Research

PhD student at the University of Geneva
Strong Gravitational Lensing and Time-Delay Cosmography

Current Research

PhD Research

2025 - Present

Supervisors

Affiliation

  • University of Geneva
  • TDCOSMO Collaboration

Department of Theoretical Physics (DPT)

Strong Gravitational Lens Modeling for Time-Delay Cosmography

Why do our measurements of the universe's expansion rate disagree, and can light bent by gravity reveal the answer?

My PhD research focuses on automating the modeling of strong gravitational lenses while maintaining cosmography-grade precision. Strong gravitational lensing occurs when a massive foreground galaxy bends light from a distant quasar, creating multiple images of the same source. By measuring the time delays between these images, we can constrain the Hubble constant H₀.

Traditional lens modeling is time-intensive and requires significant manual effort. Within the TDCOSMO collaboration, I develop automated pipelines that can efficiently model large samples of lenses without sacrificing the accuracy needed for precision cosmology.

This work addresses the Hubble tension: the discrepancy between local measurements of H₀ (around 73 km/s/Mpc) and values from the early universe via the CMB (around 67 km/s/Mpc). Scaling up time-delay cosmography through automation will provide the statistical power needed to help resolve this tension.

As part of my research toolkit, I created the tool FITSme to easily mask FITS files.

FITS Masking Editor (FITSme)

Projects during Studies

Master Thesis

September 2024 - March 2025

Supervisors

  • Prof. Dr. Alexandre Refregier, ETH Zurich
  • Dr. Michele Bianco, ETH Zurich

Physics Department - Cosmology Group
ETH Zurich

Modeling Density Distributions in Ionized Regions in the Early Universe

Can we use AI to model where stars form?

In my master's thesis, I explore the application of AI to model and predict CDM density distributions inside ionized HII regions (bubbles) in the early universe.

The primary objective is to develop a flow-based generative model that takes a given ionized bubble as input and outputs a probabilistic density distribution of matter within that bubble. The model is trained using a dataset of bubble-density pairs, where each bubble corresponds to a 2D density slice extracted from high-resolution simulations using pyC2Ray. To achieve this, I employ normalizing flows (GLOW), which iteratively transform a simple base distribution into the target density distribution.

Semester Project

January 2024 - June 2024

Supervisors

  • Prof. Dr. Philippe Jetzer, University of Zurich
  • Prof. Dr. Gian Michele Graf, ETH Zurich

Physics Institute - Gravitation and Astrophysics Group
University of Zurich

Lunar Response to Gravitational Waves

Could the Moon serve as a giant gravitational wave detector and provide new confirmation of Einstein's General Relativity?

In this thesis, we review in detail the interaction between gravitational waves (GWs) and the Moon, treated as an elastic body. The aim is to combine theoretical findings with previous literature to make the topic more accessible.

Building on the theoretical framework of elasticity, we derive and linearize Cauchy's equations of motion to model the Moon's response to such a GW. By investigating toroidal and spheroidal oscillations induced by a GW in different polarizations, we derive the differential equation systems to predict the Moon's displacements, which can then be numerically solved.

Normal mode oscillation of the Moon caused by a gravitational wave
A normal mode oscillation of the Moon, caused by a gravitational wave.

Proseminar

February 2023 - June 2023

Supervisors

  • Prof. Dr. Matthias Gaberdiel, ETH Zurich
  • Dr. Matthew Lewandowski, ETH Zurich

Physics Department - String Theory Group
ETH Zurich

Three-String Interaction

How can the geometry of string world-sheets unlock new insights into quantum scattering?

In this report, we explain how the world-sheet of a string can be viewed as a Riemann surface. This is essential when calculating quantum mechanical scattering amplitudes, which in string theory characterize the probability of different scattering occurring.

In order to map the upper half-plane of the complex plane onto a polygon, the Schwarz-Christoffel map is introduced. As a result, we can find a canonical representation of the world-sheet of three strings interacting by considering it as a degenerate polygon.

World sheet of a three string interaction as a degenerate polygon
Illustration of the idea to view the world sheet of a three string interaction as a degenerate polygon.

Laboratory Work

2022

Paul Scherrer Institute (PSI)
Villigen, Switzerland

Muon Spin Rotation Study on Type-I Superconductivity

Conducted a muon spin rotation study on Type-I superconductivity in lead (Pb) at the Paul Scherrer Institute laboratory. This experimental work provided hands-on experience with advanced particle physics techniques and superconductor characterization.