Long-term spectral study of the black hole Cygnus X-1 using INTEGRAL. (arXiv:1904.09112v1 [astro-ph.HE])

Long-term spectral study of the black hole Cygnus X-1 using INTEGRAL. (arXiv:1904.09112v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Cangemi_F/0/1/0/all/0/1">F. Cangemi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beuchert_T/0/1/0/all/0/1">T. Beuchert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Siegert_T/0/1/0/all/0/1">T. Siegert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grinberg_V/0/1/0/all/0/1">V. Grinberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilms_J/0/1/0/all/0/1">J. Wilms</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodriguez_J/0/1/0/all/0/1">J. Rodriguez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kreykenbohm_I/0/1/0/all/0/1">I. Kreykenbohm</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Laurent_P/0/1/0/all/0/1">P. Laurent</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pottschmidt_K/0/1/0/all/0/1">K. Pottschmidt</a>

We utilize the joint capabilities of IBIS and SPI to perform a state-resolved
20–2000,keV analysis of the microquasar Cygnus X-1. In both LHS and HSS, the
spectral analysis reveals the presence of a high-energy tail above 400,keV in
addition to a standard, Compton-like continuum in the 20–400,keV range. We
study the polarisation properties of the hard X-ray radiation, as well as of
the polarisation of this high-energy tail. Polarisation is detected in the LHS
in agreement with previous work. We find potential variations of the LHS
polarisation with time and no polarisation detection in the HSS.

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