Quenching of the radio jet during the X-ray high state of GX 339-4

We have observed the black hole candidate X-ray binary GX 339-4 at radio wavelengths before, during and after the 1998 high/soft X-ray state transition. We find that the radio emission from the system is strongly correlated with the hard X-ray emission and is reduced by a factor > 25 during the high/soft state compared to the more usual low/hard state. At the points of state transition we note brief periods of unusually optically-thin radio emission which may correspond to discrete ejection events. We propose that in the low/hard state black hole X-ray binaries produce a quasi-continuous outflow, in the high/soft state this outflow is suppressed, and that state transitions often result in one or more discrete ejection events. Future models for low/hard states, such as ADAF/ADIOS solutions, need to take into account strong outflow of relativistic electrons from the system. We propose that the inferred Comptonising corona and the base of the jet-like outflow are the same thing, based upon the strong correlation between radio and hard X-ray emission in GX 339-4 and other X-ray binaries, and the similarity in inferred location and composition of these two components.Comment: Accepted for publication in ApJ Letter

Low Frequency Radio Observations of GRS1915+105 with GMRT

We present the first detailed low frequency radio measurements of the galactic microquasar GRS1915+105 with GMRT. Simultaneous observations were carried out at 610 and 244 MHz. Our data does not show any signature of spectral turn over even at low radio frequency of 244 MHz. We propose that while the radio emission at high radio frequencies could predominantly come from compact jets, the emission at lower frequency originates in the lobes at the end of the jet which acts like a reservoir of low energy electrons.Comment: 7 pages, 3 figure

Études spectro-temporelles de microquasars en rayons X (oscillations quasi-périodiques et couplage accrétion-éjection)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Spectral variability of Cygnus X-1 during an intermediate state

We report the results of a simultaneous radio (Ryle telescope) and hard X-ray INTEGRAL observation of Cygnus X-1 during an intermediate state. During the 4 day long observation the broad band (3-200 keV) luminosity varied by up to a factor of 2.6 and the source showed an important spectral variability. A principal component analysis demonstrates that most of this variability occurs through 2 independent modes. The first mode consists in changes in the overall luminosity on time scale of hours with almost constant spectra (responsible for 68% of the variance). We interpret this variability mode as variations of the dissipation rate in the corona, possibly associated with magnetic flares. The second variability mode consists in a pivoting of the spectrum around ~10 keV (27% of the variance). It acts on a longer time-scale: initially soft, the spectrum hardens in the first part of the obervation and then softens again. This pivoting pattern is strongly correlated with the radio (15 GHz) emission: radio fluxes are stronger when the INTEGRAL spectrum is harder. We propose that the pivoting mode represents a "mini" state transition from a nearly High Soft State to a nearly Low Hard State, and back. This mini-transition would be caused by changes in the soft cooling photons flux in the hot Comptonising plasma associated with an increase of the temperature of the accretion disc. The jet power then appears to be anti-correlated with the disc luminosity and unrelated to the coronal power

UvA-DARE (Digital Academic Repository) Link to publication Citation for published version (APA): QUENCHING OF THE RADIO JET DURING THE X-RAY HIGH STATE OF GX 339Ϫ4

Quenching of the radio jet during the x-ray high state in GX 339-4 Fender, R.P.; Corbel, S.; Tzioumis, A.K.; Sood, R.; McIntyre, V.; Campbell-Wilson, D.; Durouchoux, P.; Harmon, B.A. Published in: Astrophysical Journal DOI: 10.1086/312128 Link to publication Citation for published version (APA): Fender, R. P., Corbel, S., Tzioumis, A. K., Sood, R., McIntyre, V., Campbell-Wilson, D., ... Harmon, B. A. (1999). Quenching of the radio jet during the x-ray high state in GX 339-4. Astrophysical Journal, 519, L165-L168. https://doi.org/10.1086/312128 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 29 Jun 2019 L165 The Astrophysical Journal, 519:L165-L168, 1999 July 10 ᭧ 1999. The American Astronomical Society. All rights reserved. Printed in U.S.A. ABSTRACT We have observed the black hole candidate X-ray binary GX 339Ϫ4 at radio wavelengths before, during, and after the 1998 high/soft X-ray state transition. We find that the radio emission from the system is strongly correlated with the hard X-ray emission and is reduced by a factor of ≥25 during the high/soft state compared with the more usual low/hard state. At the points of state transition, we note brief periods of unusually optically thin radio emission that may correspond to discrete ejection events. We propose that in the low/hard state, black hole X-ray binaries produce a quasi-continuous outflow, that in the high/soft state, this outflow is suppressed, and that state transitions often result in one or more discrete ejection events. Future models for low/hard states, such as advection-dominated solutions, need to take into account the strong outflow of relativistic electrons from the system. We propose that the inferred Comptonizing corona and the base of the jetlike outflow are the same thing, based on the strong correlation between radio and hard X-ray emission in GX 339Ϫ4 and other X-ray binaries and on the similarity in inferred location and composition of these two components. QUENCHING OF THE RADIO JET DURING THE X-RAY HIGH STATE OF GX 339Ϫ