Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 2019 | Published
Journal Article Open

Tracking the variable jets of V404 Cygni during its 2015 outburst

Abstract

We present multifrequency monitoring observations of the black hole X-ray binary V404 Cygni throughout its 2015 June outburst. Our data set includes radio and mm/sub-mm photometry, taken with the Karl G. Jansky Very Large Array, Arc-Minute MicroKelvin Imager Large Array, Sub-millimeter Array, James Clerk Maxwell Telescope, and the Northern Extended Millimetre Array, combined with publicly available infrared, optical, UV, and X-ray measurements. With these data, we report detailed diagnostics of the spectral and variability properties of the jet emission observed during different stages of this outburst. These diagnostics show that emission from discrete jet ejecta dominated the jet emission during the brightest stages of the outburst. We find that the ejecta became fainter, slower, less frequent, and less energetic, before the emission transitioned (over 1–2 d) to being dominated by a compact jet, as the outburst decayed towards quiescence. While the broad-band spectrum of this compact jet showed very little evolution throughout the outburst decay (with the optically thick to thin synchrotron jet spectral break residing in the near-infrared/optical bands; ∼2–5 × 10^(14) Hz), the emission still remained intermittently variable at mm/sub-mm frequencies. Additionally, we present a comparison between the radio jet emission throughout the 2015 and previous 1989 outbursts, confirming that the radio emission in the 2015 outburst decayed significantly faster than in 1989. Lastly, we detail our sub-mm observations taken during the 2015 December mini-outburst of V404 Cygni, which demonstrate that, similar to the main outburst, the source was likely launching jet ejecta during this short period of renewed activity.

Additional Information

© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2018 October 12. Received 2018 October 10; in original form 2018 June 8. Published: 23 October 2018. The authors thank the anonymous referee for constructive feedback that improved the manuscript. We wish to sincerely thank all the National Radio Astronomy Observatory, SMA, JCMT, and IRAM NOEMA staff that supported us during this observing campaign. The authors also offer a special thanks to the IRAM NOEMA Director, Karl-Fredrich Schuster, for granting our NOEMA DDT request. AJT thanks Craig Heinke and Bailey Tetarenko for useful discussions on accretion disc contributions in broad-band spectra of X-ray binaries. AJT is supported by an Natural Sciences and Engineering Research Council of Canada (NSERC) Post-Graduate Doctoral Scholarship (PGSD2-490318-2016). AJT and GRS are supported by NSERC Discovery Grants. JCAMJ is the recipient of an Australian Research Council Future Fellowship (FT140101082). SBM acknowledges support from VICI grant Nr. 639.043.513/520, funded by the Netherlands Organisation for Scientific Research (NWO). TDR acknowledges support from the NWO Veni Fellowship, grant number 639.041.646. DA acknowledges support from the Royal Society. This work is based on observations carried out under project numbers S15DE and D15AB with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the engineers and staff of the Mullard Radio Astronomy Observatory for maintenance and operation of AMI, which is supported by the Universities of Cambridge and Oxford. The AMI telescope acknowledges support from the European Research Council under grant ERC-2012-StG-307215 LODESTONE. The SMA is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, and is funded by the Smithsonian Institution and the Academia Sinica. The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan; Academia Sinica Institute of Astronomy and Astrophysics; the Korea Astronomy and Space Science Institute; the Operation, Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments, budgeted from the Ministry of Finance (MoF) of China and administrated by the Chinese Academy of Sciences (CAS), as well as the National Key R&D Program of China (No. 2017YFA0402700). Additional funding support is provided by the Science and Technology Facilities Council of the United Kingdom and participating universities in the United Kingdom and Canada. The authors also wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research.

Attached Files

Published - sty2853.pdf

Files

sty2853.pdf
Files (4.3 MB)
Name Size Download all
md5:985c43a876073216b3217d1ff1ed60de
4.3 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023