Studies of X-ray Emissions in High Magnetic Fields based on Magnetar Observations

• Project/Area Number: 24540309
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Japan Aerospace Exploration Agency (2013-2014); Waseda University (2012)
• Principal Investigator: NAKAGAWA Yujin 独立行政法人宇宙航空研究開発機構, 宇宙科学研究所, 宇宙航空プロジェクト研究員 (50513454)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000); Fiscal Year 2014: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2013: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2012: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: マグネター / 超強磁場中性子星 / パルサー

Outline of Final Research Achievements

Magnetars, which are highly magnetized neutron stars with field strengths of ~10**14 G, show persistent X-ray emission as well as sporadic bursts. I have been proposing a model that the persistent emission consists of numerous micro bursts of various sizes. In our model, intensity variations of the persistent emission should be larger than the values expected from the Poisson distribution. I thus quantitatively calculated intensity RMS variations for 11 magnetars (21 observations) observed by the Suzaku satellite. As a result, the RMS variations are significantly greater than the values expected from the Poisson distribution.

Research Products

• [Journal Article] Sub-MeV band observation of a hard burst from AXP 1E 1547.0-5408 with the Suzaku Wide-band All-sky Monitor (2015)
  • Author(s): T. Yasuda, W. B. Iwakiri, M. S. Tashiro, Y. Terada, T. Kouzu, T. Enoto, et al.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: TBD Issue: 3 Pages: 12-12
  • DOI: 10.1093/pasj/psv011
  • Peer Reviewed / Open Access
• [Journal Article] Suzaku Discovery of Energy Dependent Intensity Variations in Persistent X-ray Emission of Magnetars (2014)
  • Author(s): Nakagawa Yujin E., Ebisawa Ken
  • Journal Title: Suzaku-MAXI 2014: Expanding the Frontiers of the X-ray Universe, proceedings of a conference held 19-22 February, 2014 at Ehime University, Japan. Edited by M. Ishida, R. Petre, and K. Mitsuda Volume: -
  • Open Access
• [Journal Article] Wide-band spectra of magnetar burst and persistent emission (2013)
  • Author(s): Nakagawa Y. E., Makishima K., Enoto T., Sakamoto T., Mihara T., Sugizaki M., Yamaoka K., Hurley K., Yoshida A., Gandhi P., Tashiro M., Morii M.
  • Journal Title: Memorie della Societa Astronomica Italiana Volume: v.84 Pages: 560-563
• [Journal Article] All-sky observations by Suzaku wide-band all-sky monitor (2013)
  • Author(s): Ohno M., Hanabata Y., Kawano T., Takaki K., Nakamura R., Tanaka Y., Fukazawa Y., Ueno H., Tashiro M., Terada Y., Iwakiri W., Yasuda T., Asahina M., Kobayashi S., Sakamoto A., Ishida Y., Sugimoto S., Akiyama M., Ohmori N., Yamauchi M., Nakagawa Y. E., Sugita S., Yamaoka K., Kokubun M., Takahashi T., Urata Y., et al.
  • Journal Title: Memorie della Societa Astronomica Italiana Volume: v.84 Pages: 735-736
• [Journal Article] Suzaku View of Recent Magnetar and Magnetar-related Objects (2013)
  • Author(s): Enoto T., Makishima K., Shibata S., Nakagawa Y., Sakamoto T.
  • Journal Title: Astronomical Notes Volume: Volume 335
• [Journal Article] Spectral Evolution of a New X-ray Transient MAXI J0556-332 Observed by MAXI, Swift, and RXTE (2013)
  • Author(s): Mutsumi Sugizaki
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 65
  • Peer Reviewed
• [Journal Article] Wide-Band Spectra of Magnetar Burst and Persistent Emission (2013)
  • Author(s): Yujin E. Nakagawa
  • Journal Title: Memorie della Societa Astronomica Italiana Volume: 未定
• [Journal Article] Spectral Comparison of Weak Short Bursts to the Persistent X-rays from the Magnetar 1E 1547.0-5408 in its 2009 Outbursts (2012)
  • Author(s): T., Enoto, Y., E., Nakagawa, et al.
  • Journal Title: Monthly Notice of the Royal Astronomical Society Volume: 427 Issue: 4 Pages: 2824-2840
  • DOI: 10.1111/j.1365-2966.2012.22086.x
  • Peer Reviewed
• [Presentation] Energy Dependent Intensity Variations of Persistent X-ray Emission of Magnetars (2014)
  • Author(s): Yujin E. Nakagawa, Ken Ebisawa
  • Organizer: Swift 10 Years Discovery
  • Place of Presentation: ローマ（イタリア）
  • Year and Date: 2014-12-04 – 2014-12-05
• [Presentation] 「すざく」衛星によるマグネターのX線定常放射のエネルギー依存性のある強度揺らぎの研究 (2014)
  • Author(s): 中川友進、海老沢研
  • Organizer: 日本天文学会2014年秋季年会
  • Place of Presentation: 山形大学（山形県・山形市）
  • Year and Date: 2014-09-13
• [Presentation] Suzaku Discovery of Energy Dependent Intensity Variations in Persistent X-ray Emission of Magnetars (2014)
  • Author(s): Yujin E. Nakagawa, Ken Ebisawa
  • Organizer: Suzaku-MAXI 2014
  • Place of Presentation: Ehime University (Ehime, Japan)
• [Presentation] Energy Dependent Intensity Variations in Persistent X-ray Emissions of Magnetars
  • Author(s): Yujin E. Nakagawa, Ken Ebisawa
  • Organizer: Explosive Transients: Lighthouses of the Universe
  • Place of Presentation: Petros M. Nomikos Conference Center (Santorini, Greece)
• [Presentation] 「すざく」衛星を用いたマグネターのX線定常放射におけるエネルギー依存性のある強度揺らぎの研究
  • Author(s): 中川友進、海老沢研
  • Organizer: 日本天文学会2014年春季年会
  • Place of Presentation: 国際基督教大学（東京）
• [Presentation] X-ray Emission in Magnetar Short Bursts
  • Author(s): Yujin E. Nakagawa
  • Organizer: マグネター研究交流会
  • Place of Presentation: 理化学研究所（埼玉）
• [Presentation] 「すざく」によるマグネターのX線定常放射の強度揺らぎの研究
  • Author(s): 中川友進、海老沢研
  • Organizer: 日本天文学会秋季年会
  • Place of Presentation: 東北大学（宮城）
• [Presentation] 「すざく」衛星による活動期のAXP 4U 0142+614の観測的研究
  • Author(s): 中川友進
  • Organizer: 日本天文学会2012年秋季年会
  • Place of Presentation: 大分大学（大分県）
• [Presentation] Wide-Band Spectra of Magnetar Burst and Persistent Emission
  • Author(s): Yujin E. Nakagawa
  • Organizer: X-ray Astronomy: towards the next 50 years!
  • Place of Presentation: Museo Nazionale Della Scienza E Della Tecnologia Leonardo Da Vinci (Italy)
• [Presentation] Software Development for CALET and X-ray Observations of Magnetars with Suzaku
  • Author(s): Yujin E. Nakagawa
  • Organizer: 卓越した大学院拠点形成支援事業 スタートアップ・シンポジウム
  • Place of Presentation: 早稲田大学（東京都）
• [Presentation] 「すざく」による活動期のAXP 4U 0142+614のX線観測
  • Author(s): 中川友進
  • Organizer: 日本天文学会2013年春季年会
  • Place of Presentation: 埼玉大学（埼玉県）