DIAGNOSTICS OF AGN-DRIVEN MOLECULAR OUTFLOWS IN ULIRGs FROM HERSCHEL-PACS OBSERVATIONS OF OH AT 119 μm

Journal Article · Tue Oct 01 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/775/2/127· OSTI ID:22270867

Spoon, H. W. W.; Lebouteiller, V. ^[1]; Farrah, D. ^[2]; González-Alfonso, E. ^[3]; Bernard-Salas, J. ^[4]; Urrutia, T. ^[5]; Rigopoulou, D.; Verma, A. ^[6]; Westmoquette, M. S. ^[7]; Smith, H. A. ^[8]; Afonso, J. ^[9]; Pearson, C. ^[10]; Cormier, D. ^[11]; Efstathiou, A. ^[12]; Borys, C. ^[13]; Etxaluze, M. ^[14]

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1. Cornell University, CRSR, Space Sciences Building, Ithaca, NY 14853 (United States)
2. Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States)
3. Departamento de Física y Matemáticas, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain)
4. Department of Physical Sciences, Milton Keynes MK7 6AA (United Kingdom)
5. Leibniz Institut für Astrophysik, Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
6. Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)
7. European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)
8. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
9. Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisbon (Portugal)
10. RAL Space, Rutherford Appleton Laboratory, Harwell, Oxford OX11 0QX (United Kingdom)
11. Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg (Germany)
12. School of Sciences, European University Cyprus, Diogenes Street, Engomi, 1516 Nicosia (Cyprus)
13. Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States)
14. Departamento de Astrofísica. Centro de Astrobiología. CSIC-INTA. Torrejón de Ardoz, E-28850 Madrid (Spain)

We report on our observations of the 79 and 119 μm doublet transitions of OH for 24 local (z < 0.262) ULIRGs observed with Herschel-PACS as part of the Herschel ULIRG Survey (HERUS). Some OH 119 μm profiles display a clear P-Cygni shape and therefore imply outflowing OH gas, while other profiles are predominantly in absorption or are completely in emission. We find that the relative strength of the OH emission component decreases as the silicate absorption increases. This result locates the OH outflows inside the obscured nuclei. The maximum outflow velocities for our sources range from less than 100 to ∼2000 km s{sup –1}, with 15/24 (10/24) sources showing OH absorption at velocities exceeding 700 km s{sup –1} (1000 km s{sup –1}). Three sources show maximum OH outflow velocities exceeding that of Mrk231. Since outflow velocities above 500-700 km s{sup –1} are thought to require an active galactic nucleus (AGN) to drive them, about two-thirds of our ULIRG sample may host AGN-driven molecular outflows. This finding is supported by the correlation we find between the maximum OH outflow velocity and the IR-derived bolometric AGN luminosity. No such correlation is found with the IR-derived star formation rate. The highest outflow velocities are found among sources that are still deeply embedded. We speculate that the molecular outflows in these sources may be in an early phase of disrupting the nuclear dust veil before these sources evolve into less-obscured AGNs. Four of our sources show high-velocity wings in their [C II] fine-structure line profiles, implying neutral gas outflow masses of at least (2-4.5) × 10{sup 8} M{sub ☉}.

• OSTI ID: 22270867
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 775; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
BOLOMETERS
CARBON IONS
FINE STRUCTURE
GALAXIES
GALAXY NUCLEI
HYDROXIDES
JETS
LUMINOSITY
MASS
QUASARS
STAR EVOLUTION
STARS
VELOCITY