ENGLISH: The pre-publication version of my invited article “Fordern galaktische Zwerge die Kosmologie heraus” (“Do galactic dwarfs challenge cosmology”) has been published online now. It will appear in print in early 2024 in the German magazine “Physik in unserer Zeit” (Physics in our times), which targets an audience with broader physics (e.g. physicists, engineers, teachers) in contrast to a specialist audience. So it is a good opportunity for all those interested in learning a bit more about my research without having to go through primary research articles of reviews. The article is open access, too!

GERMAN: Die Vorabversion meines eingeladenen Artikels “Fordern galaktische Zwerge die Kosmologie heraus” ist jetzt online veröffentlicht worden. Er wird in gedruckter Form Anfang 2024 in der Zeitschrift “Physik in unserer Zeit” erscheinen, die sich nicht an ein Fachpublikum, sondern an ein breiteres Publikum mit Physik-Vorbildung richtet (z.B. Physiker, Ingenieure, Lehrer). Der Text ist also eine gute Gelegenheit für alle, die etwas mehr über meine Forschung erfahren möchten, ohne sich durch primäre Forschungsartikel oder Reviews arbeiten zu müssen. Der Artikel ist außerdem frei zugänglich!

With my collaborators around Francois Hammer (GEPI, Paris Observatory) we have published a new series of papers on the dwarf galaxies surrounding the Milky Way:

1. “The accretion history of the Milky Way – I. How it shapes globular clusters and dwarf galaxies“, Hammer, F., Li, H., Mamon, G. A., Pawlowski, M. S., Bonifacio, P., Jiao, Y., Wang, H., Wang, J., Yang, Y. (2023), MNRAS, 519, 5059.
2. “The accretion history of the Milky Way. II. Internal kinematics of globular clusters and of dwarf galaxies“, Hammer, F., Wang, J., Mamon, G. A., Pawlowski, M. S., Yang, Y., Jiao, Y., Li, H., Bonifacio, P., Caffau, E., Wang, H. (2023), MNRAS, 527, 2718.
3. “The Accretion History of the Milky Way: III. Hydrodynamical Simulations of Galactic Dwarf Galaxies at First Infall“, Wang, J., Hammer, F., Yang, Y., Pawlowski, M. S., Mamon, G. A., Wang, H. (2023), arXiv: 2311.05687

The results indicate that many of them might have been accreted only recently, which in turn does not give them much time to be transformed from the gas-rich, rotating dwarfs found at larger distances from the Milky Way, to the gas-free pressure-supported dwarf spheroidals in the vicinity of our Galaxy. We propose that gas-dominated, dark matter free dwarfs might fit the bill, as they are both transformed quickly and also undergo “ram-pressure breaking” which slows them down. Upon being stripped of their gas by the hot halo of the Milky Way, their stellar distribution expands (see this video). Interestingly, this can explain why for many observed dwarfs stars are now found at very large distances. Ultimately, the dwarfs end up out of equilibrium, which means that common estimates of their dark matter content that must assume equilibrium might be unreliable. 

If you want to know a bit more without reading the papers in full: press releases on the topic were just published by both the Leibniz Institute for Astrophysics and the Paris Observatory.

I just received news that I was selected as one of the “100 wichtigsten Köpfe der Berliner Wissenschaft 2023“, one of the 100 most important minds in science in Berlin, by the local newspaper Tagesspiegel. They wrote that they picked those scientists who they consider are moving the science region Berlin. To quote from their email to me (translated from German):

Who made the Berlin research region shine this year? The Tagesspiegel editorial team of Berlin Science has identified the 100 most important personalities. They work at universities or research institutions. From biochemistry to artificial intelligence to mobility. These minds enrich with studies, solicit funding in the millions, do excellent teaching and have an impact on public debates. All of them are preparing the groundwork for tomorrow’s innovations.

I am honored to have been chosen, especially looking at the impressive list of who else was selected. The one hundred persons were presented in a series of articles starting October 9, with my profile appearing on October 20. All chosen researchers are also invited to a networking event in the Tagesspiegel Headquarters on November 3.

Here is what they wrote about me:

It is a great honor and pleasure to be hosting a symposium by the International Astronomical Union in Potsdam. IAUS 379 is titled “Dynamical Masses of Local Group Galaxies”, and will bring 150 participants to Potsdam, 85% of those in person but others remotely.  This conference has been in the making for a year, and I’ve been heavily involved as both a co-chair of the Scientific Organizing Committee (SOC) and the Local Organizing Committee (LOC), so it took up a big chunk of my time. But now that the program is ready, the logistics are prepared, and the details of running the meeting are planned, I am very much looking forward to welcoming many wonderful friends, collaborators, and colleagues for what will be an exciting, interesting, and interactive conference.

Press release by AIP about the symposium: “Galaxies put on the scales at IAU Symposium in Potsdam”

Conference website: https://iaus379.aip.de

My newest paper has now been accepted for publication in Astronomy & Astrophysics and its preprint is now available on the arXiv. It is titled “The intervelocity of galaxy pairs in ΛCDM – The observed velocity peak at ~130 km/s is not unique to MOND“. In it, we investigate whether the mutual velocity of galaxy pairs shows a peak comparable to that found in observational studies. Such a peak had been explained by the dark matter alternative Modified Newtonian Dynamics (MOND), but whether it is present in cosmological simulations was unclear. I have summarized the background and main results of our paper on Twitter.

The paper is the result of a true team effort by my new research group at the AIP. We had worked on this in a “project-in-a-day” fashion, which turned out to be not only very productive, but also was an excellent team bonding and mentoring technique. In shortYou can read more about that in my Twitter thread.

I feel honored to have been selected as a finalist for the Falling Walls Science Breakthroughs of the Year 2022 in Physical Sciences with my “Cosmic Choreographies” research project studying systems of satellite galaxies, how they compare to cosmological expectations, and whether they challenge our understanding of the composition of the Universe, dark matter, and gravity.

Check out the full list of the 30 finalists in this category here.