4U 1822-371 is a typical edge-on eclipsing low mass X-ray binary and the prototype of accre- tion disk coronal sources. We report on the results of a spectral analysis over the energy range 0.5-45 keV observed by Suza...4U 1822-371 is a typical edge-on eclipsing low mass X-ray binary and the prototype of accre- tion disk coronal sources. We report on the results of a spectral analysis over the energy range 0.5-45 keV observed by Suzaku in 2006. We extract spectra from five orbital phases. The spectra can be equally well described by various previously proposed models: an optically thick model described by a partially cov- ered cutoff power law and an optically thin model described by a blackbody plus a cutoff power law. The optically thick model requires a covering fraction of about 55%, while the optically thin model requires a temperature of the central source of about 0.16 keV. The spectrum in the optically thick model also shows the previously detected cyclotron line feature at ~30 keV with the same Suzaku observation. This fea- ture confirms the presence of a strong magnetic field. The Fe Ks fluorescent line strengths as well as the detected Fe xxvI strengths are similar to previous Chandra and XMM-Newton detections in our phased spectral analysis; however, we also observe strong Fe xxvI during the eclipse, which indicates a slightly larger central corona.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11273062)supported by the 100 talents program of the Chinese Academy of Sciences
文摘4U 1822-371 is a typical edge-on eclipsing low mass X-ray binary and the prototype of accre- tion disk coronal sources. We report on the results of a spectral analysis over the energy range 0.5-45 keV observed by Suzaku in 2006. We extract spectra from five orbital phases. The spectra can be equally well described by various previously proposed models: an optically thick model described by a partially cov- ered cutoff power law and an optically thin model described by a blackbody plus a cutoff power law. The optically thick model requires a covering fraction of about 55%, while the optically thin model requires a temperature of the central source of about 0.16 keV. The spectrum in the optically thick model also shows the previously detected cyclotron line feature at ~30 keV with the same Suzaku observation. This fea- ture confirms the presence of a strong magnetic field. The Fe Ks fluorescent line strengths as well as the detected Fe xxvI strengths are similar to previous Chandra and XMM-Newton detections in our phased spectral analysis; however, we also observe strong Fe xxvI during the eclipse, which indicates a slightly larger central corona.