Study of variations of cyclotron lines in neutron stars with luminosity and pulse phase using PC cluster.

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03934
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: Nagano National College of Technology
• Principal Investigator: Nishimura Osamu 長野工業高等専門学校, 情報エレクトロニクス系, 教授 (10259864)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: X線パルサー / 中性子星 / サイクロトロン線 / 磁場

Outline of Final Research Achievements

I compute cyclotron absorption line in neutron stars numerically, building a model that is able to reproduce a variation of the observed energy of absorption line with luminosity. In Vela X-1, the energy of the absorption line tends to decrease once and then increase with increasing luminosity. I examined double absorption features are formed via gravitational light bending. As a result, I found that the absorption line is likely to be formed via gravitational light bending. That suggests that in Vela X-1 the magnetic field strength becomes 5 times stronger than the value that the energy of the absorption line has implied. I also tried calculating absorption lines in A0535+262. In this object, the characteristics similar to Vela X-1 can be explained by the same model. Thus, the two absorption lines in A0535+262 can be formed by gravitational light bending. Therefore, my simulations suggest that A0535+262 is an object having a superstrong magnetic field over the 13 power of 10.

Free Research Field

X線天文学

Academic Significance and Societal Importance of the Research Achievements

宇宙において最も強い磁場を持つ天体の中性子星の磁場強度を直接測定できる唯一の方法であるサイクロトロン吸収線のエネルギーについて、シミュレーションを行った。中性子性の磁極付近で形成される降着円柱内での降着ガスによるドップラー効果と重力による光の曲がる効果を考慮することによって、観測結果と一致する新たな結果を得ることができた。これにより今まで見積もられていた磁場の強度よりも５倍程度強い磁場を持つ可能性について示唆することができた。今後のより詳細な観測データにより、この結果が正しいかどうかがより明確になると予想される。