Dr. Ghassem Gozaliasl

ESA Picture of the Month (April 2025): Led the COSMOS-Web galaxy group team that discovered the largest sample of galaxy groups detected by the James Webb Space Telescope. This groundbreaking work, featured as ESA's official Picture of the Month, reveals galaxy groups from when the Universe was only 1.9 billion years old—pushing the boundaries of cosmic archaeology and our understanding of early structure formation.

June 2025: We successfully created and publicly released the largest deep space catalogue ever created from the James Webb Space Telescope's COSMOS-Web survey. This unprecedented dataset from 255 hours of JWST observations is now publicly available in an easily searchable format, democratizing access to the early universe for scientists, students, educators, and the public worldwide.

"Our public release of the largest deep space catalogue ever created represents a remarkable step for science and society. We have democratized access to the early universe, enabling not only scientists but also students, educators, and the public to explore our cosmic origins interactively. It's especially exciting that we, as researchers from Finland, have contributed to this effort — showcasing how global collaboration and open science are shaping the future of discovery." - Dr. Gozaliasl

International Recognition: Our COSMOS-Web data release has been covered by major international institutions, with our team's contributions specifically highlighted by Rochester Institute of Technology in their official announcement. RIT emphasized how our research traces "how galaxies shut down star formation, undergo morphological transformation, and how these processes are shaped by their environment across cosmic time, even predicting galaxy properties using AI-driven methods."

Official Coverage: Aalto University News | RIT Official Release

Two JWST images from our COSMOS-Web survey were selected as the European Space Agency's Picture of the Month for April 2025. The April image highlights a major discovery from a project I led as the head of the COSMOS-Web Galaxy Groups Working Team. Our team detected the largest and deepest sample of galaxy groups observed to date, extending out to redshift z = 3.7, or approximately 12 billion light-years away. This was made possible by the largest General Observer program in JWST Cycle 1, and represents a significant step forward in tracing the formation of massive cosmic structures in the early universe. The featured image—created by me for this project and published as Figure 1 in Toni, Gozaliasl et al. (2025)—was selected as the ESA Picture of the Month for April 2025. On the left is the original deep JWST image, and on the right, a processed overlay map reveals the hot gas distribution (in purple), tracing the presence of massive dark matter halos.

Official ESA Links: composite JWST+HST images | Extended X-ray Emission Overlay Article: Toni, Gozaliasl et al. 2025

Credit: ESA/Webb, NASA & CSA, G. Gozaliasl, A. Koekemoer, M. Franco, and the COSMOS-Web team

Comprehensive study of Brightest Group Galaxies (BGGs) spanning cosmic time from the local universe to early epochs. This research catalog covers an unprecedented redshift range of 0.08 < z < 3.7, tracing the evolution of the most massive galaxies in group environments across over 11 billion years of cosmic history.

The composite image below showcases the diversity of brightest group galaxies identified through our COSMOS-Web survey, revealing how these massive central galaxies have evolved through mergers, accretion, and environmental interactions across cosmic time. The catalog represents a cornerstone dataset for understanding galaxy formation and the growth of massive structures in the universe.

Composite image of Brightest Group Galaxies from the COSMOS-Web catalog spanning redshifts 0.08 < z < 3.7, demonstrating the morphological diversity and evolution of massive central galaxies across cosmic time.

Article: Gozaliasl et al. 2025

Credit: ESA/Webb, NASA & CSA, G. Gozaliasl, A. Koekemoer, M. Franco, and the COSMOS-Web team

Led groundbreaking research (Abedini, Gozaliasl et al. 2025): "COSMOS-Web: Estimating Physical Parameters of Galaxies Using Self-Organizing Maps" - A revolutionary application of unsupervised machine learning to extract physical properties of galaxies directly from JWST photometric data.

Using Self-Organizing Maps (SOMs), we developed a novel method to estimate key galaxy parameters including redshift, stellar mass, star formation rate (SFR), specific SFR (sSFR), and age out to z=3.5. The approach efficiently projects high-dimensional galaxy color information onto interpretable 2D maps, revealing how physical properties vary among galaxies with similar spectral energy distributions.

Validation & Performance: First validated using HORIZON-AGN simulation mock catalogs, then successfully applied to real COSMOS-Web observations. Performance metrics (NMAD and RMSE typically 0.1-0.3) demonstrate exceptional accuracy despite the complexity of real galaxy populations.

Complete workflow of the Self-Organizing Maps methodology: from input HORIZON-AGN and COSMOS-Web data through training phases to final galaxy parameter predictions. The SOM effectively maps high-dimensional photometric data to physical properties across different redshift bins.

Worldwide Recognition: Dr. Gozaliasl's research achievements have generated unprecedented global media coverage across multiple breakthroughs:

Coverage Languages: English, Indonesian, Vietnamese, Finnish, Portuguese, Spanish, German, Italian, and more

Prolific Research Portfolio: With 220+ peer-reviewed publications, Dr. Gozaliasl has established himself as a leading figure in modern astrophysics. His work spans high-impact journals including Astronomy & Astrophysics, Monthly Notices of the Royal Astronomical Society, Astrophysical Journal, and Nature Machine Intelligence.

Leading Interdisciplinary Scientist bridging astrophysics, artificial intelligence, and computational physics. Currently directing the "USA-pilot" (FARIA) project of PlasmaAI while serving as Docent at the University of Helsinki. Dual Ph.D. holder with extensive expertise in galaxy evolution, machine learning applications in astronomy, and space mission data analysis. Team Leader for groundbreaking COSMOS-Web discoveries featured as ESA's Picture of the Month and creator of the largest publicly available deep space catalog. Active member of major international collaborations including the Euclid Consortium and multiple ESA missions.

Scientific Leadership: Successfully led international collaborations across three continents, published 220+ peer-reviewed papers, and contributed to major space missions. Recognized as Docent at the University of Helsinki, demonstrating excellence in both research and teaching.

Technical Innovation: Developed cutting-edge algorithms for space mission data quality, created novel AI applications for medical diagnostics during COVID-19, and pioneered machine learning approaches for astronomical big data challenges.

Recent Breakthrough: In April 2025, led the COSMOS-Web galaxy group team to discover the largest sample of galaxy groups detected by the James Webb Space Telescope, featured as ESA's Picture of the Month. This work pushed galaxy group detection back to when the Universe was only 1.9 billion years old, representing a major leap in our understanding of early cosmic structure formation.