SCYON Abstract

Received on June 14 2011

Evidence for Environmentally Dependent Cluster Disruption in M83

AuthorsN. Bastian (1,2), A. Adamo (3), M. Gieles (4), H.J.G.L.M. Lamers (5), S.S. Larsen (5), E. Silva-Villa (5), L.J. Smith (6), R. Kotulla (7), I.S. Konstantopoulos (8), G. Trancho (9), and E. Zackrisson (3)
Affiliation(1) School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
(2) Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany
(3) Department of Astronomy, Stockholm University, Oscar Klein Centre, AlbaNova, Stockholm SE-106 91, Sweden
(4) Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
(5) Astronomical Institute, Utrecht University, Princetonplein 5, NL-3584CC Utrecht, the Netherlands
(6) Space Telescope Science Institute and European Space Agency, 3700 San Martin Drive, Baltimore, MD 21218, USA
(7) Department of Physics, University of Wisconsin, Milwaukee, WI 53201-0431, USA
(8) Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA
(9) Gemini Observatory, Casilla 603, La Serena, Chile
Accepted byMonthly Notices of the Royal Astronomical Society
Contactbastian@usm.lmu.edu
URLhttp://xxx.lanl.gov/abs/1106.2427
Links

Abstract

Using multi-wavelength imaging from the Wide Field Camera 3 on the Hubble Space Telescope we study the stellar cluster populations of two adjacent fields in the nearby face-on spiral galaxy, M83. The observations cover the galactic centre and reach out to ~6 kpc, thereby spanning a large range of environmental conditions, ideal for testing empirical laws of cluster disruption. The clusters are selected by visual inspection to be centrally concentrated, symmetric, and resolved on the images. We find that a large fraction of objects detected by automated algorithms (e.g. SExtractor or Daofind) are not clusters, but rather are associations. These are likely to disperse into the field on timescales of tens of Myr due to their lower stellar densities and not due to gas expulsion (i.e. they were never gravitationally bound). We split the sample into two discrete fields (inner and outer regions of the galaxy) and search for evidence of environmentally dependent cluster disruption. Colour-colour diagrams of the clusters, when compared to simple stellar population models, already indicate that a much larger fraction of the clusters in the outer field are older by tens of Myr than in the inner field. This impression is quantified by estimating each cluster's properties (age, mass, and extinction) and comparing the age/mass distributions between the two fields. Our results are inconsistent with "universal" age and mass distributions of clusters, and instead show that the ambient environment strongly affects the observed populations.