03.02.2026

Erfolgreiche Verteidigung at IAAT von Frau Yujia Du

Ms. Yujia Du, now Dr. Du, successfully defended her PhD thesis on January 27, presenting a comprehensive study of accreting X-ray pulsars, a class of high-mass X-ray binaries hosting strongly magnetized neutron stars.

In her thesis, Ms. Du investigated the spectral and timing properties of two representative systems: the Be/X-ray binary EXO 2030+375 and the wind-fed pulsar Vela X-1, using data from major X-ray observatories including Insight-HXMT, Swift/BAT, and NuSTAR.

For EXO 2030+375, observations during a 2021 giant outburst and a 2022 Type I outburst revealed strong luminosity- and energy-dependent changes in pulse profiles, providing evidence for transitions between super-critical and sub-critical accretion regimes. Phase-resolved spectroscopy further highlighted complex variations of spectral parameters across the pulse phase.

The study of Vela X-1 focused on the long-term evolution of cyclotron resonance scattering features. The results confirm that the previously observed decay of the harmonic cyclotron line energy has ended, and report the first detection of a transient increase between 2020 and 2023, pointing to a possible sudden change in magnetic field configuration or accretion geometry.

Overall, this work provides new observational insights into the emission mechanisms, accretion geometry, and magnetic-field evolution in accreting X-ray pulsars. An excellent example of observational study in X-ray astrophysics.

We warmly congratulate Ms. Yujia Du on the successful completion of her PhD and wish her all the best for her future scientific career.

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