NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITH<i>NuSTAR</i>

Bachetti, Matteo; Harrison, Fiona A.; Cook, Rick; Tomsick, John A.; Schmid, Christian; Grefenstette, Brian W.; Barret, D.; Boggs, Steven E.; Christensen, Finn Erland; Craig, William W.; Fabian, A. C.; Fürst, Felix; Gandhi, P.; Hailey, Charles J.; Kara, Erin; Maccarone, Thomas J.; Miller, J. M.; Pottschmidt, K.; Stern, Daniel; Uttley, P.; Walton, D. J.; Wilms, J.; Zhang, William W.

doi:10.1088/0004-637x/800/2/109

Cited by 92 publications

(94 citation statements)

References 73 publications

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“…Timing analysis of NuSTAR observations I-IV is presented by Bachetti et al (2015). The power spectral density (PSD) between 0.001-200 Hz is consistent with typical hard-state PSDs and is described well by three Lorentzian components (see, e.g., Belloni et al 2005).…”

Section: Nustarmentioning

confidence: 56%

THE COMPLEX ACCRETION GEOMETRY OF GX 339–4 AS SEEN BYNuSTARANDSWIFT

Fürst

Nowak

Tomsick

et al. 2015

ApJ

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110

108

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We present spectral analyses of five Nuclear Spectroscopic Telescope Array and Swift observations of GX 339-4 taken during a failed outburst during the summer of 2013. These observations cover Eddington luminosity fractions in the range ≈0.9%-6%. Throughout this outburst GX 339-4 stayed in the hard state and all five observations show similar X-ray spectra, with a hard power law with a photon index near 1.6, and significant contribution from reflection. Using simple reflection models we find unrealistically high iron abundances. Allowing for different photon indices for the continuum incident on the reflector relative to the underlying observed continuum results in a statistically better fit and reduced iron abundances. With a photon index around 1.3, the input power law on the reflector is significantly harder than that which is directly observed. We study the influence of different emissivity profiles and geometries and consistently find an improvement when using separate photon indices. The inferred inner accretion disk radius is strongly model dependent, but we do not find evidence for a truncation radius larger than r 100 g in any model. The data do not allow independent spin constraints, but the results are consistent with the literature (i.e., a 0 > ). Our best-fit models indicate an inclination angle in the range 40°-60°, consistent with limits on the orbital inclination but higher than reported in the literature using standard reflection models. The iron line around 6.4 keV is clearly broadened, and we detect a superimposed narrow core as well. This core originates from a fluorescent region outside the influence of the strong gravity of the black hole. Additionally, we discuss possible geometries.

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Section: Nustarmentioning

confidence: 56%

THE COMPLEX ACCRETION GEOMETRY OF GX 339–4 AS SEEN BYNuSTARANDSWIFT

Fürst

Nowak

Tomsick

et al. 2015

ApJ

Self Cite

110

108

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“…For the NuSTAR observation, we used the technique described by Bachetti et al (2015) to calculate the cospectrum, a proxy of the power density spectrum, to account for the wellknown effects of the NuSTAR instrumental dead time. We obtained light curves with a bin time of 0.025 s separately for the focal plane modules A and B, calculated the Fourier transform on each detector, produced the cross-power density spectrum and took the real part of it, normalized following Belloni & Hasinger (1990a).…”

Section: Analysis Methodsmentioning

confidence: 99%

“…Since the frequencies involved are well below 100 Hz, we then corrected the measured rms by dividing it by the ratio between incident and detected photons as described in Bachetti et al (2015).…”

Section: Analysis Methodsmentioning

confidence: 99%

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

Huppenkothen

Younes

Ingram

et al. 2017

ApJ

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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.

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“…For the NuSTAR data, these are actually cospectra between the two focal plane modules or FPMs. The cospectrum is the real component of the cross spectrum between the two X--ray detectors 13 , employed as a means to cancel dead time distortions to the PSDs. Both the optical and X--ray PSDs were computed using light curve segments of duration 512 s, and we restrict analysis for both energies to the Nyquist frequency of the optical of ≈13.5 Hz after mild frequency binning.…”

Section: Power Spectramentioning

confidence: 99%

“…For further details on the procedure, see ref. 13 for details on NuSTAR PSD extraction, and ref. 5 for details on the optical PSDs of V404 Cygni.…”

Section: Power Spectramentioning

confidence: 99%

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

et al. 2017

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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...

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NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITHNuSTAR

Cited by 92 publications

References 73 publications

THE COMPLEX ACCRETION GEOMETRY OF GX 339–4 AS SEEN BYNuSTARANDSWIFT

THE COMPLEX ACCRETION GEOMETRY OF GX 339–4 AS SEEN BYNuSTARANDSWIFT

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

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

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