diff --git a/assets/FFI/Forward-Model-Constraints.svg b/assets/FFI/Forward-Model-Constraints.svg index 7706e0f..68ad09a 100644 --- a/assets/FFI/Forward-Model-Constraints.svg +++ b/assets/FFI/Forward-Model-Constraints.svg @@ -1,3 +1,3 @@ -
Lensing Forward Model
Optimized convergence maps
Optimized Initial Conditions
Simulator
Optimized Final Field
\ No newline at end of file +Optimized convergence maps
Optimized Initial Conditions
Simulator
Optimized Final Field
\ No newline at end of file diff --git a/assets/FFI/Forward-Model.svg b/assets/FFI/Forward-Model.svg index 846caca..fa791db 100644 --- a/assets/FFI/Forward-Model.svg +++ b/assets/FFI/Forward-Model.svg @@ -1,3 +1,3 @@ -
Lensing Forward Model
Initial Conditions
Simulator
Final Field
Convergence maps
\ No newline at end of file +

Initial Conditions
Simulator
Final Field
Convergence maps
\ No newline at end of file diff --git a/paris2024/index.qmd b/paris2024/index.qmd index 8bbda97..e645f3f 100644 --- a/paris2024/index.qmd +++ b/paris2024/index.qmd @@ -1543,6 +1543,108 @@ Let's now look at example of usage in cosmology. ::: +--- + + +## Forward Modeling in Cosmology {style="font-size: 20px;"} + +:::{.columns} + +::: {.column width="50%"} + +#### Weak Lensing Model + +- **Prediction**: + - A simulator generates observations from initial conditions and cosmological parameters. + +- **Inference**: + - The simulated results are compared with actual observations. + - Optimal initial conditions and parameters are inferred to closely match the observed data. + + +:::{.fragment fragment-index=2} + +:::{.solutionbox} + +::: {.solutionbox-header style="font-size: 20px;"} + +Scaling Challenges + +::: + +::::{.solutionbox-body style="font-size: 19px;"} + + +- **Software**: Existing tools like **JaxPM** or **PMWD** already exist. +- **Resolution Today**: these differentiable simulators currently support up to **130 million particles** $512^3$. +- **Ideal Resolution**: Billion-particle simulations are necessary for high accuracy $1024^3$ and more. +- (See **Hugo's** and **Justine's** talks for more details) +- We need to scale up to multiple GPUs and nodes to reach the required resolution. + +:::: + +:::: + +::: + +::: + +::: {.column width="50%"} + +:::{.r-stack} + +::: {.fragment fragment-index=1 .fade-out} + +![Forward Modeling (Prediction)](assets/FFI/Forward-Model.svg){fig-align="center" width="100%"} + +::: + +::: {.fragment fragment-index=1 .fade-in} + +![Forward Modeling (Inference)](assets/FFI/Forward-Model-Constraints.svg){fig-align="center" width="100%"} + +::: + +::: + +::: + +::: + + +:::{.notes} + +**So before diving into multi-node tools for cosmology, let's see how they can benefit forward modeling.** +- Forward modeling is a cornerstone of cosmological inference, linking theoretical predictions with observed data. + +In forward modeling, the goal is to replace an explicit likelihood function with a simulator. The process involves: + + +1. **Prediction**: + - The simulator generates synthetic observables, such as convergence maps, using initial conditions and cosmological parameters. + - These observables mimic the universe's large-scale structure under specific physical assumptions. + +2. **Inference**: + - Simulated results are compared to actual observations (e.g., from telescopes). + - Through iterative refinement, we infer the parameters that best match the observed universe, like dark matter density or Hubble constant. + + +1. **Resolution Today**: + - Simulations operate with 250,000–130 million particles (512^3). + - These scales capture broad features but miss finer details essential for precision cosmology. + +2. **Ideal Resolution**: + - Billion-particle simulations are critical for matching the accuracy demanded by modern cosmological surveys. + - These simulations uncover small-scale phenomena like non-linear clustering. + +3. **Tools**: + - Tools like **JaxPM** and **PMWD** handle simulations up to 130 million particles on a single GPU. + - Scaling beyond this requires multi-node, distributed approaches. + + +::: + + --- ## jaxDecomp : Components for Distributed Particle Mesh Simulations {style="font-size: 22px;"} @@ -1582,16 +1684,9 @@ Let's now look at example of usage in cosmology. - **Multi-Node Supports** - Works seamlessly across multiple nodes. -::: - -:::{.fragment fragment-index=5} - Supports Different Sharding strategies -::: - -:::{.fragment fragment-index=6} - - Open-source and available on **PyPI** ::: @@ -1645,7 +1740,7 @@ Let's now look at example of usage in cosmology. #### Strong Scaling -![](assets/jaxDecomp/strong_scaling.png){fig-align="center" width="95%"} +![](assets/jaxDecomp/strong_scaling.png){fig-align="center" width="100%"} ::: @@ -1654,7 +1749,7 @@ Let's now look at example of usage in cosmology. #### Weak scaling -![](assets/jaxDecomp/weak_scaling.png){fig-align="center" width="95%"} +![](assets/jaxDecomp/weak_scaling.png){fig-align="center" width="100%"} ::: @@ -2094,75 +2189,3 @@ will explain scaling in here --- -## Forward Modeling in Cosmology {style="font-size: 20px;"} - -:::{.columns} - -::: {.column width="50%"} - -#### Weak Lensing Model - -- **Prediction**: - - A simulator generates observations from initial conditions and cosmological parameters. - -- **Inference**: - - The simulated results are compared with actual observations. - - Optimal initial conditions and parameters are inferred to closely match the observed data. - - -:::{.solutionbox} - -::: {.solutionbox-header style="font-size: 20px;"} - -Scaling Challenges - -::: - -::::{.solutionbox-body style="font-size: 19px;"} - -- **Resolution Today**: Simulations currently use around **250,000 to 130 million particles**. -- **Ideal Resolution**: Billion-particle simulations are necessary for high accuracy. -- **Software**: Tools like **JaxPM** or **PMWD** support up to ~130 million particles on a single GPU. - -:::: - -:::: - -::: - -::: {.column width="50%"} - -:::{.r-stack} - -::: {.fragment fragment-index=1 .fade-out} - -![](assets/FFI/Forward-Model.svg){fig-align="center" width="75%"} - -::: - -::: {.fragment fragment-index=1 .fade-in-then-out} - -![](assets/FFI/Forward-Model-FinalField.svg){fig-align="center" width="75%"} - -::: - -::: {.fragment fragment-index=2 .fade-in-then-out} - -![](assets/FFI/Forward-Model-Constraints.svg){fig-align="center" width="75%"} - -::: - -::: - -::: - -::: - - -:::{.notes} - -- **Simulations in Cosmology**: These simulations model the universe's evolution to reproduce observed structures, helping infer parameters like dark matter density, dark energy, and other cosmological constants. -- **Resolution Requirement**: Simulations with more particles provide finer details, making convergence maps closer to observed data. Current particle counts (130 million) are still limited compared to the **billion-particle simulations** required for accurate cosmological inference. - -::: -