The University of Southampton
University of Southampton Institutional Repository

A global spectral study of black hole x-ray binaries

A global spectral study of black hole x-ray binaries
A global spectral study of black hole x-ray binaries
We report on a consistent and comprehensive spectral analysis of the X-ray emission of 25 black hole X-ray binaries. All publicly available observations of the black hole binaries in the RXTE archive were analysed. Three different types of model were fitted to investigate the spectral changes occurring during an outburst. For the population, as well as for each binary and each outburst from each binary, we construct two diagnostic diagrams. The hardness intensity/luminosity diagram (HID/HLD), the X-ray colour against the flux/luminosity of the binary, is most useful when studying a single binary. However, to compare different binary systems, the disc fraction luminosity diagram (DFLD) is more useful. The DFLD uses the luminosities of the disc and power-law components to calculate the ratio of the disc luminosity to the total luminosity, resulting in a more physical value, which is analogous to the X-ray colour calculated for X-ray binaries. The tracks of the outbursts populate the DFLD more evenly than the HLD. We discuss the limitations of both diagnostic diagrams for the study of the X-ray binary outbursts and clearly illustrate how the two diagrams map on to each other for real outburst data. The similarity of the X-ray colour and disc fraction behaviour over time during an outburst originally seen in GX 339?4 data is seen in other sources' outbursts. We extract the peak luminosities in a single outburst, as well as the luminosities at the transitions away from and returning to the power-law-dominated state for each outburst. The distribution of the luminosities at the transition from the power-law to the disc-dominated state peaks at around 0.3LEdd , the same as the peak of the distribution of the peak luminosities in an outburst. Using the disc fraction to calculate the transition luminosities shows that the distributions of the luminosities for the transitions away from and returning to the power-law-dominated state are both broad and appear to overlap. Using the change in disc fraction to calculate the date when a transition occurred is not drastically different from obtaining the dates from changes in the timing behaviour of the X-ray binary. In addition, we calculate the rate of motion of an X-ray binary through the DFLD during an outburst, a diagnostic which has the potential to be used as a comparison with populations of active galactic nuclei. The fastest rate of motion is on the egress and ingress from the power-law-dominated state. A further region of increased speed through the diagram occurs in the disc-dominated state on the return to the power-law-dominated state. Finally, we compare the measured X-ray luminosities with a small number of contemporaneous radio measurements. Overall, this is the most comprehensive and uniform global study of black hole X-ray binaries to date.
accretion, accretion discs, binaries general, ISM, jets, outflows, x-rays
1365-2966
61-82
Dunn, R.J.H.
3fc1e745-8cef-42b9-b706-6498d8762d64
Fender, R.P.
c802ddfc-25a3-4c0e-899d-11c405c705d1
Körding, E.G.
9994d82a-6493-4d3e-9337-9096f74ac5d8
Belloni, T.
a6a0a7f0-68d9-411a-97ee-75479ce1aeac
Cabanac, C.
b1d189de-5db0-4ea3-aa26-075fdb280e2a
Dunn, R.J.H.
3fc1e745-8cef-42b9-b706-6498d8762d64
Fender, R.P.
c802ddfc-25a3-4c0e-899d-11c405c705d1
Körding, E.G.
9994d82a-6493-4d3e-9337-9096f74ac5d8
Belloni, T.
a6a0a7f0-68d9-411a-97ee-75479ce1aeac
Cabanac, C.
b1d189de-5db0-4ea3-aa26-075fdb280e2a

Dunn, R.J.H., Fender, R.P., Körding, E.G., Belloni, T. and Cabanac, C. (2010) A global spectral study of black hole x-ray binaries. Monthly Notices of the Royal Astronomical Society, 403 (1), 61-82. (doi:10.1111/j.1365-2966.2010.16114.x).

Record type: Article

Abstract

We report on a consistent and comprehensive spectral analysis of the X-ray emission of 25 black hole X-ray binaries. All publicly available observations of the black hole binaries in the RXTE archive were analysed. Three different types of model were fitted to investigate the spectral changes occurring during an outburst. For the population, as well as for each binary and each outburst from each binary, we construct two diagnostic diagrams. The hardness intensity/luminosity diagram (HID/HLD), the X-ray colour against the flux/luminosity of the binary, is most useful when studying a single binary. However, to compare different binary systems, the disc fraction luminosity diagram (DFLD) is more useful. The DFLD uses the luminosities of the disc and power-law components to calculate the ratio of the disc luminosity to the total luminosity, resulting in a more physical value, which is analogous to the X-ray colour calculated for X-ray binaries. The tracks of the outbursts populate the DFLD more evenly than the HLD. We discuss the limitations of both diagnostic diagrams for the study of the X-ray binary outbursts and clearly illustrate how the two diagrams map on to each other for real outburst data. The similarity of the X-ray colour and disc fraction behaviour over time during an outburst originally seen in GX 339?4 data is seen in other sources' outbursts. We extract the peak luminosities in a single outburst, as well as the luminosities at the transitions away from and returning to the power-law-dominated state for each outburst. The distribution of the luminosities at the transition from the power-law to the disc-dominated state peaks at around 0.3LEdd , the same as the peak of the distribution of the peak luminosities in an outburst. Using the disc fraction to calculate the transition luminosities shows that the distributions of the luminosities for the transitions away from and returning to the power-law-dominated state are both broad and appear to overlap. Using the change in disc fraction to calculate the date when a transition occurred is not drastically different from obtaining the dates from changes in the timing behaviour of the X-ray binary. In addition, we calculate the rate of motion of an X-ray binary through the DFLD during an outburst, a diagnostic which has the potential to be used as a comparison with populations of active galactic nuclei. The fastest rate of motion is on the egress and ingress from the power-law-dominated state. A further region of increased speed through the diagram occurs in the disc-dominated state on the return to the power-law-dominated state. Finally, we compare the measured X-ray luminosities with a small number of contemporaneous radio measurements. Overall, this is the most comprehensive and uniform global study of black hole X-ray binaries to date.

This record has no associated files available for download.

More information

Published date: 22 February 2010
Keywords: accretion, accretion discs, binaries general, ISM, jets, outflows, x-rays

Identifiers

Local EPrints ID: 147235
URI: http://eprints.soton.ac.uk/id/eprint/147235
ISSN: 1365-2966
PURE UUID: e5012703-d151-4d57-8f14-e06f06fc5b45

Catalogue record

Date deposited: 27 May 2010 15:48
Last modified: 14 Mar 2024 00:58

Export record

Altmetrics

Contributors

Author: R.J.H. Dunn
Author: R.P. Fender
Author: E.G. Körding
Author: T. Belloni
Author: C. Cabanac

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×