New Insights from MIGHTEE Survey: 104 Quasars Analyzed by MeerKAT

A comprehensive analysis of 104 quasars has been conducted by a team of astronomers led by Dr. Sarah V. White at Rhodes University, utilizing the MeerKAT radio telescope in South Africa. This study, part of the MIGHTEE (MeerKAT International GHz Tiered Extragalactic Exploration) survey, aims to deepen our understanding of the formation and evolution of galaxies, particularly focusing on active galactic nuclei (AGNs) like quasars. The findings, published on July 26, 2025, reveal that only about 5% of the quasars studied are classified as radio-loud, which aligns with previous research that suggests a predominance of radio-quiet quasars in the universe.

Quasars, or quasi-stellar objects, are the extremely bright cores of distant galaxies powered by supermassive black holes. They emit energy across the electromagnetic spectrum, making them crucial to astrophysical research. The MIGHTEE survey represents one of the most ambitious efforts to map the extragalactic sky, allowing researchers to study galaxy evolution over cosmic time.

According to Dr. White, the team focused on Type 1 quasars—unobscured objects that exhibit broad emission lines—located primarily in the COSMOS and XMM-LSS regions. The quasars analyzed span a significant range of distances, with redshifts between 0.6 and 3.41, indicating that some are billions of light-years away. The median redshift was calculated at approximately 1.68, suggesting that most of these quasars are observed from a time when the universe was less than half its current age.

A particularly noteworthy aspect of this study is the sensitivity of the radio data collected, which allowed for the identification of faint radio sources. This ability has revealed that a smaller fraction of the quasars exhibit radio emissions predominantly driven by AGN activity compared to earlier analyses. Dr. White and her team posit that these findings may be attributed to the enhanced sensitivity of their observations, which are capable of detecting lower flux-density levels.

Moreover, the study suggests a significant increase in the proportion of quasars characterized as potential starburst galaxies with higher redshifts: from approximately 31-38% at lower redshifts to 63% among the most distant sources examined. This trend complicates the traditional 'radio-excess' method used to classify AGNs, indicating a need for future research to refine techniques for identifying and analyzing AGN contributions.

The implications of this research extend beyond mere classification of quasars; it presents a more nuanced perspective on the interplay between star formation and AGN activity in the early universe. With ongoing advancements in radio astronomy, researchers hope to uncover more about the role these distant objects play in the cosmic landscape, providing insight into the evolution of galaxies and the universe as a whole.

This study reflects a significant step forward in the field of astrophysics and highlights the innovative capabilities of the MeerKAT telescope in uncovering the mysteries of the cosmos. As Dr. White notes, further investigations will continue to shed light on the complex relationships between quasars, black holes, and galaxy formation, ultimately enriching our understanding of cosmic evolution.