Document Type
Article
Publication Date
11-1-2023
Abstract
We report the first detection of the X-ray polarization of the bright transient Swift J1727.8−1613 with the Imaging X-ray Polarimetry Explorer. The observation was performed at the beginning of the 2023 discovery outburst, when the source resided in the bright hard state. We find a time- and energy-averaged polarization degree of 4.1% ± 0.2% and a polarization angle of 2.°2 ± 1.°3 (errors at 68% confidence level; this translates to ∼20σ significance of the polarization detection). This finding suggests that the hot corona emitting the bulk of the detected X-rays is elongated, rather than spherical. The X-ray polarization angle is consistent with that found in submillimeter wavelengths. Since the submillimeter polarization was found to be aligned with the jet direction in other X-ray binaries, this indicates that the corona is elongated orthogonal to the jet.
Publication Source (Journal or Book title)
Astrophysical Journal Letters
Recommended Citation
Veledina, A., Muleri, F., Dovčiak, M., Poutanen, J., Ratheesh, A., Capitanio, F., Matt, G., Soffitta, P., Tennant, A., Negro, M., Kaaret, P., Costa, E., Ingram, A., Svoboda, J., Krawczynski, H., Bianchi, S., Steiner, J., García, J., Kravtsov, V., Nitindala, A., Ewing, M., Mastroserio, G., Marinucci, A., Ursini, F., Tombesi, F., Tsygankov, S., Yang, Y., Weisskopf, M., Trushkin, S., Egron, E., Iacolina, M., Pilia, M., & Marra, L. (2023). Discovery of X-Ray Polarization from the Black Hole Transient Swift J1727.8−1613. Astrophysical Journal Letters, 958 (1) https://doi.org/10.3847/2041-8213/ad0781