Properties of the cluster population of NGC 1566 and their implications

• Published in: Monthly notices of the Royal Astronomical Society 2016-08, Vol.460 (2), p.2087-2102
• Main Authors: Hollyhead, K., Adamo, A., Bastian, N., Gieles, M., Ryon, J. E.
• Format: Article
• Language: English
• Subjects: Astronomy; Galactic clusters; Galaxies; galaxies: individual: NGC1566; galaxies: star clusters: general; Luminosity; Mathematical models; Photometry; Power law; Slopes; Star formation rate; Stars & galaxies
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stw1142

We present results of a photometric study into the cluster population of NGC 1566, a nearby grand design spiral galaxy, sampled out to a Galactocentric radius of ≈5.5 kpc. The shape of the mass-limited age distribution shows negligible variation with radial distance from the centre of the galaxy, and demonstrates three separate sections, with a steep beginning, flat middle and steep end. The luminosity function can be approximated by a power law at lower luminosities with evidence of a truncation at higher luminosity. The power-law section of the luminosity function of the galaxy is best fitted by an index ≈− 2, in agreement with other studies, and is found to agree with a model luminosity function, which uses an underlying Schechter mass function. The recovered power law slope of the mass distribution shows a slight steepening as a function of galactocentric distance, but this is within error estimates. It also displays a possible truncation at the high mass end. Additionally, the cluster formation efficiency (Γ) and the specific U-band luminosity of clusters (T L (U)) are calculated for NGC 1566 and are consistent with values for similar galaxies. A difference in NGC 1566, however, is that the fairly high star formation rate is in contrast with a low ΣSFR and Γ, indicating that Γ can only be said to depend strongly on ΣSFR, not the star formation rate.