Timing Analysis of V404 Cyg during Its Brightest Outburst with INTEGRAL/SPI

Journal Article · Tue Oct 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA89EA· OSTI ID:22875721

Rodi, J.; Jourdain, E.; Roques, J. P. ^[1]

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1. Université de Toulouse, UPS-OMP, IRAP Toulouse (France)

The outburst of V404 Cyg during the summer of 2015 reached unparalleled intensities at X-ray and soft gamma-ray energies with fluxes >50 Crab in the 20–50 keV energy band. To date, studies in the hard X-ray/soft gamma-ray energy domain have focused primarily on the energy spectra. In this work, a timing analysis has been performed with INTEGRAL/SPI data in the 20–300 keV energy range for INTEGRAL revolution 1557, which corresponds to the brightest flare of V404 Cyg (on 2015 June 26). The power spectra are fit with broken power-law and multi-Lorentzian models and compared with previously reported results of V404 Cyg flaring activity from 1989 and 2015. Also, we took advantage of the good signal-to-noise ratio obtained above 70 keV to quantify the timing/fast-variability properties of the source as a function of energy. We then point out similarities of V404 Cyg with the black hole transient V4641 Sgr. Like V4641 Sgr, we found that the power spectra of V404 Cyg during high flux periods did not possess the expected flat-top feature typically seen in a hard spectral state. Interpretations are proposed in the framework of the fluctuating-propagation model to explain the observed properties.

• OSTI ID: 22875721
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 848; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
COMPARATIVE EVALUATIONS
ENERGY DEPENDENCE
ENERGY SPECTRA
GAMMA RADIATION
HARD X RADIATION
KEV RANGE
SIGNAL-TO-NOISE RATIO
STARS