The gravitational wave detectors have unveiled a population of massive black holes that do not resemble those observed in the Milky Way¹⁻³ and whose origin is debated⁴⁻⁶. According to one possible explanation, these black holes may have formed from density fluctuations in the early Universe (primordial black holes)⁷⁻⁹, and they should comprise from several to 100% of dark matter to explain the observed black hole merger rates¹⁰⁻¹². If such black holes existed in the Milky Way dark matter halo, they would cause long-timescale gravitational microlensing events lasting years¹³. The previous experiments were not sufficiently sensitive to such events¹⁴⁻¹⁷. Here we present the results of the search for long-timescale microlensing events among the light curves of nearly 80 million stars located in the Large Magellanic Cloud that were monitored for 20 years by the OGLE survey¹⁸. We did not find any events with timescales longer than one year, whereas all shorter events detected may be explained by known stellar populations. We find that compact objects in the mass range from 1.8 × 10⁻⁴ to 6.3 M_⊙ cannot compose more than 1% of dark matter, and those in the mass range from 1.3 × 10⁻⁵ to 860 M_⊙ cannot make up more than 10% of dark matter. Thus, primordial black holes in this mass range cannot simultaneously explain a significant fraction of dark matter and gravitational wave events.

引力波探测器揭示了一群大质量黑洞，它们与银河系中观测到的黑洞不同 ¹⁻³ ，而且其起源存在争议 ⁴⁻⁶ 。根据一种可能的解释，这些黑洞可能是由早期宇宙（原始黑洞）的密度涨落形成的 ⁷⁻⁹ ，并且它们应该包含几％到100％的暗物质，以解释所观察到的黑洞合并率 ¹⁰⁻¹² 。如果银河系暗物质晕中存在这样的黑洞，它们将引起持续数年的长时尺度引力微透镜事件 ¹³ 。之前的实验对此类事件不够敏感 ¹⁴⁻¹⁷ 。在这里，我们展示了在大麦哲伦星云中近 8000 万颗恒星的光变曲线中寻找长期尺度微透镜事件的结果，这些恒星由 OGLE 巡天监测了 20 年 ¹⁸ 。我们没有发现任何时间尺度超过一年的事件，而检测到的所有较短事件都可以用已知的恒星群体来解释。我们发现质量范围为1.8 × 10 ⁻⁴ 到6.3 M _⊙ 的致密天体不能构成超过1%的暗物质，而质量范围为1.3 × 10的致密天体不能构成超过1%的暗物质。 ⁻⁵ 到 860 M _⊙ 不能构成超过 10% 的暗物质。因此，这个质量范围内的原初黑洞无法同时解释大部分暗物质和引力波事件。