Netherlands Astronomy Conference 2025

Euclid's view on galaxy quenching

28 May 2025, 16:15

15m

Fletcher Landgoed Hotel Holthurnsche Hof

Plenary

Speaker

Pablo Corcho Caballero (Kapteyn Astronomical Institute, University of Groningen)

Description

Understanding the processes that drive the quenching of star formation in galaxies is crucial for unveiling the mechanisms that shape galaxy evolution. Quenching transforms actively star-forming galaxies into passive systems on very short timescales of a few hundred Myr, influencing the overall structure, morphology, and chemical composition of galaxies across cosmic time. Investigating quenching helps address fundamental questions about the interplay between internal processes, such as feedback from active galactic nuclei or supernovae, and external factors like environmental effects in dense galaxy clusters or groups.

The Euclid mission is set to revolutionize our understanding of galaxy evolution by mapping both the Universe's large-scale structure and the internal structure of galaxies with unprecedented precision. As part of the first Euclid Quick Data Release (Corcho-Caballero+25), we investigated the star formation histories (SFHs) of galaxies at $0Corcho-Caballero+23). By applying Bayesian inference to optical-to-near-infrared photometry, we measured average specific star formation rates over multiple timescales, probing the derivative of the SFH, categorizing galaxies as Ageing (secularly evolving), Quenched (recently halted star formation), or Retired (dominated by old stars). To validate our method, we compared results with synthetic observations from the IllustrisTNG simulation. We present two alternative and complementary classification methods: a posterior-based classification and a model-driven classification that exploits the predictive power of IllustrisTNG.

In the nearby Universe (z<0.1), our analysis reveals consistent results with previous findings: approximately 70% of galaxies are classified as Ageing, 10% to 20% are Retired, and the remaining fraction (10%-20%) experienced a sudden truncation of star formation within the last Gyr. In terms of stellar mass, Ageing and Retired galaxies largely dominate the low- and high-mass ends. The fraction of Retired galaxies surpasses Quenched systems at stellar masses above $3\times10^{10} M_\odot$. The temporal evolution of these populations shows a rising fraction of Ageing galaxies and a decreasing fraction of Retired galaxies at higher redshifts. Interestingly, the Quenched fraction remains relatively stable across mass and redshift ranges.

In term of their physical properties, we explored the mass-size-metallicity relation for each population: Ageing galaxies align with disk morphologies and low stellar metallicities; Retired galaxies are compact and chemically enriched; and Quenched galaxies present an intermediate profile, more compact and evolved than Ageing systems. Despite possible selection biases, this work highlights Euclid's immense potential for shedding light on the physical mechanisms driving galaxy quenching and evolution.