Institute for Astronomy and Astrophysics

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25.07.2025

Another successful defence at IAAT

Dr. Menglei Zhou Successfully Defends Doctoral Thesis at IAAT

[Translate to English:] Dr. Zhou with Dr. Grinberg and Prof. Santangelo.

July 22, 2025 – Dr. Menglei Zhou has successfully defended his doctoral thesis at the Institute of Astronomy and Astrophysics (IAAT), marking a significant milestone in his academic career.
Dr. Zhou joined the High Energy Astrophysics (HEA) section of IAAT under a fellowship from the Chinese Scholar Council. During his doctoral studies, he was hosted by the HEA and received support, including funding for conferences and research meetings, enabling him to contribute meaningfully to the field. Dr. Zhou research was supervised by Dr. Victoria Grinberg, today at the European Space Agency, and Prof. Andrea Santangelo.

Research on Compact Objects: Black Holes and Neutron Stars 

Dr. Zhou’s research focused on compact objects—black holes and neutron stars—which serve as natural laboratories for studying matter and radiation under extreme gravitational, magnetic, and relativistic conditions. His work involved systematic investigations of accretion and emission processes in Galactic black hole binaries and X-ray pulsars, with particular emphasis on Cygnus X-1, GRS 1915+105, and 4U 1907+09.

Key Findings and Contributions
   • Cygnus X-1: Using data from Insight-HXMT, Dr. Zhou analyzed timing and spectral properties across different accretion states. His work revealed how reflection features, variability, and coherence evolve during state transitions.
   • GRS 1915+105: Through a multi-year observational campaign with NICER and HXMT, he captured the source’s transition from a soft to an obscured state, uncovering changes in disk wind ionization and providing insights into the link between accretion flow geometry and wind dynamics.
   • 4U 1907+09: Leveraging IXPE (Imaging X-ray Polarimetry Explorer), Dr. Zhou conducted the first detailed polarization measurements of this X-ray pulsar. His phase-resolved analyses unveiled a stable magnetospheric geometry and the impact of short-term variability on emission.

Paving the Way for Future Research 
By integrating spectral, timing, and polarimetric techniques, Dr. Zhou’s work advances our understanding of accretion processes and energy release in compact objects. His findings highlight the power of multi-dimensional diagnostics and set the stage for groundbreaking studies with future missions like eXTP and Athena.

The IAAT congratulates Dr. Zhou on this outstanding achievement and looks forward to his continued contributions to high-energy astrophysics.

List of Dr. Zhou’s publication
Publications done at IAAT:

As leading author:

  1. Probing the polarized emission from the accretion-powered pulsar 4U 1907+09 with IXPE.
    Zhou, M., Ducci, L., Liu, H., Tsygankov, S., Forsblom, S., ... & Santangelo, A. (Accepted for publication in A&A)
  2. Dimming GRS 1915+105 observed with NICER and Insight–HXMT.
    Zhou, M., Grinberg, V., Santangelo, A., Bambi, C., Bu, Q., ... & Tuo, Y. (2025). A&A, 694, A104.
  3. The spectral-timing analysis of Cygnus X-1 with Insight-HXMT.
    Zhou, M., Grinberg, V., Bu, Q., Santangelo, A., Cangemi, F., ... & Zhang, S.-N. (2022). A&A, 666, A172.

As  co-author:

  1. First look at Vela X-1 with XRISM. A simultaneous campaign with XMM-Newton and NuSTAR.
    Diez, C. M., Dupourqué, S., Zhou, M., Quintin, E., Matzeu, G. A., Fürst, F., Kretschmar, P. (under peer review)
  2. The 2024 outburst of 1A 1744-361 observed by NICER and Insight-HXMT: Type-I X-ray burst and persistent emission.
    Wang, P., Chen, Y., Ji, L., Wang, Y., Piraino, S., Liu, H., Santangelo, A., Zhang, S., Zhang, S.-N., Kong, L., Dai, X., Ge, M., Tao, L., Zhou, M., Yang, Z. (Accepted for publication in A&A)
  3. Variable structures in the stellar wind of the HMXB Vela X-1.
    Abalo, L., Kretschmar, P., Fürst, F., Diez, C. M., El Mellah, I., Grinberg, V., Guainazzi, M., Martínez-Núñez, S., Manousakis, A., Amato, R., Zhou, M. & Beijersbergen, M. W. (2024). A&A, 692, A188
  4. Unveiling the rebrightening mechanism of GRS 1915+105: Insights from a change in the quasi-periodic oscillations and from a wind analysis.
    Dai, X., Kong, L., Ji, L., Zhou, M., Shui, Q., Wang, P., Zhang, Shu & Santangelo, A. (2024). A&A, 692, A117
  5. Likely detection of magnetic field related LFQPO in the soft X-ray rebrightening of GRS 1915+105.
    Kong, L., Ji, L., Santangelo, A., Zhou, M. and Shui, Q. & Zhang, Shu. (2024). A&A, 686, A211
  6. Spin measurement of 4U 1543-47 with Insight-HXMT and NICER from its 2021 outburst. A test of accretion disk models at high luminosities.
    Yorgancioglu, E. S., Bu, Q. C., Santangelo, A., Tao, L., Davis, S. W., Vahdat, A., Kong, L. D., Piraino, S., Zhou, M. & Zhang, S. N. (2023). A&A, 677, A79
  7. Observing the onset of the accretion wake in Vela X-1.
    Diez, C. M., Grinberg, V., Fürst, F., El Mellah, I., Zhou, M., Santangelo, A., Martínez-Núñez, S., Amato, R., Hell, N. & Kretschmar, P. (2023). A&A, 674, A147

Publications done at Fudan:

As leading author:

  1. Thermal spectra of thin accretion discs of finite thickness around Kerr black holes.
    Zhou, M., Abdikamalov, A. B., Ayzenberg, D., Bambi, C., Grinberg, V., & Tripathi, A. (2020). MNRAS, 496(1), 497-503.
  2. Modeling uncertainties in x-ray reflection spectroscopy measurements. I. Impact of higher order disk
    images.Zhou, M., Ayzenberg, D., Bambi, C., & Nampalliwar, S. (2020). PRD, 101(4), 043010.
  3. XSPEC model for testing the Kerr black hole hypothesis using the continuum-fitting method.
    Zhou, M., Abdikamalov, A. B., Ayzenberg, D., Bambi, C., Liu, H., & Nampalliwar, S. (2019) PRD, 99(10), 104031.
  4. Singularity-free black holes in conformal gravity: New observational constraints.
    Zhou, M., Abdikamalov, A. B., Ayzenberg, D., Bambi, C., Modesto, L., Nampalliwar, S., & Xu, Y. (2019). Europhysics Letters, 125(3), 30002.
  5. Testing conformal gravity with the supermassive black hole in 1H 0707−495.
    Zhou, M., Cao, Z., Abdikamalov, A., Ayzenberg, D., Bambi, C., ... & Nampalliwar, S. (2018). PRD, 98(2), 024007.
  6. Iron Kα line of Kerr black holes with Proca hair.
    Zhou, M., Bambi, C., Herdeiro, C. A., & Radu, E. (2017). PRD, 95(10), 104035.
  7. Search for astrophysical rotating Ellis wormholes with X-ray reflection spectroscopy.
    Zhou, M., Cardenas-Avendano, A., Bambi, C., Kleihaus, B., & Kunz, J. (2016). PRD, 94(2), 024036.

As co-supervisor:

  1. X-ray reflection spectroscopy with Kaluza-Klein black holes.
    Zhu, J., Abdikamalov, A. B., Ayzenberg, D., Azreg-Aïnou, M., Bambi, C., Jamil, M., Nampalliwar, S., Tripathi, A., & Zhou, M. (2020). The European Physical Journal C, 80(7), 622.
  2. Relativistic reflection spectra of super-spinning black holes.
    Zhou, B., Tripathi, A., Abdikamalov, A. B., Ayzenberg, D., Bambi, C., Nampalliwar, S., & Zhou, M. (2020). The European Physical Journal C, 80(5), 400.
  3. Distinguishing black holes and naked singularities with iron line spectroscopy.
    Liu, H., Zhou, M., & Bambi, C. (2018). Journal of Cosmology and Astroparticle Physics, 2018(08), 044.
  4. Iron line spectroscopy of black holes in asymptotically safe gravity.
    Zhang, Y., Zhou, M., & Bambi, C. (2018). The European Physical Journal C, 78(5), 376.
  5. Iron Kα line of Proca stars.
    Shen, T., Zhou, M., Bambi, C., Herdeiro, C. A., & Radu, E. (2017). Journal of Cosmology and Astroparticle Physics, 2017(08), 014.
  6. Testing Einstein-dilaton-Gauss-Bonnet gravity with the reflection spectrum of accreting black holes.
    Zhang, H., Zhou, M., Bambi, C., Kleihaus, B., Kunz, J., & Radu, E. (2017). Physical Review D, 95(10), 104043.
  7. Iron Kα line of boson stars.
    Cao, Z., Cardenas-Avendano, A., Zhou, M., Bambi, C., Herdeiro, C. A., & Radu, E. (2016). Journal of Cosmology and Astroparticle Physics, 2016(10), 003.
  8. Iron Kα line of Kerr black holes with scalar hair.
    Ni, Y., Zhou, M., Cardenas-Avendano, A., Bambi, C., Herdeiro, C. A., & Radu, E. (2016). Journal of Cosmology and Astroparticle Physics, 2016(07), 049.

Not as leading author or co-supervisor, but with substantial contributions:

  1. Testing the Kerr black hole hypothesis using X-ray reflection spectroscopy and a thin disk model with
    finite thickness.
    Abdikamalov, A. B., Ayzenberg, D., Bambi, C., Dauser, T., Garcia, J. A., ... & Zhou, M. (2020). ApJ, 899(1), 80.

There are also several publications in which I am listed as a co-author. Please see the full publication list via "https://ui.adsabs.harvard.edu/search/q=orcid%3A0000-0001-8250-3338".
 

In the figure Dr. Zhou with Dr. Grinberg and Prof. Santangelo.

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