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Feb
25
Thu
Cake talk by Vasily Kokorev (DAWN)
Feb 25 @ 14:00 – 14:30

The Evolving Interstellar Medium of Star-Forming Galaxies

In this talk I would like to provide a status update regarding the current and upcoming projects of my PhD. This week we have passed a milestone by submitting our work where we analyse the far-infrared properties of ∼4,700 star-forming galaxies at z <4.5, drawn from the deepest, super-deblended catalogues in the GOODS-N and COSMOS fields. We develop a novel panchromatic SED fitting algorithm, STARDUST, that models the emission from stars, AGN, and infrared emission arising from dust heated by star formation without relying on energy balance assumptions. With our code we recover robust estimates of FIR properties of our objects, and through a set of simulations we quantify how the quality of our estimates is affected by the photometric coverage and uncertainty in photoz. In particular, we focus on the dust-to-stellar mass ratio, which we find to be increasing by a factor of 10 from z= 0 to z= 2, while remaining flat at higher−z, mirroring the evolution of the gas fraction. Finally, we construct the dust mass functions (DMF) of star-forming galaxies up to z=1 by the transforming the stellar mass function to DMF through the scaling relations, that we derive in our work. Reassuringly, we find that the evolution off dust-to-stellar mass ratio, and the recovered DMFs are in good agreement both with observational data, and the theoretical predictions of the Horizon-AGN and IllustrisTNG simulations.

Mar
4
Thu
Cake talk by Hannah Stacey (MPA Garching)
Mar 4 @ 14:00 – 14:30

100-pc resolution of z~2 quasar host galaxies with ALMA: witnessing the formation of compact spheroids

With the advent of ALMA, the interstellar medium of high-redshift galaxies can be probed at remarkable resolution and sensitivity. We push the limits of ALMA even further by studying strongly lensed galaxies where we are able to probe structures of 10s–100s parsecs in scale. Using novel lens modelling techniques, we reconstruct the molecular interstellar medium (ISM) structure and kinematics of z~2 galaxies hosting luminous quasars, to give a new perspective on the physical processes that drive the formation and evolution of quiescent galaxies, from birth to quiescence. A key aspect in this study is how spheroids formed very high stellar densities and grew concurrently with their supermassive black holes. We find evidence the quasar host galaxies are observed in a stage during a rapid transformation into compact spheroids, where a high density of dynamically unstable gas leads to efficient star formation and black hole accretion. Furthermore, I present first results of mapping the structure and kinematics across the CO ladder – the highest resolution of the molecular ISM for a quasar host at cosmic noon – which demonstrates a highly non-homogeneous ISM.