• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Mass and Radius determination of magnetic cataclysmic variables utilizing X-ray emission generated from accreting plasma flows

Research Project

Project/Area Number 21K03623
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 16010:Astronomy-related
Research InstitutionJapan Aerospace EXploration Agency

Principal Investigator

Mori Hideyuki  国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 招聘研究員 (20432354)

Project Period (FY) 2021-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2023: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2022: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2021: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
KeywordsX線天文学 / 強磁場激変星 / 白色矮星 / 重力赤方偏移 / プラズマ物理 / プラズマモデル
Outline of Research at the Start

本研究では、白色矮星の表面近傍に形成されるプラズマ降着流のX線精密分光観測を通じて、白色矮星の質量と半径を同時に決定する手法を確立する。特性X線の電離状態と、白色矮星の自転に伴うエネルギー変化、すなわちドップラーシフトから、降着流内部の温度・速度場構造を観測的に決定する。さらに白色矮星表面でのコンプトン散乱も考慮して、降着流の物理状態を忠実に再現するX線放射モデルを構築する。アーカイブを含むX線観測データにこの新放射モデルを適用して、白色矮星の質量と半径を精密決定する。

Outline of Final Research Achievements

We detected significant redshifts from characteristic X-ray emission lines of hydrogen-like magnesium, silicon, and sulfur ions in the X-ray spectra of RX J1712.6-2414, a magnetic cataclysmic variable, which were obtained from the Chandra High-Energy Grating observation. These redshifts were significantly larger than the Doppler shifts of the corresponding elements contained in plasma flow accreting onto a white dwarf (WD), harbored in RX J1712.6-2414. While the line-of-sight plasma velocities are estimated to be ~ 100 km/s from the prevailing accretion-flow model, those derived from the redshifts were in a range of 200 - 500 km/s. We considered several effects to mitigate the discrepancy of the energy shifts. Finally, we concluded that a gravitational redshift is a main contributor, which enables us to directly measure the gravitational potential near the WD surface. Hence, it provides us with a new method of the mass determination; the WD mass was estimated to be > 0.9 Msun.

Academic Significance and Societal Importance of the Research Achievements

本研究では、強磁場激変星におけるX線スペクトルの重力赤方偏移を世界で初めて検出した。X線は白色矮星表面近傍から放射されるため、星表面での重力ポテンシャルの深さを観測量として直接測定できることになる。したがって、可視光光度曲線の変動から求まる連星質量比や、X線スペクトルから衝撃波加熱されたプラズマの最大温度を推定して重力ポテンシャルを求める方法とは独立に、白色矮星の質量を推定する新たな手法を与える。また従来のプラズマ降着流モデルから計算されるドップラー効果よりも輝線エネルギーのずれへの寄与が大きく、重力赤方偏移を反映したセルフコンシステントなX線スペクトルモデルの構築が必須であることが分かった。

Report

(4 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Research-status Report
  • 2021 Research-status Report
  • Research Products

    (3 results)

All 2023 2022

All Journal Article (1 results) (of which Int'l Joint Research: 1 results,  Peer Reviewed: 1 results,  Open Access: 1 results) Presentation (2 results) (of which Int'l Joint Research: 1 results)

  • [Journal Article] Gravitational Redshift Detection from the Magnetic White Dwarf Harbored in RX J1712.6?24142023

    • Author(s)
      Hayashi Takayuki、Mori Hideyuki、Mukai Koji、Terada Yukikatsu、Ishida Manabu
    • Journal Title

      The Astrophysical Journal

      Volume: 953 Issue: 1 Pages: 30-30

    • DOI

      10.3847/1538-4357/acd001

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Presentation] 強磁場激変星RX J1712.6-2414からの重力赤方偏移2023

    • Author(s)
      林多佳由、森英之、向井浩二、石田学、寺田幸功
    • Organizer
      日本天文学会2023秋季年会
    • Related Report
      2023 Annual Research Report
  • [Presentation] X-ray observation of a diskless intermediate polar, RX J1712.6-2414, with Suzaku2022

    • Author(s)
      Hideyuki Mori, Takayuki Hayashi, Manabu Ishida, Yukikatsu Terada, Yoshitomo Maeda
    • Organizer
      44th COSPAR Scientific Assembly
    • Related Report
      2022 Research-status Report
    • Int'l Joint Research

URL: 

Published: 2021-04-28   Modified: 2025-01-30  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi