Dr. Philipp Frank

Dr. Philipp Frank

Machine Learning & Astrophysics

Building probabilistic ML methods — variational inference, Gaussian processes, differentiable programming — and deploying them on some of the largest datasets in astrophysics.

About Me

I develop machine learning and probabilistic inference methods and apply them to scientific problems in astrophysics. As a KIPAC Fellow at KIPAC, Stanford University, I build scalable Bayesian algorithms — including variational inference, Gaussian processes, normalizing flows, and differentiable programming frameworks — that turn noisy, incomplete observational data into high-fidelity reconstructions of physical systems.

My primary application domain is 3D mapping of the interstellar medium, where I use ML to push reconstructions to unprecedented scales in both size and resolution and to incorporate multiple tracers for a comprehensive picture of Galactic structure. This work sheds light on the mechanisms of star formation and galaxy dynamics across scales only accessible through our unique vantage point within the Milky Way.

I did my PhD and a followup Postdoc at the Faculty of Physics at LMU Munich and the Max-Planck-Institute for Astrophysics, where I built the theoretical foundations for geometric variational inference and contributed ML-driven applications spanning radio interferometric imaging (M87* black hole), X- and gamma-ray imaging, cosmic-ray air-shower reconstruction, and 3D Galactic dust and gas mapping.

Research Highlights

Building ML methods for scientific inference — from variational algorithms and scalable GPs to real-world deployments on billion-object datasets.

Bayesian reconstruction of the M87* black hole shadow
Bayesian Imaging

Variable Structures in M87*

Probabilistic image reconstruction of the M87* black hole shadow from sparse interferometric data, using high-dimensional variational inference to resolve time-variable structure in the emission ring.

Nature Astronomy, 2022 · Shared first author
Geometric variational inference schematic
Variational Inference

Geometric Variational Inference

A variational inference algorithm that exploits information geometry to navigate complex, high-dimensional posterior landscapes. Uses coordinate transformations to turn difficult posteriors into near-Gaussian problems, enabling scalable approximate inference.

Entropy, 2021 · Cover Story
Gaussian Processes

Parsec-Scale 3D Dust Map

Large-scale Gaussian process regression on millions of stellar observations to infer a continuous 3D dust density field at parsec resolution — scaling GP methods to problems with billions of effective degrees of freedom.

Astronomy & Astrophysics, 2024
ReplicationBench evaluation framework for AI agents in astrophysics
AI Agents

ReplicationBench

A benchmark for evaluating whether AI agents can replicate full astrophysics research papers — testing faithfulness and correctness across experimental setup, data analysis, and code generation on expert-validated tasks.

arXiv, 2025 · cs.CL / astro-ph.IM
Spatio-temporal field dynamics inference
Probabilistic ML

Field Dynamics Inference

Learning dynamical systems from data: jointly inferring the state trajectory and the governing interaction kernel (Green's function) of a stochastic PDE from noisy, partial observations using structured generative models.

Annalen der Physik, 2021 · Phys. Rev. E, 2017
NIFTy.re Bayesian reconstruction example
JAX / Open Source

NIFTy & NIFTy.re

Core developer of NIFTy — a JAX-based probabilistic programming framework for Gaussian processes, variational inference, and differentiable forward modeling. Powers 20+ published scientific reconstructions.

JOSS, 2024 · Used across 20+ publications

Publications

See also: Google Scholar

First Author

Preprints

Co-Author

Preprints

Conference Proceedings (co-author)

Theses

Software & ML Frameworks

GraphGP

Scalable Gaussian processes via nearest-neighbor graphs — enabling GP regression on millions of data points with GPU acceleration (CUDA).

NIFTy / NIFTy.re

JAX-based probabilistic programming framework for Gaussian processes, geometric variational inference, and differentiable forward modeling.

J-UBIK

JAX-accelerated Universal Bayesian Imaging Kit — differentiable inference pipelines for multi-domain astrophysical imaging.

LensCharm

Bayesian strong gravitational lensing reconstruction using structured generative models and variational inference.

DENSe

Non-parametric Bayesian density estimation for Poisson-distributed count data with learned correlation structure.

Dynamic VLBI resolve

Probabilistic imaging pipeline for dynamic radio interferometry — joint inference of time-varying structure from sparse Fourier-plane data.

Data Products

Teaching & Mentoring

ML & Inference Courses

  • Variational, Flow-Based, and Diffusion Models for Astrophysics — Lecturer, AstroAI Workshop 2025, Center for Astrophysics, Harvard; event, recording
  • Scientific Computing in Astrophysics — Guest Lecturer (ML methods), Yale University, April 2024.
  • Bayesian Imaging for Radio Astronomy — Block course on ML-based image reconstruction, AIMS, Cape Town, February 2024.
  • Information Theory & Information Field Theory — Head tutor for graduate ML/inference course, LMU Munich, 2017–2020; course.

Co-Supervised Master Students

  • Martin Reiß — Polarimetric Tomography of Galactic Dust
  • David Gorbunov — Density Reconstruction using Geometric Variational Inference
  • Johannes Zacherl — Probabilistic Autoencoder using Fisher Information
  • Matteo Guardiani — Non-parametric Bayesian Causal Modeling
  • Vincent Eberle — Efficient Representation of Instrument Responses
  • Sara Milosevic — Astrophysical Data Analysis with Variational Autoencoders
  • Margret Westerkamp — Dynamical Field Inference via Ghost Fields
  • Morten Giese — Inference of the Atmospheric Electron Density with LOFAR Data

Other Teaching

Research Visits

Talks, Conferences & Workshops

(Co-)Organized Workshops

Invited Talks

Conferences & Workshops

Media

Contact

phfrank (at) stanford.edu
web (at) ph-frank.de