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Title: Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni
Authors: Kimura, Mariko
Isogai, Keisuke
Kato, Taichi  kyouindb  KAKEN_id
Ueda, Yoshihiro
Nakahira, Satoshi
Shidatsu, Megumi
Enoto, Teruaki  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0003-1244-3100 (unconfirmed)
Hori, Takafumi
Nogami, Daisaku
Littlefield, Colin
Ishioka, Ryoko
Chen, Ying-Tung
King, Sun-Kun
Wen, Chih-Yi
Wang, Shiang-Yu
Lehner, Matthew J.
Schwamb, Megan E.
Wang, Jen-Hung
Zhang, Zhi-Wei
Alcock, Charles
Axelrod, Tim
Bianco, Federica B.
Byun, Yong-Ik
Chen, Wen-Ping
Cook, Kem H.
Kim, Dae-Won
Lee, Typhoon
Marshall, Stuart L.
Pavlenko, Elena P.
Antonyuk, Oksana I.
Antonyuk, Kirill A.
Pit, Nikolai V.
Sosnovskij, Aleksei A.
Babina, Julia V.
Baklanov, Aleksei V.
Pozanenko, Alexei S.
Mazaeva, Elena D.
Schmalz, Sergei E.
Reva, Inna V.
Belan, Sergei P.
Inasaridze, Raguli Ya.
Tungalag, Namkhai
Volnova, Alina A.
Molotov, Igor E.
Miguel, Enrique de
Kasai, Kiyoshi
Stein, William L.
Dubovsky, Pavol A.
Kiyota, Seiichiro
Miller, Ian
Richmond, Michael
Goff, William
Andreev, Maksim V.
Takahashi, Hiromitsu
Kojiguchi, Naoto
Sugiura, Yuki
Takeda, Nao
Yamada, Eiji
Matsumoto, Katsura
James, Nick
Pickard, Roger D.
Tordai, Tamás
Maeda, Yutaka
Ruiz, Javier
Miyashita, Atsushi
Cook, Lewis M.
Imada, Akira
Uemura, Makoto
Author's alias: 木邑, 真理子
磯貝, 桂介
上田, 佳宏
加藤, 太一
野上, 大作
Keywords: High-energy astrophysics
Stars
Issue Date: 6-Jan-2016
Publisher: Nature Publishing Group
Journal title: Nature
Volume: 529
Issue: 7584
Start page: 54
End page: 58
Abstract: How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disk, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. In fact, such oscillations have been observed only in sources with a high mass-accretion rate, such as GRS 1915+105 (refs 2, 3). These large-amplitude, relatively slow timescale, phenomena are thought to have physical origins distinct from those of X-ray or optical variations with small amplitudes and fast timescales (less than about 10 seconds) often observed in other black-hole binaries--for example, XTE J1118+480 (ref. 4) and GX 339−4 (ref. 5). Here we report an extensive multi-colour optical photometric data set of V404 Cygni, an X-ray transient source containing a black hole of nine solar masses (and a companion star) at a distance of 2.4 kiloparsecs (ref. 8). Our data show that optical oscillations on timescales of 100 seconds to 2.5 hours can occur at mass-accretion rates more than ten times lower than previously thought. This suggests that the accretion rate is not the critical parameter for inducing inner-disk instabilities. Instead, we propose that a long orbital period is a key condition for these large-amplitude oscillations, because the outer part of the large disk in binaries with long orbital periods will have surface densities too low to maintain sustained mass accretion to the inner part of the disk. The lack of sustained accretion--not the actual rate--would then be the critical factor causing large-amplitude oscillations in long-period systems.
Description: ブラックホール近傍から出る規則的なパターンを持つ光の変動を可視光で初めて捉えることに成功 -ブラックホールの「またたき」を直接目で観測できる機会に期待-. 京都大学プレスリリース. 2016-01-07.
Rights: This is the accepted manuscript of the article is available at http://dx.doi.org/10.1038/nature16452.
The full-text file will be made open to the public on 7 July 2016 in accordance with publisher's 'Terms and Conditions for Self-Archiving'.
This is not the published version. Please cite only the published version. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
URI: http://hdl.handle.net/2433/203010
DOI(Published Version): 10.1038/nature16452
Related Link: http://www.kyoto-u.ac.jp/ja/research/research_results/2015/160107_1.html
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