Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
An imperfect double: probing the physical origin of the low-frequency quasi-periodic oscillation and its harmonic in black hole binaries
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
2014 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 438, no 1, 657-662 p.Article in journal (Refereed) Published
Abstract [en]

We extract the spectra of the strong low-frequency quasi-periodic oscillation (QPO) and its harmonic during the rising phase of an outburst in the black hole binary XTE J1550-564. We compare these frequency-resolved spectra to the time-averaged spectrum and the spectrum of the rapid (<0.1 s) variability. The spectrum of the time-averaged emission can be described by a disc, a Compton upscattered tail and its reflection. The QPO spectrum is very similar to the spectrum of the most rapid variability, implying it arises in the innermost regions of the flow. It contains little detectable disc, and its Compton spectrum is generally harder and shows less reflection than in the time-averaged emission. The harmonic likewise contains little detectable disc component, but has a Compton spectrum which is systematically softer than the QPO, softer even than the Compton tail in the time-averaged emission. We interpret these results in the context of the truncated disc model, where the inner disc is replaced by a hot flow. The QPO can arise in this picture from vertical (Lense-Thirring) precession of the entire hot inner flow, and its harmonic can be produced by the angular dependence of Compton scattering within the hot flow. We extend these models to include stratification of the hot flow, so that it is softer (lower optical depth) at larger radii closer to the truncated disc, and harder (higher optical depth) in the innermost parts of the flow where the rapid variability is produced. The different optical depth with radius gives rise to different angular dependence of the Comptonized emission, weighting the fundamental to the inner parts of the hot flow, and the harmonic to the outer. This is the first model which can explain both the spectrum of the QPO, and its harmonic, in a self consistent geometry.

Place, publisher, year, edition, pages
2014. Vol. 438, no 1, 657-662 p.
Keyword [en]
accretion, accretion discs, X-rays: binaries, X-rays: individual: XTE J1550-564
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:su:diva-101241DOI: 10.1093/mnras/stt2236ISI: 000330457100067OAI: oai:DiVA.org:su-101241DiVA: diva2:703507
Note

AuthorCount:3;

Available from: 2014-03-07 Created: 2014-03-03 Last updated: 2017-12-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Axelsson, Magnus
By organisation
Department of AstronomyDepartment of PhysicsThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
In the same journal
Monthly notices of the Royal Astronomical Society
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 23 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf