The flickering radio jet from the quiescent black hole X-ray binary A0620-00

Abstract

Weakly accreting black hole X-ray binaries launch compact radio jets that persist even in the quiescent spectral state, at X-ray luminosities <1e-5 of the Eddington luminosity. However, radio continuum emission has been detected from only a few of these quiescent systems, and little is known about their radio variability. Jet variability can lead to misclassification of accreting compact objects in quiescence, and affects the detectability of black hole X-ray binaries in next-generation radio surveys. Here we present the results of a radio monitoring campaign of A0620-00, one of the best-studied and least-luminous known quiescent black hole X-ray binaries. We observed A0620-00 at 9.8 GHz using the Karl G. Jansky Very Large Array on 31 epochs from 2017 to 2020, detecting the source ~75% of the time. We see significant variability over all timescales sampled, and the observed flux densities follow a lognormal distribution with a mean of 12.5 uJy and standard deviation of 0.22 dex. In no epoch was A0620-00 as bright as in 2005 (51 +/- 7 uJy), implying either that this original detection was obtained during an unusually bright flare, or that the system is fading in the radio over time. We present tentative evidence that the quiescent radio emission from A0620-00 is less variable than that of V404 Cyg, the only other black hole binary with comparable data. Given that V404 Cyg has a jet radio luminosity ~20 times higher than A0620-00, this comparison could suggest that less luminous jets are less variable in quiescence.

9 pages, 7 figures, accepted for publication in MNRAS

References in corpus (18)

• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• The radio/X-ray domain of black hole X-ray binaries at the lowest radio luminosities
• Hot accretion flow in black hole binaries: a link connecting X-rays to the infrared
• 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
• Measuring fundamental jet properties with multi-wavelength fast timing of the black hole X-ray binary MAXI J1820+070
• Zooming in on a sleeping giant: milliarcsecond HSA imaging of the black hole binary V404 Cyg in quiescence
• The observed mass distribution of Galactic black hole LMXBs is biased against massive black holes
• The First Simultaneous X-Ray/Radio Detection of the First Be/BH System MWC 656
• Multiwavelength observations of the black hole X-ray binary A0620-00 in quiescence
• Hibernating black holes revealed by photometric mass functions
• Radio & X-ray detections of GX 339--4 in quiescence using MeerKAT and Swift
• Radio Variability from a Quiescent Stellar Mass Black Hole Jet
• The MAVERIC Survey: Radio catalogs and source counts from deep Very Large Array imaging of 25 Galactic globular clusters
• GS 2000+25: The Least Luminous Black Hole X-ray Binary
• Toward a Larger Sample of Radio Jets from Quiescent Black Hole X-ray Binaries
• ALMA observations of A0620-00: fresh clues on the nature of quiescent black hole X-ray binary jets
• The MAVERIC survey: A catalogue of radio sources in southern globular clusters from the Australia Telescope Compact Array

Cited by in corpus (1)

• Quiescent black hole X-ray binaries as multi-messenger sources