Nikki Arendse

Postdoctoral researcher at Stockholm University

Research interests

Hubble constant & sound horizon tension

One of the most outstanding problems in current-day cosmology is the Hubble tension: low-redshift measurements calibrated by Cepheids obtain a higher Hubble constant than observations from the Cosmic Microwave Back-ground radiation. We have investigated the tension more broadly in terms of the sound horizon, a fundamental distance scale in the early Universe.

Gravitationally lensed supernovae

A promising new way to shed light on cosmological tensions is with gravitationally lensed supernovae, by measuring the lens properties and time delays between supernova images. Currently, we are searching for them with the Zwicky Transient Facility, and within a few years the Vera Rubin Observatory will join the hunt.

Galaxy cluster masses

Galaxy clusters allow us to calculate the matter density and amplitude of clustering in the Universe. By employing a deep learning network that takes in the galaxy's projected positions and line-of-sight velocities, we have estimated the masses of 800 galaxy clusters from the SDSS Legacy Survey and constructed a cluster mass function that is consistent with the standard cosmological model.

About me

After completing my Astronomy masters at the University of Groningen and my PhD at the University of Copenhagen, I am currently a postdoctoral researcher at the Oskar Klein Centre at Stockholm University.

I am fascinated by open questions in cosmology, such as the tension between measurements from the early and late Universe. To address this discrepancy, I have used observations from gravitationally lensed quasars, type Ia supernovae, and Baryon Acoustic Oscillations. At the moment, my focus is on exploring the potential of strongly lensed supernovae.

I like to work at the intersections of observations, theory, and simulations, and to explore statistical inference and machine learning techniques to obtain new insights about the Universe. Additionally, I am passionate about finding creative ways to present research.

In my free time I enjoy bouldering, drawing, painting, and hiking in the beautiful nature reserves around Stockholm.

Get in touch

I’m always happy to talk about research ideas or any questions you may have!