Starburst activity in aROSATnarrow emission-line galaxy
Gunn, KF; McHardy, IM; Almaini, O; et al.Shanks, T; Sumner, TJ; Muxlow, TWB; Efstathiou, A; Jones, LR; Croom, SM; Manners, JC; Newsam, AM; Mason, KO; Serjeant, SBG; Rowan-Robinson, M
Date: 11 June 2001
Journal
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Publisher DOI
Abstract
We present multiwaveband photometric and optical spectropolarimetric observations of the R=15. 9 narrow emission-line galaxy R117_A which lies on the edge of the error circle of the ROSAT X-ray source R117. The overall spectral energy distribution of the galaxy is well modelled by a combination of a normal spiral galaxy and a ...
We present multiwaveband photometric and optical spectropolarimetric observations of the R=15. 9 narrow emission-line galaxy R117_A which lies on the edge of the error circle of the ROSAT X-ray source R117. The overall spectral energy distribution of the galaxy is well modelled by a combination of a normal spiral galaxy and a moderate-strength burst of star formation. The far-infrared and radio emission is extended along the major axis of the galaxy, indicating an extended starburst.
On positional grounds, the galaxy is a good candidate for the identification of R117, and the observed X-ray flux is very close to what would be expected from a starburst of the observed far-infrared and radio fluxes. Although an obscured high-redshift QSO cannot be entirely ruled out as contributing some fraction of the X-ray flux, we find no candidates to K=20. 8 within the X-ray error box, and so conclude that R117_A is responsible for a large fraction, if not all, of the X-ray emission from R117.
Searches for indicators of an obscured AGN in R117_A have so far proven negative; deep spectropolarimetric observations show no signs of broad lines to a limit of 1 per cent and, for the observed far-infrared and radio emission, we would expect 10 times greater X-ray flux if the overall emission were powered by an AGN. We therefore conclude that the X-ray emission from R117 is dominated by starburst emission from the galaxy R117_A.
Mathematics and Statistics
Faculty of Environment, Science and Economy
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