Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system III. Dipping in the low/hard state

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Details zur Publikation

Autorinnen und Autoren: Hirsch M, Hell N, Grinberg V, Ballhausen R, Nowak MA, Pottschmidt K, Schulz NS, Dauser T, Hanke M, Kallman TR, Brown G, Wilms J
Zeitschrift: Astronomy & Astrophysics
Jahr der Veröffentlichung: 2019
Band: 626
ISSN: 1432-0746


We present an analysis of three Chandra High Energy Transmission Gratings observations of the black hole binary Cyg X-1/HDE 226868 at different orbital phases. The stellar wind that is powering the accretion in this system is characterized by temperature and density inhomogeneities including structures, or "clumps", of colder, more dense material embedded in the photoionized gas. As these clumps pass our line of sight, absorption dips appear in the light curve. We characterize the properties of the clumps through spectral changes during various dip stages. Comparing the silicon and sulfur absorption line regions (1.6-2.7 keV 7.7-4.6 angstrom) in four levels of varying column depth reveals the presence of lower ionization stages, i.e., colder or denser material, in the deeper dip phases. The Doppler velocities of the lines are roughly consistent within each observation, varying with the respective orbital phase. This is consistent with the picture of a structure that consists of differently ionized material, in which shells of material facing the black hole shield the inner and back shells from the ionizing radiation. The variation of the Doppler velocities compared to a toy model of the stellar wind, however, does not allow us to pin down an exact location of the clump region in the system. This result, as well as the asymmetric shape of the observed lines, point at a picture of a complex wind structure.

FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Ballhausen, Ralf
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Dauser, Thomas Dr.
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Hanke, Manfred
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Hirsch, Maria
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik

Einrichtungen weiterer Autorinnen und Autoren

Eberhard Karls Universität Tübingen
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Hirsch, M., Hell, N., Grinberg, V., Ballhausen, R., Nowak, M.A., Pottschmidt, K.,... Wilms, J. (2019). Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system III. Dipping in the low/hard state. Astronomy & Astrophysics, 626.

Hirsch, Maria, et al. "Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system III. Dipping in the low/hard state." Astronomy & Astrophysics 626 (2019).


Zuletzt aktualisiert 2019-28-06 um 11:08