Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338)

Mariko Kimura; Taichi Kato; Keisuke Isogai; Hyungsuk Tak; Megumi Shidatsu; Hiroshi Itoh; Tamás Tordai; Kiyoshi Kasai; William Goff; Seiichiro Kiyota; Roger D. Pickard; Katsura Matsumoto; Naoto Kojiguchi; Yuki Sugiura; Eiji Yamada; Taiki Tatsumi; Atsushi Miyashita; Pavol A. Dubovsky; Igor Kudzej; Enrique de Miguel; William L. Stein; Yutaka Maeda; Elena P. Pavlenko; Aleksei A. Sosnovskij; Julia V. Babina; Lewis M. Cook; Daisaku Nogami

doi:10.1093/MNRAS/STX1555

Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338)

Mariko Kimura, Taichi Kato, Keisuke Isogai, Hyungsuk Tak, Megumi Shidatsu, Hiroshi Itoh, Tamás Tordai, Kiyoshi Kasai, William Goff, Seiichiro Kiyota, Roger D. Pickard, Katsura Matsumoto, Naoto Kojiguchi, Yuki Sugiura, Eiji Yamada, Taiki Tatsumi, Atsushi Miyashita, Pavol A. Dubovsky, Igor Kudzej, Enrique de MiguelWilliam L. Stein, Yutaka Maeda, Elena P. Pavlenko, Aleksei A. Sosnovskij, Julia V. Babina, Lewis M. Cook, Daisaku Nogami

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Abstract

We present optical multicolour photometry of V404 Cyg during the outburst from 2015 December to 2016 January together with the simultaneous X-ray data. This outburst occurred less than sixmonths after the previous outburst in 2015 June-July. These two outbursts in 2015 were of a slow-rise and rapid-decay type and showed large-amplitude (~2mag) and short-term (~10 min-3 h) optical variations even at low luminosity (0.01-0.1L_Edd). We found correlated optical and X-ray variations in two ~1 h time intervals and obtained a Bayesian estimate of an X-ray delay against the optical emission, which is ~30-50 s, during those two intervals. In addition, the relationship between the optical and X-ray luminosities was L_opt ∝ L_X^0.25-0.29 at that time. These features cannot be easily explained by the conventional picture of transient black hole binaries, such as canonical disc reprocessing and synchrotron emission related to a jet. We suggest that the disc was truncated during those intervals and that the X-ray delays represent the required time for the propagation of mass accretion flow to the inner optically thin region with a speed comparable to the free-fall velocity.

Original language	English (US)
Pages (from-to)	373-382
Number of pages	10
Journal	Monthly Notices of the Royal Astronomical Society
Volume	471
Issue number	1
DOIs	https://doi.org/10.1093/MNRAS/STX1555
State	Published - 2017

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1093/MNRAS/STX1555

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Kimura, M., Kato, T., Isogai, K., Tak, H., Shidatsu, M., Itoh, H., Tordai, T., Kasai, K., Goff, W., Kiyota, S., Pickard, R. D., Matsumoto, K., Kojiguchi, N., Sugiura, Y., Yamada, E., Tatsumi, T., Miyashita, A., Dubovsky, P. A., Kudzej, I., ... Nogami, D. (2017). Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338). Monthly Notices of the Royal Astronomical Society, 471(1), 373-382. https://doi.org/10.1093/MNRAS/STX1555

@article{596e5807b8314135baa343fe336c502a,

title = "Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338)",

abstract = "We present optical multicolour photometry of V404 Cyg during the outburst from 2015 December to 2016 January together with the simultaneous X-ray data. This outburst occurred less than sixmonths after the previous outburst in 2015 June-July. These two outbursts in 2015 were of a slow-rise and rapid-decay type and showed large-amplitude (~2mag) and short-term (~10 min-3 h) optical variations even at low luminosity (0.01-0.1LEdd). We found correlated optical and X-ray variations in two ~1 h time intervals and obtained a Bayesian estimate of an X-ray delay against the optical emission, which is ~30-50 s, during those two intervals. In addition, the relationship between the optical and X-ray luminosities was Lopt ∝ LX0.25-0.29 at that time. These features cannot be easily explained by the conventional picture of transient black hole binaries, such as canonical disc reprocessing and synchrotron emission related to a jet. We suggest that the disc was truncated during those intervals and that the X-ray delays represent the required time for the propagation of mass accretion flow to the inner optically thin region with a speed comparable to the free-fall velocity.",

author = "Mariko Kimura and Taichi Kato and Keisuke Isogai and Hyungsuk Tak and Megumi Shidatsu and Hiroshi Itoh and Tam{\'a}s Tordai and Kiyoshi Kasai and William Goff and Seiichiro Kiyota and Pickard, {Roger D.} and Katsura Matsumoto and Naoto Kojiguchi and Yuki Sugiura and Eiji Yamada and Taiki Tatsumi and Atsushi Miyashita and Dubovsky, {Pavol A.} and Igor Kudzej and {de Miguel}, Enrique and Stein, {William L.} and Yutaka Maeda and Pavlenko, {Elena P.} and Sosnovskij, {Aleksei A.} and Babina, {Julia V.} and Cook, {Lewis M.} and Daisaku Nogami",

note = "Publisher Copyright: {\textcopyright} 2017 The Authors.",

year = "2017",

doi = "10.1093/MNRAS/STX1555",

language = "English (US)",

volume = "471",

pages = "373--382",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

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Kimura, M, Kato, T, Isogai, K, Tak, H, Shidatsu, M, Itoh, H, Tordai, T, Kasai, K, Goff, W, Kiyota, S, Pickard, RD, Matsumoto, K, Kojiguchi, N, Sugiura, Y, Yamada, E, Tatsumi, T, Miyashita, A, Dubovsky, PA, Kudzej, I, de Miguel, E, Stein, WL, Maeda, Y, Pavlenko, EP, Sosnovskij, AA, Babina, JV, Cook, LM & Nogami, D 2017, 'Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338)', Monthly Notices of the Royal Astronomical Society, vol. 471, no. 1, pp. 373-382. https://doi.org/10.1093/MNRAS/STX1555

TY - JOUR

T1 - Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338)

AU - Kimura, Mariko

AU - Kato, Taichi

AU - Isogai, Keisuke

AU - Tak, Hyungsuk

AU - Shidatsu, Megumi

AU - Itoh, Hiroshi

AU - Tordai, Tamás

AU - Kasai, Kiyoshi

AU - Goff, William

AU - Kiyota, Seiichiro

AU - Pickard, Roger D.

AU - Matsumoto, Katsura

AU - Kojiguchi, Naoto

AU - Sugiura, Yuki

AU - Yamada, Eiji

AU - Tatsumi, Taiki

AU - Miyashita, Atsushi

AU - Dubovsky, Pavol A.

AU - Kudzej, Igor

AU - de Miguel, Enrique

AU - Stein, William L.

AU - Maeda, Yutaka

AU - Pavlenko, Elena P.

AU - Sosnovskij, Aleksei A.

AU - Babina, Julia V.

AU - Cook, Lewis M.

AU - Nogami, Daisaku

PY - 2017

Y1 - 2017

N2 - We present optical multicolour photometry of V404 Cyg during the outburst from 2015 December to 2016 January together with the simultaneous X-ray data. This outburst occurred less than sixmonths after the previous outburst in 2015 June-July. These two outbursts in 2015 were of a slow-rise and rapid-decay type and showed large-amplitude (~2mag) and short-term (~10 min-3 h) optical variations even at low luminosity (0.01-0.1LEdd). We found correlated optical and X-ray variations in two ~1 h time intervals and obtained a Bayesian estimate of an X-ray delay against the optical emission, which is ~30-50 s, during those two intervals. In addition, the relationship between the optical and X-ray luminosities was Lopt ∝ LX0.25-0.29 at that time. These features cannot be easily explained by the conventional picture of transient black hole binaries, such as canonical disc reprocessing and synchrotron emission related to a jet. We suggest that the disc was truncated during those intervals and that the X-ray delays represent the required time for the propagation of mass accretion flow to the inner optically thin region with a speed comparable to the free-fall velocity.

AB - We present optical multicolour photometry of V404 Cyg during the outburst from 2015 December to 2016 January together with the simultaneous X-ray data. This outburst occurred less than sixmonths after the previous outburst in 2015 June-July. These two outbursts in 2015 were of a slow-rise and rapid-decay type and showed large-amplitude (~2mag) and short-term (~10 min-3 h) optical variations even at low luminosity (0.01-0.1LEdd). We found correlated optical and X-ray variations in two ~1 h time intervals and obtained a Bayesian estimate of an X-ray delay against the optical emission, which is ~30-50 s, during those two intervals. In addition, the relationship between the optical and X-ray luminosities was Lopt ∝ LX0.25-0.29 at that time. These features cannot be easily explained by the conventional picture of transient black hole binaries, such as canonical disc reprocessing and synchrotron emission related to a jet. We suggest that the disc was truncated during those intervals and that the X-ray delays represent the required time for the propagation of mass accretion flow to the inner optically thin region with a speed comparable to the free-fall velocity.

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U2 - 10.1093/MNRAS/STX1555

DO - 10.1093/MNRAS/STX1555

M3 - Article

AN - SCOPUS:85051203942

SN - 0035-8711

VL - 471

SP - 373

EP - 382

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1

ER -

Rapid optical variations correlated with X-rays in the 2015 second outburst of V404 Cygni (GS 2023+338)

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