The spatially resolved [CII]-to-gas conversion factor in early galaxies

by Dr Livia Vallini (INAF-OAS Bologna)

Thursday 15 May 2025, 11:30 → 12:30 Europe/Rome

Sala Jappelli (Osservatorio astronomico di Padova)

Understanding how efficiently gas collapses into stars during the Epoch of Reionization (EoR) is key to shedding light on galaxy evolution. On global scales, this process is quantified by the depletion time (tdep=Mgas/SFR), while on spatially resolved scales, by the slope and normalization of the Kennicutt-Schmidt relation. The [CII] line traced by ALMA has emerged as a powerful gas tracer in EoR sources and, together with the SFR inferred from both rest-frame UV and IR continuum, is often used to derive the depletion time. In this talk, by leveraging the SERRA cosmological zoom-in simulation, I will discuss how the [CII]-to-gas conversion factor (α_CII) varies with the interstellar medium properties. Dense, metal-rich, and bursty regions of the ISM exhibit high [CII] surface brightness, leading to lower conversion factors toward galaxy centres. Moreover I will show how the conversion factor depends on the galaxy compactness. I will discuss the implications of these findings in light of recent [CII] non-detections in JWST-selected galaxies at z>10, which impose strong constraints on their cold gas content and suggest very short depletion times.

 

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https://unipd.zoom.us/j/85273198731?pwd=V1ZiNE9ZWUN4ZTdIUzJsTFo0Z3U2Zz09
Meeting ID: 852 7319 8731
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