Molecular hydrogen and Paα emission in cooling flow galaxies

Heino Falcke, M. J. Rieke, G. H. Rieke, Chris Simpson, Andrew S. Wilson

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We present near-infrared spectra that were obtained in order to search for Paα and molecular hydrogen lines in edge-darkened (FR I-type) radio galaxies with bright Ha emission in the redshift range 0.0535 < z < 0.15. We find that all three galaxies in our sample (PKS 0745-191, PKS 1346+26, and PKS 2322-12) associated with strong cooling flows also have strong Paα and H2 1-0 5(1) through S(5) emission, while other radio galaxies do not. Together with earlier observations, this confirms the claims that cooling flow galaxies are copious emitters of molecular hydrogen with large H2 1-0 S(3)/Paα ratios in the range 0.5-2. The emission is centrally concentrated within the inner few kiloparsecs and could come from warm (T ≃ 1000-1500 K) molecular material that is being deposited by the cooling flow. We speculate that the H2 emission could be related to the interaction between the jets and this molecular gas.

Original languageEnglish (US)
Pages (from-to)L155-L158
JournalAstrophysical Journal
Issue number2 PART II
StatePublished - 1998


  • Cooling flows
  • Galaxies: clusters: general
  • Galaxies: elliptical and lenticular, cD galaxies: ISM
  • Galaxies: jets

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Molecular hydrogen and Paα emission in cooling flow galaxies'. Together they form a unique fingerprint.

Cite this