Document Type
Article
Publication Date
2-1-2024
Abstract
We report on X-ray polarization measurements of the extragalactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud, using a ∼850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is unresolved by IXPE. No statistically significant polarization is detected for the image-averaged data, giving a 99% confidence polarization upper limit (MDP99) of 5.3% in the 2–8 keV energy range. However, a phase-resolved analysis detects polarization for both the nebula and pulsar in the 4–6 keV energy range. For the PWN defined as the off-pulse phases, the polarization degree (PD) of (24.5 ± 5.3)% and polarization angle (PA) of (78.1 ± 6.2)° is detected at 4.6σ significance level, consistent with the PA observed in the optical band. In a single on-pulse window, a hint of polarization is measured at 3.8σ with PD of (50.0 ± 13.1)% and PA of (6.2 ± 7.4)°. A “simultaneous” PSR/PWN analysis finds two bins at the edges of the pulse exceeding 3σ PD significance, with PD of (68 ± 20)% and (62 ± 20)%; intervening bins at 2–3σ significance have lower PD, hinting at additional polarization structure.
Publication Source (Journal or Book title)
Astrophysical Journal
Recommended Citation
Xie, F., Wong, J., La Monaca, F., Romani, R., Heyl, J., Kaaret, P., Di Marco, A., Bucciantini, N., Liu, K., Ng, C., Di Lalla, N., Weisskopf, M., Costa, E., Soffitta, P., Muleri, F., Bachetti, M., Pilia, M., Rankin, J., Fabiani, S., Agudo, I., Antonelli, L., Baldini, L., Baumgartner, W., Bellazzini, R., Bianchi, S., Bongiorno, S., Bonino, R., Brez, A., Capitanio, F., Castellano, S., Cavazzuti, E., Chen, C., & Ciprini, S. (2024). First Detection of Polarization in X-Rays for PSR B0540-69 and Its Nebula. Astrophysical Journal, 962 (1) https://doi.org/10.3847/1538-4357/ad17ba