KWKEDUSE WORKU

SELECTED WORK

Some of the questions
I’ve worked on.

My research has taken me from particle trajectories to distant galaxies. Here are three projects, with the papers and a closer look at the results.

2024 / RELIC NEUTRINOS

Following neutrinos
through a halo.

Gravity changes how relic neutrinos move and where they accumulate. We developed Cheetah to calculate those trajectories and density profiles around spherical dark-matter halos quickly enough to explore different physical assumptions.

The code also lets us study other non-cold relics. Below are two animations from my defense showing the trajectories in the calculation.

Keduse Worku, Nashwan Sabti & Marc Kamionkowski · 2024

Rapid Methods for Modeling Overdensities of Massive Neutrinos and Other Non-Cold Relics

Read the paper ↗Cheetah code ↗

INSIDE THE CALCULATION

Start with a path.
Then put the paths together.

One choice of starting angle and speed, shown at three radial positions. Watch how the path bends as the dark-matter halo grows.

Halo mass: 10¹⁵ solar masses · Neutrino mass: 0.3 eV

From my PhD defense · Numerical trajectories calculated with Cheetah

Worku et al. (2025) · Figure 1, left panelSource figure ↗

MACS0647 / JWST

Finding galaxies
in the distant past.

A foreground galaxy cluster magnifies the light of distant galaxies. This is the field we studied with JWST.

We combined imaging and spectroscopy to build a catalog of distant galaxy candidates and investigate their physical properties. The cyan labels mark objects with spectroscopic redshifts.

What to look for

The circles locate the candidates among the foreground objects. The labels connect these points of light to the measurements in the paper.

Read the MACS0647 paper ↗

21-CM / COSMIC DAWN

A different clock
for the early universe.

Primordial magnetic fields can change when early structure forms. In our models, that leaves a signature in the 21-cm signal from hydrogen.

Each color below represents a different magnetic-field amplitude. Follow how the troughs and peaks shift relative to the dashed, zero-field reference.

HOW A MAGNETIC FIELD REACHES THE 21-CM SIGNAL

Magnetic fields add power on small scales.

We start by including primordial magnetic fields in the matter power spectrum. That changes the initial conditions for structure formation.

Worku, Cruz & Kamionkowski (2026) · Figure 2Source figure ↗

Left: the sky-averaged 21-cm brightness temperature.

Right: the power in spatial fluctuations of that signal.

Reading the axis: higher redshift means an earlier universe.

Read the Cosmic Dawn paper ↗

EARLIER WORK

CMB foregrounds
and cross-correlations.

My earlier work included using Planck and ACT observations to study dust and cosmic infrared background contamination in thermal Sunyaev–Zeldovich maps. I also worked on cross-correlations of the integrated Sachs–Wolfe and thermal Sunyaev–Zeldovich effects to investigate dark energy.

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