Detection of Very Low-frequency, Quasi-periodic Oscillations in the 2015 Outburst of V404 Cygni
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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2017
- DOI:
- 10.3847/1538-4357/834/1/90
- arXiv:
- arXiv:1610.08653
- Bibcode:
- 2017ApJ...834...90H
- Keywords:
-
- methods: statistical;
- relativistic processes;
- stars: black holes;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 17 pages, 9 figures, published in ApJ