ALMA observations of A0620-00: fresh clues on the nature of quiescent black hole X-ray binary jets

Abstract

We report on ALMA continuum observations of the black hole X-ray binary A0620-00, at an X-ray luminosity nine orders of magnitude sub-Eddington. The system was significantly detected at 98 GHz (at $44\pm 7\mu \mathrm{Jy}$) and only marginally at 233 GHz ($20\pm 8\mu \mathrm{Jy}$), about 40 days later. These results suggest either an optically thin sub-mm synchrotron spectrum, or highly variable sub-mm jet emission on month timescales. Although the latter appears more likely, we note that, at the time of the ALMA observations, A0620-00 was in a somewhat less active optical-IR state than during all published multi-wavelength campaigns when a flat-spectrum, partially self-absorbed jet has been suggested to extend from the radio to the mid-IR regime. Either interpretation is viable in the context of an internal shock model, where the jet's spectral shape and variability are set by the power density spectrum of the shells' Lorentz factor fluctuations. While strictly simultaneous radio-mm-IR observations are necessary to draw definitive conclusions for A0620-00, the data presented here, in combination with recent radio and sub-mm results from higher luminosity systems, demonstrate that jets from black hole X-ray binaries exhibit a high level of variability - either in flux density or intrinsic spectral shape, or both - across a wide spectrum of Eddington ratios. This is not in contrast with expectations from an internal shock model, where lower jet power systems can be expected to exhibit larger fractional variability owing to an overall decrease in synchrotron absorption.

Accepted by MNRAS

References in corpus (19)

• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• Jet-dominated advective systems: radio and X-ray luminosity dependence on the accretion rate
• The radio/X-ray domain of black hole X-ray binaries at the lowest radio luminosities
• Revisiting the radio/X-ray flux correlation in the black hole V404 Cyg: from outburst to quiescence
• The spectral energy distribution of quiescent black hole X-ray binaries: new constraints from Spitzer
• The spectral energy distribution of compact jets powered by internal shocks
• The 2015 Decay of the Black Hole X-ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition into Quiescence
• The Eccentric Accretion Disc of the Black Hole A0620-00
• Constraints on Relativistic Jets in Quiescent Black Hole X-ray Binaries from Broadband Spectral Modeling
• Zooming in on a sleeping giant: milliarcsecond HSA imaging of the black hole binary V404 Cyg in quiescence
• Multiwavelength observations of the black hole X-ray binary A0620-00 in quiescence
• The First Simultaneous X-Ray/Radio Detection of the First Be/BH System MWC 656
• Radio Variability from a Quiescent Stellar Mass Black Hole Jet
• A new method for extending solutions to the self-similar relativistic magnetohydrodynamics equations for black hole outflows
• Sub-mm Jet Properties of the X-Ray Binary Swift J1745$-$26
• Polarized synchrotron emission in quiescent black hole X-ray transients
• Optical Precursors to Black Hole X-ray Binary Outbursts: An evolving synchrotron jet spectrum in Swift J1357.2-0933
• The mass of the black hole in 1A 0620-00, revisiting the ellipsoidal light curve modeling
• Simultaneous multiwavelength observations of V404 Cygni during its 2015 June outburst decay strengthen the case for an extremely energetic jet-base

Cited by in corpus (9)

• The hybrid radio/X-ray correlation of the black hole transient MAXI J1348-630
• Multi-wavelength emission from magnetically arrested disks around isolated black holes
• Toward a Larger Sample of Radio Jets from Quiescent Black Hole X-ray Binaries
• The flickering radio jet from the quiescent black hole X-ray binary A0620-00
• The Origin of Radio Emission in Black Hole X-ray Binaries
• An Observational Signature of Sub-Equipartition Magnetic Fields in the Spectra of Black Hole Binaries
• The Disk Veiling Effect of the Black Hole Low-Mass X-ray Binary A0620-00
• Scale-invariance of black hole accretion: modeling emission from a black hole X-ray binary with relativistic accretion flow simulations
• The black hole X-ray binary MAXI J1348$-$630 in quiescence