Persona: Alonso-Herrero, Almudena
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Centro de Astrobiologia
El Centro de Astrobiología (CAB) es un centro mixto de investigación en astrobiología, dependiente tanto del Instituto Nacional de Técnica Aeroespacial (INTA) como del Consejo Superior de Investigaciones Científicas (CSIC).
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Alonso-Herrero
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Publicación Acceso Abierto ALMA Polarimetry Measures Magnetically Aligned Dust Grains in the Torus of NGC 1068(The Institute of Physics (IOP), 2020-04-14) López Rodríguez, E.; Alonso-Herrero, Almudena; García Burillo, S.; Gordon, M. S.; Ichikawa, K.; Imanishi, M.; Kameno, S.; Levenson, N. A.; Nikutta, R.; Packham, C.; https://creativecommons.org/licenses/by-nc-nd/4.0/; National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); 0000-0001-5357-6538; 0000-0002-1913-2682; 0000-0002-4377-903X; 0000-0001-6186-8792; 0000-0002-5158-0063; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737The obscuring structure surrounding active galactic nuclei (AGN) can be explained as a dust and gas flow cycle that fundamentally connects the AGN with their host galaxies. This structure is believed to be associated with dusty winds driven by radiation pressure. However, the role of magnetic fields, which are invoked in almost all models for accretion onto a supermassive black hole and outflows, has not been thoroughly studied. Here we report the first detection of polarized thermal emission by means of magnetically aligned dust grains in the dusty torus of NGC 1068 using ALMA Cycle 4 polarimetric dust continuum observations (007, 4.2 pc; 348.5 GHz, 860 mu m). The polarized torus has an asymmetric variation across the equatorial axis with a peak polarization of 3.7% 0.5% and position angle of 109 degrees 2 degrees (B-vector) at similar to 8 pc east from the core. We compute synthetic polarimetric observations of magnetically aligned dust grains assuming a toroidal magnetic field and homogeneous grain alignment. We conclude that the measured 860 mu m continuum polarization arises from magnetically aligned dust grains in an optically thin region of the torus. The asymmetric polarization across the equatorial axis of the torus arises from (1) an inhomogeneous optical depth and (2) a variation of the velocity dispersion, i.e., a variation of the magnetic field turbulence at subparsec scales, from the eastern to the western region of the torus. These observations and modeling constrain the torus properties beyond spectral energy distribution results. This study strongly supports that magnetic fields up to a few parsecs contribute to the accretion flow onto the active nuclei.Publicación Restringido Star formation and nuclear activity in luminous infrared galaxies: an infrared through radio review(Springer Link, 2021-01-13) Pérez Torres, Miguel; Mattila, S.; Efstathiou, A.; Alonso-Herrero, Almudena; Aalto, S.; European Commission (EC); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Pérez Torres, 0000-0001-5654-0266; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Nearby galaxies offer unique laboratories allowing multi-wavelength spatially resolved studies of the interstellar medium, star formation and nuclear activity across a broad range of physical conditions. In particular, detailed studies of individual local luminous infrared galaxies (LIRGs) are crucial for gaining a better understanding of these processes and for developing and testing models that are used to explain statistical studies of large populations of such galaxies at high redshift for which it is currently impossible to reach a sufficient physical resolution. Here, we provide an overview of the impact of spatially resolved infrared, sub-millimetre and radio observations in the study of the interstellar medium, star formation and active galactic nuclei as well as their interplay in local LIRGs. We also present an overview of the modelling of their spectral energy distributions using state-of-the-art radiative transfer codes. These contribute necessary and powerful ‘workhorse’ tools for the study of LIRGs (and their more luminous counterparts) at higher redshifts which are unresolved in observations. We describe how spatially-resolved time-domain observations have recently opened a new window to study the nuclear activity in LIRGs. We describe in detail the observational characteristics of Arp 299 which is one of the best studied local LIRGs and exemplifies the power of the combination of time-domain and high-resolution observations at infrared to radio wavelengths together with radiative transfer modelling used to explain the spectral energy distributions of its different components. We summarise the previous achievements obtained using high-spatial resolution observations and provide an outlook into what we can expect to achieve with future facilities.Publicación Acceso Abierto Modeling the Strongest Silicate Emission Features of Local Type 1 AGNs(The Institute of Physics (IOP), 2020-02-24) Martínez Paredes, M.; González Martín, O.; Esparza Arredondo, D.; Kim, M.; Alonso-Herrero, Almudena; Krongold, Y.; Hoang, T.; Ramos Almeida, C.; Aretxaga, I.; Dultzin, D.; Hodgson, J.; Martínez Paredes, M. [0000-0002-0088-0103]; González Martín, O. [0000-0002-2356-8358]; Hoang, T. [0000-0003-2017-0982]; Aretzaga, I. [0000-0002-6590-3994]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We measure the 10 and 18 μm silicate features in a sample of 67 local (z < 0.1) type 1 active galactic nuclei (AGN) with available Spitzer spectra dominated by nonstellar processes. We find that the 10 μm silicate feature peaks at ${10.3}_{-0.9}^{+0.7}\,\mu {\rm{m}}$ with a strength (Sip = ln fp(spectrum)/fp(continuum)) of ${0.11}_{-0.36}^{+0.15}$, while the 18 μm one peaks at ${17.3}_{-0.7}^{+0.4}\,\mu {\rm{m}}$ with a strength of ${0.14}_{-0.06}^{+0.06}$. We select from this sample sources with the strongest 10 μm silicate strength (${\sigma }_{{\mathrm{Si}}_{10\mu {\rm{m}}}}\gt 0.28$, 10 objects). We carry out a detailed modeling of the infrared spectrometer/Spitzer spectra by comparing several models that assume different geometries and dust composition: a smooth torus model, two clumpy torus models, a two-phase medium torus model, and a disk+outflow clumpy model. We find that the silicate features are well modeled by the clumpy model of Nenkova et al., and among all models, those including outflows and complex dust composition are the best. We note that even in AGN-dominated galaxies, it is usually necessary to add stellar contributions to reproduce the emission at the shortest wavelengths.Publicación Acceso Abierto ALMA observations of CS in NGC 1068: Chemistry and excitation(Oxford Academics: Blackwell Publishing, 2020-07-02) Scourfield, M.; Viti, S.; García Burillo, S.; Saintonge, A.; Combes, F.; Fuente, A.; Henkel, C.; Alonso-Herrero, Almudena; Harada, N.; Takano, S.; Nakajima, T.; Martín, S.; Krips, M.; Van der Werf, P. P.; Aalto, S.; Usero, A.; Kohno, K.; Agencia Estatal de Investigación (AEI); Alonso Herrero, A. [0000-0001-6794-2519]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We present results from Atacama Large Millimeter/submillimeter Array (ALMA) observations of CS from the nearby galaxy NGC 1068 (∼14 Mpc). This Seyfert 2 barred galaxy possesses a circumnuclear disc (CND, r ∼ 200 pc) and a starburst ring (SB ring, r ∼ 1.3 kpc). These high-resolution maps (∼0.5 arcsec, ∼35 pc) allow us to analyse specific sub-regions in the galaxy and investigate differences in line intensity ratios and physical conditions, particularly those between the CND and SB ring. Local thermodynamic equilibrium (LTE) analysis of the gas is used to calculate CS densities in each sub-region, followed by the non-LTE analysis conducted using the radiative transfer code RADEX to fit observations and constrain gas temperature, CS column density and hydrogen density. Finally, the chemical code UCLCHEM is used to reconstruct the gas, allowing an insight into its origin and chemical history. The density of hydrogen in the CND is found to be ≥105 cm−2, although exact values vary, reaching 106 cm−2 at the active galactic nucleus. The conditions in the two arms of the SB ring appear similar to one another, though the density found (∼104 cm−2) is lower than in the CND. The temperature in the CND increases from east to west, and is also overall greater than found in the SB ring. These modelling methods indicate the requirement for multiphase gas components in order to fit the observed emission over the galaxy. A larger number of high-resolution transitions across the SLED may allow for further constraining of the conditions, particularly in the SB ring.Publicación Acceso Abierto Torus model properties of an ultra-hard X-ray selected sample of Seyfert galaxies(Oxford Academics: Oxford University Press, 2019-04-10) García Bernete, I.; Ramos Almeida, C.; Alonso-Herrero, Almudena; Ward, M. J.; Acosta Pulido, J. A.; Pereira Santaella, Miguel; Hernán Caballero, A.; Asensio Ramos, A.; González Martín, O.; Levenson, N. A.; Mateos, S.; Carrera, F. J.; Ricci, C.; Roche, P. F.; Márquez Pérez, Isabel; Packham, C.; Masegosa, J.; Fuller, L.; Agencia Estatal de Investigación (AEI); Science and Technology Facilities Council (STFC); Ministerio de Economía y Competitividad (MINECO); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We characterize for the first time the torus properties of an ultra-hard X-ray (14–195 keV) volume-limited (DL < 40 Mpc) sample of 24 Seyfert (Sy) galaxies (BCS40 sample). The sample was selected from the Swift/BAT nine-month catalogue. We use high angular resolution nuclear infrared (IR) photometry and N-band spectroscopy, the CLUMPY torus models and a Bayesian tool to characterize the properties of the nuclear dust. In the case of the Sy1s, we estimate the accretion disc contribution to the subarcsecond resolution nuclear IR SEDs (∼0.4 arcsec) which is, on average, 46 ± 28, 23 ± 13, and 11 ± 5 per cent in the J, H, and K bands, respectively. This indicates that the accretion disc templates that assume a steep fall for longer wavelengths than 1 μm might underestimate its contribution to the near-IR emission. Using both optical (broad versus narrow lines) and X-ray (unabsorbed versus absorbed) classifications, we compare the global posterior distribution of the torus model parameters. We confirm that Sy2s have larger values of the torus covering factor (CT ∼ 0.95) than Sy1s (CT ∼ 0.65) in our volume-limited Seyfert sample. These findings are independent of whether we use an optical or X-ray classification. We find that the torus covering factor remains essentially constant within the errors in our luminosity range and there is no clear dependence with the Eddington ratio. Finally, we find tentative evidence that even an ultra-hard X-ray selection is missing a significant fraction of highly absorbed type 2 sources with very high covering factor tori.Publicación Acceso Abierto Interactions between large-scale radio structures and gas in a sample of optically selected type 2 quasars(EDP Sciences, 2021-06-10) Villar Martín, M.; Emonts, Bjorn H. C.; Cabrera Lavers, A.; Bellocchi, Enrica; Storchi Bergmann, T.; Alonso-Herrero, Almudena; Humphrey, A.; Dall´Agnol de Oliveira, B.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Fundacao para a Ciencia e a Tecnologia (FCT); Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Context. The role of radio mode feedback in non radio-loud quasars needs to be explored in depth to determine its true importance. Its effects can be identified based on the evidence of interactions between the radio structures and the ambient ionised gas. Aims. We investigate this interaction in a sample of 13 optically selected type 2 quasars (QSO2) at z < 0.2 with the Very Large Array (VLA) FIRST Survey radio detections, none of which are radio-loud. The ranges of [OIII]λ5007 and monochromatic radio luminosities are log(L[OIII]/erg s−1) ∼ 42.08–42.79 and log(P1.4 GHz/erg s−1 Hz−1) ∼ 30.08−31.76. All of them show complex optical morphologies, with signs of distortion across tens of kpc due to mergers and interactions. Methods. We searched for evidence of interactions between the radio structures and the ionised gas by characterising and comparing their morphologies. The former was traced by narrow band Hα images obtained with the GTC 10.4 m Spanish telescope and the Osiris instrument. The latter is traced by VLA radio maps obtained with A and B configurations to achieve both high resolution and brightness sensitivity. Results. The radio luminosity has an active galatic nucleus (AGN) component in 11 our of 13 QSO2, which is spatially extended in our radio data in 9 of them (jets, lobes, or other). The relative contribution of the extended radio emission to the total P1.4 GHz is in most cases in the range from 30% to 90%. The maximum sizes are in the range of dRmax of around a few to 500 kpc. The QSO2 undergoing interaction or merger events appear to be invariably associated with ionised gas spread over large spatial scales with maximum distances from the AGN in the range rmax ∼ 12−90 kpc. The morphology of the ionised gas at < 30 kpc is strongly influenced by AGN related processes. Evidence for radio-gas interactions exist in 10 out of 13 QSO2; that is, in all but one with confirmed AGN radio components. The interactions are identified across different spatial scales, from the nuclear narrow line region up to tens of kpc. Conclusions. Although this sample cannot be considered representative of the general population of QSO2, it supports the idea that large-scale low to modest power radio sources can exist in radio-quiet QSO2, which can provide a source of feedback on scales of the spheroidal component of galaxies and well into the circumgalactic medium, in systems where radiative mode feedback is expected to dominate.Publicación Acceso Abierto A proto-pseudobulge in ESO 320-G030 fed by a massive molecular inflow driven by a nuclear bar(EDP Sciences, 2021-01-07) González Alfonso, E.; Pereira Santaella, Miguel; Fischer, J.; García Burillo, S.; Yang, C.; Alonso-Herrero, Almudena; Colina, L. ; Ashby, M. L. N.; Smith, H. A.; Rico Villas, F.; Martín Pintado, J.; Cazzoli, Sara; Stewart, F. P.; National Aeronautics and Space Administration (NASA); Agencia Estatal de Investigación (AEI); Comunidad de Madrid; European Commission (EC); 0000-0001-5285-8517; 0000-0001-6697-7808; 0000-0003-0444-6897; 0000-0002-8117-9991; 0000-0001-6794-2519; 0000-0002-7705-2525; 0000-0001-8266-8298; Centros de Excelencia Severo Ochoa, INSTITUTO DE ASTROFISICA DE ANDALUCIA (IAA), SEV-2017-0709; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737Galaxies 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.Publicación Acceso Abierto Mid-IR cosmological spectrophotometric surveys from space: Measuring AGN and star formation at the cosmic noon with a SPICA-like mission(Cambridge University Press, 2021-04-23) Spignoglio, L.; Mordini, S.; Fernández Ontiveros, J. A.; Alonso-Herrero, Almudena; Armus, L.; Bisigello, L.; Calura, F.; Carrera, F. J.; Cooray, A.; Dannerbauer, H.; Decarli, R.; Egami, E.; Elbaz, D.; Franceschini, A.; González Alfonso, E.; Graziani, L.; Gruppioni, C.; Hatziminaoglou, Evanthia; Kaneda, H.; Kohno, K.; Labiano, Alvaro; Magdis, Georgios E.; Malkan, M. A.; Matsuhara, H.; Nagao, T.; Naylor, D.; Pereira Santaella, Miguel; Pozzi, F.; Rodighiero, G.; Roelfsema, Peter; Serjeant, S.; Vignali, C.; Wang, L.; Yamada, T.; Agenzia Spaziale Italiana (ASI); Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Spignoglio, L. [0000-0001-8840-1551]; Fernández Ontiveros, J. A. [0000-0001-9490-899X]; Gruppioni, C. [0000-0002-5836-4056]; Graziani, L. [0000-0002-9231-1505]; Unidad de Excelencia Científica María de Maeztu Instituto de Astrofísica de Cantabria, MDM-2017-0765; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We use the SPace Infrared telescope for Cosmology and Astrophysics (SPICA) project as a template to demonstrate how deep spectrophotometric surveys covering large cosmological volumes over extended fields (1– ) with a mid-IR imaging spectrometer (17– ) in conjunction with deep photometry with a far-IR camera, at wavelengths which are not affected by dust extinction can answer the most crucial questions in current galaxy evolution studies. A SPICA-like mission will be able for the first time to provide an unobscured three-dimensional (3D, i.e. x, y, and redshift z) view of galaxy evolution back to an age of the universe of less than 2 Gyrs, in the mid-IR rest frame. This survey strategy will produce a full census of the Star Formation Rate (SFR) in the universe, using polycyclic aromatic hydrocarbons (PAH) bands and fine-structure ionic lines, reaching the characteristic knee of the galaxy luminosity function, where the bulk of the population is distributed, at any redshift up to . Deep follow-up pointed spectroscopic observations with grating spectrometers onboard the satellite, across the full IR spectral range (17– ), would simultaneously measure Black Hole Accretion Rate (BHAR), from high-ionisation fine-structure lines, and SFR, from PAH and low- to mid-ionisation lines in thousands of galaxies from solar to low metallicities, down to the knee of their luminosity functions. The analysis of the resulting atlas of IR spectra will reveal the physical processes at play in evolving galaxies across cosmic time, especially its heavily dust-embedded phase during the activity peak at the cosmic noon ( –3), through IR emission lines and features that are insensitive to the dust obscuration.Publicación Acceso Abierto Cold molecular gas and PAH emission in the nuclear and circumnuclear regions of Seyfert galaxies(EDP Sciences, 2020-07-07) Rosario, D.; Alonso-Herrero, Almudena; Pereira Santaella, Miguel; Rigopoulou, Dimitra; García Bernete, I.; García Burillo, S.; Domínguez Fernández, A. J.; Combes, F.; Davies, R. I.; Díaz Santos, T.; Esparza Borges, E.; González Martín, O.; Hernán Caballero, A.; Hicks, E. K. S.; Hönig, S. F.; Levenson, N. A.; Ramos Almeida, C.; Roche, P. F.; Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Science and Technology Facilities Council (STFC); Universidad Nacional Autónoma de México (UNAM); European Research Council (ERC); National Aeronautics and Space Administration (NASA); 0000-0001-8353-649X; 0000-0003-0699-6083; 0000-0002-0001-3587; 0000-0002-8524-8413; 0000-0003-4949-7217; 0000-0002-6353-1111We investigate the relation between the detection of the 11.3 mu m polycyclic aromatic hydrocarbon (PAH) feature in the nuclear (similar to 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 mu m PAH feature contain more cold molecular gas (median 1.6x10(7) M-circle dot) and have higher column densities (N(H-2) = 2x10(23) 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 mu m PAH detection than in those with a detection. The Spitzer/IRS PAH ratios on circumnuclear scales (similar to 4 ''similar to 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 H-2 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 similar to 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.Publicación Acceso Abierto Excitation and acceleration of molecular outflows in LIRGs: The extended ESO 320-G030 outflow on 200-pc scales(EDP Sciences, 2020-11-06) Pereira Santaella, Miguel; Colina, L. ; García Burillo, S.; González Alfonso, E.; Alonso-Herrero, Almudena; Arribas, Santiago; Cazzoli, Sara; Piqueras López, Javier; Rigopoulou, Dimitra; Usero, A.; Comunidad de Madrid; Agencia Estatal de Investigación (AEI); Usero, A. [0000-0003-1242-505X]; Pereira Santaella, M. [0000-0002-4005-9619]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737We used high-spatial resolution (70 pc; 03) 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.
