A Challenging View of the 2015 Summer V404 Cyg Outburst at High Energy With Integral/Spi: The Finale*

Jourdain, E.; Roques, J. P.; Rodi, J.

doi:10.3847/1538-4357/834/2/130

Cited by 25 publications

(31 citation statements)

References 18 publications

(18 reference statements)

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“…Many papers have dealt with the timing and spectral properties of the exceptional flares in different energy bands (e.g. Rodriguez et al 2015;Natalucci et al 2015;Roques et al 2015;Kimura et al 2015;Jenke et al 2016;Martí et al 2016;Gandhi et al 2016;Loh et al 2016;Jourdain et al 2017;Rodi et al 2017;Walton et al 2017;Motta et al 2017a;Sánchez-Fernández et al 2017;Maitra et al 2017;Tachibana et al 2017;Tetarenko et al 2017Tetarenko et al , 2019. Here in this paper we have focused instead on the optical study of the nebular phase and subsequent decay, with the aim of constraining the physics of the outflow.…”

Section: Discussionmentioning

confidence: 99%

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Accretion and outflow in V404 Cyg

Casares

Muñoz-Darias

Sánchez

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We study the optical evolution of the 2015 outburst in V404 Cyg, with emphasis on the peculiar nebular phase and subsequent decay to quiescence. From the decay timescale of the Balmer emission associated with the nebula we measure an outflow mass M wind 4 × 10 −6 M . Remarkably, this is ∼100 times larger than the accreted mass and ∼10% of the total mass stored in the disc. The wind efficiency must therefore be significantly larger than previous estimates for black hole transients, suggesting that radiation pressure (in addition to other mechanisms such as Compton-heating) plays a key role in V404 Cyg. In addition, we compare the evolution of the 2015 and 1989 outbursts and find clear similarities (namely a large luminosity drop ∼10 d after the X-ray trigger, followed by a brief nebular phase) but also remarkable differences in decay timescales and long-term evolution of the Hα profile. In particular, we see evidence for a rapid disc contraction in 2015, consistent with a burst of mass transfer. This could be driven by the response of the companion to hard X-ray illumination, most notably during the last gigantic (super-Eddington) flare on 25 June 2015. We argue that irradiation and consequential disc wind are key factors to understand the different outburst histories in 1989 and 2015. In the latter case, radiation pressure may be responsible for the abrupt end of the outburst through depleting inner parts of the disc, thus quenching accretion and X-ray irradiation. We also present a refined orbital period and updated ephemeris.

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Section: Discussionmentioning

confidence: 99%

“…After 12 days of frantic activity, and following a gigantic 8-hr flare that peaked above 50 Crab in hard X-rays, the outburst suddenly ended (Sánchez-Fernández et al 2017;Jourdain et al 2017). The rapid luminosity drop that followed revealed a brief nebular phase never seen before in any other BH XRT ; see also Rahoui et al 2017).…”

Section: Introductionmentioning

confidence: 97%

Accretion and outflow in V404 Cyg

Casares

Muñoz-Darias

Sánchez

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…During the 1989 outburst, short-term X-ray variability was observed (e.g., Życki et al 1999). On June 15th in 2015, it underwent a short outburst after 26 years of quiescence (Barthelmy et al 2015a) and showed large flares in radio (Mooley et al 2015;Tetarenko et al 2015), infrared (Tanaka et al 2016), optical (Rodriguez et al 2015;Martí et al 2016;Gandhi et al 2016), X-ray (King et al 2015;Natalucci et al 2015;Negoro et al 2015;Segreto et al 2015;Walton et al 2017;Radhika et al 2016;Jourdain et al 2017;Huppenkothen et al 2017) and gamma-ray wavelengths (Roques & Jourdain 2016;Siegert et al 2016;Jenke et al 2016;Loh et al 2016;Piano et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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

Kimura

Katô

Isogai

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present optical multi-colour photometry of V404 Cyg during the outburst from December, 2015 to January, 2016 together with the simultaneous X-ray data. This outburst occurred less than 6 months after the previous outburst in June-July, 2015. These two outbursts in 2015 were of a slow rise and rapid decay-type and showed large-amplitude (∼2 mag) and short-term (∼10 min-3 hours) optical variations even at low luminosity (0.01-0.1L Edd ). We found correlated optical and X-ray variations in two ∼1 hour 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 luminosity was L opt ∝ L 0.25−0.29 X 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 propagation of mass accretion flow to the inner optically-thin region with a speed comparable to the free-fall velocity.

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“…One example would be the microquasar V404 Cygni (e.g. Rodriguez et al 2015;Roques et al 2015;Siegert et al 2016a;Jourdain et al 2017Jourdain et al ) during revolutions 1554Jourdain et al -1557 activity, the variability of the sky emission is only subject to the physics of the sources themselves. This means that the change of the BG amplitude, θ k,t , depends on the process which resulted in the BG γ-ray photon.…”

Section: Spi Data Analysismentioning

confidence: 99%

Background modelling for γ-ray spectroscopy with INTEGRAL/SPI

Siegert

Diehl

Weinberger

et al. 2019

A&A

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Context. The coded-mask spectrometer-telescope SPI on board the INTErnational Gamma-Ray Astrophysics Laboratory (INTE-GRAL) records photons in the energy range between 20 and 8000 keV. A robust and versatile method to model the dominating instrumental background (BG) radiation is difficult to establish for such a telescope in the rapidly changing space environment. Aims. From long-term monitoring of SPI's Germanium detectors, we built up a spectral parameter data base (Diehl et al. 2018), which characterises the instrument response as well as the BG behaviour. We aim to build a self-consistent and broadly applicable BG model for typical science cases of INTEGRAL/SPI, based on this data base. Methods. The general analysis method for SPI relies on distinguishing between illumination patterns on the 19-element Germanium detector array from BG and sky in a maximum likelihood framework. We illustrate how the complete set of measurements, even including the exposures of the sources of interest, can be used to define a BG model. The observation strategy of INTEGRAL makes it possible to determine individual BG components, originating from continuum and γ-ray line emission. We apply our method to different science cases, including point-like, diffuse, continuum, and line emission, and evaluate the adequacy in each case. Results. From likelihood values and the number of fitted parameters, we determine how strong the impact of the unknown BG variability is. We find that the number of fitted parameters, i.e. how often the BG has to be re-normalised, depends on the emission type (diffuse with many observations over a large sky region, or point-like with concentrated exposure around one source), and the spectral energy range and bandwidth. A unique time scale, valid for all analysis issues, is not applicable for INTEGRAL/SPI, but must and can be inferred from the chosen data set. Conclusions. We conclude that our BG modelling method is usable in a large variety of INTEGRAL/SPI science cases, and provides nearly systematics-free and robust results.

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A Challenging View of the 2015 Summer V404 Cyg Outburst at High Energy With Integral/Spi: The Finale*

Cited by 25 publications

References 18 publications

Accretion and outflow in V404 Cyg

Accretion and outflow in V404 Cyg

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

Background modelling for γ-ray spectroscopy with INTEGRAL/SPI

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