Colloquium Abstract - Patil - 2026Feb20

February 20, 2026

11:00am Mountain

Pallavi Patil (JHU)

 

From Gas-Rich Galaxies to Quiescence at Cosmic Noon: How Radio AGN Shape Galaxy Evolution

 

Abstract

The peak epoch of galaxy assembly at z~1-3 is a critical phase for supermassive black holes-galaxy-co-evolution. During this period, radio-mode AGN feedback is expected to regulate star formation (SF) within dense environments, yet the timing, energetics, and effectiveness of young radio jets remain poorly constrained. In this talk, I first characterize young radio AGN embedded in dense ISM at cosmic noon. By combining extreme WISE MIR colors with compact radio emission, we identify a sample of ultra-luminous, heavily obscured quasars at z~0.5-3. High-resolution VLA/VLBA imaging reveals that most sources are compact (<2kpc) and exhibit spectral properties indicative of recently triggered jets. Follow-up ALMA CO mapping, together with optical/IR spectroscopy and X-ray data, show Compton-thick nuclei residing in gas-rich hosts with ongoing SF, suggesting that these systems represent an early phase of jet–ISM coupling. Building on this, I then examine whether radio AGN ultimately drive the rapid suppression of SF. Using deep VLA observations of quenching galaxies in the UKIDSS Ultra Deep Field, I assess the prevalence of jetted AGN during the post-starburst phase at cosmic noon. Only ~4% of massive galaxies host detectable jetted AGN, and stacking constrains their residual SF to only a few M☉/yr. Together, these results indicate that while young radio jets are common in gas-rich systems, radio AGN-driven quenching impact may be episodic or delayed. Finally, I highlight how the ngVLA, in synergy with ALMA, will enable transformative, multi-scale studies of jet–ISM feedback across diverse AGN populations, directly connecting black hole growth to the SF regulation over cosmic time.


Local Host: Lucas Hunt

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