INTEGRAL/IBIS polarization detection in the hard and soft intermediate states of Swift J1727.8-1613

Bouchet T, Rodriguez J, Cangemi F, Thalhammer P, Laurent P, Grinberg V, Wilms J, Pottschmidt K (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Astronomy & Astrophysics EDP Sciences

Book Volume: 688

Article Number: L5

DOI: 10.1051/0004-6361/202450826

Abstract

Aims. Soft γ-ray emission (100 keV - 10 MeV) has previously been detected in the hard state of several microquasars. In some sources, this emission was found to be highly polarized and was suggested to be emitted at the base of the jet. Until now, no γ-ray polarization had been found in any other state. Methods. Using INTEGRAL/IBIS, we studied the soft γ-ray spectral and polarization properties of Swift J1727.8-1613 throughout its outburst. Results. We detect a highly polarized spectral component in both the hard intermediate state and the early stages of the soft intermediate state above 210 keV. In the hard intermediate state, the polarization angle significantly deviates from the compact jet angle projected onto the sky, whereas in the soft intermediate they are closely aligned. This constitutes the first detection of jet-aligned polarization in the soft γ-ray for a microquasar. We attribute this polarized spectral component to synchrotron emission from the jet, which indicates that some of the jet might persist into the softer states.

Authors with CRIS profile

Philipp Thalhammer Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut Jörn Wilms Professur für Astronomie und Astrophysik

Involved external institutions

Université Paris-Saclay FR France (FR) Université Sorbonne Paris Cité FR France (FR) European Space Research and Technology Centre (ESTEC, ESA) NL Netherlands (NL) National Aeronautics and Space Administration (NASA) US United States (USA) (US)

How to cite

APA:

Bouchet, T., Rodriguez, J., Cangemi, F., Thalhammer, P., Laurent, P., Grinberg, V.,... Pottschmidt, K. (2024). INTEGRAL/IBIS polarization detection in the hard and soft intermediate states of Swift J1727.8-1613. Astronomy & Astrophysics, 688. https://doi.org/10.1051/0004-6361/202450826

MLA:

Bouchet, T., et al. "INTEGRAL/IBIS polarization detection in the hard and soft intermediate states of Swift J1727.8-1613." Astronomy & Astrophysics 688 (2024).

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