Journal Article

Radio continuum emission and H <span class="smallCaps">i</span> gas accretion in the NGC 5903/5898 compact group of early-type galaxies

Gopal-Krishna, Mukul Mhaskey, Paul J. Wiita, S. K. Sirothia, N. G. Kantharia and C. H. Ishwara-Chandra

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 2, pages 1053-1059
Published in print June 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI:
Radio continuum emission and H i gas accretion in the NGC 5903/5898 compact group of early-type galaxies

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We discuss the nature of the multicomponent radio continuum and H i emission associated with the nearby galaxy group comprised of two dominant ellipticals, NGC 5898 and NGC 5903, and a dwarf lenticular ESO 514−G003. Striking new details of radio emission are unveiled from the second Data Release of the ongoing TIFR GMRT Sky Survey (TGSS) which provides images with a resolution of ∼24 × 18 arcsec2 and a typical rms noise of 5 mJy at 150 MHz. Previous radio observations of this compact triplet of galaxies include images at higher frequencies of the radio continuum as well as H i emission, the latter showing huge H i trails originating from the vicinity of NGC 5903 where H i is in a kinematically disturbed state. The TGSS 150-MHz image has revealed a large asymmetric radio halo around NGC 5903 and also established that the dwarf S0 galaxy ESO 514−G003 is the host to a previously known bright double radio source. The radio emission from NGC 5903 is found to have a very steep radio spectrum (α∼−1.5) and to envelope a network of radio continuum filaments bearing a spatial relationship to the H i trails. Another noteworthy aspect of this triplet of early-type galaxies highlighted by the present study is that both its radio-loud members, namely NGC 5903 and ESO 514−G003, are also the only galaxies that are seen to be connected to an H i filament. This correlation is consistent with the premise that cold gas accretion is of prime importance for triggering powerful jet activity in the nuclei of early-type galaxies.

Keywords: galaxies: active; galaxies: elliptical and lenticular, cD; galaxies: interactions; galaxies: ISM; galaxies: jets; radio continuum: general

Journal Article.  3735 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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