@inproceedings{aadb855b1c94457fa95852cdcd1a87bc,
title = "Clouds, winds, and jets in the luminous X-ray source circinus X-1",
abstract = "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.",
author = "Schulz, {N. S.} and Brandt, {W. N.} and Galloway, {D. K.} and D. Chakrabarty and S. Heinz",
year = "2006",
language = "English (US)",
isbn = "9290929154",
series = "European Space Agency, (Special Publication) ESA SP",
number = "604",
pages = "201--206",
booktitle = "X-ray Universe 2005",
edition = "604",
note = "X-ray Universe 2005 ; Conference date: 26-09-2005 Through 30-09-2005",
}