A survey of HC3N in extragalactic sources. Is HC3N a tracer of activity in ULIRGs?
Journal article, 2011

Context. HC3N is a molecule that is mainly associated with Galactic star-forming regions, but it has also been detected in extragalactic environments. Aims. To present the first extragalactic survey of HC3N, when combining earlier data from the literature with six new single-dish detections, and to compare HC3N with other molecular tracers (HCN, HNC), as well as other properties (silicate absorption strength, IR flux density ratios, C II flux, and megamaser activity). Methods. We present mm IRAM 30 m, OSO 20 m, and SEST observations of HC3N rotational lines (mainly the J = 10-9 transition) and of the J = 1-0 transitions of HCN and HNC. Our combined HC3N data account for 13 galaxies (excluding the upper limits reported for the non-detections), while we have HCN and HNC data for more than 20 galaxies. Results. A preliminary definition "HC3N-luminous galaxy" is made based upon the HC3N/HCN ratio. Most (similar to 80%) HC3N-luminous galaxies seem to be deeply obscured galaxies and (U) LIRGs. A majority (similar to 60% or more) of the HC3N-luminous galaxies in the sample present OH mega- or strong kilomaser activity. A possible explanation is that both HC3N and OH megamasers need warm dust for their excitation. Alternatively, the dust that excites the OH megamaser offers protection against UV destruction of HC3N. A high silicate absorption strength is also found in several of the HC3N-luminous objects, which may help the HC3N to survive. Finally, we find that a high HC3N/HCN ratio is related to a high dust temperature and a low C II flux.


nearby galaxies

galaxies: ISM

galaxies: starburst

radio lines:


starburst galaxies

ultraluminous infrared galaxies

galactic nuclei

ISM: molecules

radio lines: ISM



interstellar clouds

spiral galaxies


dense molecular gas

galaxies: active


Johan Lindberg

University of Copenhagen

Nordic Optical Telescope

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Susanne Aalto

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Francesco Costagliola

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

J. P. Perez-Beaupuits

Max Planck Society

University of Groningen

Raquel Monje

California Institute of Technology (Caltech)

Sebastien Muller

Chalmers, Earth and Space Sciences, Onsala Space Observatory

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 527 23 A150

Subject Categories

Astronomy, Astrophysics and Cosmology



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