PhD Candidate · UT Austin · Expected Aug 2026

Saiyang Zhang

张赛旸

PhD Candidate in Theoretical & Computational Astrophysics

Cosmic Frontier Center · Weinberg Institute · University of Texas at Austin

Connecting dark matter physics, primordial black holes, and JWST observations of the early Universe.

🎉Incoming CITA Fellow & Arts and Science Postdoctoral Fellow · University of Toronto · Fall 2026

Curriculum Vitae GitHub

Scholar NASA/ADS INSPIRE LinkedIn Email

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01 / About

About Me

Growing up in Beijing, I developed a deep appreciation for science and the mysteries of the universe. After completing high school, I moved to the US to pursue undergraduate studies at Colgate University in Astronomy/Physics and Applied Mathematics.

Currently, I'm a 6th-year doctoral candidate at the University of Texas at Austin, advised by Volker Bromm, specializing in theoretical and computational astrophysics. My research focuses on dark matter, the early universe, and cosmological evolution — studying dark matter candidates like Primordial Black Holes (PBHs), Weakly Interacting Massive Particles (WIMPs), Warm Dark Matter (WDM), and Self-interacting Dark Matter (SIDM), and their astrophysical effects on early universe objects like Population III stars and Supermassive Black Holes.

Beyond traditional astrophysics, I am increasingly interested in the intersection of machine learning and scientific discovery — particularly in applying large language models (LLMs) and simulation-based inference to accelerate research in cosmology and dark matter detection, as well as studying AI systems as a new domain of scientific inquiry.

Beyond my academic pursuits, I have a profound love for nature and sports. I enjoy downhill skiing, mountain hiking, football (⚽), and tennis. I have conquered four 14ers in Colorado, and there are more to go.

Research Interests

Dark Matter (PBHs, WIMPs, SIDM)Early Universe & Pop III Stars Supermassive Black HolesLarge-Scale StructureHigh-Performance ComputingMachine Learning

Education

Ph.D. in Physics

University of Texas at Austin · Cosmic Frontier Center · Weinberg Institute

Advisor: Volker Bromm · Aug 2020 – Aug 2026 (exp.)

“Imprints of the Primordial Black Holes over Cosmic History”

Candidate

M.A. in Physics

University of Texas at Austin · Cosmic Frontier Center · Weinberg Institute

Advisor: Katherine Freese · Aug 2020 – Dec 2024

“Detecting Supermassive Dark Stars with the Roman Space Telescope”

Graduated

B.A. in Astronomy/Physics & Applied Mathematics

Colgate University · Magna cum laude

Advisor: Cosmin Ilie · 2015 – 2019

Graduated

Awards & Fellowships

Dissertation Writing Fellowship

UT Austin · 2025 · $24,000

Robert S. Davis and Lyell P. Davis Scholarship Fund

UT Austin · 2024 · $1,000

Graduate School Professional Development Award

UT Austin · 2024 / 2025 / 2026 · $2,250

APS DAP Student/Postdoc Travel Grant

American Physical Society · 2022 · $600

Joseph C. Amato & Anthony F. Aveni Award (Excellence in Thesis)

Colgate University · 2019

Referee: Astronomical Journal (AJ), Physical Review D (PRD), Physical Review Letters (PRL)

Peer Review Service · 2025–present

📸 Life Outside Research

Sigma — my older cat 🐱

Eta — my younger cat 🐱

ITC Luncheon Talk, Harvard Center for Astrophysics 🎤 (Apr 2025)

Torreys Peak, Colorado 🏔️ (14,267 ft)

02 / Research

Research Areas

Bridging particle physics and astrophysics to uncover the nature of dark matter and the first objects in the Universe.

Primordial Black Holes (PBHs)

Dark Matter · Early Universe

Using N-body simulations with GIZMO and semi-analytical models to investigate PBHs’ astrophysical impacts — from influencing first star formation and cosmic radiation background during reionization, to seeding supermassive black holes like Abell2744-QSO1 observed by JWST. Future observations with JWST, Roman, and SKA will be critical in distinguishing PBH-driven structure formation from standard ΛCDM.

Supermassive Dark Stars (SMDSs)

Dark Matter · Early Universe

Supermassive dark stars are luminous stellar objects formed in the early Universe at redshift z∼10–20, powered by dark matter annihilation. Using Roman Space Telescope and JWST spectroscopy — particularly the HeII 1640 absorption line as a “smoking gun” — we can differentiate SMDSs from early galaxies via spectral, photometric, and morphological signatures.

Particle Dark Matter & Pop III Stars

Dark Matter

Pop III stars and neutron stars offer unique cosmic laboratories for probing particle dark matter microphysics in regimes inaccessible to terrestrial experiments. Developed a multiscatter capture framework to study DM particles gravitationally captured by stars, leading to observable consequences such as DM annihilation heating or stellar mass truncation. Extended to superheavy DM and constraints below the neutrino floor.

Media Coverage

Research covered by international science media

11 articles

Primordial Black Holes & JWST

10 articles

Phys.org

Apr. 2026

A monster black hole appeared first, then its galaxy began to grow around it

PBHRead article →

📄 Related: Maiolino et al. 2026, MNRAS 548 (contribution: co-author)

Daily Galaxy

Jan. 2026

This Starless Monster Black Hole May Be Older Than the First Galaxies

PBHRead article →

📄 Related: Zhang et al. 2026, ApJL 1000, L19

Interesting Engineering

Jan. 2026

50 million times heavier than Sun: This black hole breaks rules of how galaxies are formed

PBHRead article →

📄 Related: Zhang et al. 2026, ApJL 1000, L19

New Scientist

Jan. 2026

Gargantuan black hole may be a remnant from the dawn of the universe

PBHRead article →

📄 Related: Zhang et al. 2026, ApJL 1000, L19

The Guardian

Sep. 2025

'A paradigm change': black hole spotted that may have been created moments after big bang

PBHRead article →