A relation between circumnuclear HI, dust, and optical cores in low-power radio galaxies

Abstract

From new observations and literature data we investigate the presence of HI, dust, and optical cores in the central kiloparsec of low-power radio galaxies. The goal of this pilot study is to identify physical relations between these components, which can help us to study kinematics and feeding mechanisms in future samples of active galaxies. Our results are consistent with neutral gas being associated with dust on sub-kiloparsec scales. Objects that have HI absorption always have significant amounts of dust in their host galaxy. If there is no visible dust in the host galaxy, there is also no HI absorption. The presence of an unresolved optical core correlates with the HI column density, with the core being absent in high column density sources. This work opens a path for studying the kinematics of cold material in the central regions of active galaxies by combining information of HI absorption and molecular lines. Consistent with previous work, we find no evidence for a compact, parsec-scale obscuring torus in low-power radio galaxies.

Accepted for publication in A&A

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• The active nuclei of z<1.0 3CRR radio sources
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Cited by in corpus (5)

• The HI absorption "Zoo"
• The interstellar and circumnuclear medium of active nuclei traced by HI 21-cm absorption
• The peculiar radio galaxy 4C 35.06: a case for recurrent AGN activity?
• HI absorption associated with Norma's brightest cluster galaxy
• Detection of a radio-filled X-ray cavity within the interstellar medium of NGC 5141