NASAのロマン宇宙望遠鏡はどのように原始ブラックホールを探すのか?(How NASA’s Roman Mission Will Hunt for Primordial Black Holes)

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2024-05-07 NASA

NASAのナンシー・グレース・ロマン宇宙望遠鏡が、これまで検出されていなかった「フェザーウェイト(低質量)」クラスのブラックホールを発見する可能性があると科学者が予測しています。これらは、原始的な小さなブラックホールで、一部は地球と同程度の質量を持つと考えられています。これらは、宇宙の初期の混沌とした瞬間に形成された可能性があります。これらのブラックホールの発見は、理論物理学の分野に大きな影響を与え、宇宙の暗黒物質の一部を説明する手がかりを提供するかもしれません。

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ナンシー・グレース・ロマン宇宙望遠鏡で地球質量の始原ブラックホールを可視化する Revealing terrestrial-mass primordial black holes with the Nancy Grace Roman Space Telescope

William DeRocco, Evan Frangipane, Nick Hamer, Stefano Profumo, and Nolan Smyth
Physical Review D  Published 8 January 2024
DOI:https://doi.org/10.1103/PhysRevD.109.023013

NASAのロマン宇宙望遠鏡はどのように原始ブラックホールを探すのか?(How NASA’s Roman Mission Will Hunt for Primordial Black Holes)

ABSTRACT

Gravitational microlensing is one of the strongest observational techniques to observe nonluminous astrophysical bodies. Existing microlensing observations provide tantalizing evidence of a population of low-mass objects whose origin is unknown. These events may be caused by terrestrial-mass free-floating planets or by exotic objects such as primordial black holes. However, the nature of these objects cannot be resolved on an event-by-event basis, as the induced light curve is degenerate for lensing bodies of identical mass. One must instead statistically compare distributions of lensing events to determine the nature of the lensing population. While existing surveys lack the statistics required to identify multiple subpopulations of lenses, this will change with the launch of the Nancy Grace Roman Space Telescope. Roman’s Galactic Bulge Time Domain Survey is expected to observe hundreds of low-mass microlensing events, enabling a robust statistical characterization of this population. In this paper, we show that by exploiting features in the distribution of lensing event durations, Roman will be sensitive to a subpopulation of primordial black holes hidden amongst a background of free-floating planets. Roman’s reach will extend to primordial black hole dark matter fractions as low as ƒPBH=10−4 at peak sensitivity, and will be able to conclusively determine the origin of existing ultrashort-timescale microlensing events. A positive detection would provide evidence that a significant fraction of the cosmological dark matter consists of macroscopic, nonluminous objects.

1701物理及び化学
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