Jet-powered Molecular Hydrogen Emission from Radio Galaxies

December 2010 • 2010ApJ...724.1193O

Authors • Ogle, Patrick • Boulanger, Francois • Guillard, Pierre • Evans, Daniel A. • Antonucci, Robert • Appleton, P. N. • Nesvadba, Nicole • Leipski, Christian

Abstract • H₂ pure-rotational emission lines are detected from warm (100-1500 K) molecular gas in 17/55 (31% of) radio galaxies at redshift z < 0.22 observed with the Spitzer IR Spectrograph. The summed H₂ 0-0 S(0)-S(3) line luminosities are L(H₂) = 7 × 10³⁸-2 × 10⁴² erg s^-1, yielding warm H₂ masses up to 2 × 10¹⁰ M _sun. These radio galaxies, of both FR radio morphological types, help to firmly establish the new class of radio-selected molecular hydrogen emission galaxies (radio MOHEGs). MOHEGs have extremely large H₂ to 7.7 μm polycyclic aromatic hydrocarbon (PAH) emission ratios: L(H₂)/L(PAH7.7) = 0.04-4, up to a factor 300 greater than the median value for normal star-forming galaxies. In spite of large H₂ masses, MOHEGs appear to be inefficient at forming stars, perhaps because the molecular gas is kinematically unsettled and turbulent. Low-luminosity mid-IR continuum emission together with low-ionization emission line spectra indicates low-luminosity active galactic nuclei (AGNs) in all but three radio MOHEGs. The AGN X-ray emission measured with Chandra is not luminous enough to power the H₂ emission from MOHEGs. Nearly all radio MOHEGs belong to clusters or close pairs, including four cool-core clusters (Perseus, Hydra, A2052, and A2199). We suggest that the H₂ in radio MOHEGs is delivered in galaxy collisions or cooling flows, then heated by radio-jet feedback in the form of kinetic energy dissipation by shocks or cosmic rays.

Links

• PREPRINT http://arxiv.org/abs/1009.4533
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2010ApJ...724.1193O
• ELECTR https://doi.org/10.1088%2F0004-637X%2F724%2F2%2F1193
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2010ApJ...724.1193O
• PDF https://iopscience.iop.org/article/10.1088/0004-637X/724/2/1193/pdf
• PDF https://stacks.iop.org/0004-637X/724/1193/pdf
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2010ApJ...724.1193O
• DATA https://cda.harvard.edu/chaser?obsid=909,7881,9313,10232,10908
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2010ApJ...724.1193O
• DATA https://irsa.ipac.caltech.edu/bibdata/2010/O/2010ApJ...724.1193O.html