Tracking optical variability and outflows across the accretion states of the black hole transient MAXI J1820+070

Abstract

We present a study of the minute-timescale optical variability and spectroscopic outflow signatures in the black hole X-ray binary MAXI J1820+070 during its 2018 outburst and re-brightenings. Minute-cadence, multi-filter optical light curves were obtained with the Las Cumbres Observatory network and the Al Sadeem Observatory (UAE) over 2018-2020, complemented by X-ray data from Swift/BAT, XRT, and MAXI. We also acquired contemporaneous low-resolution optical spectra with the 2.1 m OAN San Pedro Martir and OAGH Cananea telescopes (Mexico) and the 1.5 m G.D. Cassini telescope at Loiano (Italy). The optical fractional rms peaks in the hard state and is dominated by short-timescale flickering that strengthens toward longer wavelengths, suggesting that the variability is jet-driven. In this scenario, inflow fluctuations inject velocity perturbations at the jet base (internal shock model). The variability is quenched in the soft state, with any residual signal likely linked to accretion-flow fluctuations. This behaviour supports the accretion-ejection coupling in black hole binaries and shows that the jet's variability signature extends to optical wavelengths in all hard states. In the faintest hard states, residual optical variability may instead trace cyclo-synchrotron emission from the hot flow. The spectra show double-peaked emission lines and tentative cold-wind signatures during the hard state. Such winds were reported during the main 2018 outburst; here we find evidence of their presence also in later re-brightenings. Their absence in the soft state likely reflects stronger disc ionisation from the higher X-ray flux, suppressing low-ionisation optical features.

Accepted for publication in A&A

References in corpus (41)

• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• The corona contracts in a black-hole transient
• Global optical/infrared - X-ray correlations in X-ray binaries: quantifying disc and jet contributions
• Geometrical constraints on the origin of timing signals from black holes
• An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070
• A radio parallax to the black hole X-ray binary MAXI J1820+070
• Hot accretion flow in black hole binaries: a link connecting X-rays to the infrared
• The binary mass ratio in the black hole transient MAXI J1820+070
• Rapid optical and X-ray timing observations of GX 339-4: flux correlations at the onset of a low/hard state
• The spectral energy distribution of compact jets powered by internal shocks
• Insight-HXMT observations of jet-like corona in a black hole X-ray binary MAXI J1820+070
• Hard-state accretion disk winds from black holes: the revealing case of MAXI J1820+070
• An overview of jets and outflows in stellar mass black holes
• X-ray and Optical Monitoring of State Transitions in MAXI J1820+070
• Measuring fundamental jet properties with multi-wavelength fast timing of the black hole X-ray binary MAXI J1820+070
• The Soft State of the Black Hole Transient Source MAXI J1820+070: Emission from the Edge of the Plunge Region?
• Relativistic X-ray jets from the black hole X-ray binary MAXI J1820+070
• Near-infrared emission lines trace the state-independent accretion disc wind of the black hole transient MAXI J1820+070
• Optical precursors to X-ray binary outbursts
• Rapid compact jet quenching in the Galactic black hole candidate X-ray binary MAXI J1535-571
• A Black Hole X-ray Binary at $\sim$100 Hz: Multiwavelength Timing of MAXI J1820+070 with HiPERCAM and NICER
• Lorentz Factors of compact jets in Black hole X-ray binaries
• Multiwavelength Observations of EXO 0748-676 - I. Reprocessing of X-ray Bursts
• A shared accretion instability for black holes and neutron stars
• Multi-Wavelength Variability. Accretion and Ejection at the Fastest Timescales
• Hard-state optical wind during the discovery outburst of the black-hole X-ray dipper MAXI J1803-298
• Enhanced optical activity 12 days before X-ray activity, and a 4 day X-ray delay during outburst rise, in a low-mass X-ray binary
• Discovery of optical outflows and inflows in the black hole candidate GRS 1716-249
• Internal shocks driven by accretion flow variability in the compact jet of the black hole binary GX 339-4
• Discovery of optical and infrared accretion disc wind signatures in the black hole candidate MAXI J1348-630
• Fast infrared variability from the black-hole candidate MAXI J1535$-$571 and tight constraints on the modelling
• Physical constraints from near-infrared fast photometry of the black-hole transient GX 339-4
• The Evolution of Rapid Optical/X-ray Timing Correlations in the Initial Hard State of MAXI J1820+070
• Chasing the break: Tracing the full evolution of a black hole X-ray binary jet with multi-wavelength spectral modeling
• Multiwavelength observations of MAXI J1820+070 during its outburst decay and subsequent mini-outburst
• A multi-wavelength study of the hard and soft states of MAXI J1820+070 during its 2018 outburst
• Testing jet geometries and disk-jet coupling in the neutron star LMXB 4U 0614+091 with the internal shocks model
• Multi-wavelength view of the galactic black-hole binary GRS 1716-249
• Fast X-ray/IR observations of the black hole transient Swift~J1753.5--0127: from an IR lead to a very long jet lag
• The Accretion-Ejection Connection in the Black Hole X-ray Binary MAXI J1820$+$070
• Optical and X-ray timing analysis of the 2018-2020 outburst and rebrightening of the black-hole transient MAXI J1820+070

Cited by in corpus (1)

• Accretion disc winds in X-ray binaries