Kazan Federal University Digital Repository

Superorbital variability of X-ray and radio emission of Cyg X-1 - I. Emission anisotropy of precessing sources

Show simple item record

dc.contributor.author Ibragimov A.
dc.contributor.author Zdziarski A.
dc.contributor.author Poutanen J.
dc.date.accessioned 2018-09-18T20:31:14Z
dc.date.available 2018-09-18T20:31:14Z
dc.date.issued 2007
dc.identifier.issn 0035-8711
dc.identifier.uri https://dspace.kpfu.ru/xmlui/handle/net/140727
dc.description.abstract We study theoretical interpretations of the ∼150-d (superorbital) modulation observed in X-ray and radio emission of Cyg X-1 in the framework of models connecting this phenomenon to precession. Precession changes the orientation of the emission source (either disc or jet) relative to the observer. This leads to emission modulation due to an anisotropic emission pattern of the source or orientation-dependent amount of absorbing medium along the line of sight or both. We consider, in particular, anisotropy patterns of blackbody-type emission, thermal Comptonization in slab geometry, jet/outflow beaming and absorption in a coronal-type medium above the disc. We then fit these models to the data from the Rossi X-ray Timing Explorer All-Sky Monitor, CGRO BATSE and the Ryle and Green Bank radio telescopes, and find relatively small best-fitting angles between the precession and the orbital planes, ∼10°- 20°. The thermal Comptonization model for the X-ray emission explains well the observed decrease in the variability amplitude from 1 to 300 keV as a result of a reduced anisotropy of the emission due to multiple scatterings. Our modelling also yields the jet bulk velocity of ∼(0.3-0.5)c, which is in agreement with the previous constraint from the lack of an observed counterjet and the lack of short-term X-ray/radio correlations. © 2007 RAS.
dc.relation.ispartofseries Monthly Notices of the Royal Astronomical Society
dc.subject Accretion, accretion discs
dc.subject Radiation mechanisms: thermal
dc.subject Radio continuum: stars
dc.subject Stars: individual: Cyg X-1
dc.subject X-rays: binaries
dc.subject X-rays: stars
dc.title Superorbital variability of X-ray and radio emission of Cyg X-1 - I. Emission anisotropy of precessing sources
dc.type Article
dc.relation.ispartofseries-issue 2
dc.relation.ispartofseries-volume 381
dc.collection Публикации сотрудников КФУ
dc.relation.startpage 723
dc.source.id SCOPUS00358711-2007-381-2-SID35148858726


Files in this item

This item appears in the following Collection(s)

  • Публикации сотрудников КФУ Scopus [24551]
    Коллекция содержит публикации сотрудников Казанского федерального (до 2010 года Казанского государственного) университета, проиндексированные в БД Scopus, начиная с 1970г.

Show simple item record

Search DSpace


Advanced Search

Browse

My Account

Statistics