Project:	Modeling how dark matter structure forms under gravity to test dark energy (JPL AO No. 16824)
Discipline:	Astronomy/Astrophysics
Mentor:	Dida Markovic, (JPL), katarina.markovic@jpl.nasa.gov, Phone: (818) 354-9981
Background:	We have entered the era of precision cosmology, where flagship missions like the Euclid (launched in 2023) and Roman (launching this September) space telescopes will have mapped the universe with unprecedented detail by the beginning of the next decade. These missions aim to map billions of galaxies across cosmic time, providing a "high-definition" view of the universe's evolution. Recent analyses have begun to hint at potential deviations from the standard cosmological model (ΛCDM), particularly regarding the dynamical behavior of dark energy (w0​−wa​). While ΛCDM treats dark energy as a constant vacuum energy, these new signals suggest it may be dynamic—changing its density as the universe expands. To explore these emerging signals without being restricted to specific theoretical models, it is becoming increasingly important to adopt flexible, model-independent frameworks. These tools allow us to characterize the growth of cosmic Large-Scale Structure (LSS)—the "cosmic web" of matter—under the influence of gravity without being biased by prior assumptions.
Description:	Effective Field Theory of Large-Scale Structure (EFTofLSS) is an enhanced version of perturbation theory for LSS. In the same way that engineers use effective theories to describe fluid dynamics without tracking every individual molecule, EFTofLSS allows cosmologists to model the distribution of matter on large scales while accounting for the complex, non-linear physics occurring on smaller scales. The objective of this project is to implement a model-independent "bootstrap" extension of the EFTofLSS. This approach seeks to capture modified gravity or dark energy physics by parameterizing the underlying equations of motion rather than assuming a specific, pre-defined model. To achieve this, the student will: - Master Advanced Analysis: Gain proficiency in LSS analysis techniques, specifically focusing on how matter density fluctuations evolve over time. - Code Development: Under the mentorship of JPL scientists, the student will extend a state-of-the-art cosmological code. - One-Loop Implementation: The primary task is to incorporate a one-loop matter power spectrum calculation. This involves computing higher-order corrections to the linear theory of gravity to accurately model "beyond-$ \Lambda ext{CDM} $" scenarios. - Application: The resulting code will serve as a flexible engine for quantifying deviations from the standard model in weak gravitational lensing (the bending of light by dark matter) and galaxy clustering analyses. These contributions will directly impact the data pipeline for flagship surveys like Euclid and Roman, helping to determine if our current understanding of gravity requires a fundamental rewrite.
References:	EFTofLSS note: Baldauf, Tobias, ’Effective Field Theory of Large-Scale Structure’, https://doi.org/10.1093/oso/9780198855743.003.0007 First application of EFTofLSS: Guido d’Amico et al JCAP05(2020)005, https://iopscience.iop.org/article/10.1088/1475-7516/2020/05/005 Extension of EFTofLSS with model-independent (bootstrap) approach: Marco Marinucci et al, JCAP10(2024)051, https://iopscience.iop.org/article/10.1088/1475-7516/2024/10/051
Student Requirements:	Background in astrophysics or cosmology is preferable. Prior experience with coding and data analysis is required
Location / Safety:	Project building and/or room locations: . Student will need special safety training: .
Programs:	This AO can be done under the following programs:   Program    Available To        SURF@JPL    both Caltech and non-Caltech students  Click on a program name for program info and application requirements.