Speaker
Description
Satellite galaxies in clusters are significantly more likely to be red and passive than similar mass galaxies in the field. This fact is known as the environmental quenching of galaxy star formation, which is believed to be driven by the ram pressure stripping (RPS). The large velocity differences between the infalling galaxies and the intracluster medium (ICM) result in a strong ram pressure on their interstellar medium (ISM), which can strip it from their stellar disk. The stripped ISM clouds can be studied at various wavelengths, including the radio band, thanks to the synchrotron emission produced by the magnetic fields and relativistic electrons embedded in them. The advent of LOFAR has been revolutionary for the study of RPS in clusters and groups. At low frequencies, the stripped tails can extend for up to 100 kpc in the galaxies’ wakes, making them easily detectable in the radio sky. With the exceptional resolution and sensitivity of LOFAR surveys, over a hundred new RPS galaxies have been discovered in the northern sky, proving that RPS is not an isolated occurrence but rather a common phase experienced by every cluster galaxy. Additionally, LOFAR has detected numerous RPS radio tails in groups, demonstrating that this process is also prevalent in low-mass systems, contrary to previous expectations. Furthermore, combined LOFAR, MUSE, MeerKAT, and Chandra studies have provided new insights into the evolution of stripped ISM clouds in the ICM, shedding light on the astrophysical processes of magnetized plasma mixing.
In my talk, I will provide an overview of the current understanding of ram pressure stripping at radio wavelengths and outline the key open questions driving the field. Looking forward, the Square Kilometre Array (SKA) promises to be a transformative instrument. SKA-Low will extend these studies to the southern hemisphere, enabling synergies with major observatories like the upcoming Extremely Large Telescope (ELT). The combined power of SKA Low and Mid will allow us to map radio emission with a spectral index down to α=−2 at a 5-arcsecond resolution. SKA-Mid will also explore the magnetic field geometry induced by the ram pressure, via the detection of polarized emission, and the evolution of the neutral ISM phase, traced by the 21-cm emission.
| Topics | Galaxy Clusters & LSS (relativistic particles and magnetic fields) |
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