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Synergies of LSS with CMB S4 Session

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Discussion Topics

  • Plans, current status and development needed
    • Challenges & approaches for proposed analyses
    • Infrastructure needs
    • Coordination between surveys / Common infrastructure
  • Stretch goal: Come up with a plan for Snowmass 2021 proposals / contributions to existing ones

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Snowmass 2021

  • Restarts September 2021
  • Will resume with White Paper writing stage
    • White paper submission deadline: 15 March 2022
    • No LOI needed
  • CF6: Dark Energy and Cosmic Acceleration: Complementarity of Probes and New Facilities
    • Higher-order statistics with galaxy and CMB surveys - Jia Liu et al.
    • Improving Cosmological Constraints by Cross-correlating Galaxy and CMB surveys - Eric Baxter et al.
    • Theory and Computing Across LSST, DESI, and CMB-S4 - Kyle Dawson et al.
    • Multi-Wavelength Simulations - Yuuki Omori et al.
    • Cycle and symbiosis AI and Cosmology - Brian Nord et al.
  • Can we identify additional areas that should be included in snowmass 2021?
  • Snowmass planning session at CMB S4 meeting:
    • Session intro: Thursday 10:35am-10:50am Pacific
    • Parallel: Thursday 11:10am-2:00pm Pacific
    • Session summary: Friday 09:10am-09:45am Pacific
  • More information: https://snowmass21.org/start

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Planned analyses: Challenges & possible approaches

  • Emulator-based methods promising, needs to be tested / applied to data
  • Quantification of this within Rubin
    • Linear x halofit problematic for LSST
    • Simulations x PT: use expansion from LPT and use advected values from sims
  • Baryonic effects
    • Also for CMB lensing, ell~1000 (CMB S4)
    • Use secondaries to learn about baryons
  • Correlated systematics
    • MW: dust modulates number counts, correlated with MW foregrounds for CMB
  • Analysis methods: likelihood-based vs. SBI vs. Bayesian pipelines

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Infrastructure needs / Priorities / Coordination

Homogeneous analysis pipelines

  • Notes as bullet points

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Infrastructure needs / Priorities / Coordination

Joint simulations:

  • ML to boost no of realizations
  • Can ML realizations be used for covariance/forward-modeling?
    • mmDL: variance seems to be reproduced
  • Need large number of input cosmologies
  • Including baryonic physics / marginalization / survey systematics -> can we decouple baryonic effects from cosmology
  • Gains of SBI:

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Snowmass 2021 plans

  • Notes as bullet points

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Session summary: Plans for work going forward

  • Challenges and approaches for proposed analyses:
  • Infrastructure needs:
  • Building towards a common infrastructure:
  • Tasks:
  • Snowmass 2021 plans:

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