Effect of clustering on primordial black hole microlensing constraints

Abstract

Stellar microlensing observations tightly constrain compact object dark matter in the mass range $(10^{-11}-10^3)M_{\odot }$. Primordial Black Holes (PBHs) form clusters, and it has been argued that these microlensing constraints are consequently weakened or evaded. For the most commonly studied PBH formation mechanism, the collapse of large gaussian curvature perturbations generated by inflation, the clusters are sufficiently extended that the PBHs within them act as individual lenses. We find that if the typical mass of the clusters is sufficiently large, $\gtrsim 10^6{M}_{\odot }$, then the event duration distribution can deviate significantly from that produced by a smooth dark matter distribution, in particular at the shortest durations. As a consequence of this, the probability distribution of the number of observed events is non-Poissonian, peaking at a lower value, with an extended tail to large numbers of events. However, for PBHs formed from the collapse of large inflationary perturbations, the typical cluster is expected to contain $\sim 10^3$ PBHs. In this case the effect of clustering is negligibly small, apart from for the most massive PBHs probed by decade-long stellar microlensing surveys ($M_{\mathrm{PBH}}\sim 10^3{M}_{\odot }$).

8 pages, 2 figures. v2: minor changes to method, no changes to results. v3: minor changes to formatting to comply with new UKRI Open Access rules, no changes to science. v4: version to appear in JCAP, minor changes

References in corpus (10)

• Primordial Black Holes as Dark Matter
• Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds
• Primordial Black Holes as Dark Matter: Recent Developments
• The merger rate of primordial-black-hole binaries
• Constraints on Earth-mass primordial black holes from OGLE 5-year microlensing events
• Microlensing and dynamical constraints on primordial black hole dark matter with an extended mass function
• Primordial Black Hole Dark Matter and the LIGO/Virgo observations
• New Constraints on Macroscopic Compact Objects as a Dark Matter Candidate from Gravitational Lensing of Type Ia Supernovae
• Microlensing constraints on clustered primordial black holes
• Introduction to Gravitational Microlensing

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