Welcome!

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Martin S. Sloth is a professor at University of Southern Denmark (SDU), and group leader for the Universe Origins group. He is the first professor of theoretical cosmology in Denmark. The pioneers of theoretical cosmology include the likes of Einstein, Penrose, Hawking, Guth, Weinberg, and Peebles. We mainly work on understanding the origin of the universe, dark matter, and dark energy. You can find more information about our research here. If you are interested in more popular descriptions of our research, you can look for some of our outreach activities here. Finally, on the group page, you can find a description of the group members.

E-mail: sloth@sdu.dk

Publications of M. S. Sloth: HEP-INSPIRE, Google Scholar.

 

New paper with Mathias Garny, Florian Niedermann, and Henrique Rubira. We show that Hot NEDE provides a UV completion of SIDR and stepped models, bringing them in agreement with the BBN constraints when addressing the Hubble tension: https://arxiv.org/abs/2404.07256

Exciting new results from DESI today on the large-scale structure of the universe and the measurement of baryonic acoustic oscillations (BAO). The first takeaway relating to New Early Dark Energy (NEDE) as a solution to the Hubble tension is the product of the drag-epoch sound horizon and the scaled Hubble constant of rdh = (101.8 ± 1.3) Mpc, slightly higher than previous measurements.

This might mean that one needs a smaller reduction of the sound horizon to achieve the same increase of H0—as illustrated by superimposing (by eye on the iPad) the constraint on the plot of Know and Millea from 2019 below — making it marginally easier to resolve the Hubble tension within NEDE.

An interesting paper from this morning, https://arxiv.org/abs/2312.11074,  points out that (N)EDE-type models could potentially also resolve the problem of early galaxy formation found by JWST, as was also hinted at in a previous study https://arxiv.org/abs/2208.01611. The authors point out that the region of (N)EDE parameter space required for solving the JWST problem is the same region of (N)EDE parameter space needed for solving the H0 tension.

Check out the excellent talk by my collaborator, Florian Niedermann, on New Early Dark Energy (NEDE) in the CosmoVerse seminar series linked below.

Two interesting new papers:


One indicates that new physics in the dark sector at the two scales, the eV scale and a ULA scale, close to those inherent in the Cold NEDE solution to the Hubble tension, could be required by eBOSS Lyman-alpha data https://arxiv.org/abs/2311.16377.


And one that constrains a corner of NEDE parameter space in more detail from the microphysics of the phase transition https://arxiv.org/abs/2311.16222, emphasizing the requirement of a fast phase transition.

The ESA Euclid experiment will map around a billion galaxies in the next six years and give us new insights into the properties of Dark Matter and Dark Energy. Today, Euclid released its first pictures: Euclid’s first images.

Euclids view of the Perseus cluster of galaxies

Not all approaches to the Hubble tension are equally good or bad. Some recent discussion seems to ignore the fact that early-time approaches like New Early Dark Energy also fit the CMB better than Lambda-CDM independent of the Hubble tension ( https://arxiv.org/abs/2305.08895 ).