Between January 12th and 15th, 2026, the University of Arizona’s Cosmology Lab hosted the “Arizona Winter School on Multi-Probe Cosmology in the Roman ST Era,” in collaboration with the Roman Science Collaboration and the Roman project. The Roman-focused school covered topics relevant to the work of the HLIS PIT, and many PIT members participated in this event as organizers, hosts, lecturers, and attendees. 

The winter school itself was primarily organized by Tim Eifler and Elisabeth Krause, both active PIT members. Eifler is also currently the lead of the PIT’s Cosmological Parameter Inference Pipeline (CPIP) Working Group (WG). Throughout the week, participants engaged with lectures and workshops covering a range of cosmology-related topics, including weak lensing, Type Ia supernovae, CMB cross-correlations, and multi-probe inference strategies. Many of these lectures and tutorial sessions were led by PIT members, including:

• "Weak lensing" by Chris Hirata, co-lead of the Shape and Color Measurement (SCM) WG

• "Roman Space Telescope SC Overview" by Ami Choi (former SCM WG co-lead), Jeff Kruk, and Julie McEnery

• "Roman and Rubin Synergies" by Michael Troxel (PIT Inclusion co-chair and DESC representative)

• "Multi-probe Concepts (3x2 and Beyond)" by Elisabeth Krause (PIT member and HLWAS Definition Committee Member)

• "Machine Learning Accelerated Inference Frameworks” by Vivian Miranda and Tim Eifler (co-chairs of PIT CPIP WG)

Links to the recorded talks and lectures are posted on the winter school website here.

In addition to the PIT members involved in organizing the winter school, many members of our team attended as participants. Further, twelve early-career PIT members presented research highlights during the lightning talk sessions:

• Misha Rashkovetskyi, “tSZ-split Clustering of DESI Galaxies”

• Kaili Cao, “Fisher Forecasts for Cosmological Yields from 3×2pt Analysis of the Roman High Latitude Imaging Survey”

• Nihar Dalal, “Deciphering Baryonic Feedback from ACT tsz Galaxy Clusters”

• Y. Megan Zhao, “Scattering Transform On The Sphere Applied to Weak Lensing”

• Yufei Zhen, “Photo-z Calibration for Roman with Self-Organizing Maps”

• Navin Chaurasiya, “Impact of photometric redshift errors on galaxy-dark halo connection in HSC survey”

• Katherine Laliotis, “Instrument-level systematics for weak lensing with Roman and Rubin”

• Charlie Mpetha, “Fundamental Physics with Galaxy Clusters”

• Michael Gabe, “Poisson Noise Bias Corrections”

• HyeongHan Kim, “Near-IR Weak-Lensing Measurements in the CANDELS Fields”

• Haley Bowden, “Inferring Halo Properties from Galaxy Nearest Neighbors” & “Neural Network Emulators for Roman 3x2pt Analyses”

• Raul Teixeira, “DES intrinsic alignment self-calibration and HSC 2x2pt”

Several of these talks have associated posters, which can be found in the gallery here. The PIT would like to extend a huge thank you to all of our early career scientists (ECS) contributing essential work to the PIT’s goals, and to the winter school organizers for the opportunity to showcase our ECS members’ work.

In summary, the Arizona winter school was a great success, thanks in part to efforts from our own PIT members. We represented exciting ongoing research topics, and highlighted work from our members. We look forward to PIT participation in future cosmology workshops to come!