Meerkat Image Unveils Magnetized Filaments at the Milky Way's Core

In this Ashram video, Alex McColgan explains the Meerkat telescope's landmark radio image of the Milky Way's center. The mosaic reveals hundreds of long, magnetized, one dimensional filaments up to 150 light years long and 1 to 3 light years wide, along with prominent radio bubbles. Tracing the discovery from Ferhad Yusuf Zadehs early hints of real structures to the 2022 full-array Meerkat image, the film outlines how high-pass filtering and careful data analysis uncovered a population of non-thermal filaments emitting synchrotron radiation. The discussion connects these filaments to past Sagittarius A* outbursts and broader galactic feedback, and it points toward future observations with the Square Kilometre Array.

Overview

The video presents the Meerkat survey of the Milky Way center, culminating in a detailed radio image that dramatically improves our view of the central molecular zone and its magnetized structures.

The Meerkat Survey: Data and Processing

Over three years, the 6.5 square degree mosaic was built from 20 tiles surveyed with the full Meerkat array, using frequencies from 856 to 1712 MHz. The team gathered about 70 terabytes of raw data, equivalent to roughly 700 hours of 4K video, and processed it with a high pass filter based on the difference of Gaussians to suppress background and highlight fine structures. The mosaic was made possible only by employing the full 60–62 dishes at any given time, bringing Sagittarius A* into sharp relief amid the crowded Galactic Center environment.

Filaments: Properties and Evidence

The resulting panorama reveals hundreds of non-thermal filaments, each 1–3 light years across but extending as long as 150 light years. They appear individually, in pairs, or in clusters, frequently aligned and spaced at roughly an astronomical unit apart. Infrared data show no counterparts in that spectrum, supporting the interpretation that these are non-thermal, magnetized filaments emitting synchrotron radiation. The filaments also show polarization and spectral properties consistent with strong magnetic fields and relativistic electrons, ruling out simple thermal gas emission.

Origins and Connections to Sagittarius A*

One striking finding is the association of the filaments with large radio bubbles discovered in 2019, which stretch above and below the Galactic Plane. The authors propose a magnetized, cosmic-ray driven wind as a framework for filament formation, potentially tied to past energetic outbursts from Sagittarius A* about 100 thousand to a million years ago. A steepening of filament emissions with galactic latitude suggests electrons aging as they move away from the plane, hinting at the timing and geometry of the central engine’s activity.

Broader Implications and Future Prospects

The study offers important clues about how supermassive black holes might regulate star formation via episodic outflows, a concept linked to Fermi bubbles seen in gamma rays. The Meerkat results also motivate cross-wavelength investigations with gamma-ray observatories and, in the future, the Square Kilometre Array which will be vastly more sensitive. The findings in multiple galaxies imply a common mechanism for magnetic field channeling and cosmic-ray transport, with potential implications for galaxy evolution and feedback processes.

Conclusion

The Meerkat image marks a watershed moment in Galactic Center studies, transforming chaos into a structured, magnetized network of filaments and bubbles. Ongoing and future observations across the electromagnetic spectrum are expected to refine the origin scenarios and illuminate how central activity shapes the Milky Way and other galaxies.