HIGH-RESOLUTION
                    <i>CHANDRA</i>
                    HETG SPECTROSCOPY OF V404 CYGNI IN OUTBURST

King, A. L.; Miller, J. M.; Raymond, J. C.; Reynolds, M. T.; Morningstar, Warren R.

doi:10.1088/2041-8205/813/2/l37

Cited by 87 publications

(116 citation statements)

References 35 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…The small FWHM measured for the Iron-Kα line in our spectrum indicates that the line, as previously suggested by, e.g., Oosterbroek et al (1996) and King et al (2015), is likely produced far away from the central BH.…”

Section: Iron-kα Linesupporting

confidence: 76%

The black hole binary V404 Cygni: a highly accreting obscured AGN analogue

Motta

Kajava

Sánchez–Fernández

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Typical black hole binaries in outburst show spectral states and transitions, characterized by a clear connection between the inflow onto the black hole and outflows from its vicinity. The transient stellar mass black hole binary V404 Cyg apparently does not fit in this picture. Its outbursts are characterized by intense flares and intermittent plateau and low-luminosity states, with a dynamical intensity range of several orders of magnitude on time-scales of hours. During the 2015 June-July X-ray outburst a joint Swift and INTEGRAL observing campaign captured V404 Cyg in one of these plateau states. The simultaneous Swift/XRT and INTE-GRAL /JEM-X/ISGRI spectrum is reminiscent of that of obscured/absorbed AGN. It can be modelled as a Comptonization spectrum, heavily absorbed by a partial covering, high-column density material (N H ≈ 1 − 3 × 10 24 cm −2 ), and a dominant reprocessed component, including a narrow Iron-Kα line. Such spectral distribution can be produced by a geometrically thick accretion flow able to launch a clumpy outflow, likely responsible for both the high intrinsic absorption and the intense reprocessed emission observed. Similarly to what happens in certain obscured AGN, the low-flux states might not be (solely) related to a decrease in the intrinsic luminosity, but could instead be caused by an almost complete obscuration of the inner accretion flow.

show abstract

Section: Iron-kα Linesupporting

confidence: 76%

The black hole binary V404 Cygni: a highly accreting obscured AGN analogue

Motta

Kajava

Sánchez–Fernández

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…In summary, our estimates provide robust upper limits to the elevation of optical jet emission zone, to within correction factors of order unity. We finally note the presence of a significant disc wind that has been observed in V404 Cygni 24,25 . Detailed analysis of the cold (optically--emitting) phase of this wind places its formation region at the outer accretion disc, which has an extent of 10 12 cm.…”

Section: Power Spectramentioning

confidence: 66%

An elevation of 0.1 light-seconds for the optical jet base in an accreting Galactic black hole system

et al. 2017

View full text Add to dashboard Cite

Relativistic plasma jets are observed in many accreting black holes. According to theory, coiled magnetic fields close to the black hole accelerate and collimate the plasma, leading to a jet being launched 1-3 . Isolating emission from this acceleration and collimation zone is key to measuring its size and understanding jet formation physics. But this is challenging because emission from the jet base cannot be easily disentangled from other accreting components. Here, we show that rapid optical flux variations from a Galactic black--hole binary are delayed with respect to X--rays radiated from close to the black hole by ~0.1 seconds, and that this delayed signal appears together with a brightening radio jet. The origin of these sub--second optical variations has hitherto been controversial 4-8 . Not only does our work strongly support a jet origin for the optical variations, it also sets a characteristic elevation of ≲10 3 Schwarzschild radii for the main inner optical emission zone above the black hole 9 , constraining both internal shock 10 and magnetohydrodynamic 11 models. Similarities with blazars 12,13 suggest that jet structure and launching physics could potentially be unified under mass--invariant models. Two of the best--studied jetted black hole binaries show very similar optical lags 8,14,15 , so this size scale may be a defining feature of such systems. In June 2015, the Galactic X--ray binary V404 Cygni underwent the brightest outburst of an X-ray binary so far this century. We coordinated simultaneous optical observations from the William Herschel Telescope with X--ray observations from the NuSTAR space observatory on the morning of June 25. These were high frame--rate optical observations taken by the ULTRACAM instrument, sampling timescales down to 35.94 milliseconds (ms). Both optical and X--ray light curves show variability on a broad range of timescales characteristic of this source 15,16 (Fig. 1). The AMI telescope provided contiguous radio coverage throughout this period. Details of the observations may be found in Methods. These coordinated observations occurred on June 25, the day preceding the peak of the 2015 outburst. When the optical observations began, the X--ray intensity was two orders of magnitude below peak, and the spectrum was dominated by low--energy X--rays (i.e., it was in a state characterised as being relatively 'soft'). Steady, compact jet activity is not expected in such a state, and consistent with this, the radio spectral index is negative, as is typical of emission from discrete optically--thin ejecta. NuSTAR observations were interrupted about 2000 seconds later due to a period of Earth occultation, which separates the two halves (hereafter, 'epochs') of the sequence under consideration. At some point during this occultation, the source underwent a dramatic and very rapid change in its X--ray spectral state. When NuSTAR emerged from Earth occultation, the spectrum was instead found to have pivoted towards high energies, with a larger fraction of X--ray counts above 1...

show abstract

“…The observations with IDs 17696 and 17697 were taken on 2015 June 22, 13:39:21 UT and 2015 June 23, 21:25:32 UT, for a total of 21 and 25 ks, respectively (see also King et al 2015).…”

Section: Chandramentioning

confidence: 99%

“…The source's brightness required placement of the zeroth grating order off the CCD in order to protect the detector (see King et al 2015 for more details). At the same time, dithering produces a prominent QPO (visible both in the light curves as well as the periodograms at 746 s. Dithering mostly affects counts near the source (i.e., closer to the edges of the detector) and at higher energies.…”

Section: Chandramentioning

confidence: 99%

Detection of Very Low-Frequency, Quasi-Periodic Oscillations in the 2015 Outburst of V404 Cygni

Huppenkothen

Younes

Ingram

et al. 2017

ApJ

View full text Add to dashboard Cite

In 2015 June, the black hole X-ray binary (BHXRB) V404 Cygni went into outburst for the first time since 1989. Here, we present a comprehensive search for quasi-periodic oscillations (QPOs) of V404 Cygni during its recent outburst, utilizing data from six instruments on board five different X-ray missions: Swift/XRT, Fermi/GBM, Chandra/ACIS, INTEGRAL's IBIS/ISGRI and JEM-X, and NuSTAR. We report the detection of a QPO at 18 mHz simultaneously with both Fermi/GBM and Swift/XRT, another example of a rare but slowly growing new class of mHz-QPOs in BHXRBs linked to sources with a high orbital inclination. Additionally, we find a duo of QPOs in a Chandra/ACIS observation at 73 mHz and 1.03 Hz, as well as a QPO at 136 mHz in a single Swift/ XRT observation that can be interpreted as standard Type-C QPOs. Aside from the detected QPOs, there is significant structure in the broadband power, with a strong feature observable in the Chandra observations between 0.1 and 1 Hz. We discuss our results in the context of current models for QPO formation.

show abstract

HIGH-RESOLUTION CHANDRA HETG SPECTROSCOPY OF V404 CYGNI IN OUTBURST

Cited by 87 publications

References 35 publications

The black hole binary V404 Cygni: a highly accreting obscured AGN analogue

The black hole binary V404 Cygni: a highly accreting obscured AGN analogue

An elevation of 0.1 light-seconds for the optical jet base in an accreting Galactic black hole system

Detection of Very Low-Frequency, Quasi-Periodic Oscillations in the 2015 Outburst of V404 Cygni

Contact Info

Product

Resources

About