On the globular cluster formation history of NGC 5128

S. Kaviraj, I. Ferreras, S.-J. Yoon, S. K. Yi
2005 Astronomy and Astrophysics  
We deduce the globular cluster formation history of the nearby elliptical NGC 5128 by using a phenomenological chemical enrichment model to reproduce its observed metallicity distribution function (MDF). We derive the observed MDF using recently obtained U and B photometry of the NGC 5128 GC system, with (U-B) used as the metallicity indicator. We test whether the observed MDF can be reproduced using a single starburst at high redshift followed by passive evolution (monolithic scenario). Our
more » ... ults strongly indicate that this scenario is incapable of reproducing the observed MDF of the NGC 5128 GC system. At least one more major starburst is required. A persistent feature of our best-fit models is a strong GC formation episode in the first 1-2 Gyrs, followed by a second formation episode typically after 10-12 Gyrs. Roughly one-third of the stellar mass in the GC system is created in this late starburst, producing clusters that are potentially less than 1 Gyr old. Although we do not have adequate resolution in the model or in the observed MDF to make a reliable claim about the possibility of additional GC formation episodes, our results suggest that the GCs in this galaxy did not form solely in a monolithic collapse and seem to support observational evidence which indicates that NGC 5128 is a merger remnant.
doi:10.1051/0004-6361:20041328 fatcat:eu2ggxlk3bg75cadb76siidsh4