3-2-P, German Research Foundation (DFG) KR4801/1-1, German Research Foundation (DFG) KR4801/2-1

We used high-spatial resolution (70 pc; 0$ {{\overset{\prime\prime}{.}}} $3) CO multi-transition (J = 1-0, 2-1, 4-3, and 6-5) ALMA data to study the physical conditions and kinematics of the cold molecular outflow in the local luminous infrared galaxy (LIRG) ESO 320-G030 (d = 48 Mpc, LIR/L = 1011.3). ESO 320-G030 is a double-barred isolated spiral, but its compact and obscured nuclear starburst (SFR ∼15 M yr-1; AV ∼40 mag) resembles those of ultra-luminous infrared galaxies (LIR/L > 1012). In the outflow, the CO(1-0)/CO(2-1) ratio is enhanced with respect to the rest of the galaxy and the CO(4-3) transition is undetected. This indicates that the outflowing molecular gas is less excited than the molecular gas in the nuclear starburst (i.e., outflow launching site) and in the galaxy disk. Non-local thermodynamic equilibrium radiative transfer modeling reveals that the properties of the molecular clouds in the outflow differ from those of the nuclear and disk clouds: The kinetic temperature is lower (Tkin ∼ 9 K) in the outflow, and the outflowing clouds have lower column densities. Assuming a 10-4 CO abundance, the large internal velocity gradients, 60-45+250 km s-1 pc-1, imply that the outflowing molecular clouds are not bound by self-gravity. All this suggests that the life-cycle (formation, collapse, dissipation) of the galaxy disk molecular clouds might differ from that of the outflowing molecular clouds which might not be able to form stars. The low kinetic temperature of the molecular outflow remains constant at radial distances between 0.3 and 1.7 kpc. This indicates that the heating by the hotter ionized outflow phase is not efficient and may favor the survival of the molecular gas phase in the outflow. The spatially resolved velocity structure of the outflow shows a 0.8 km s-1 pc-1 velocity gradient between 190 pc and 560 pc and then a constant maximum outflow velocity of about 700-800 km s-1 up to 1.7 kpc. This could be compatible with a pure gravitational evolution of the outflow, which would require coupled variations of the mass outflow rate and the outflow launching velocity distribution. Alternatively, a combination of ram pressure acceleration and cloud evaporation could explain the observed kinematics and the total size of the cold molecular phase of the outflow. © ESO 2020., MPS acknowledges support from the Comunidad de Madrid through the Atracción de Talento Investigador Grant 2018-T1/TIC11035, PID2019-105423GA-I00 (MCIU/AEI/FEDER,UE), and STFC through Grants ST/N000919/1 and ST/N002717/1. L. C. acknowledge financial support by the Spanish MICINN under Grant ESP2017-83197. A. A.-H., S. G.-B., and A. U. acknowledge support through Grant PGC2018-094671-B-I00 (MCIU/AEI/FEDER,UE). E. GA is a Research Associate at the HarvardSmithsonian Center for Astrophysics, and thanks the Spanish Ministerio de Economía y Competitividad for support under project ESP2017-86582-C4- 1-R. J. P.-L. acknowledge financial support by the Spanish MICINN under Grant AYA2017-85170-R. M. P. S., A. A.-H., L. C., J. P.-L. and S. A. work was done under project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu”- Centro de Astrobiología (INTA-CSIC). DR acknowledges support from ST/S000488/1 and the University of Oxford Fell Fund. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00263.S, ADS/JAO.ALMA#2013.1.00271.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc

Context. Understanding the dominant heating mechanism in the nuclei of galaxies is crucial to understanding star formation in starbursts (SBs), active galactic nuclei (AGN) phenomena, and the relationship between star formation and AGN activity in galaxies. Analysis of the carbon monoxide (12CO) rotational ladder versus the infrared continuum emission (hereafter, 12CO/IR) in galaxies with different types of activity reveals important differences between them. Aims. We aim to carry out a comprehensive study of the nearby composite AGN-SB galaxy, NGC 4945, using spectroscopic and photometric data from the Herschel satellite. In particular, we want to characterize the thermal structure in this galaxy using a multi-transition analysis of the spatial distribution of the 12CO emission at different spatial scales. We also want to establish the dominant heating mechanism at work in the inner region of this object at smaller spatial scales (200 pc). Methods. We present far-infrared (FIR) and sub-millimeter (sub-mm) 12CO line maps and single spectra (from Jup = 3 to 20) using the Heterodyne Instrument for the Far Infrared (HIFI), the Photoconductor Array Camera and Spectrometer (PACS), and the Spectral and Photometric Imaging REceiver (SPIRE) onboard Herschel, and the Atacama Pathfinder EXperiment (APEX). We combined the 12CO/IR flux ratios and the local thermodynamic equilibrium (LTE) analysis of the 12CO images to derive the thermal structure of the interstellar medium (ISM) for spatial scales raging from 200 pc to 2 kpc. In addition, we also present single spectra of low- (12CO, 13CO and [CI]) and high-density (HCN, HNC, HCO+, CS and CH) molecular gas tracers obtained with APEX and HIFI applying LTE and non-LTE (NLTE) analyses. Furthermore, the spectral energy distribution of the continuum emission from the FIR to sub-mm wavelengths is also presented. Results. From the NLTE analysis of the low- and high-density tracers, we derive gas volume densities (103-106 cm-3) for NGC 4945 that are similar to those found in other galaxies with different types of activity. From the 12CO analysis we find a clear trend in the distribution of the derived temperatures and the 12CO/IR ratios. It is remarkable that at intermediate scales (360 pc-1 kpc, or 19″-57″) we see large temperatures in the direction of the X-ray outflow while at smaller scales (200 pc-360 pc, or ∼9″-19″), the highest temperature, derived from the high-J lines, is not found toward the nucleus but toward the galaxy plane. The thermal structure derived from the 12CO multi-transition analysis suggests that mechanical heating, like shocks or turbulence, dominates the heating of the ISM in the nucleus of NGC4945 located beyond 100 pc (5″) from the center of the galaxy. This result is further supported by published models, which are able to reproduce the emission observed at high-J (PACS) 12CO transitions when mechanical heating mechanisms are included. Shocks and/or turbulence are likely produced by the barred potential and the outflow observed in X-rays., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

We investigate the relation between the detection of the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature in the nuclear (∼24-230 pc) regions of 22 nearby Seyfert galaxies and the properties of the cold molecular gas. For the former we use ground-based (0.3-0.6″ resolution) mid-infrared (mid-IR) spectroscopy. The cold molecular gas is traced by ALMA and NOEMA high (0.2-1.1″) angular resolution observations of the CO(2-1) transition. Galaxies with a nuclear detection of the 11.3 μm PAH feature contain more cold molecular gas (median 1.6 × 107 MO ) and have higher column densities (N(H2) = 2 × 1023 cm-2) over the regions sampled by the mid-IR slits than those without a detection. This suggests that molecular gas plays a role in shielding the PAH molecules in the harsh environments of Seyfert nuclei. Choosing the PAH molecule naphthalene as an illustration, we compute its half-life in the nuclear regions of our sample when exposed to 2.5 keV hard X-ray photons. We estimate shorter half-lives for naphthalene in nuclei without a 11.3 μm PAH detection than in those with a detection. The Spitzer/IRS PAH ratios on circumnuclear scales (∼4″ ∼ 0.25-1.3 kpc) are in between model predictions for neutral and partly ionized PAHs. However, Seyfert galaxies in our sample with the highest nuclear H2 column densities are not generally closer to the neutral PAH tracks. This is because in the majority of our sample galaxies, the CO(2-1) emission in the inner ∼4″ is not centrally peaked and in some galaxies traces circumnuclear sites of strong star formation activity. Spatially resolved observations with the MIRI medium-resolution spectrograph on the James Webb Space Telescope will be able to distinguish the effects of an active galactic nucleus (AGN) and star formation on the PAH emission in nearby AGN., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

The Taffy system stands out as one of the strongest gas-rich galaxy mergers with little star formation (SF) activity. We study the causes of this SF inefficiency by observing with the IRAM 30m telescope the line emission of several species in 6 positions. We report clear detections of tracers of bulk (12CO and 13CO) and dense (HCN and HCO+) molecular gas in all regions, as well as evidence for shocks (SiO J=2–1) over the intergalactic bridge. Our observations not only confirm the SF inefficiency of the bulk gas, but they also show that the SF efficiency of the dense gas phase is abnormally low too (∼1 dex below ULIRGs). The dense gas fraction (∝ HCN/CO) only shows small variations across the entire system, with a typical value of 4%. Although this fraction is somewhat low compared to other interacting/merging systems, it is similar to the values measured in the disk of nearby, normal star-forming galaxies. Finally, we use the outstanding properties of the Taffy system to place constraints on some of the turbulence-regulated SF models from the literature.

We compare mid-IR and ALMA far-IR images of 12 nearby Seyferts selected from GATOS. The mid-IR unresolved emission contributes more than 60% of the nuclear emission in most galaxies. By contrast, the ALMA 870micron continuum emission is mostly resolved and typically along the torus equatorial direction (Paper I, Garcia-Burillo et al. 2021). The Eddington ratios and nuclear hydrogen column densities NH of half the sample are favorable to launching polar and/or equatorial dusty winds, according to simulations. Six show mid-IR extended emission in the polar direction as traced by the NLR and perpendicular to the ALMA emission. In a few, the nuclear NH might be too high to uplift large quantities of dusty material along the polar direction. Five galaxies have low NH and/or Eddington ratios and thus polar dusty winds are not likely. We generate new CAT3D-WIND disk-wind model images. At low wind-to-disk cloud ratios the far-IR model images have disk- and ring-like morphologies. The X-shape associated with dusty winds is seen better in the far-IR at intermediate-high inclinations for the extended-wind configurations. In most models, the mid-IR emission comes from the inner part of the disk/cone. Extended bi-conical and one-sided polar mid-IR emission is seen in extended-wind configurations and high wind-to-disk cloud ratios. When convolved to our resolution, the model images reproduce qualitative aspects of the observed morphologies. Low-intermediate wind-to-disk ratios are required to account for the large fractions of unresolved mid-IR emission. This work and Paper I provide observational support for the torus+wind scenario. The wind component is more relevant at high Eddington ratios and/or AGN luminosities, and polar dust emission is predicted at NH of up to $10^{24}$cm$^{-2}$. The torus/disk component, on the other hand, prevails at low luminosities and/or Eddington ratios. (Abridged), 27 pages, 27 figures. Accepted for publication in A&A

Studying the molecular component of the interstellar medium in metal-poor galaxies has been challenging because of the faintness of carbon monoxide emission, the most common proxy of H2. Here we present new detections of molecular gas at low metallicities, and assess the physical conditions in the gas through various CO transitions for 8 galaxies. For one, NGC 1140 (Z/Zsun ~ 0.3), two detections of 13CO isotopologues and atomic carbon, [CI](1-0), and an upper limit for HCN(1-0) are also reported. After correcting to a common beam size, we compared 12CO(2-1)/12CO(1-0) (R21) and 12CO(3-2)/12CO(1-0) (R31) line ratios of our sample with galaxies from the literature and find that only NGC 1140 shows extreme values (R21 ~ R31 ~ 2). Fitting physical models to the 12CO and 13CO emission in NGC 1140 suggests that the molecular gas is cool (kinetic temperature Tkin= $10^6$ cm$^{-3}$), with moderate CO column density (NCO ~ $10^{16}$ cm$^{-2}$) and low filling factor. Surprisingly, the [12CO]/[13CO] abundance ratio in NGC 1140 is very low (~ 8-20), lower even than the value of 24 found in the Galactic Center. The young age of the starburst in NGC 1140 precludes 13C enrichment from evolved intermediate-mass stars; instead we attribute the low ratio to charge-exchange reactions and fractionation, because of the enhanced efficiency of these processes in cool gas at moderate column densities. Fitting physical models to 12CO and [CI](1-0) emission in NGC 1140 gives an unusually low [12CO]/[12C] abundance ratio, suggesting that in this galaxy atomic carbon is at least 10 times more abundant than 12CO., 26 pages, 21 figures, 2 appendices, A&A, in press

We derive molecular-gas-phase $^{12}$C/$^{13}$C isotope ratios for the central few 100 pc of the three nearby starburst galaxies NGC 253, NGC 1068, and NGC 4945 making use of the $\lambda$ $\sim$ 3 mm $^{12}$CN and $^{13}$CN $N$ = 1--0 lines in the ALMA Band 3. The $^{12}$C/$^{13}$C isotopic ratios derived from the ratios of these lines range from 30 to 67 with an average of 41.6 $\pm$ 0.2 in NGC 253, from 24 to 62 with an average of 38.3 $\pm$ 0.4 in NGC 1068, and from 6 to 44 with an average of 16.9 $\pm$ 0.3 in NGC 4945. The highest $^{12}$C/$^{13}$C isotopic ratios are determined in some of the outskirts of the nuclear regions of the three starburst galaxies. The lowest ratios are associated with the northeastern and southwestern molecular peaks of NGC 253, the northeastern and southwestern edge of the mapped region in NGC 1068, and the very center of NGC 4945. In case of NGC 1068, the measured ratios suggest inflow from the outer part of NGC 1068 into the circum-nuclear disk through both the halo and the bar. Low $^{12}$C/$^{13}$C isotopic ratios in the central regions of these starburst galaxies indicate the presence of highly processed material., Comment: Accepted for publication in A&A

We report ALMA observations of CO(3-2) emission in a sample of 7 Seyfert/LINER galaxies at the unprecedented spatial resolution of 0.1'' = 4-9 pc. Our aim is to explore the close environment of AGN, and the dynamical structures leading to its fueling. The selected galaxies host low-luminosity AGN, and have a wide range of activity types, and barred or ringed morphologies. The observed maps reveal the existence of circum-nuclear disk structures, defined by their morphology and decoupled kinematics. We call these structures "molecular tori", even though they appear often as disks, without holes in the center. They have varied orientations, unaligned with their host galaxy. The radius of the tori ranges from 6 to 27 pc, and their mass from 0.7 10$^7$ to 3.9 10$^7$ Msun. At larger scale, the gas is always piled up in a few 100~pc scale resonant rings, that play the role of a reservoir to fuel the nucleus. In some cases, a trailing spiral is observed inside the ring, providing evidence for feeding processes. Most frequently, the torus and the AGN are slightly off-centered, with respect to the bar-resonant ring position, implying that the black hole is wandering by a few 10~pc amplitude around the center of mass of the galaxy. Our spatial resolution allows us to measure gas velocities inside the sphere of influence of the central black holes. By fitting the observations with different simulated cubes, varying the torus inclination and the black hole mass, it is possible to estimate the mass of the central black hole, which is in general difficult for such late-type galaxies, with only a pseudo-bulge., Comment: 20 pages, 21 figures, accepted in Astron. and Astrophys

We analyze new high spatial resolution (∼60 pc) ALMA CO(2-1) observations of the isolated luminous infrared galaxy ESO 320-G030 (d = 48 Mpc) in combination with ancillary Hubble Space Telescope optical and near infrared (IR) imaging, as well as VLT/SINFONI near-IR integral field spectroscopy. We detect a high-velocity (∼450 km s) spatially resolved (size∼2.5 kpc; dynamical time ∼3 Myr) massive (∼10 M; Ṁ ∼ 2-8 M yr) molecular outflow that has originated in the central ∼250 pc. We observe a clumpy structure in the outflowing cold molecular gas with clump sizes between 60 and 150 pc and masses between 10 and 10 M. The mass of the clumps decreases with increasing distance, while the velocity is approximately constant. Therefore, both the momentum and kinetic energy of the clumps decrease outwards. In the innermost (∼100 pc) part of the outflow, we measure a hot-to-cold molecular gas ratio of 7 × 10, which is similar to that measured in other resolved molecular outflows. We do not find evidence of an ionized phase in this outflow. The nuclear IR and radio properties are compatible with strong and highly obscured star-formation (A ∼ 4.6 mag; star formation rate ∼ 15 M yr). We do not find any evidence for the presence of an active galactic nucleus. We estimate that supernova explosions in the nuclear starburst (ν ∼ 0.2 yr) can power the observed molecular outflow. The kinetic energy and radial momentum of the cold molecular phase of the outflow correspond to about 2% and 20%, respectively, of the supernovae output. The cold molecular outflow velocity is lower than the escape velocity, so the gas will likely return to the galaxy disk. The mass loading factor is ∼0.1-0.5, so the negative feedback owing to this star-formation-powered molecular outflow is probably limited., We acknowledge support from the Spanish Plan Nacional de Astronomía y Astrofísica through grants AYA2010-21161-C02-01 and AYA2012-32295. A.A.-H. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through grant AYA2015-64346-C2-1-P. B.E. acknowledges funding through the European Union FP7-PEOPLE2013-IEF grant 624351

The CO+ reactive ion is thought to be a tracer of the boundary between a HII region and the hot molecular gas. In this study, we present the spatial distribution of the CO+ rotational emission toward the Mon R2 star-forming region. The CO+ emission presents a clumpy ring-like morphology, arising from a narrow dense layer around the HII region. We compare the CO+ distribution with other species present in photon-dominated regions (PDR), such as [CII] 158 mm, H2 S(3) rotational line at 9.3 mm, polycyclic aromatic hydrocarbons (PAHs) and HCO+. We find that the CO+ emission is spatially coincident with the PAHs and [CII] emission. This confirms that the CO+ emission arises from a narrow dense layer of the HI/H2 interface. We have determined the CO+ fractional abundance, relative to C+ toward three positions. The abundances range from 0.1 to 1.9x10^(-10) and are in good agreement with previous chemical model, which predicts that the production of CO+ in PDRs only occurs in dense regions with high UV fields. The CO+ linewidth is larger than those found in molecular gas tracers, and their central velocity are blue-shifted with respect to the molecular gas velocity. We interpret this as a hint that the CO+ is probing photo-evaporating clump surfaces., Comment: The main text has 4 pages, 2 pages of Appendix, 4 figures, 1 table. Accepted for publication in Astronomy and Astrophysics letters

We present the detection and morphological characterization of hot molecular gas outflows in nearby ultra-luminous infrared galaxies (ULIRGs), using the Spectrograph for Integral Field Observations in the Near Infrared (SINFONI) on the Very Large Telescope (VLT). We detect outflows observed in the 2.12 μm H2 1-0 S(1) line for three out of four ULIRGs that we analyzed, namely IRAS 12112+0305, IRAS 14348-1447, and IRAS 22491-1808. The outflows are mapped on scales of 0.7-1.6 kpc, show typical outflow velocities of 300-500 km s-1, and appear to originate from the nuclear region. The outflows comprise hot molecular gas masses of MH2 (hot) 6-8 ×103 M . Assuming a hot-to-cold molecular gas mass ratio of 6 × 10-5, as found in nearby luminous infrared galaxies, the total (hot + cold) molecular gas mass in these outflows is expected to be MH2 (tot) 1 × 108 M . This translates into molecular mass outflow rates of H2 (tot) 30-85 M yr-1, which is a factor of a few lower than the star formation rate in these ULIRGs. In addition, most of the outflowing molecular gas does not reach the escape velocity of these merger systems, which implies that the bulk of the outflowing molecular gas is re-distributed within the system and thus remains available for future star formation. The fastest H2 outflow is seen in the Compton-thick AGN of IRAS 14348-1447, reaching a maximum outflow velocity of 900 km s-1. Another ULIRG, IRAS 17208-0014, shows asymmetric H2 line profiles different from the outflows seen in the other three ULIRGs. We discuss several alternative explanations for the line asymmetries in this system, including a very gentle galactic wind, internal gas dynamics, low-velocity gas outside the disk, or two superposed gas disks. We do not detect the hot molecular counterpart to the outflow previously detected in CO(2-1) in IRAS 17208-0014, but we note that our SINFONI data are not sensitive enough to detect this outflow if it has a small hot-to-cold molecular gas mass ratio of × 10-6., The research leading to these results was funded by the Spanish Ministerio de Economía y Competitividad (MINECO) under grants AYA2012-32295, ESP2015-68964-P, AYA2016-76682-C3-2-P, and AYA2015-54346-C2-1-P

With the incorporation of high-J molecular lines, we aim to constrain the physical conditions of the dense gas in the central region of the Seyfert 2 galaxy NGC 1068 and to determine signatures of the AGN or the starburst contribution. We used the James Clerk Maxwell Telescope to observe the J=4-3 transition of HCN, HNC, and HCO+, as well as the CN N_J=2_{5/2}-1_{3/2} and N_J=3_{5/2}-2_{5/2}, in NGC 1068. We estimate the excitation conditions of HCN, HNC, and CN, based on the line intensity ratios and radiative transfer models. We find that the bulk emission of HCN, HNC, CN, and the high-J HCO+ emerge from dense gas n(H_2)>=10^5 cm^-3). However, the low-J HCO+ lines (dominating the HCO+ column density) trace less dense (n(H_2)30 K) gas than the other molecules. The HCO+ J=4-3 line intensity, compared with the lower transition lines and with the HCN J=4-3 line, support the influence of a local XDR environment. The estimated N(CN)/N(HCN)~1-4 column density ratios are indicative of an XDR/AGN environment with a possible contribution of grain-surface chemistry induced by X-rays or shocks., Main text: 8 pages, 5 tables, 1 figure. Appendix: 7 pages, 1 table, 8 figures. Accepted for publication in A&A

We present CO(1-0) and CO(2-1) maps of the starburst/Seyfert 1 galaxy NGC 2782, obtained with the IRAM interferometer. The CO emission is aligned along the stellar nuclear bar of radius 1 kpc, configured in an elongated structure with two spiral arms at high pitch angle. At the extremity of the nuclear bar, the CO changes direction to trace two more extended spiral features at a lower pitch angle. These are the beginning of two straight dust lanes, which are aligned parallel to an oval distortion, reminiscent of a primary bar, almost perpendicular to the nuclear one. The two embedded bars appear in Spitzer IRAC near-infrared images, and HST color images, although highly obscured by dust in the latter. We compute the torques exerted by the stellar bars on the gas, and find systematically negative average torques down to the resolution limit of the images, providing evidence of gas inflow tantalizingly close to the nucleus of NGC 2782. The observations are well reproduced by numerical simulations, including gas dissipation, which predict the secondary bar decoupling, the formation of an elongated ring at the 1 kpc-radius Inner Lindblad Resonance (ILR) of the primary bar, and the gas inflow to the ILR of the nuclear bar. The presence of molecular gas inside the ILR of the primary bar, transported by a second nuclear bar, is a potential ``smoking gun''; the gas there is certainly fueling the central starburst, and in a second step could fuel directly the AGN., 23 pages, 18 figures, accepted for publication in A&A; revised 28/2/2008 with additional references for Section 7.2

The use of specific tracers of the dense molecular gas phase can help to explore the feedback of activity on the interstellar medium (ISM) in galaxies. This information is a key to any quantitative assessment of the efficiency of the star formation process in galaxies. We present the results of a survey devoted to probe the feedback of activity through the study of the excitation and chemistry of the dense molecular gas in a sample of local universe starbursts and active galactic nuclei (AGNs). Our sample includes also 17 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs). From the analysis of the LIRGs/ULIRGs subsample, published in Gracia-Carpio et al.(2007) we find the first clear observational evidence that the star formation efficiency of the dense gas, measured by the L_FIR/L_HCN ratio, is significantly higher in LIRGs and ULIRGs than in normal galaxies. Mounting evidence of overabundant HCN in active environments would even reinforce the reported trend, pointing to a significant turn upward in the Kennicutt-Schmidt law around L_FIR=10^11 L_sun. This result has major implications for the use of HCN as a tracer of the dense gas in local and high-redshift luminous infrared galaxies., Comment: 4 pages, 2 figures, contributed paper to Far-Infrared Workshop 07 (FIR 2007)

Large-scale shocks propagate in the interstellar medium of starburst and active galaxies, driven by the same mechanisms that regulate the evolution of the star formation and AGN episodes. The imprints of shocks in the chemical composition of the molecular gas provide useful means to identify those mechanisms and to asses their effects. We review some recent and on-going studies of the molecular gas chemistry in the nearby star-forming galaxies IC 342, NGC 253 and M 82, based on the well known shock tracer silicon monoxide (SiO). When mapped at high–spatial resolution the SiO emission reveals substantial differences among these galaxies. In particular, the location of shocks and their dominant driver are in correspondence with the evolutionary stage of the starburst episode. Complementary observations of other tracers of shock chemistry, like methanol (CH 3 OH), help us to improve the characterization of the shock mechanisms. We also present the first high-resolution observations of the SiO emission in the Seyfert 2 galaxy NGC 1068.

We report the detection of a massive (M(gas) > 5x10^9 Msun) molecular/dusty disk of 1.4kpc-size fueling the central engine of the Compact Symmetric Object (CSO) 4C31.04 based on high-resolution (0.5''--1.2'') observations done with the IRAM Plateau de Bure interferometer (PdBI). These observations allow for the first time to detect and map the continuum emission from dust at 218GHz in the disk of a CSO. The case for a massive disk is confirmed by the detection of strong HCO+(1--0) line emission and absorption. The molecular gas mass of 4C31.04 is in the range 0.5x10^10--5x10^10Msun. While the distribution and kinematics of the gas correspond roughly to those of a rotating disk, we find evidence of distortions and non-circular motions suggesting that the disk is not in a dynamically relaxed state. We discuss the implications of these results for the general understanding of the evolution of radio galaxies., 5 pages, 3 figures, Accepted (25/04/2007) in A&A Letters

Several studies of nearby active galaxies indicate significantly higher HCN-to-CO intensity ratios in AGN than in starburst (SB) environments. HCN enhancement can be caused by many different effects, such as higher gas densities/temperatures, UV/X-ray radiation, and non-collisional excitation. As active galaxies often exhibit intense circumnuclear SB, high angular resolution/sensitivity observations are of paramount importance to disentangling the influence of SB from that of nuclear activity on the chemistry of the surrounding molecular gas. The tight relation of HCN enhancement and nuclear activity may qualify HCN as an ideal tracer of molecular gas close to the AGN, providing complementary and additional information to that gained via CO. NGC6951 houses nuclear and SB activity, making it an ideal testbed in which to study the effects of different excitation conditions on the molecular gas. We used the new ABCD configurations of the IRAM PdBI to observe HCN(1-0) in NGC6951 at high angular resolution (1''). We detect very compact (0.4) in the nucleus than in the SB ring (0.02-0.05). As for NGC1068, this might result from a higher HCN abundance in the centre due to an X-ray dominated gas chemistry, but a higher gas density/temperature or additional non-collisional excitation of HCN cannot be entirely ruled out, based on these observations. The compact HCN emission is associated with rotating gas in a circumnuclear disk/torus., Letter accepted for publication in a special issue of A&A presenting results of the new extended configuration at the IRAM PdBI, to appear most likely around June 2007. Letter has 4 pages and 2 figures. Abstract has been shortened to meet the line limits of astrop-ph

We obtained an ALMA Cycle 0 spectral scan of the dusty LIRG NGC 4418, spanning a total of 70.7 GHz in bands 3, 6, and 7. We use a combined local thermal equilibrium (LTE) and non-LTE (NLTE) fit of the spectrum in order to identify the molecular species and derive column densities and excitation temperatures. We derive molecular abundances and compare them with other Galactic and extragalactic sources by means of a principal component analysis. We detect 317 emission lines from a total of 45 molecular species, including 15 isotopic substitutions and six vibrationally excited variants. Our LTE/NLTE fit find kinetic temperatures from 20 to 350 K, and densities between 10$^5$ and 10$^7$ cm$^{-3}$. The spectrum is dominated by vibrationally excited HC$_3$N, HCN, and HNC, with vibrational temperatures from 300 to 450 K. We find high abundances of HC$_3$N, SiO, H$_2$S, and c-HCCCH and a low CH$_3$OH abundance. A principal component analysis shows that NGC 4418 and Arp 220 share very similar molecular abundances and excitation, which clearly set them apart from other Galactic and extragalactic environments. The similar molecular abundances observed towards NCG 4418 and Arp 220 are consistent with a hot gas-phase chemistry, with the relative abundances of SiO and CH$_3$OH being regulated by shocks and X-ray driven dissociation. The bright emission from vibrationally excited species confirms the presence of a compact IR source, with an effective diameter $$350 K. The molecular abundances and the vibrationally excited spectrum are consistent with a young AGN/starburst system. We suggest that NGC 4418 may be a template for a new kind of chemistry and excitation, typical of compact obscured nuclei (CON). Because of the narrow line widths and bright molecular emission, NGC 4418 is the ideal target for further studies of the chemistry in CONs., Comment: accepted by A&A on 29/06/2015

(Abridged) We present the first high-resolution (5.6''x5.1'') images of the emission of silicon monoxide (SiO) in the nearby spiral IC342, obtained with the IRAM Plateau de Bure Interferometer. We have mapped the emission of the SiO(2-1) and H13CO+(1-0) lines in a 0.9kpcx1.3kpc region around the nucleus of IC342. The bulk of the line emission comes from a 290pc spiral arm and a r~80pc nuclear ring. The distribution of SiO clouds is mostly anticorrelated with the continuum emission at 87GHz, dominated by thermal free-free bremsstrahlung. The SiO/H13CO+ intensity ratio increases by an order of magnitude from the nuclear ring to the spiral arm. Furthermore the gas kinematics show significant differences between SiO and H13CO+ over the spiral arm, where the linewidths of SiO are 2 times larger than that of H13CO+. The average abundance of SiO in the inner r~320pc, X(SiO)>2x10^{-10}, evidences that shock chemistry is at work in IC342. We have compared the emission of SiO with another tracer of molecular shocks: the emission of methanol (CH3OH). The significant difference of the X(SiO) measured between the spiral arm (~a few 10^{-9}) and the nuclear ring (~10^{-10}) is not echoed by a comparable variation in the SiO/CH3OH intensity ratio. This implies that the typical shock velocities should be similar in both regions. In contrast, the fraction of shocked molecular gas should be 5-7 times larger in the spiral arm (up to ~10% of the available molecular gas mass over the arm region) compared to the nuclear ring. We conclude that the large-scale shocks revealed by the SiO map of IC342 are mostly unrelated with star formation and arise instead in a pre-starburst phase. Shocks are driven by cloud-cloud collisions along the potential well of the IC342 bar. The general implications for the current understanding of galaxy evolution are discussed., 15 pages, including 9 figures (6 color) and 3 tables; accepted in Astronomy & Astrophysics

We discuss the efficiency of stellar gravity torques as a mechanism to account for the feeding of the central engines of four low luminosity AGN: NGC4321, NGC4826, NGC4579 and NGC6951. These galaxies have been observed as part of the NUGA CO project, aimed at the study of AGN fueling mechanisms. Our calculations allow us to derive the characteristic time-scales for gas flows and discuss whether torques from the stellar potentials are efficient enough to drain the gas angular momentum in the inner 1 kpc of these galaxies. Results indicate paradoxically that feeding should be thwarted close to the AGN: in the four cases analyzed, gravity torques are mostly positive inside r~200pc, resulting in no inflow on these scales. As a possible solution for the paradox, we speculate that the agent responsible for driving inflow to still smaller radii is transient and thus presently absent in the stellar potential. Alternatively, the gravity torque barrier associated with the ILR of the bars in these galaxies could be overcome by other mechanisms that become competitive in due time against gravity torques. We find that viscosity can counteract moderate--to--low gravity torques on the gas if it acts on a nuclear ring of high gas surface density contrast and a few 100pc size. We propose an evolutionary scenario in which gravity torques and viscosity act in concert to produce recurrent episodes of activity during the typical lifetime of any galaxy. In this scenario the recurrence of activity in galaxies is indirectly related to that of the bar instabilities., Comment: Accepted in Astronomy and Astrophysics, 24/06/05

We have carried out a survey of reactive ions (CO + , HOC + , HC 1 8 O + , SO + ) and cyclopropenylidene (C 3 H 2 ) in three prototypical photodissociation regions (PDRs), the reflection nebula NGC 7023, the Orion Bar and the planetary nebula (PN) NGC 7027. The reactive ion CO + has been detected in all the targets with fractional abundances ranging from ∼ 10 - 1 1 to ∼a few 10 - 9 . Its spatial distribution in NGC 7023 and the Orion Bar show that CO + arises in the innermost part (A, < 2 mag) of the PDR. In NGC 7027, the CO + lines shows an expansion velocity higher than that of the CO lines. This high expansion velocity is consistent with the CO + emission arising in the high velocity layer of neutral gas which is being accelerated by the ionized gas. Photochemistry determines the chemical composition of this layer. The reactive ions HOC + and SO + have been detected in NGC 7023 and the Orion Bar. In both sources, the fractional abundance of HOC + is enhanced by a factor of ∼ 10 towards the PDRs, with typical abundances, X H O C + = 0.7-3 x 10 - 1 1 . This enhancement produces a decrease of the [HCO + ]/[HOC + ] abundance ratio towards the PDR. In fact, we have derived [HCO + ]/[HOC + ] ∼ 50-120 in NGC 7023, which is the lowest ratio measured thus far. HOC + and SO + have not been detected in NGC 7027. Interestingly, this is the source with the highest CO + abundance, X C O + = 5 × 10 - 9 . This lack of detection is interpreted as due to the peculiar chemistry of C-rich PNs, in which the abundance of oxygenated molecules, in particular H 2 O, is low. We have detected cyclopropenylidene (C 3 H 2 ) in the three target PDRs. Similarly to the reactive ions, the abundance of C 3 H 2 in NGC 7023 and the Orion Bar is a factor of 10-100 higher in the PDRs than in the foreground molecular cloud with peak values ranging from 10 - 1 0 to 10 - 9 . In NGC 7027, we measured the maximum C 3 H 2 abundance with a value of ∼10 - 8 . Similarly to the case of CO + , the high expansion velocities of the C 3 H 2 lines in NGC 7027 suggests that its emission arises in the neutral gas which is being accelerated by the ionized gas. Photodestruction of Polycyclic Aromatic Hydrocarbons (PAHs) is proposed to explain the enhanced C 3 H 2 abundance in these PDRs.

We present new high-resolution observations of the nucleus of the counter-rotating LINER NGC4826, made in the J=1-0 and J=2-1 lines of 12CO with the IRAM Plateau de Bure mm-interferometer(PdBI).The CO maps, which achieve 0.8''(16pc) resolution in the 2-1 line, fully resolve an inner molecular gas disk which is truncated at an outer radius of 700pc. The total molecular gas mass is distributed in a lopsided nuclear disk of 40pc radius and two one-arm spirals, which develop at different radii in the disk. The distribution and kinematics of molecular gas in the inner 1kpc of NGC4826 show the prevalence of different types of m=1 perturbations in the gas. Although dominated by rotation, the gas kinematics are perturbed by streaming motions related to the m=1 instabilities. The non-circular motions associated with the inner m=1 perturbations agree qualitatively with the pattern expected for a trailing wave developed outside corotation ('fast' wave). In contrast, the streaming motions in the outer m=1 spiral are better explained by a 'slow' wave. A paradoxical consequence is that the inner m=1 perturbations would not favour AGN feeding. An independent confirmation that the AGN is not being generously fueled at present is found in the low values of the gravitational torques exerted by the stellar potential for R, A&A, 2003, Paper accepted (04/06/03). For a full-resolution version of this paper see http://www.oan.es/preprints

International audience

This paper studies the global ISM content in a sample of 104 accreting galaxies, including counterrotators and polar rings, which spans the entire Hubble sequence. The molecular, atomic and hot gas content of accretors is compared to a newly compiled sample of normal galaxies. We present results of a small survey of the J=1--0 line of {12}CO with the 15m SEST telescope on a sample of 11 accretors (10 counterrotators and 1 polar ring). The SEST sample is enlarged with published data from 48 galaxies, for which observational evidence of counterrotation in the gas and/or the stars has been found. Furthermore, the available data on a sample of 46 polar ring galaxies has been compiled. It was found that the normalized content of cold gas (M_gas/L_B) in polar rings is ~1 order of magnitude higher than the reference value derived for normal galaxies. The inferred gas masses are sufficient to stabilize polar rings through self-gravity. In contrast, it was found that the cold gas content of counterrotators is close to normal for all galaxy types. Although counterrotators and polar rings probably share a common origin, the gas masses estimated here confirm that light gas rings accreted by future counterrotators may have evolved faster than the self-gravitating structures of polar rings. In this scenario, the transformation of atomic into molecular gas could be enhanced near the transition region between the prograde and the retrograde disks, especially in late-type accretors characterized by a high content of primordial gas. This is tentatively confirmed in this work: the measured H_2/HI ratio seems larger in counterrotators than in normal or polar ring galaxies for types later than S0s., Comment: 17 pages, 8 figures, accepted for publication in A&A

We have performed a comparison between the molecular gas emission and the mid IR dust component emission distributions in a sample of nearby galaxies. We have compared CO maps at high spatial resolution, from Wilson et al. (2000), Bayet et al. (2004, 2006) and from Kramer et al. (2005), with the emission distributions of ionised and neutral PAHs (PAH + ; PAH 0 ) and of very small grains (VSGs), obtained using signal processing methods as explained in Berne et al. (2007a) and Rapacioli et al. (2005). In M 82, we have also compared the dust emission maps with dense gas tracer maps (HCO and H 13 CO + data from Garcia-Burillo et al. 2002) as well as with shock tracer maps (SiO data from Garcia-Burillo et al. 2001).

Context. Carbon monoxide (CO) is widely used as a tracer of the molecular gas in almost all types of environments. However, several shortcomings of CO complicate usaging it as H-2 tracer, such as its optical depth effects, the dependence of its abundance on metallicity, or its susceptibility to dissociation in highly irradiated regions. Neutral carbon emission has been proposed to overcome some of these shortcomings and hence to help revealing the limits of CO as a measure of the molecular gas. Aims. We aim to study the general characteristics of the spatially and spectrally resolved carbon line emission in a variety of extragalactic sources and evaluate its potential as complementary H-2 tracer to CO. Methods. We used the Atacama Compact Array to map the [CI](P-3(1)-P-3(0)) line emission in the nearby starburst galaxy NGC 253 at unprecedented angular resolution (similar to 3 ''). This is the first well-resolved interferometric [CI] map of an extragalactic source. Results. We have detected the [CI] line emission at high significance levels along the central disk of NGC 253 and its edges where expanding shells have previously been found in CO. Globally, the distribution of the [CI] line emission strongly resembles that of CO, confirming the results of previous Galactic surveys that [CI] traces the same molecular gas as CO. However, we also identify a significant increase of [CI] line emission with respect to CO in (some of) the outflow or shocked regions of NGC 253, namely the bipolar outflow emerging from the nucleus. A first-order estimate of the [CI] column densities indicates abundances of [CI] that are very similar to the abundance of CO in NGC 253. Interestingly, we find that the [CI] line is marginally optically thick within the disk. Conclusions. The enhancement of the [CI]/CO line ratios (similar to 0.4-0.6) with respect to Galactic values (

We explore the potential of imaging vibrationally excited molecular emission at high angular resolution to better understand the morphology and physical structure of the dense gas in Arp~220 and to gain insight into the nature of the nuclear powering sources. Vibrationally excited emission of HCN is detected in both nuclei with a very high ratio relative to the total $L_{FIR}$, higher than in any other observed galaxy and well above what is observed in Galactic hot cores. HCN $v_2=1f$ is observed to be marginally resolved in $\sim60\times50$~pc regions inside the dusty $\sim100$~pc sized nuclear cores. Its emission is centered on our derived individual nuclear velocities based on HCO$^+$ emission ($V_{WN}=5342\pm4$ and $V_{EN}=5454\pm8$~\kms, for the western and eastern nucleus, respectively). With virial masses within $r\sim25-30$~pc based on the HCN~$v_2=1f$ line widths, we estimate gas surface densities (gas fraction $f_g=0.1$) of $3\pm0.3\times10^4~M_\odot~\rm pc^{-2}$ (WN) and $1.1\pm0.1\times10^4~M_\odot~\rm pc^{-2}$ (EN). The $4-3/3-2$ flux density ratio could be consistent with optically thick emission, which would further constrain the size of the emitting region to $>15$~pc (EN) and $>22$~pc (WN). The absorption systems that may hide up to $70\%$ of the HCN and HCO$^+$ emission are found at velocities of $-50$~\kms~(EN) and $6$, $-140$, and $-575$~\kms (WN) relative to velocities of the nuclei. Blueshifted absorptions are the evidence of outflowing motions from both nuclei. The bright vibrational emission implies the existence of a hot dust region radiatively pumping these transitions. We find evidence of a strong temperature gradient that would be responsible for both the HCN $v_2$ pumping and the absorbed profiles from the vibrational ground state as a result of both continuum and self-absorption by cooler foreground gas., 14 pages accepted for publication in A&A

Aims: Our goal is to study the chemical composition of the outflows of active galactic nuclei and starburst galaxies. Methods: We obtained high-resolution interferometric observations of HCN and HCO$^+$ $J=1\rightarrow0$ and $J=2\rightarrow1$ of the ultraluminous infrared galaxy Mrk~231 with the IRAM Plateau de Bure Interferometer. We also use previously published observations of HCN and HCO$^+$ $J=1\rightarrow0$ and $J=3\rightarrow2$, and HNC $J=1\rightarrow0$ in the same source. Results: In the line wings of the HCN, HCO$^+$, and HNC emission, we find that these three molecular species exhibit features at distinct velocities which differ between the species. The features are not consistent with emission lines of other molecular species. Through radiative transfer modelling of the HCN and HCO$^+$ outflow emission we find an average abundance ratio $X(\mathrm{HCN})/X(\mathrm{HCO}^+)\gtrsim1000$. Assuming a clumpy outflow, modelling of the HCN and HCO$^+$ emission produces strongly inconsistent outflow masses. Conclusions: Both the anti-correlated outflow features of HCN and HCO$^+$ and the different outflow masses calculated from the radiative transfer models of the HCN and HCO$^+$ emission suggest that the outflow is chemically differentiated. The separation between HCN and HCO$^+$ could be an indicator of shock fronts present in the outflow, since the HCN/HCO$^+$ ratio is expected to be elevated in shocked regions. Our result shows that studies of the chemistry in large-scale galactic outflows can be used to better understand the physical properties of these outflows and their effects on the interstellar medium (ISM) in the galaxy., Comment: 12 pages, 8 figures, accepted for publication in A&A

[Aims]: We study the analogy between local luminous and ultraluminous infrared galaxies (U/LIRGs) and high-z massive star forming galaxies (SFGs) by comparing their basic Hα structural characteristics, such as size and luminosity surface density, in an homogeneous way (i.e. same tracer, size definition, and similar physical scales). [Methods]: We use integral field spectroscopy (IFS) based Hα emission maps for a representative sample of 54 local U/LIRGs (66 galaxies) observed with INTEGRAL/WHT and VIMOS/VLT. From this initial sample, we select 26 objects with similar Hα luminosities (L(Hα)) to those of massive (i.e. M * ∼ 10 10 M ⊙ or larger) SFGs at z ∼ 2, and observed on similar physical scales. We then directly compare the sizes, and luminosity (and SFR) surface densities of these local and high-z samples. [Results]: The size of the Hα emitting region in the local U/LIRGs that we study has a wide range of values, with r 1/2(Hα) from 0.2 kpc to 7 kpc. However, about two-thirds of local U/LIRGs with L ir > 10 11.4 L ⊙ have compact Hα emission (i.e. r 1/2 < 2 kpc). The comparison sample of local U/LIRGs also contains a larger fraction (59%) of objects with compact Hα emission than the high-z sample (25%). This gives further support to the idea that for this luminosity range the size of the star forming region is a distinctive factor when comparing local and distant galaxies of similar SFRs. However, when using Hα as a tracer for both local and high-z samples, the differences are smaller than those reported using a variety of other tracers. In the L(Hα)-L(Hα) surface density (Σ Hα) plane, most of the local U/LIRGs and high-z SF galaxies follow the same trend (i.e. higher luminosity for higher surface density) and cover a similar range, except for about 20-40% of local U/LIRGs, which have a higher Σ Hα by a factor of about 10. This is considerably smaller than the factors of 1000 or more reported in similar planes (i.e. L(TIR) versus Σ TIR). Despite of the higher fraction of galaxies with compact Hα emission, a sizable group (about one-third) of local U/LIRGs are large (i.e. r 1/2 > 2 kpc). These are systems that show evidence of pre-coalescence merger activity and are indistinguishable from the massive high-z SFGs galaxies in terms of their Hα sizes, and luminosity and SFR surface densities. © 2012 ESO., MGM is supported by the German federal department for education and research (BMBF) under the project number 50OS1101. This work has been supported by the Spanish Ministry of Science and Innovation (MICINN) under grants ESP2007-65475- C02-01 and AYA2010-21161-C02-01.

[Context]: The observational study of star-formation relations in galaxies is central for unraveling the related physical processes that are at work on local and global scales. It is still debated whether star formation can be described by a universal law that remains valid in different populations of galaxies. [Aims]: We aim to expand the sample of extreme starbursts, represented by local luminous and ultra-luminous infrared galaxies (LIRGs and ULIRGs), with high-quality observations in the 1-0 line of HCN, which is taken as a proxy for the dense molecular gas content. The new data presented in this work allow us to enlarge in particular the number of LIRGs studied in HCN by a factor 3 compared to previous works. The chosen LIRG sample has a range of HCN luminosities that partly overlaps with that of the normal galaxy population. We study if a universal law can account for the star-formation relations observed for the dense molecular gas in normal star-forming galaxies and extreme starbursts and explore the validity of different theoretical prescriptions of the star-formation law. [Methods]: We have used the IRAM 30 m telescope to observe a sample of 19 LIRGs in the 1-0 lines of CO, HCN and HCO +. The galaxies were extracted from a sample of local LIRGs with available high-quality and high-resolution images obtained at optical, near and mid IR wavelengths, which probe the star-formation activity. We therefore derived the star-formation rates using different tracers and determined the sizes of the star-forming regions of all targets. [Results]: The analysis of the new data proves that the efficiency of star formation in the dense molecular gas (SFE dense) of extreme starbursts is a factor 3-4 higher compared to normal galaxies. Kennicutt-Schmidt (KS) power laws were also derived. We find a duality in KS laws that is further reinforced if we account for the likely different conversion factor for HCN (α HCN) in extreme starbursts and for the unobscured star-formation rate in normal galaxies. This result extends the more extreme bimodal behavior of star-formation laws that was derived from CO molecular lines by two recent surveys to the higher molecular densities probed by HCN lines. [Conclusions]: We compared our observations with the predictions of theoretical models in which the efficiency of star formation is determined by the ratio of a constant star-formation rate per free-fall time (SFR ff) to the local free-fall time (t ff). We find that it is possible to fit the observed differences in the SFE dense between normal galaxies and LIRGs/ULIRGs using a common constant SFR ff and a set of physically acceptable HCN densities, but only if SFR ff ∿ 0.005-0.01 and/or if α HCN is a factor of ∿a few lower than our favored values. Star-formation recipes that explicitly depend on the galaxy global dynamical time scales do not significantly improve the fit to the new HCN data presented in this work. © 2012 ESO., SGB acknowledges support from MICIN within program CONSOLIDER INGENIO 2010, under grant ’Molecular Astrophysics: The Herschel and ALMA Era–ASTROMOL’ (ref CSD2009- 00038). AAH, MPS, LC and SA acknowledge support from AYA2010-21161- C02-1. MPS also acknowledges support from the CSIC under grant JAE-Predoc- 2007.

HERSCHEL-HIFI observations of water from the intermediate mass protostar NGC7129 FIRS 2 provide a powerful diagnostic of the physical conditions in this star formation environment. Six spectral settings, covering four H216O and two H218O lines, were observed and all but one H218O line were detected. The four H2 16 O lines discussed here share a similar morphology: a narrower, \approx 6 km/s, component centered slightly redward of the systemic velocity of NGC7129 FIRS 2 and a much broader, \approx 25 km/s component centered blueward and likely associated with powerful outflows. The narrower components are consistent with emission from water arising in the envelope around the intermediate mass protostar, and the abundance of H2O is constrained to \approx 10-7 for the outer envelope. Additionally, the presence of a narrow self-absorption component for the lowest energy lines is likely due to self-absorption from colder water in the outer envelope. The broader component, where the H2O/CO relative abundance is found to be \approx 0.2, appears to be tracing the same energetic region that produces strong CO emission at high J., 6 pages, 4 figures, accepted by A&A

We present interferometric observations of the CN 1-0 (113.491 GHz), N2H+ 1-0 (93.173 GHz), H(41)a (92.034 GHz), CH3CN (91.987 GHz), CS 3-2 (146.969 GHz), c-C3H2 3-2 (145.089 GHz), H2CO 2-1 (145.603 GHz) and HC3N 16-15 (145.601 GHz) lines towards M82, carried out with the IRAM Plateau de Bure Interferometer (PdBI). PDR chemical modelling is used to interpret these observations. Our results show that the abundances of N2H+, CS and H13 CO+ remain quite constant across the galaxy confirming that these species are excellent tracers of the dense molecular gas. On the contrary, the abundance of CN increases by a factor of 3 in the inner x2 bar orbits. The [CN]/[N2 H+ ] ratio is well correlated with the H(41)a emission at all spatial scales down to 100 pc. Chemical modelling shows that the variations in the [CN]/[N2H+] ratio can be explained as the consequence of differences in the local intestellar UV field and in the average cloud sizes within the nucleus of the galaxy. Our high-spatial resolution imaging of the starburst galaxy M 82 shows that the star formation activity has a strong impact on the chemistry of the molecular gas. In particular, the entire nucleus behaves as a giant photon-dominated region (PDR) whose chemistry is determined by the local UV flux. The detection of N2H+ shows the existence of a population of clouds with Av >20 mag all across the galaxy plane. These clouds constitute the molecular gas reservoir for the formation of new stars and, although distributed all along the nucleus, the highest concentration occurs in the outer x1 bar orbits (R = 280 pc)., 19 pages, 14 figures

We present CO(1-0) and CO(2-1) maps of the LINER galaxy NGC 7217, obtained with the IRAM interferometer, at 2.4′′ x 1.9′′ and 1.2′′ x 0.8′′ resolution respectively. The nuclear ring (at r = 12′′ = 0.8 kpc) dominates the CO maps, and has a remarkable sharp surface density gradient at its inner edge. The latter is the site of the stellar/Hα ring, while the CO emission ring extends farther or is broader (500-600 pc). This means that the star formation has been more intense toward the inner edge of the CO ring, in a thin layer, just at the location of the high gas density gradient. The CO(2-1)/CO(1-0) ratio is close to 1, typical of warm optically thick gas with high density. The overall morphology of the ring is quite circular, with no evidence of non-circular velocities. In the CO(2-1) map, a central concentration might be associated with the circumnuclear ionized gas detected inside r=3′′ and interpreted as a polar ring in the literature. The CO(2-1) emission inside 3′′ coincides with a spiral dust lane, clearly seen in the HST V - I color image., N-body simulations including gas dissipation and star formation are performed to better understand the nature of the nuclear ring observed. The observed rotation curve of NGC 7217 allows two possibilities, according to the adopted mass for the disk: (1) either the disk is massive, allowing a strong bar to develop, or (2) it is dominated in mass by an extended bulge/stellar halo, and supports only a mild oval distortion. The amount of gas also plays an important role in the disk stability, and therefore the initial gas fraction was varied, with star formation reducing the total gas fraction to the observed value. The present observations support only the bulge-dominated model, which is able to account for the nuclear ring in CO and its position relative to the stellar and Hα ring. In this model, the gas content was higher in the recent past (having been consumed via star formation), and the structures formed were more self-gravitating. Only a mild bar formed, which has now vanished, but the stars formed in the highest gas density peaks toward the inner edge of the nuclear ring, which corresponds to the observed thin stellar ring. We see no evidence for an ongoing fueling of the nucleus; instead, gas inside the ring is presently experiencing an outward flow. To account for the nuclear activity, some gas infall and fueling must have occured in the recent past (a few Myr ago), since some, albeit very small, CO emission is detected at the very center. These observations have been made in the context of the NUclei of GAlaxies (NUGA) project, aimed at the study of the different mechanisms for gas fueling of AGN., S. L. is supported by a Marie Curie Individual Fellowship contract HPMF-CT-20002-01734 from the European Union.

We present a detailed analysis of ALMA Bands 7 and 9 data of CO, HCO+, HCN and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the ~ 200 pc circumnuclear disk (CND) and the ~ 1.3 kpc starburst ring (SB ring) of NGC~1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim at determining the physical characteristics of the dense gas present in the CND and whether the different line intensity ratios we find within the CND as well as between the CND and the SB ring are due to excitation effects (gas density and temperature differences) or to a different chemistry. We estimate the column densities of each species in Local Thermodynamic Equilibrium (LTE). We then compute large one-dimensional non-LTE radiative transfer grids (using RADEX) by using first only the CO transitions, and then all the available molecules in order to constrain the densities, temperatures and column densities within the CND. We finally present a preliminary set of chemical models to determine the origin of the gas. We find that in general the gas in the CND is very dense (> 10^5 cm^-3) and hot (T> 150K), with differences especially in the temperature across the CND. The AGN position has the lowest CO/HCO+, CO/HCN and CO/CS column density ratios. RADEX analyses seem to indicate that there is chemical differentiation across the CND. We also find differences between the chemistry of the SB ring and some regions of the CND; the SB ring is also much colder and less dense than the CND. Chemical modelling does not succeed in reproducing all the molecular ratios with one model per region, suggesting the presence of multi-gas phase components. The LTE, RADEX and chemical analyses all indicate that more than one gas-phase component is necessary to uniquely fit all the available molecular ratios within the CND., Accepted by A&A; please contact the author for a better version of the pdf where the resolution and positions of figures are as they will appear in the Journal

We present the first results of an ALMA spectral survey of strong absorption lines for common interstellar species in the z=0.89 molecular absorber toward the lensed blazar PKS1830-211. The dataset brings essential information on the structure and composition of the absorbing gas in the foreground galaxy. In particular, we find absorption over large velocity intervals (gtrsim 100 km/s) toward both lensed images of the blazar. This suggests either that the galaxy inclination is intermediate and that we sample velocity gradients or streaming motions in the disk plane, that the molecular gas has a large vertical distribution or extraplanar components, or that the absorber is not a simple spiral galaxy but might be a merger system. The number of detected species is now reaching a total of 42 different species plus 14 different rare isotopologues toward the SW image, and 14 species toward the NE line-of-sight. The abundances of CH, H2O, HCO+, HCN, and NH3 relative to H2 are found to be comparable to those in the Galactic diffuse medium. Of all the lines detected so far toward PKS1830-211, the ground-state line of ortho-water has the deepest absorption. We argue that ground-state lines of water have the best potential for detecting diffuse molecular gas in absorption at high redshift., Comment: Accepted for publication in A&A

Aims. We investigate the different manifestations of AGN feedback in the evolved, powerful radio source 3C293 and their impact on the molecular gas of its host galaxy, which harbors young star-forming regions and fast outflows of HI and ionized gas. Methods. We study the distribution and kinematics of the molecular gas of 3C293 using high spatial resolution observations of the CO(1-0) and CO(2-1) lines, and the 3 and 1mm continuum taken with the IRAM PdBI. We mapped the molecular gas of 3C293 and compared it with the dust and star-formation images of the host. We searched for signatures of outflow motions in the CO kinematics, and reexamined the evidence of outflowing gas in the HI spectra. We also derived the star formation rate (SFR) and efficiency (SFE) of the host with all available SFR tracers from the literature, and compared them with the SFE of young and evolved radio galaxies and normal star-forming galaxies. Results. The CO(1-0) emission line shows that the molecular gas in 3C293 is distributed along a massive (2.2E10 Msun) warped disk with diameter of 21 kpc that rotates around the AGN. Our data show that the dust and the star formation are clearly associated with the CO disk. The CO(2-1) emission is located in the inner 7 kpc (diameter) region around the AGN, coincident with the inner part of the CO(1-0) disk. Both the CO(1-0) and CO(2-1) spectra reveal the presence of an absorber against the central regions of 3C293 that is associated with the disk. We do not detect any fast (>500 km/s) outflow motions in the cold molecular gas. The host of 3C293 shows an SFE consistent with the Kennicutt-Schmidt law. The apparently low SFE of evolved radio galaxies may be caused by an underestimation of the SFR and/or an overestimation of the molecular gas densities in these sources. We find no signatures of AGN feedback in the molecular gas of 3C293., Accepted in A&A. 18 pages, 15 figures

1 Observatoire de Paris, LERMA, CNRS: UMR 8112, 61 Av. de l’Observatoire, 75014 Paris, France e-mail: francoise.combes@obspm.fr 2 Observatorio Astronomico Nacional (OAN)-Observatorio de Madrid, Alfonso XII, 3, 28014 Madrid, Spain 3 INAF – Istituto di Radioastronomia & Italian ALMA Regional Centre, via Gobetti 101, 40129 Bologna, Italy 4 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 5 IRAM, 300 rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d’Heres, France 6 Dep. of Physics & Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen road, Piscataway, NJ 08854, USA 7 CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France 8 I. Physikalisches Institut, Universitat zu Koln, Zulpicher Str. 77, 50937 Koln, Germany 9 Instituto de Astrofisica de Andalucia (CSIC), Apdo 3004, 18080 Granada, Spain 10 Max-Planck-Institut fur Astronomie (MPIA), Konigstuhl 17, 69117 Heidelberg, Germany 11 Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstr. 1, Garching bei Munchen, 81679 Munchen, Germany

Massive galaxies in the distant Universe form stars at much higher rates than today. Although direct resolution of the star forming regions of these galaxies is still a challenge, recent molecular gas observations at the IRAM Plateau de Bure interferometer enable us to study the star formation efficiency on subgalactic scales around redshift z = 1.2. We present a method for obtaining the gas and star formation rate (SFR) surface densities of ensembles of clumps composing galaxies at this redshift, even though the corresponding scales are not resolved. This method is based on identifying these structures in position-velocity diagrams corresponding to slices within the galaxies. We use unique IRAM observations of the CO(3-2) rotational line and DEEP2 spectra of four massive star forming distant galaxies - EGS13003805, EGS13004291, EGS12007881, and EGS13019128 in the AEGIS terminology - to determine the gas and SFR surface densities of the identifiable ensembles of clumps that constitute them. The integrated CO line luminosity is assumed to be directly proportional to the total gas mass, and the SFR is deduced from the [OII] line. We identify the ensembles of clumps with the angular resolution available in both CO and [OII] spectroscopy; i.e., 1-1.5". SFR and gas surface densities are averaged in areas of this size, which is also the thickness of the DEEP2 slits and of the extracted IRAM slices, and we derive a spatially resolved Kennicutt-Schmidt (KS) relation on a scale of ~8 kpc. The data generally indicates an average depletion time of 1.9 Gyr, but with significant variations from point to point within the galaxies., Comment: 6 pages, 4 figures, 2 tables, accepted by Astronomy and Astrophysics