Volume 507, Number 1, November III 2009
|Page(s)||183 - 193|
|Published online||08 September 2009|
Globular cluster system erosion in elliptical galaxies
Dep. of Physics, Sapienza, University of Roma, P.le A. Moro 5, 00185, Roma, Italy e-mail: [roberto.capuzzodolcetta;alessandra.mastrobuonobattisti]@uniroma1.it
Accepted: 5 August 2009
Context. We analyse data of 8 elliptical galaxies to study the difference between the radial distributions of their globular cluster systems (GCSs) and their galactic stellar component. In all galaxies studied, the GCS density profile is significantly flatter towards the galactic centre than that of the stars.
Aims. A flatter profile of the radial distribution of the GCS with respect to that of the galactic stellar component is a difference with astrophysical relevance. A quantitative comparative analysis of the profiles may provide insight into both galaxy and globular cluster formation and evolution. If the difference is caused by erosion of the GCS, the missing GCs in the galactic central region may have merged around the galactic centre and formed, or at least increased in mass, the galactic nucleus. Observational support to this are the correlations between the galaxy integrated absolute magnitude and the number of globular clusters lost and that between the central massive black hole mass and the total mass of globular clusters lost.
Methods. We fitted both the stellar and globular cluster system radial profiles of a set of galaxies observed at high resolution. We found that the GCS profile is less sharply peaked at the galactic centre than the stellar one. Assuming that this difference is caused by GCS evolution, starting from a radial distribution initially indistinguishable from that of stars, we can evaluate by a simple normalization procedure the number (and mass) of GCs that have “disappeared”.
Results. The number of missing globular clusters is significant, ranging from 21% to 71% of their initial population abundance in the eight galaxies examined. The corresponding mass lost to the central galactic region is (for every galaxy of the sample) in the 2.77 107–1.58 109 interval. All the transported mass towards the central galactic regions have had probably an important effect on the innermost galactic zone, including its violent transient activity (AGN) and local massive black hole formation and growth.
Key words: galaxies: general / galaxies: elliptical and lenticular, cD / galaxies: evolution / galaxies: star clusters / galaxies: nuclei
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.