Clouds, winds, and jets in the luminous X-ray source circinus X-1

N. S. Schulz, W. N. Brandt, D. K. Galloway, D. Chakrabarty, S. Heinz

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


One of the early highlights of high resolution X-ray spectroscopy was the discovery of P Cygni lines in the highly variable and luminous X-ray source Circinus X-1 during the early days of the Chandra mission. By adapting the preceding paradigm established from ASCA observations that the accretion disk around the neutron star is viewed edge-on, the the complex line structure was interpreted as a combination of accretion disk coronal line emission and absorption from a radiatively driven equatorial disk wind. The detection of ultra-relativistic radio jets at about the same time seemed to support the image of Circinus X-1 as a powerful microquasar, but also casted some doubt on the assumption that the source is viewed edge-on, but instead featured a face-on view. This not only challenges the current model for the observed X-ray emission, it could also force a complex scenario involving jets, winds, and clouds that seems quite unique among accreting compact sources. Furthermore the X-ray emission of Circinus X-l has undergone radical changes since then as it gradually slipped into a low intensity state which is even at times devoid of the typical outburst pattern with its binary orbit. We observed Circinus X-1 several times with the Chandra HETG spectrometer during this transition. We show some preliminary results from the first of these observations, which provided the unobstructed high resolution X-ray image of this source as well as an X-ray spectrum that is devoid of P Cygni lines but shows line emission as expected from ADC sources. We discuss the results in conjunction with its long-term lightcurve and investigate possible scenarios with respect to its line of sight.

Original languageEnglish (US)
Title of host publicationX-ray Universe 2005
Number of pages6
StatePublished - 2006
EventX-ray Universe 2005 - Madrid, Spain
Duration: Sep 26 2005Sep 30 2005

Publication series

NameEuropean Space Agency, (Special Publication) ESA SP
ISSN (Print)0379-6566


OtherX-ray Universe 2005

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science


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