Radio observations of NGC 2808 and other globular clusters: constraints on intermediate-mass black holes |
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Authors: | Thomas J Maccarone Mathieu Servillat |
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Institution: | University of Southampton School of Physics and Astronomy, Highfield Campus, Southampton, SO17 1BJ;Centre d'Étude Spatiale des Rayonnments, UniversitéPaul Sabatier, CNRS –9 avenue du Colonel Roche, 31400 Toulouse, France |
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Abstract: | We present the results of a deep radio observation of the globular cluster NGC 2808. We show that there are no sources detected within the core of the cluster, placing constraints on both the pulsar population of the cluster and the mass of a possible intermediate-mass black hole in NGC 2808. We compare the results for this cluster with other constraints on intermediate-mass black holes derived from accretion measures. With the exception of G1 in M 31 which has previously shown radio emission, even with considerably more conservative assumptions, only the clusters with the poorest of observational constraints are consistent with falling on the M BH–σ relation. This result is interpreted in terms of the fundamental differences between galaxies and globular clusters. |
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Keywords: | accretion accretion discs stellar dynamics globular clusters: general globular clusters: individual: NGC 2808 radio continuum: general |
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