Browsing by Author "Beswick, R."

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    Hanny's Voorwerp Evidence of AGN activity and a nuclear starburst in the central regions of IC 2497
    (EDP Sciences, 2010) Rampadarath, H.; Garrett, M. A.; Jozsa, G. I. G.; Muxlow, T.; Oosterloo, T. A.; Paragi, Z.; Beswick, R.; van Arkel, H.; Keel, W. C.; Schawinski, K.; Leiden University; Leiden University - Excl LUMC; University of Manchester; Jodrell Bank Centre for Astrophysics; Swinburne University of Technology; University of Groningen; University of Alabama Tuscaloosa; Yale University
    We present high-and intermediate resolution radio observations of the central region in the spiral galaxy IC 2497, performed using the European VLBI Network (EVN) at 18 cm, and the Multi-Element Radio Linked Interferometer Network (MERLIN) at 18 cm and 6 cm. We detect two compact radio sources, with brightness temperatures above 10(5) K, suggesting that they are related to AGN activity. We show that the total 18 cm radio emission from the galaxy is dominated neither by these compact sources nor large-scale emission, but extended emission confined within a sub-kpc central region. IC 2497 therefore appears as a typical luminous infrared galaxy that exhibits a nuclear starburst with a massive star formation rate (M > 5 M(circle dot)) of 12.4 M(circle dot)/yr. These results are in line with the hypothesis that the ionisation nebula "Hanny's Voorwerp" at a distance of similar to 15-25 kpc from the galaxy is ionised by the radiation cone of the AGN.