Gas surface density, star formation rate surface density, and the   maximum mass of young star clusters in a disk galaxy. I. The flocculent   galaxy M33
  We analyze the relationship between maximum cluster mass, M_max, and surface densities of total gas (Sigma_gas), molecular gas (Sigma_H2) and star formation rate (Sigma_SFR) in the flocculent galaxy M33, using published gas data and a catalog of more than 600 young star clusters in its disk. By comparing the radial distributions of gas and most massive cluster masses, we find that M_max is proportional to Sigma_gas^4.7, M_max is proportional Sigma_H2^1.3, and M_max is proportional to Sigma_SFR^1.0. We rule out that these correlations result from the size of sample; hence, the change of the maximum cluster mass must be due to physical causes. 
Rosa A. Gonzalez-Lopezlira (UNAM, Bonn), Jan Pflamm-Altenburg (Bonn),   Pavel Kroupa (Bonn)
astro-ph.GA