Accretion and Outflow in V404 Cyg

Abstract

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~4x10^{-6} Msun. 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 Halpha 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.

Accepted for publication in MNRAS, 11 pages, 8 figures, 3 Tables

References in corpus (15)

• A rapidly-changing jet orientation in the stellar-mass black hole V404 Cygni
• Orbital Evolution of an Accreting Millisecond Pulsar: Witnessing the Banquet of a Hidden Black Widow?
• Repetitive Patterns in Rapid Optical Variations in the Nearby Black-hole Binary V404 Cygni
• The 2015 Decay of the Black Hole X-ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition into Quiescence
• Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion
• Flares, wind and nebulae: the 2015 December mini-outburst of V404 Cygni
• High-energy gamma-ray observations of the accreting black hole V404 Cygni during its June 2015 outburst
• Zooming in on a sleeping giant: milliarcsecond HSA imaging of the black hole binary V404 Cyg in quiescence
• The luminosity dependence of thermally-driven disc winds in low-mass X-ray binaries
• Mass transfer variation in the outburst model of dwarf novae and soft X-ray transients
• Radio Variability from a Quiescent Stellar Mass Black Hole Jet
• The nova-like nebular optical spectrum of V404 Cygni at the beginning of the 2015 outburst decay
• Simultaneous multiwavelength observations of V404 Cygni during its 2015 June outburst decay strengthen the case for an extremely energetic jet-base
• Timing Analysis of V404 Cyg during Its Brightest Outburst with INTEGRAL/SPI
• MITSuME observation of V404 Cygni in the 2015 outburst: Two optical variable components with different variability

Cited by in corpus (8)

• Near-infrared emission lines trace the state-independent accretion disc wind of the black hole transient MAXI J1820+070
• The impact of thermal winds on the outburst lightcurves of black hole X-ray binaries
• Discovery of optical outflows and inflows in the black hole candidate GRS 1716-249
• The origin of optical emission lines in the soft state of X-ray binary outbursts: the case of MAXI J1820+070
• Soft X-ray emission lines in the X-ray binary Swift J1858.6-0814 observed with XMM-Newton-RGS: disc atmosphere or wind?
• Rapid spectral transition of the black hole binary V404 Cyg
• On the wind-driven relaxation cycle in accretion disks
• Change in the orbital period of a binary system due to an outburst in a windy accretion disc