[Physics-talks] Astro Seminar: Novel Methods for Lyman-Alpha Forest Cosmology

[Celina Yamakawa]

Good morning everyone,

You are invited to attend the following seminar:

*Title:* Novel Methods for Lyman-alpha Forest Cosmology
*Speaker:* Wynne Turner (OSU)
*Date:* Tuesday, February 10, 2026
*Time:* 11:00 AM
*Location:* Physics Building, Reading Room (3rd floor)

One of the biggest open questions in cosmology is the nature of dark
energy. The Lyman-alpha (Lyα) forest is the most powerful probe of the
expansion history at redshifts 2 < z < 4, where cosmological parameters can
be measured from its two-point correlation function through features such
as the BAO scale and the Alcock-Paczyński (AP) effect. However, current
analyses are limited by the quasar continuum fitting process, which removes
information on large scales and distorts the correlation function on all
scales. To address this, I developed the Lyα Continuum Analysis Network
(LyCAN), a convolutional neural network that predicts the forest continuum
solely based on longer-wavelength spectral features. I will present LyCAN
results on DESI DR1 data, providing the most precise measurement to date of
the effective optical depth evolution. Additionally, since LyCAN predicts
independently of the forest region, it preserves large-scale information
valuable for cosmology. I will also present cosmological forecasts
demonstrating that knowledge of the true continuum could improve AP
parameter constraints by up to ~15%, which is analogous to increasing the
Lyα forest survey area by roughly 40%. Realizing this improvement will
strengthen the Lyα forest’s ability to distinguish between competing
cosmological models at high redshift, and I will conclude by discussing
future prospects for achieving this measurement.

We hope you can join us!


-- 


Celina Yamakawa

Assistant to the Department Chair | Administrative & Events Coordinator

Physics & Astronomy Department

900 University Ave
<https://www.google.com/maps/search/900+University+Ave?entry=gmail&source=g>,
Physics Bldg. RM 3047B, Riverside CA 92521
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