Journal Article

Spectroscopic confirmation of Hα-selected satellite galaxies

Clare F. Ivory and Phil A. James

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 4, pages 2549-2555
Published in print February 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI:
Spectroscopic confirmation of Hα-selected satellite galaxies

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We present a spectroscopic test confirming the potential of narrow-band optical imaging as a method for detecting star-forming satellites around nearby galaxies. To date the efficiency of such methods, and particularly the fraction of false detections resulting from its use, has not been tested. In this paper we use optical spectroscopy to verify the nature of objects that are apparently emission-line satellites, taken from imaging presented elsewhere. Observations of 12 probable satellites around 11 host galaxies are presented and used to compare the recession velocities of the host and satellite. This test confirms, in all cases, that there is a genuine line emission, that the detected line is Hα and that the satellites have similar recession velocities to their hosts with a maximum difference of ∼250 km s−1, consistent with their being gravitationally bound companions. We conclude that the spectroscopy has confirmed that narrow-band imaging through Hα filters is a reliable method for detecting genuine, star-forming satellites with low contamination from galaxies seen in projection along the line of sight.

Keywords: galaxies: dwarf; galaxies: general; galaxies: spiral

Journal Article.  4972 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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