TY - JOUR
T1 - Evidence for two distinct stellar initial mass functions
T2 - Revisiting the effects of cluster dynamical evolution
AU - Zaritsky, Dennis
AU - Colucci, Janet E.
AU - Pessev, Peter M.
AU - Bernstein, Rebecca A.
AU - Chandar, Rupali
PY - 2013/6/20
Y1 - 2013/6/20
N2 - We measure the velocity dispersions of six galactic globular clusters using spatially integrated spectra, to test for the effects of internal dynamical evolution in the stellar mass-to-light ratios, Υ*, of star clusters. In particular, we revisit whether the low values of Υ* that we found in our previous study, from which we concluded that there are at least two population of stellar clusters with distinct stellar initial mass functions, are artificially depressed by relaxation driven mass loss. The combination of our previous sample of five old clusters and these six now provide an order of magnitude range in cluster mass with which to explore this issue. We find no relationship between cluster mass, or relaxation time, and Υ*. Because relaxation is mass dependent, we conclude that the values of Υ* for these clusters are not strongly affected by dynamical effects, and so confirm the presence of the population of clusters with low Υ*.
AB - We measure the velocity dispersions of six galactic globular clusters using spatially integrated spectra, to test for the effects of internal dynamical evolution in the stellar mass-to-light ratios, Υ*, of star clusters. In particular, we revisit whether the low values of Υ* that we found in our previous study, from which we concluded that there are at least two population of stellar clusters with distinct stellar initial mass functions, are artificially depressed by relaxation driven mass loss. The combination of our previous sample of five old clusters and these six now provide an order of magnitude range in cluster mass with which to explore this issue. We find no relationship between cluster mass, or relaxation time, and Υ*. Because relaxation is mass dependent, we conclude that the values of Υ* for these clusters are not strongly affected by dynamical effects, and so confirm the presence of the population of clusters with low Υ*.
KW - galaxies: evolution
KW - galaxies: fundamental parameters
KW - stars: formation
KW - stars: luminosity function, mass function
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U2 - 10.1088/0004-637X/770/2/121
DO - 10.1088/0004-637X/770/2/121
M3 - Article
AN - SCOPUS:84878801528
SN - 0004-637X
VL - 770
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 121
ER -