Xiaosheng Zhao

Xiaosheng Zhao

Postdoctoral Fellow, Johns Hopkins University

📧 xzhao113@jh.edu | Google Scholar | ORCID | GitHub

About Me

My research focuses on developing and applying machine learning methods for astrophysics and cosmology, spanning both Galactic archaeology and early-universe inference. At Johns Hopkins University, I currently work on spectral foundation models—such as SpecCLIP and its fine-tuned extensions—for cross-survey generalization across LAMOST, Gaia XP, DESI, Prime Focus Spectrograph (PFS), etc. I am also interested in the inference of dark matter profile from dwarf spheroidal galaxies with PFS. My previous doctoral research at Tsinghua University explored the epoch of reionization using simulation-based inference (SBI) and optimal summary statistics, and introduced generative approaches (e.g., diffusion models) for astrophysical image synthesis. Broadly, I am interested in connecting data-driven representation learning with physical interpretability to extract scientific insights from large, heterogeneous astronomical datasets.

Selected Publications

LoRA figure

Fine-tuning Stellar Spectra Foundation Models with LoRA

Zhao, X., Ting, Y.-S., Szalay, A. S., Huang, Y., 2025, ICML ML4Astro Workshop

Lightweight adaptation approach for pre-trained spectral models, achieving few-shot generalization to DESI spectra.

SpecCLIP figure

SpecCLIP: Aligning and Translating Spectroscopic Measurements for Stars

Zhao, X., Huang, Y., Xue, G., Xiao Kong, et al., 2025 (submitted)

Foundation model for stellar spectra enabling cross-survey generalization between LAMOST LRS and Gaia XP.

DDPM figure

Can Diffusion Models Conditionally Generate Astrophysical Images?

Zhao, X., Ting, Y.-S., Diao, K., Mao, Y., 2023, Monthly Notices of the Royal Astronomical Society, 526, 1699

Applies denoising diffusion probabilistic models (DDPM) for conditional astrophysical image generation, bridging physical priors and deep generative modeling.

3D Lightcone Inference figure

Simulation-Based Inference of Reionization Parameters from 3D Tomographic 21 cm Lightcone Images

Zhao, X., Mao, Y., Cheng, C., Wandelt, B. D., 2022, Astrophysical Journal, 926, 151

Introduced a simulation-based inference framework that constrains reionization parameters directly from 3D 21 cm lightcone images.

Education & Experience

Postdoctoral Fellow, Johns Hopkins University

Aug 2024 – Present | Baltimore, USA
Supervisors: Prof. Alex Szalay & Prof. Rosemary Wyse

Visiting, University of Chinese Academy of Sciences/NAOC

Jul 2024 – Aug 2024 | Host: Prof. Yang Huang
Focus: stellar spectra foundation models.

Visiting, Institut d'Astrophysique de Paris

2022 – 2024 | Mentor: Prof. Benjamin D. Wandelt
Focus: (explainable) ML for astrophysics and cosmology

PhD in Astronomy, Tsinghua University

2018 – 2024 | Advisor: Prof. Yi Mao
Thesis: Exploring the Epoch of Reionization with Machine Learning

BSc in Physics, Wuhan University

2014 – 2018

Talks & Highlights