史上最も明るいガンマ線バーストが重元素の起源探索に役立つ(Brightest gamma-ray burst of all time aids search for origin of heavy elements)

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2024-04-12 ペンシルベニア州立大学(PennState)

2022年10月に初めて検出された史上最も明るいガンマ線バースト(GRB)GRB 221009Aは、NASAのJWSTを使用して調査され、その超新星の爆発が重元素の誕生地である可能性があるかどうかが検証されました。ペンシルベニア州立大学の天文学者を含む国際研究チームがこの研究を行い、超新星から重元素の痕跡を見つけることはできませんでした。これにより、この爆発が重元素を生産する主要な源ではない可能性が示唆されました。

<関連情報>

JWSTがGRB 221009Aに関連する超新星を検出、rプロセス信号は検出されず JWST detection of a supernova associated with GRB 221009A without an r-process signature

Peter K. Blanchard,V. Ashley Villar,Ryan Chornock,Tanmoy Laskar,Yijia Li,Joel Leja,Justin Pierel,Edo Berger,Raffaella Margutti,Kate D. Alexander,Jennifer Barnes,Yvette Cendes,Tarraneh Eftekhari,Daniel Kasen,Natalie LeBaron,Brian D. Metzger,James Muzerolle Page,Armin Rest,Huei Sears,Daniel M. Siegel & S. Karthik Yadavalli
Nature Astronomy  Published:12 April 2024
DOI:https://doi.org/10.1038/s41550-024-02237-4

史上最も明るいガンマ線バーストが重元素の起源探索に役立つ(Brightest gamma-ray burst of all time aids search for origin of heavy elements)

Abstract

Identifying the sites of r-process nucleosynthesis, a primary mechanism of heavy element production, is a key goal of astrophysics. The discovery of the brightest gamma-ray burst (GRB) to date, GRB 221009A, presented an opportunity to spectroscopically test the idea that r-process elements are produced following the collapse of rapidly rotating massive stars. Here we present James Webb Space Telescope observations of GRB 221009A obtained +168 and +170 rest-frame days after the gamma-ray trigger, and demonstrate that they are well described by a SN 1998bw-like supernova (SN) and power-law afterglow, with no evidence for a component from r-process emission. The SN, with a nickel mass of approximately 0.09 M, is only slightly fainter than the brightness of SN 1998bw at this phase, which indicates that the SN is not an unusual GRB-SN. This demonstrates that the GRB and SN mechanisms are decoupled and that highly energetic GRBs are not likely to produce significant quantities of r-process material, which leaves open the question of whether explosions of massive stars are key sources of r-process elements. Moreover, the host galaxy of GRB 221009A has a very low metallicity of approximately 0.12 Z and strong H2 emission at the explosion site, which is consistent with recent star formation, hinting that environmental factors are responsible for its extreme energetics.

1701物理及び化学
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