A rapidly changing jet orientation in the stellar-mass black-hole system V404 Cygni

Abstract

Powerful relativistic jets are one of the main ways in which accreting black holes provide kinetic feedback to their surroundings. Jets launched from or redirected by the accretion flow that powers them should be affected by the dynamics of the flow, which in accreting stellarmass black holes has shown increasing evidence for precession 1 due to frame dragging effects that occur when the black hole spin axis is misaligned with the orbital plane of its companion star 2 . Recently, theoretical simulations have suggested that the jets can exert an additional torque on the accretion flow 3 , although the full interplay between the dynamics of the accretion flow and the launching of the jets is not yet understood. Here we report a rapidly changing jet orientation on a timescale of minutes to hours in the black hole X-ray binary V404 Cygni, detected with very long baseline interferometry during the peak of its 2015 outburst.We show that this can be modelled as Lense-Thirring precession of a vertically-extended slim disk that arises from the super-Eddington accretion rate 4 . Our findings suggest that the dynamics of the precessing inner accretion disk could play a role in either directly launching or redirecting the jets within the inner few hundred gravitational radii. Similar dynamics should be expected in any strongly-accreting black hole whose spin is misaligned with the inflowing gas, both affecting the observational characteristics of the jets, and distributing the black hole feedback more uniformly over the surrounding environment 5, 6 .During the 2015 outburst 7 of the black hole X-ray binary system V404 Cygni 8 , we conducted high-angular resolution radio monitoring with the Very Long Baseline Array (VLBA). Our obser-3 vations (Extended Data Table 1) spatially resolved the jets in this system, on size scales of up to 5 milliarcseconds (12 a.u. at the known distance of 2.39 ± 0.14 kpc 9 ; see examples in Figure 1).These jets evolved in both morphology and brightness on timescales of minutes.The orientation of the jets on the plane of the sky varied between epochs, ranging between −30.6°and +5.6°east of north (Figure 1, 2, and Extended Data Table 2). This range encompasses the orientation inferred from the position angle of the linearly-polarised radio emission 10 measured during the 1989 outburst (−16 ± 6°east of north; we state all uncertainties at 68% confidence) 11 .Moreover, during a period of intense radio and sub-millimetre flaring on June 22nd 12 , we observed multiple ejection events spanning a similar range of orientations over a single four-hour observation ( Figure 1), implying extremely rapid changes in the jet axis.The time-resolved images from June 22nd (see Supplementary Video) show a series of ballistically-moving ejecta that persist for tens of minutes before fading below the detection threshold of ≈ 10 mJy. The radio emission is dominated by a stationary core that is always present, allowing us to perform relative astrometry on the ejecta. The ejecta appear on both sides of the core, with prop...

NuSTAR Observations of the Transient Galactic Black Hole Binary Candidate Swift J1858.6–0814: A New Sibling of V404 Cyg and V4641 Sgr?

“…Given that the inclination of the inner accretion disk of J1858 appears to be low, this explanation appears less likely to be applicable to J1858. However, misalignments of ∼ 15 • between the orbit of the system and the inner accretion disk have been observed in Cygnus X-1 (see e.g., Tomsick et al 2014;Walton et al 2016) and even larger misalignments (possibly ∼ 30 • − 50 • ) have been observed in the two systems V4641 Sgr and V404 Cyg (Maccarone 2002;Miller-Jones et al 2019), which are very similar to J1858. Thus, the possibility of a large misalignment between the inclination of the orbit and inner accretion disk, leading to the obscuration of the inner regions of the accretion disk by a flared disk, cannot be entirely ruled out.…”

A review of quasi-periodic oscillations from black hole X-ray binaries: Observation and theory

“…Here, precession and disc rotation are both anti-clockwise. Adapted from an animation made by ICRAR in association with [144] (the original movie can be found at https: //vimeo.com/332582739).…”

“…Perhaps the most spectacular evidence of misalignment is the recent result of Miller-Jones et al [144], who used very long baseline interferometry to discover that the jets of V404 Cygni are precessing. The half opening angle of the precession cone is ∼ 18 • , and the precession period is in the range ∼ 1 second to 2.6 hours (the pattern of sampling makes it difficult to estimate the precession period, or even to conclusively confirm that that the changes in jet orientation are periodic).…”

Lorentz Factors of Compact Jets in Black Hole X-Ray Binaries

“…Moreover, there is increasing evidence that at least in some sources the inner disk is precessing (see for eg. Ogilvie & Dubus 2001;Liska et al 2018;Motta et al 2018b;Miller-Jones et al 2019) and perhaps that causes (some of) the discrepancy between inclinations measured through X-ray reflection models. On the other hand, the discrepancy in inclinations estimated from optical measurements is usually only a few degrees (Kreidberg et al 2012).…”