Document Type
Article
Publication Date
10-1-2024
Abstract
We present multiwavelength polarization measurements of the luminous blazar Mrk 501 over a 14 month period. The 2-8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100 ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical-infrared polarization measurements were also available in the B, V, R, I, and J bands, as were radio polarization measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at >3 above the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE observations, the X-ray polarization degree remained higher than, or similar to, the R-band optical polarization degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission arises from different regions.
Publication Source (Journal or Book title)
Astrophysical Journal
Recommended Citation
Chen, C., Liodakis, I., Middei, R., Kim, D., Di Gesu, L., Di Marco, A., Ehlert, S., Errando, M., Negro, M., Jorstad, S., Marscher, A., Wu, K., Agudo, I., Poutanen, J., Mizuno, T., Kouch, P., Lindfors, E., Borman, G., Grishina, T., Kopatskaya, E., Larionova, E., Morozova, D., Savchenko, S., Troitsky, I., Troitskaya, Y., Vasilyev, A., Zhovtan, A., Aceituno, F., Bonnoli, G., Casanova, V., Escudero, J., Agís-González, B., & Husillos, C. (2024). X-Ray and Multiwavelength Polarization of Mrk 501 from 2022 to 2023. Astrophysical Journal, 974 (1) https://doi.org/10.3847/1538-4357/ad63a1