DESI Year 1 Results: Baryon Acoustic Oscillations


There has been a lot of excitement around the ICCUB today – the press have been here and everything – ahead of the release of the Year 1 results from the Dark Energy Spectroscopic Instrument (DESI). The press release from the Lawrence Berkeley Laboratory in California can be found here.

The papers were just released at 5pm CEST and can be found here. The key results pertain to Baryon Acoustic Oscillations (BAOs) which can be used to track the expansion rate and geometry of the Universe. This is one of the techniques that will be used by Euclid.

There’s a lot of technical information to go through and I have to leave fairly soon. Fortunately we have seminar tomorrow that will explain everything at a level I can understand:

I will update this post with a bit more after the talk, but for the time being I direct you to the high-level cosmological implications are discussed in this paper (which is Paper VI from DESI).

If your main interest is in the Hubble Tension then I direct you to this Figure:

Depending on the other data sets included, the value obtained is around 68.5 ± 0.7 in the usual units, closer to the (lower) Planck CMB value than the (higher) Supernovae values but not exactly in agreement; the error bars are quite small too.

You might want to read my thoughts about distances estimated from angular diameters compared with distances measured using luminosity distances here.

If you’re wondering whether there is any evidence for departures from the standard cosmology, another pertinent comment is:

In summary, DESI data, both alone and in combination with other cosmological probes, do not show any evidence for a constant equation of state parameter different from −1 when a flat wCDM model is assumed.

DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations

More complicated models of time-varying dark energy might work, but there’s no strong evidence from the current data.

That’s all from me for now, but feel free to comment through the box below with any hot takes!

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