backLimits on planetary-mass primordial black holes from the OGLE high-cadence survey of the Magellanic Clouds
Observations of the Galactic bulge revealed an excess of short-timescale gravitational microlensing events that are generally attributed to a large population of free-floating or wide-orbit exoplanets. However, in recent years, some authors suggested that planetary-mass primordial black holes (PBHs) comprising a substantial fraction (1-10%) of the dark matter in the Milky Way may be responsible for these events. If that was the case, a large number of short-timescale microlensing events should also be seen toward the Magellanic Clouds.
We present the results of a high-cadence survey of the Magellanic Clouds carried out from October 2022 through May 2024 as part of the OGLE-IV project. We observed almost 35 million source stars located in the central regions of the Large and Small Magellanic Clouds and found only one long-timescale microlensing event candidate. No short-timescale events were detected despite high sensitivity to such events. That allows us to infer the strongest available limits on the frequency of planetary-mass PBHs in dark matter. We find that PBHs and other compact objects with masses from 1.4 ⨉ 10-8 M⊙ (half of the Moon mass) to 0.013 M⊙ (planet/brown dwarf boundary) may comprise at most 1% of dark matter. That rules out the PBH origin hypothesis for the short-timescale events detected toward the Galactic bulge and indicates they are caused by the population of free-floating or wide-orbit planets.
95% upper limits on the fraction of dark matter in the form of primordial black holes and other compact objects.
The results of this study and the underlying OGLE data are available to the astronomical community from the OGLE Internet Archive.
PLEASE cite the following paper when using the data or referring to these OGLE results:
Mróz et al., 2024, arXiv:2410.06251
Any comments about the data and the form of their presentation are welcome as they can improve the future releases of OGLE analysis. Send your messages to this address.
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