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 339â '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.
| Original language | English |
|---|---|
| Pages (from-to) | 54-58 |
| Number of pages | 5 |
| Journal | Nature |
| Volume | 529 |
| Issue number | 7584 |
| DOIs | |
| Publication status | Published - 2016 Jan 6 |
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Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni. / Kimura, Mariko; Isogai, Keisuke; Kato, Taichi; Ueda, Yoshihiro; Nakahira, Satoshi; Shidatsu, Megumi; Enoto, Teruaki; 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.
In: Nature, Vol. 529, No. 7584, 06.01.2016, p. 54-58.Research output: Contribution to journal › Article
TY - JOUR
T1 - Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni
AU - Kimura, Mariko
AU - Isogai, Keisuke
AU - Kato, Taichi
AU - Ueda, Yoshihiro
AU - Nakahira, Satoshi
AU - Shidatsu, Megumi
AU - Enoto, Teruaki
AU - Hori, Takafumi
AU - Nogami, Daisaku
AU - Littlefield, Colin
AU - Ishioka, Ryoko
AU - Chen, Ying Tung
AU - King, Sun Kun
AU - Wen, Chih Yi
AU - Wang, Shiang Yu
AU - Lehner, Matthew J.
AU - Schwamb, Megan E.
AU - Wang, Jen Hung
AU - Zhang, Zhi Wei
AU - Alcock, Charles
AU - Axelrod, Tim
AU - Bianco, Federica B.
AU - Byun, Yong-Ik
AU - Chen, Wen Ping
AU - Cook, Kem H.
AU - Kim, Dae Won
AU - Lee, Typhoon
AU - Marshall, Stuart L.
AU - Pavlenko, Elena P.
AU - Antonyuk, Oksana I.
AU - Antonyuk, Kirill A.
AU - Pit, Nikolai V.
AU - Sosnovskij, Aleksei A.
AU - Babina, Julia V.
AU - Baklanov, Aleksei V.
AU - Pozanenko, Alexei S.
AU - Mazaeva, Elena D.
AU - Schmalz, Sergei E.
AU - Reva, Inna V.
AU - Belan, Sergei P.
AU - Inasaridze, Raguli Ya
AU - Tungalag, Namkhai
AU - Volnova, Alina A.
AU - Molotov, Igor E.
AU - Miguel, Enrique De
AU - Kasai, Kiyoshi
AU - Stein, William L.
AU - Dubovsky, Pavol A.
AU - Kiyota, Seiichiro
AU - Miller, Ian
AU - Richmond, Michael
AU - Goff, William
AU - Andreev, Maksim V.
AU - Takahashi, Hiromitsu
AU - Kojiguchi, Naoto
AU - Sugiura, Yuki
AU - Takeda, Nao
AU - Yamada, Eiji
AU - Matsumoto, Katsura
AU - James, Nick
AU - Pickard, Roger D.
AU - Tordai, Tamás
AU - Maeda, Yutaka
AU - Ruiz, Javier
AU - Miyashita, Atsushi
AU - Cook, Lewis M.
AU - Imada, Akira
AU - Uemura, Makoto
PY - 2016/1/6
Y1 - 2016/1/6
N2 - 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 339â '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.
AB - 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 339â '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.
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U2 - 10.1038/nature16452
DO - 10.1038/nature16452
M3 - Article
VL - 529
SP - 54
EP - 58
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7584
ER -