DETECTION OF VERY LOW-FREQUENCY, QUASI-PERIODIC OSCILLATIONS IN THE 2015 OUTBURST OF V404 CYGNI

• Published in: The Astrophysical journal 2017-01, Vol.834 (1), p.90
• Main Authors: Huppenkothen, D., Younes, G., Ingram, A., Kouveliotou, C., Göğüş, E., Bachetti, M., Sánchez-Fernández, C., Chenevez, J., Motta, S., van der Klis, M., Granot, J., Gehrels, N., Kuulkers, E., Tomsick, J. A., Walton, D. J.
• Format: Article
• Language: English
• Subjects: Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BINARY STARS; BLACK HOLES; Broadband; COSMIC X-RAY BURSTS; INCLINATION; methods: statistical; MHZ RANGE; OSCILLATIONS; PERIODICITY; Quasi-Periodic Oscillations; relativistic processes; RELATIVISTIC RANGE; stars: black holes; X RADIATION; X ray binaries; X ray stars; X-rays: binaries
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/834/1/90

ABSTRACT 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.