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Molecular Hydrogen and Paschen-alpha Emission in Cooling Flow Galaxies

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

We present near-infrared spectra obtained to search for Pa-alpha and molecular hydrogen lines in edge-darkened (FR I-type) radio galaxies with bright Halpha 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, & PKS2322-12) which are associated with strong cooling flows also have strong Pa-alpha and H_2 (1-0) S(1) through S(5) emission, while other radio galaxies do not. Together with earlier observations this confirms claims that cooling flow galaxies are copious emitters of molecular hydrogen with large H_2 (1-0) S(3)/Pa-alpha ratios in the range 0.5 to 2. The emission is centrally concentrated within the inner few kiloparsec and could come from warm (T ~ 1000-1500 K) molecular material which is being deposited by the cooling flow. We speculate that the H_2 emission could be related to the interaction between the jets and this molecular gas.

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Heino Falcke, M. J. Rieke, G. H. Rieke, Chris Simpson, Andrew S. Wilson. 1997-12-18. Molecular Hydrogen and Paschen-alpha Emission in Cooling Flow Galaxies. https://doi.org/10.1086/311176

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