| 1. |
- Bouyoucef, S E, et al.
(author)
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Poster Session 2 : Monday 4 May 2015, 08
- 2015
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In: European Heart Journal Cardiovascular Imaging. - : Oxford University Press (OUP). - 2047-2404 .- 2047-2412. ; 16 Suppl 1
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Journal article (peer-reviewed)
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| 2. |
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| 3. |
- Aalto, Susanne, 1964, et al.
(author)
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Probing highly obscured, self-absorbed galaxy nuclei with vibrationally excited HCN
- 2015
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 584
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Journal article (peer-reviewed)abstract
- We present high resolution (0.'' 4) IRAM PdBI and ALMA mm and submm observations of the (ultra) luminous infrared galaxies ((U)LIRGs) IRAS 17208-0014, Arp220, IC 860 and Zw049.057 that reveal intense line emission from vibrationally excited (nu(2) = 1) J = 3-2 and 4-3 HCN. The emission is emerging from buried, compact (r 5 x 10(13) L-circle dot kpc(-2). These nuclei are likely powered by accreting supermassive black holes (SMBHs) and/or hot (>200 K) extreme starbursts. Vibrational, nu(2) = 1, lines of HCN are excited by intense 14 mu m mid-infrared emission and are excellent probes of the dynamics, masses, and physical conditions of (U)LIRG nuclei when H-2 column densities exceed 10(24) cm(-2). It is clear that these lines open up a new interesting avenue to gain access to the most obscured AGNs and starbursts. Vibrationally excited HCN acts as a proxy for the absorbed mid-infrared emission from the embedded nuclei, which allows for reconstruction of the intrinsic, hotter dust SED. In contrast, we show strong evidence that the ground vibrational state (. = 0), J = 3-2 and 4-3 rotational lines of HCN and HCO+ fail to probe the highly enshrouded, compact nuclear regions owing to strong self-and continuum absorption. The HCN and HCO+ line profiles are double-peaked because of the absorption and show evidence of non-circular motions-possibly in the form of in-or outflows. Detections of vibrationally excited HCN in external galaxies are so far limited to ULIRGs and early-type spiral LIRGs, and we discuss possible causes for this. We tentatively suggest that the peak of vibrationally excited HCN emission is connected to a rapid stage of nuclear growth, before the phase of strong feedback.
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| 4. |
- Aalto, Susanne, 1964, et al.
(author)
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High resolution observations of HCN and HCO+J = 3–2 in the disk and outflow of Mrk 231 -- Detection of vibrationally excited HCN in the warped nucleus
- 2015
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 574, s. 85-
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Journal article (peer-reviewed)abstract
- Aims. Our goal is to study molecular gas properties in nuclei and large scale outflows/winds from active galactic nuclei (AGNs) and starburst galaxies.Methods. We obtained high resolution (0.̋25 to 0.̋90) observations of HCN and HCO+J = 3 → 2 of the ultraluminous QSO galaxy Mrk 231 with the IRAM Plateau de Bure Interferometer (PdBI).Results. We find luminous HCN and HCO+J = 3 → 2 emission in the main disk and we detect compact (r ≲ 0''̣1 (90 pc)) vibrationally excited HCN J = 3 → 2ν2 = 1f emission centred on the nucleus. The velocity field of the vibrationally excited HCN is strongly inclined (position angle PA = 155°) compared to the east-west rotation of the main disk. The nuclear (r ≲ 0.̋1) molecular mass is estimated to 8 × 108 M⊙ with an average N(H2) of 1.2 × 1024 cm-2. Prominent, spatially extended (≳350 pc) line wings are found for HCN J = 3 → 2 with velocities up to ± 750 km s-1. Line ratios indicate that the emission is emerging in dense gas n = 104−5 × 105 cm-3 of elevated HCN abundance X(HCN) = 10-8−10-6. The highest X(HCN) also allows for the emission to originate in gas of more moderate density. We tentatively detect nuclear emission from the reactive ion HOC+ with HCO+/HOC+ = 10−20.Conclusions. The HCN ν2 = 1f line emission is consistent with the notion of a hot, dusty, warped inner disk of Mrk 231 where the ν2 = 1f line is excited by bright mid-IR 14 μm continuum. We estimate the vibrational temperature Tvib to 200−400 K. Based on relative source sizes we propose that 50% of the main HCN emission may have its excitation affected by the radiation field through IR pumping of the vibrational ground state. The HCN emission in the line wings, however, is more extended and thus likely not strongly affected by IR pumping. Our results reveal that dense clouds survive (and/or are formed) in the AGN outflow on scales of at least several hundred pc before evaporating or collapsing. The elevated HCN abundance in the outflow is consistent with warm chemistry possibly related to shocks and/or X-ray irradiated gas. An upper limit to the mass and momentum flux is 4 × 108 M⊙ and 12LAGN/c, respectively, and we discuss possible driving mechanisms for the dense outflow.
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| 5. |
- Burillo, S. G., et al.
(author)
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High-resolution imaging of the molecular outflows in two mergers: IRAS 17208-0014 and NGC 1614
- 2015
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 580
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Journal article (peer-reviewed)abstract
- Context. Galaxy evolution scenarios predict that the feedback of star formation and nuclear activity (AGN) can drive the transformation of gas-rich spiral mergers into (ultra) luminous infrared galaxies and, eventually, lead to the build-up of QSO/elliptical hosts. Aims. We study the role that star formation and AGN feedback have in launching and maintaining the molecular outflows in two starburst-dominated advanced mergers, NGC 1614 (DL = 66 Mpc) and IRAS 17208-0014 (DL = 181 Mpc), by analyzing the distribution and kinematics of their molecular gas reservoirs. Both galaxies present evidence of outflows in other phases of their ISM. Methods. We used the Plateau de Bure interferometer (PdBI) to image the CO(10) and CO(21) line emissions in NGC 1614 and IRAS 17208-0014, respectively, with high spatial resolution (0: 0051: 002). The velocity fields of the gas were analyzed and modeled to find the evidence of molecular outflows in these sources and characterize the mass, momentum, and energy of these components. Results. While most (95%) of the CO emission stems from spatially resolved (23 kpc-diameter) rotating disks, we also detect in both mergers the emission from high-velocity line wings that extend up to -500-700 km s1, well beyond the estimated virial range associated with rotation and turbulence. The kinematic major axis of the line-wing emission is tilted by 90 in NGC 1614 and by 180 in IRAS 17208-0014 relative to the major axes of their respective rotating disks. These results can be explained by the existence of non-coplanar molecular outflows in both systems: the outflow axis is nearly perpendicular to the rotating disk in NGC 1614, but it is tilted relative to the angular momentum axis of the rotating disk in IRAS 17208-0014. Conclusions. In stark contrast to NGC 1614, where star formation alone can drive its molecular outflow, the mass, energy, and momentum budget requirements of the molecular outflow in IRAS 17208-0014 can be best accounted for by the existence of a so far undetected (hidden) AGN of LAGN71011 L The geometry of the molecular outflow in IRAS 17208-0014 suggests that the outflow is launched by a non-coplanar disk that may be associated with a buried AGN in the western nucleus.
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