TY - JOUR
T1 - A supra-massive population of stellar-mass black holes in the globular cluster Palomar 5
AU - Gieles, Mark
AU - Erkal, Denis
AU - Antonini, Fabio
AU - Balbinot, Eduardo
AU - Peñarrubia, Jorge
N1 - Funding Information:
M.G. and E.B. acknowledge financial support from the European Research Council (grant number ERC StG-335936, CLUSTERS) and M.G. acknowledges support from the Spanish Ministry of Science and Innovation through a Europa Excelencia grant (EUR2020-112157). F.A. acknowledges support from a Rutherford fellowship (grant number ST/P00492X/2) from the Science and Technology Facilities Council. E.B. acknowledges financial support from a Vici grant from the Netherlands Organisation for Scientific Research (NWO). M.G. thanks G. Pérez Forcadell for installing the GPU server at the ICCUB on which all the simulations were run. We thank R. Ibata for sharing the data of Pal 5’s surface density profile, Ł. Wyrzykowski for discussions on microlensing and S. Aarseth, K. Nitadori and L. Wang for maintaining NBODY6 and NBODY6++GPU and making the codes publicly available. M.G. and F.A. thank L. Wang and S. Banerjee for discussions on the recent SSE and BSE updates and the implementation in NBODY6++GPU. This research made use of ASTROPY, a community-developed core Python package for astronomy92,93 (http://www.astropy.org).
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2021/9
Y1 - 2021/9
N2 - Palomar 5 is one of the sparsest star clusters in the Galactic halo and is best known for its spectacular tidal tails, spanning over 20° across the sky. With N-body simulations, we show that both distinguishing features can result from a stellar-mass black hole population, comprising ~20% of the present-day cluster mass. In this scenario, Palomar 5 formed with a ‘normal’ black hole mass fraction of a few per cent, but stars were lost at a higher rate than black holes, such that the black hole fraction gradually increased. This inflated the cluster, enhancing tidal stripping and tail formation. A billion years from now, the cluster will dissolve as a 100% black hole cluster. Initially denser clusters end up with lower black hole fractions, smaller sizes and no observable tails. Black hole-dominated, extended star clusters are therefore the likely progenitors of the recently discovered thin stellar streams in the Galactic halo.
AB - Palomar 5 is one of the sparsest star clusters in the Galactic halo and is best known for its spectacular tidal tails, spanning over 20° across the sky. With N-body simulations, we show that both distinguishing features can result from a stellar-mass black hole population, comprising ~20% of the present-day cluster mass. In this scenario, Palomar 5 formed with a ‘normal’ black hole mass fraction of a few per cent, but stars were lost at a higher rate than black holes, such that the black hole fraction gradually increased. This inflated the cluster, enhancing tidal stripping and tail formation. A billion years from now, the cluster will dissolve as a 100% black hole cluster. Initially denser clusters end up with lower black hole fractions, smaller sizes and no observable tails. Black hole-dominated, extended star clusters are therefore the likely progenitors of the recently discovered thin stellar streams in the Galactic halo.
UR - http://www.scopus.com/inward/record.url?scp=85109629283&partnerID=8YFLogxK
U2 - 10.1038/s41550-021-01392-2
DO - 10.1038/s41550-021-01392-2
M3 - Article
AN - SCOPUS:85109629283
SN - 2397-3366
VL - 5
SP - 957
EP - 966
JO - Nature Astronomy
JF - Nature Astronomy
IS - 9
ER -