DES Supernovae - Beyond ΛCDM (Ryan Camilleri & Tamara Davis)

Cosmology from Home registration: cosmologyfromhome.com/registr...
Ryan Camilleri and Tamara Davis tell us about how they have examined models beyond ΛCDM using the Dark Energy Survey's wonderful supernova catalogue. Tantalisingly, they find that a number of models are "moderately preferred" over ΛCDM (in model comparison speak).
They also, very admirably, check whether crucial aspects of the DES pipeline are model dependent or not. They find that, so long as the reference model is close-ish to the true model then the pipeline is accurate. "Close-ish" is very generous here as well, as they even found in simulations that when one processed the data with models 10σ from the truth, the subsequent parameter constraints were still within 1σ of the truth. The moral of this is that, even though the supernovae were processed assuming ΛCDM, so long as the true cosmology isn't too far from ΛCDM then this doesn't matter.
This means, if you have your own model that they haven't tested, you don't need to simulate the entire DES analysis pipeline to analysis your model, you can do your model comparison at the level of the Hubble diagram. Nice!
Paper: arxiv.org/abs/2406.05048
Ryan: smp.uq.edu.au/profile/13102/r...
Tamara: smp.uq.edu.au/profile/186/tam...

[@talks_curator728]

*Index to Key Parts of the Talk*
[00:00] Shaun's intro
[01:41] Opening comments by Ryan
[02:20] Two takeaways to remember
[03:06] Motivation for this work, starting with ΛCDM overview
[05:01] So why go beyond ΛCDM?
[06:13] What is beyond ΛCDM? Testing different models
[07:18] Parametric forms of Λ
[09:28] Dvali-Gabadadze-Porrati (DBP) models
[10:04] Chaplygin Gas models
[11:13] Timescape cosmology
[14:12] Why these models were tested vs other options
[15:31] Observations -> Hubble Diagram
[16:08] DES-SN5YR Pipeline
[23:10] The Omega_m - w degeneracy; intro of Q_H parameter
[25:21] Model constraints
[29:43] Model comparisons
[35:37] What's next?

[@thorntontarr2894]

Now after a second watch of this work, this particular CT needs to be more widely seen because it represents the reason DES and/or DESI projects are done: we want to know what is really there vs. what is modeled. Beginning @6:15 we are offered what these DES data can do to guide selection of models that represent the expansion of the Universe. This is fundamental!
Based a previous comment by Shaun after the original CT by these two presenters, Ryan (he's young) will likely witness the unveiling of how the Universe expanded which awaits future data presented by Vera Rubin Observatory and the space-based observatories.