J/ApJ/874/13ivo://CDS.VizieR/J/ApJ/874/13doi:10.26093/cds/vizier.18740013CDSPlotkin R.M.Miller-Jones J.C.A.Chomiuk L.Strader J.Bruzewski S.,Bundas A.Smith K.R.Ruan J.J.2021-03-23T12:18:09Z2020-09-09T12:49:37ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frx-ray-binary-starsblack-holesradio-sourcesRelativistic outflows are believed to be a common feature of black hole X-ray binaries (BHXBs) at the lowest accretion rates, when they are in their "quiescent" spectral state. However, we still lack a detailed understanding of how quiescent jet emission varies with time. Here we present 24yr of archival radio observations (from the Very Large Array and the Very Long Baseline Array) of the BHXB V404 Cygni in quiescence (totaling 150 observations from 1.4 to 22GHz). The observed flux densities follow lognormal distributions with means and standard deviations of (<logf{nu}>,{sigma}_logf{nu}_)=(-0.53,0.19) and (-0.53,0.30) at 4.9 and 8.4GHz, respectively (where f{nu} is the flux density in units of mJy). As expected, the average radio spectrum is flat with a mean and standard deviation of (<{alpha}_r_,{sigma}_{alpha}r_)=(0.02,0.65), where f{nu}{propto}{nu}^{alpha}_r_^. We find that radio flares that increase the flux density by factors of 2-4 over timescales as short as <10 minutes are commonplace, and that long-term variations (over 10-4000 day timescales) are consistent with shot-noise impulses that decay to stochastic variations on timescales <~10 days (and perhaps as short as tens of minutes to several hr). We briefly compare the variability characteristics of V404 Cygni to jetted active galactic nuclei, and we conclude with recommendations on how to account for variability when placing quiescent BHXB candidates with radio luminosities comparable to V404 Cygni (L_R_~10^28^erg/s) onto the radio/X-ray luminosity plane.2019ApJ...874...13Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/874/13CatalogResearchIsServedByTAP VizieR generic servicerelated-toVIII/99 : Catalogue of Radio Stars (Wendker, 2001)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)J/A+A/493/339 : XMM-Newton serendipitous Survey. V. (Watson+, 2009)J/AJ/138/1874 : MOJAVE. VI. Kinematic analysis of blazar jets (Lister+, 2009)J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)J/MNRAS/428/2500 : GX 339-4 radio/X-ray flux correlation (Corbel+, 2013)J/ApJ/764/135 : Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)J/ApJS/210/18 : X-ray survey of the Galactic Bulge (CXOGBS) (Jonker+, 2014)J/BaltA/24/395 : X-ray and radio sources in binaries (Malkov+, 2015)J/A+A/587/A61 : BlackCAT, stellar-mass BH in X-ray (Corral-Santana+, 2016)J/ApJ/826/37 : Fermi/GBM obs. of V404 Cygni 2015 outburst (Jenke+, 2016)J/ApJS/222/15 : WATCHDOG: an all-sky database of Gal. BHXBs (Tetarenko+, 2016)J/MNRAS/471/1468 : Transient BH X-ray binaries XMM obs. (Eckersall+, 2017)J/ApJ/853/150 : Spectral analysis of low-mass X-ray binaries (Sonbas+, 2018)J/ApJ/869/171 : Chandra observations of NuSTAR sources (Tomsick+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/874/13https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/874/13http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/874/13https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/874/13https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/874/13http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/874/13GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/ApJ/874/13/table2Catalog of radio observationsPIDProgram identifiermeta.id;obscharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs[1991/2015] Year of observationtime.epochMJD[48524.9/57239.2] Modified Julian daydtime.epochdoubleConfigConfiguration (1)phys.atmol.configuration;instr.setupcharTos[4.2/540] Dwell time on V404 Cygnimintime.epochfloatFreq[1.4/22.5] Central observing frequencyGHzem.freqfloatl_fnuUpper limit flag on fnumeta.code.errorcharfnu[0.1/37]? Flux density or 5{sigma} upper limitmJyphot.flux.density;em.radiofloatnullablee_fnu[0.005/0.18]? Error in fnumJystat.errorfloatnullablel_Sp+IndexLimit flag on Sp+Indexmeta.code.errorcharSp+Index[-1.97/1.8]? Spectral index alpha (f_{nu}_~{nu}^+alpha^)pos.eq.rafloatnullablee_Sp+Index[0.03/0.44]? Error in Sp+Indexstat.errorfloatnullableFluxcalSource used for flux calibration (3C286 or 3C48)meta.idcharPhasecalSource used to solve complex gains (2007+404, 2023+318 or 2025+337)meta.idcharPIPrincipal investigator of VLA programobs.observerchar