TY - JOUR
T1 - Primordial black holes as dark matter
T2 - Constraints from compact ultra-faint dwarfs
AU - Zhu, Qirong
AU - Vasiliev, Eugene
AU - Li, Yuexing
AU - Jing, Yipeng
N1 - Funding Information:
We thank the anonymous referee for a constructive report which has helped improve our paper. It is our great pleasure to thank Avi Loeb, Lars Hernquist, Savvas Koushiappas and Peter Mészáros for stimulating discussions. YL acknowledges support from NSF grants AST-0965694, AST-1009867, AST-1412719, and MRI-1626251. The numerical computations and data analysis in this paper have been carried out on the CyberLAMP cluster supported by MRI-1626251, operated and maintained by the Institute for CyberScience at the Pennsylvania State University, as well as the Odyssey cluster supported by the FAS Division of Science, Research Computing Group at Harvard University. The Institute for Gravitation and the Cosmos is supported by the Eberly College of Science and the Office of the Senior Vice President for Research at the Pennsylvania State University. EV acknowledges support from the European Research Council under the 7th Framework Programme (grant 321067).
Publisher Copyright:
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - The ground-breaking detections of gravitational waves from black hole mergers by LIGOhave rekindled interest in primordial black holes (PBHs) and the possibility of dark matterbeing composed of PBHs. It has been suggested that PBHs of tens of solar masses could serveas dark matter candidates. Recent analytical studies demonstrated that compact ultra-faintdwarf galaxies can serve as a sensitive test for the PBH dark matter hypothesis, since stars insuch a halo-dominated system would be heated by the more massive PBHs, their present-daydistribution can provide strong constraints on PBH mass. In this study, we further explore thisscenario with more detailed calculations, using a combination of dynamical simulations andBayesian inference methods. The joint evolution of stars and PBH dark matter is followedwith a Fokker-Planck code PHASEFLOW. We run a large suite of such simulations for differentdark matter parameters, then use a Markov chain Monte Carlo approach to constrain the PBHproperties with observations of ultra-faint galaxies. We find that two-body relaxation betweenthe stars and PBH drives up the stellar core size, and increases the central stellar velocitydispersion. Using the observed half-light radius and velocity dispersion of stars in the compactultra-faint dwarf galaxies as joint constraints, we infer that these dwarfs may have a cored darkmatter halo with the central density in the range of 1-2 M pc-3, and that the PBHs may havea mass range of 2-14 M if they constitute all or a substantial fraction of the dark matter.
AB - The ground-breaking detections of gravitational waves from black hole mergers by LIGOhave rekindled interest in primordial black holes (PBHs) and the possibility of dark matterbeing composed of PBHs. It has been suggested that PBHs of tens of solar masses could serveas dark matter candidates. Recent analytical studies demonstrated that compact ultra-faintdwarf galaxies can serve as a sensitive test for the PBH dark matter hypothesis, since stars insuch a halo-dominated system would be heated by the more massive PBHs, their present-daydistribution can provide strong constraints on PBH mass. In this study, we further explore thisscenario with more detailed calculations, using a combination of dynamical simulations andBayesian inference methods. The joint evolution of stars and PBH dark matter is followedwith a Fokker-Planck code PHASEFLOW. We run a large suite of such simulations for differentdark matter parameters, then use a Markov chain Monte Carlo approach to constrain the PBHproperties with observations of ultra-faint galaxies. We find that two-body relaxation betweenthe stars and PBH drives up the stellar core size, and increases the central stellar velocitydispersion. Using the observed half-light radius and velocity dispersion of stars in the compactultra-faint dwarf galaxies as joint constraints, we infer that these dwarfs may have a cored darkmatter halo with the central density in the range of 1-2 M pc-3, and that the PBHs may havea mass range of 2-14 M if they constitute all or a substantial fraction of the dark matter.
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U2 - 10.1093/mnras/sty079
DO - 10.1093/mnras/sty079
M3 - Article
AN - SCOPUS:85043489597
VL - 476
SP - 2
EP - 11
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 1
ER -