Astronomers Analyze 104 Quasars in Groundbreaking MIGHTEE Study

A team of astronomers from Rhodes University and collaborating institutions conducted an extensive analysis of 104 quasars identified through the MIGHTEE survey, utilizing data from the MeerKAT radio telescope in South Africa. This research, published on July 16, 2025, on the pre-print server arXiv, aims to deepen understanding of quasars and their various properties.

Quasars, or quasi-stellar objects, are among the universe’s most luminous and distant entities, playing a critical role in numerous astrophysical and cosmological studies. As active galactic nuclei (AGN), they emit electromagnetic radiation across a spectrum that includes radio, infrared, visible, ultraviolet, and X-ray wavelengths. The MIGHTEE survey, part of an ongoing effort to image the extragalactic sky, focuses on exploring the cosmic evolution of galaxies, including AGNs.

Insights into Quasar Characteristics

The research team, led by Sarah V. White, meticulously examined data from the COSMOS and XMM-LSS fields within the MIGHTEE survey. They focused on unobscured Type I quasars, which are characterized by broad emission lines. The selected quasars exhibited a range of redshifts between 0.6 and 3.41, with a median redshift of approximately 1.68.

The study’s findings revealed that the radio-loudness fraction for these quasars is estimated at 5%, aligning with previous observations from other quasar samples. Notably, the research indicated that the proportion of quasars with radio emissions dominated by AGN is lower than findings from other studies within the MIGHTEE sample. The astronomers hypothesized that this discrepancy may arise from the lower radio flux-density limit of the images, enhancing sensitivity to lower radio luminosities linked to star formation.

Moreover, the analysis highlighted a significant increase in the fraction of potential starburst galaxies among higher redshift quasars, jumping from 31-38% to 63% for sources at the highest redshifts. This trend suggests that identifying whether AGN dominate total radio emissions becomes increasingly complex as redshift increases.

Implications for Future Research

The authors of the study emphasize that the heightened incidence of starbursts in quasars at higher redshifts complicates the application of the “radio-excess” method for determining AGN dominance in radio emissions. They concluded by urging a reevaluation of methods for selecting and analyzing AGNs to account for these nuanced findings.

This research not only contributes to the understanding of quasar properties but also poses important considerations for future studies in astrophysics. The work was rigorously reviewed and fact-checked, reinforcing its credibility within the scientific community.

For more information, refer to the original study by Sarah V. White et al titled “MIGHTEE: A first look at MIGHTEE quasars,” available on arXiv.