TY - JOUR
T1 - Radial variation of the stellar mass functions in the globular clusters M15 and M30
T2 - Clues of a non-standard IMF?
AU - Cadelano, M.
AU - Dalessandro, E.
AU - Webb, J. J.
AU - Vesperini, E.
AU - Lattanzio, D.
AU - Beccari, G.
AU - Gomez, M.
AU - Monaco, L.
N1 - Funding Information:
The authors thank the anonymous referee for the careful reading of the paper and the constructive comments. We also thank B. Lanzoni for useful discussion. MC and ED acknowledge financial support by the project Light-on-Dark granted by MIUR through PRIN2017 contract (PI: Ferraro).
Publisher Copyright:
© 2020 The Author(s).
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/12/1
Y1 - 2020/12/1
N2 - We exploit a combination of high-resolution Hubble Space Telescope and wide-field ESO-VLT observations to study the slope of the global mass function (αG) and its radial variation (α(r)) in the two dense, massive and post core-collapse globular clusters M15 and M30. The available data set samples the clusters' main sequence down to ∼0.2 M⊙ and the photometric completeness allows the study of the mass function between 0.40 M⊙ and 0.75 M⊙ from the central regions out to their tidal radii. We find that both clusters show a very similar variation in α(r) as a function of clustercentric distance. They both exhibit a very steep variation in α(r) in the central regions, which then attains almost constant values in the outskirts. Such a behaviour can be interpreted as the result of long-term dynamical evolution of the systems driven by mass-segregation and mass-loss processes. We compare these results with a set of direct N-body simulations and find that they are only able to reproduce the observed values of α(r) and αG at dynamical ages (t/trh) significantly larger than those derived from the observed properties of both clusters. We investigate possible physical mechanisms responsible for such a discrepancy and argue that both clusters might be born with a non-standard (flatter/bottom-lighter) initial mass function.
AB - We exploit a combination of high-resolution Hubble Space Telescope and wide-field ESO-VLT observations to study the slope of the global mass function (αG) and its radial variation (α(r)) in the two dense, massive and post core-collapse globular clusters M15 and M30. The available data set samples the clusters' main sequence down to ∼0.2 M⊙ and the photometric completeness allows the study of the mass function between 0.40 M⊙ and 0.75 M⊙ from the central regions out to their tidal radii. We find that both clusters show a very similar variation in α(r) as a function of clustercentric distance. They both exhibit a very steep variation in α(r) in the central regions, which then attains almost constant values in the outskirts. Such a behaviour can be interpreted as the result of long-term dynamical evolution of the systems driven by mass-segregation and mass-loss processes. We compare these results with a set of direct N-body simulations and find that they are only able to reproduce the observed values of α(r) and αG at dynamical ages (t/trh) significantly larger than those derived from the observed properties of both clusters. We investigate possible physical mechanisms responsible for such a discrepancy and argue that both clusters might be born with a non-standard (flatter/bottom-lighter) initial mass function.
KW - galaxies: star clusters: general
KW - Galaxy: kinematics and dynamics
KW - globular clusters: individual
KW - stars: mass function
UR - http://www.scopus.com/inward/record.url?scp=85096944253&partnerID=8YFLogxK
U2 - 10.1093/mnras/staa2759
DO - 10.1093/mnras/staa2759
M3 - Article
AN - SCOPUS:85096944253
SN - 0035-8711
VL - 499
SP - 2390
EP - 2400
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -