Simultaneous Multiwavelength Observations of V404 Cygni during its 2015 June Outburst Decay Strengthen the Case for an Extremely Energetic Jet-base

Maitra, D.; Scarpaci, John; Grinberg, V.; Reynolds, M. T.; Markoff, Sera; Maccarone, Thomas J.; Hynes, R. I.

doi:10.3847/1538-4357/aa98a0

Cited by 16 publications

(19 citation statements)

References 69 publications

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“…These results are also in agreement with the recent work of Maitra et al (2017), who present several lines of evidence to suggest that the optical emission was dominated by the compact jet on MJD 57200, and theorize the spectral break lies above the optical V band at this time (∼ 5.5 × 10 14 Hz). As the spectral break probes the jet base (where jet particles are first accelerated to high energies), Maitra et al (2017) theorize that a spectral break at such a high frequency suggests the jet base was very compact and energetic at this point in the outburst. If this is the case, our spectral break measurements imply these conditions persisted as the system faded toward quiescence.…”

Section: Compact Jet Behavioursupporting

confidence: 93%

“…For example, on MJD 57204 the sub-mm emission displays a large variability amplitude of F var ∼ 85%, while the epochs taken ∼ 24 hours prior to and following the MJD 57204 epoch, show little to no variability (see Figure 4). Maitra et al (2017) have suggested that strong optical frequency variability (also probing the jet base region, but closer to the black hole than probed by submm frequencies) occurring a few days earlier on MJD 57200, could be caused by a disruption in the feeding of the jet. In this situation, the mass outflow rate changes sporadically in response to a change in the mass inflow rate through the disc.…”

Section: Compact Jet Behaviourmentioning

confidence: 99%

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Tracking the variable jets of V404 Cygni during its 2015 outburst

Tetarenko

Sivakoff

Miller-Jones

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present multi-frequency monitoring observations of the black hole X-ray binary V404 Cygni throughout its June 2015 outburst. Our data set includes radio and mm/sub-mm photometry, taken with the Karl G. Jansky Very Large Array, Arc-Minute MicroKelvin Imager Large Array, Sub-millimeter Array, James Clerk Maxwell Telescope, and the Northern Extended Millimetre Array, combined with publicly available infrared, optical, UV, and X-ray measurements. With these data, we report detailed diagnostics of the spectral and variability properties of the jet emission observed during different stages of this outburst. These diagnostics show that emission from discrete jet ejecta dominated the jet emission during the brightest stages of the outburst. We find that the ejecta became fainter, slower, less frequent, and less energetic, before the emission transitioned (over 1-2 days) to being dominated by a compact jet, as the outburst decayed toward quiescence. While the broad-band spectrum of this compact jet showed very little evolution throughout the outburst decay (with the optically thick to thin synchrotron jet spectral break residing in the near-infrared/optical bands; ∼ 2 − 5 × 10 14 Hz), the emission still remained intermittently variable at mm/sub-mm frequencies. Additionally, we present a comparison between the radio jet emission throughout the 2015 and previous 1989 outbursts, confirming that the radio emission in the 2015 outburst decayed significantly faster than in 1989. Lastly, we detail our sub-mm observations taken during the December 2015 mini-outburst of V404 Cygni, which demonstrate that, similar to the main outburst, the source was likely launching jet ejecta during this short period of renewed activity.

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Section: Compact Jet Behavioursupporting

confidence: 93%

Section: Compact Jet Behaviourmentioning

confidence: 99%

Tracking the variable jets of V404 Cygni during its 2015 outburst

Tetarenko

Sivakoff

Miller-Jones

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…It has been found to reach more extreme values than other BHXBs, which exhibit an optically thick to optically thin jet synchrotron break at lower frequencies (Russell et al 2013). Maitra et al (2017) found evidence that the break frequency was higher than the optical frequencies during their observations at ∼MJD 57200. However, Russell et al (2013) during the 1989 outburst.…”

Section: Flares Displaying No Time Lagsmentioning

confidence: 89%

“…They found no lags or lags of only fractions of seconds to several seconds. Maitra et al (2017) did not find lags between their optical observations and the X-ray light curves during the June 2015 outburst and proposed the origin of the optical emission to be a compact region most likely originating in a jet outflow. Gandhi et al (2017) measured optical lags of 0.1 s in two epochs of their June 2015 observations, which they attributed to the elevation of the optical jet base of the system.…”

Section: Introductionmentioning

confidence: 93%

Optical/X-ray correlations during the V404 Cygni June 2015 outburst

Alfonso-Garzón

Sánchez–Fernández

Charles

et al. 2018

A&A

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Context. We present a multiwavelength analysis of the simultaneous optical and X-ray light curves of the microquasar V404 Cyg during the June 2015 outburst. Aims. We have performed a comprehensive analysis of all the INTEGRAL/IBIS, JEM–X, and OMC observations during the brightest epoch of the outburst, along with complementary NuSTAR, AAVSO, and VSNET data, to examine the timing relationship between the simultaneous optical and X-ray light curves, in order to understand the emission mechanisms and physical locations. Methods. We have identified all optical flares that have simultaneous X-ray observations, and performed a cross-correlation analysis to estimate the time delays between the optical and soft and hard X-ray emission. We also compared the evolution of the optical and X-ray emission with the hardness ratios. Results. We have identified several types of behaviour during the outburst. On many occasions, the optical flares occur simultaneously with X-ray flares, but at other times, positive and negative time delays between the optical and X-ray emission are measured. Conclusions. We conclude that the observed optical variability is driven by different physical mechanisms, including reprocessing of X-rays in the accretion disc and/or the companion star, interaction of the jet ejections with surrounding material or with previously ejected blobs, and synchrotron emission from the jet.

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“…Several lines of evidence suggest that, at least during the active state, the spectral properties of the radio jet in A0620-00 resemble those of higher Eddington ratios systems, such as V404 Cygni, where a partially self-absorbed synchrotron spectrum extends all the way from radio up to mid-IR wavelengths (e.g. Russell et al 2013a,b;Tetarenko et al 2015;Maitra et al 2017). Arguably the most compelling piece of evidence for this comes from broadband SED modelling.…”

Section: A0620-00's Jet: Spectral Extent and Variabilitymentioning

confidence: 99%

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

Gallo

Plotkin

Miller-Jones

et al. 2019

Monthly Notices of the Royal Astronomical Society

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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 ± 7 µJy) and only marginally at 233 GHz (20 ± 8 µJy), 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 flatspectrum, 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.

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Simultaneous Multiwavelength Observations of V404 Cygni during its 2015 June Outburst Decay Strengthen the Case for an Extremely Energetic Jet-base

Cited by 16 publications

References 69 publications

Tracking the variable jets of V404 Cygni during its 2015 outburst

Tracking the variable jets of V404 Cygni during its 2015 outburst

Optical/X-ray correlations during the V404 Cygni June 2015 outburst

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

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