ALMA as a sensitive probe of the stellar IMF across the cosmic time

At the heart of interpreting starlight, IR and radio continuum (typically
dominated by massive stars) in terms of star-formation rate (SFR) in individual
galaxies or averaged over cosmological volumes, the stellar Initial Mass
Function (IMF) is described as a nearly-universal function in the Galaxy and
nearby galaxies. It was only relatively recently that ISM environments were
identified where the initial conditions of star formation can be dramatically
different, inducing an IMF towards top-heavy (i.e. having more massive stars)
in starbursts, and bottom-heavy in early-type galaxies (ETG). However
such studies
are extremely difficult or impossible for the dust-enshrouded star-forming
systems where we expect different IMFs. We bring along the state-of-the-art
chemical evolution models with well-calibrated yields from stellar
nucleosynthesis, time-delay effect, and star formation history, and combine
with new radiative transfer modelling in multiple transitions multiple species
of C,N,O isotopologues, opening up an unexpected new gate of exploring the IMFs
in dust-rich galaxies, especially for those in the Early Universe. In the talk
we will discuss the physical origins for the top-heavy IMF in starburst
systems, present our new ALMA proof observations in a few strongly lensed dusty
starburst galaxies at high redshift, and compare them with different types of
local galaxies, connecting high redshift SMGs with local ETGs.


See Speaker

Zhi-Yu Zhang (University of Edinburgh/ESO)
KIAA, First floor meeting room
Wed, 2017-06-14 12:00 to 13:00