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Discovery of kpc-scale line emission in barred galaxies, not linked to AGN or star formation

James, PA and Percival, SM (2015) Discovery of kpc-scale line emission in barred galaxies, not linked to AGN or star formation. Monthly Notices of the Royal Astronomical Society, 450 (4). pp. 3503-3513. ISSN 0035-8711

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Abstract

We present an analysis of the optical line emission from nearby barred galaxies, and in particular look at the radial range occupied by the bar. In many cases this region is marked by what we term a 'star formation desert', with a marked deficit of HII regions in optical narrow-band H-alpha imaging. Here we present long-slit spectroscopy revealing that such regions do have line emission, but that it is low-level, spatially smooth and almost ubiquitous. The relative strengths of the H-alpha and the spectrally adjacent [NII] lines in the regions are completely discrepant from those associated with star formation regions, and more closely match expectations for 'LINER' regions. We quantify the total line emission from these extended, kpc-scale regions, and determine the spurious contribution it would make to the determined star formation rate of these galaxies if interpreted as normal H-alpha emission. We concur with previous studies that link this LINER emission to old stellar populations, e.g. post-asymptotic giant branch stars, and propose these strongly-barred early-type spirals as a prime location for further tests of such emission.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 12 Aug 2015 08:45
Last Modified: 12 Aug 2015 08:45
DOI or Identification number: 10.1093/mnras/stv846
URI: http://researchonline.ljmu.ac.uk/id/eprint/1828

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