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Resolving Cosmic Noon: Planck-selected extremely-luminous dusty starbursts magnified by strong gravitational lensing

Presentation #214.03D in the session Strong and Weak Gravitational Lensing.

Published onJun 29, 2022
Resolving Cosmic Noon: Planck-selected extremely-luminous dusty starbursts magnified by strong gravitational lensing

The brightest objects in the submillimeter sky are a population of dusty star-forming galaxies (DSFGs), which host extreme IR luminosities (1012-14 Lsun) reflecting enormous star formation rates of 100-10,000 Msun/yr. However, the physical mechanisms by which they fuel (and later extinguish) this maximal starburst phase remain poorly understood. While DSFGs are presumed to be the progenitors of the massive early-type galaxies seen locally, they have no suitable low-z analogs, so direct observation is the only tenable approach. Existing telescopes are largely incapable of reaching the milliarcsecond-scale resolution required to observe star formation at crucial 100-parsec physical scales, so our best solution is to use strong gravitational lensing. By magnifying and amplifying distant objects, lensing offers a view of high-redshift galaxies that is usually only afforded by the local Universe. To this end, we have identified a pilot sample of 30 lensed DSFGs using the all-sky Planck and WISE surveys. This PASSAGES sample (Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts) includes several of the most luminous objects ever discovered in the Universe.

In this dissertation talk, I will discuss the application of parametric lens modeling for a subset of 15 PASSAGES objects to high-resolution (0.1-0.5”) imaging of stellar light by HST at 1.6 micron, dust and molecular CO by ALMA at 1mm, and star formation by JVLA at 6 GHz. Correcting for lensing magnification reveals objects that are still intrinsically very luminous (>1013 Lsun), rivaling even the brightest unlensed galaxies known. I will review ongoing work to interpret the source-plane kinematics and structure of molecular gas in these objects, providing insight into how stellar mass is being assembled at prodigious rates. Lastly, we investigate the de-lensed size of dust continuum-emitting regions to ascertain if these galaxies are approaching hypothesized limits on maximal star formation surface densities, above which radiation pressure ought to halt further conversion of gas into stars.


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