Marcel S. Pawlowski
@8minutesold.bsky.social
Astrophysicist studying cosmic choreographies of dwarf galaxies. Junior Research Group Leader at AIP, Street Photographer (he/him)
Autor des Buchs „Von tanzenden Galaxien, Dunkler Materie, und anderen kosmischen Rätseln“
Potsdam, Germany
Autor des Buchs „Von tanzenden Galaxien, Dunkler Materie, und anderen kosmischen Rätseln“
Potsdam, Germany
Look what finally arrived! The proceedings of our International Astronomical Union Symposium 379 „Dynamical Masses of Local Group Galaxies“. 🌌🧪🔭☄️
Which was held in early 2023, with all manuscripts submitted later that same year. So it took CUP only *checks notes* two years to publish.
Which was held in early 2023, with all manuscripts submitted later that same year. So it took CUP only *checks notes* two years to publish.
November 27, 2025 at 12:36 PM
Look what finally arrived! The proceedings of our International Astronomical Union Symposium 379 „Dynamical Masses of Local Group Galaxies“. 🌌🧪🔭☄️
Which was held in early 2023, with all manuscripts submitted later that same year. So it took CUP only *checks notes* two years to publish.
Which was held in early 2023, with all manuscripts submitted later that same year. So it took CUP only *checks notes* two years to publish.
Rather than finding primordial DM halo in line with expectations from simulations, we infer a profile that is odd in two regards: significantly less centrally concentrated (shallow core), but also dropping faster in the outskirts (steep decline). Much less concentrated than DM-only halos, too.
4/6
4/6
November 26, 2025 at 1:59 PM
Rather than finding primordial DM halo in line with expectations from simulations, we infer a profile that is odd in two regards: significantly less centrally concentrated (shallow core), but also dropping faster in the outskirts (steep decline). Much less concentrated than DM-only halos, too.
4/6
4/6
To test the robustness of the results, a range of plausible baryonic mass distributions (within observational uncertainties) are used. No matter what empirical baryonic mass distribution is adopted, the inferred primordial halo profiles remain very similar. And odd:
3/6
3/6
November 26, 2025 at 1:59 PM
To test the robustness of the results, a range of plausible baryonic mass distributions (within observational uncertainties) are used. No matter what empirical baryonic mass distribution is adopted, the inferred primordial halo profiles remain very similar. And odd:
3/6
3/6
Cold dark matter only simulations predict a certain halo profile, but once baryons (gas+stars) collapse in the center they pull the DM inward. We invert that baryonic compression process: using the present-day rotation curve and baryonic mass distribution to infer the original DM distribution.
2/6
2/6
November 26, 2025 at 1:59 PM
Cold dark matter only simulations predict a certain halo profile, but once baryons (gas+stars) collapse in the center they pull the DM inward. We invert that baryonic compression process: using the present-day rotation curve and baryonic mass distribution to infer the original DM distribution.
2/6
2/6
Happy Halloween!
October 31, 2025 at 8:56 PM
Happy Halloween!
While the trip was pretty long, I was surprised to have made it all the way to Andromeda.
October 16, 2025 at 12:40 PM
While the trip was pretty long, I was surprised to have made it all the way to Andromeda.
After my lecture we had a fun excursion to the National Astronomical Research Institute of Thailand yesterday afternoon. Got to see their planetarium and some workshops where they coat telescope mirrors.
October 16, 2025 at 12:40 PM
After my lecture we had a fun excursion to the National Astronomical Research Institute of Thailand yesterday afternoon. Got to see their planetarium and some workshops where they coat telescope mirrors.
Made it to Thailand. Already learned that you can buy vegetables at the airport, where the bathroom also had an interesting name. Now making some final edits on my lecture slides while fighting the jet lag with coffee.
October 13, 2025 at 10:02 AM
Made it to Thailand. Already learned that you can buy vegetables at the airport, where the bathroom also had an interesting name. Now making some final edits on my lecture slides while fighting the jet lag with coffee.
And now on to the more demanding part of this trip, getting to Chiang Mai in Thailand to give a lecture for the WE-Heraeus and NARIT Cosmology School. First leg is a train trip to Madrid, then flights to Doha and Bangkok. If all goes according to plan, it’ll take me 31 hours door to door.
October 11, 2025 at 6:44 AM
And now on to the more demanding part of this trip, getting to Chiang Mai in Thailand to give a lecture for the WE-Heraeus and NARIT Cosmology School. First leg is a train trip to Madrid, then flights to Doha and Bangkok. If all goes according to plan, it’ll take me 31 hours door to door.
After an intense IAU Symposium on galaxy outskirts with lots of interesting talks but too little time to chat with everyone, I got a half day to enjoy beautiful Cordoba yesterday.
October 11, 2025 at 5:35 AM
After an intense IAU Symposium on galaxy outskirts with lots of interesting talks but too little time to chat with everyone, I got a half day to enjoy beautiful Cordoba yesterday.
Intriguingly, the simulated dwarfs align nicely with the observed dwarf galaxies, lying systematically above the extrapolated RAR. Their scatter is smaller, but if we mock-observe the simulations and add realistic errors, the scatter becomes comparable at the low-acceleration end. 6/7
October 9, 2025 at 8:55 AM
Intriguingly, the simulated dwarfs align nicely with the observed dwarf galaxies, lying systematically above the extrapolated RAR. Their scatter is smaller, but if we mock-observe the simulations and add realistic errors, the scatter becomes comparable at the low-acceleration end. 6/7
We also investigate several isolated dwarf galaxies of similar stellar mass in the high-resolution EDGE simulations in a ΛCDM cosmology. Since we have perfect knowledge of the mass distributions in the simulations, we can use them to confirm that our approach reliably infers their RAR. 5/7
October 9, 2025 at 8:55 AM
We also investigate several isolated dwarf galaxies of similar stellar mass in the high-resolution EDGE simulations in a ΛCDM cosmology. Since we have perfect knowledge of the mass distributions in the simulations, we can use them to confirm that our approach reliably infers their RAR. 5/7
Turns out that the dwarf indeed deviate, almost all lying systematically above the extrapolated RAR (black solid line). Note that MOND's external field effect would make them lie below the RAR, and that Carina and Draco (similar distances, orbits, baryonic masses) show very different behaviour. 4/7
October 9, 2025 at 8:55 AM
Turns out that the dwarf indeed deviate, almost all lying systematically above the extrapolated RAR (black solid line). Note that MOND's external field effect would make them lie below the RAR, and that Carina and Draco (similar distances, orbits, baryonic masses) show very different behaviour. 4/7
Mariana now looks for the first time at the *radially resolved* RAR for 12 dwarfs with stellar masses in the range of 10^4 to 10^7 M⊙. She infers their mass profiles from their stellar line-of-sight velocities and the GravSphere Jeans modelling code, and computes the RAR from that. 3/7
October 9, 2025 at 8:55 AM
Mariana now looks for the first time at the *radially resolved* RAR for 12 dwarfs with stellar masses in the range of 10^4 to 10^7 M⊙. She infers their mass profiles from their stellar line-of-sight velocities and the GravSphere Jeans modelling code, and computes the RAR from that. 3/7
Back in 2017, in @lellifede.bsky.social's famous RAR paper (ui.adsabs.harvard.edu/abs/2017ApJ....) we had already looked at dwarf galaxies. We found the fainter ones deviate from the RAR's extrapolation, but back then we only had one data point per dwarf, and only little data for some of these. 2/7
October 9, 2025 at 8:55 AM
Back in 2017, in @lellifede.bsky.social's famous RAR paper (ui.adsabs.harvard.edu/abs/2017ApJ....) we had already looked at dwarf galaxies. We found the fainter ones deviate from the RAR's extrapolation, but back then we only had one data point per dwarf, and only little data for some of these. 2/7
Heading to Cordoba in Spain for IAU Symposium 403 ‘The Hidden Beauty of the Galactic Outskirts’, and from there to Chiang Mai in Thailand to give a lecture on dwarf galaxies and small-scale problems for the German-Thai ‘WE-Heraeus & NARIT Cosmology School 2025 – Galaxies and Beyond’. 🔭☄️
October 7, 2025 at 6:35 AM
Heading to Cordoba in Spain for IAU Symposium 403 ‘The Hidden Beauty of the Galactic Outskirts’, and from there to Chiang Mai in Thailand to give a lecture on dwarf galaxies and small-scale problems for the German-Thai ‘WE-Heraeus & NARIT Cosmology School 2025 – Galaxies and Beyond’. 🔭☄️
Facebook reminded me that exactly 12 years ago there was another government shutdown in the U.S.
I had arrived for my first postdoc just before, applied for a SSN, but the shutdown delayed getting assigned one. Which meant that I couldn’t be paid my salary until 2 months after my international move
I had arrived for my first postdoc just before, applied for a SSN, but the shutdown delayed getting assigned one. Which meant that I couldn’t be paid my salary until 2 months after my international move
October 1, 2025 at 8:42 AM
Facebook reminded me that exactly 12 years ago there was another government shutdown in the U.S.
I had arrived for my first postdoc just before, applied for a SSN, but the shutdown delayed getting assigned one. Which meant that I couldn’t be paid my salary until 2 months after my international move
I had arrived for my first postdoc just before, applied for a SSN, but the shutdown delayed getting assigned one. Which meant that I couldn’t be paid my salary until 2 months after my international move
Just returned from a meeting last week, and already had to get up early for the next trip. To Brussels this time, for a workshop on “Knowledge Transfer for Policy Making” at the @leibniz-gemeinschaft.de and European Parliament.
September 10, 2025 at 6:20 AM
Just returned from a meeting last week, and already had to get up early for the next trip. To Brussels this time, for a workshop on “Knowledge Transfer for Policy Making” at the @leibniz-gemeinschaft.de and European Parliament.
Nice end-of-semester surprise: someone from the Potsdam Graduate School appeared in my team meeting to give me a special recognition in their SUPERvisor Award.
Feels like enough of a reward to work with this amazing team, but I take any excuse to celebrate these great people with great coffee. 😉
Feels like enough of a reward to work with this amazing team, but I take any excuse to celebrate these great people with great coffee. 😉
August 8, 2025 at 8:30 AM
Nice end-of-semester surprise: someone from the Potsdam Graduate School appeared in my team meeting to give me a special recognition in their SUPERvisor Award.
Feels like enough of a reward to work with this amazing team, but I take any excuse to celebrate these great people with great coffee. 😉
Feels like enough of a reward to work with this amazing team, but I take any excuse to celebrate these great people with great coffee. 😉
I'm being informed that a package for me was delivered to my neighbor "Drzwi3p" ... 🤷♂️
July 24, 2025 at 10:35 AM
I'm being informed that a package for me was delivered to my neighbor "Drzwi3p" ... 🤷♂️
You know what, maybe we should see this as an opportunity to turn things around and go on the offensive!
Here's a quick AI-written new theory on how bridges work. Has a lot of sciency-words and such, so sounds legit.
Here's a quick AI-written new theory on how bridges work. Has a lot of sciency-words and such, so sounds legit.
July 16, 2025 at 12:08 PM
You know what, maybe we should see this as an opportunity to turn things around and go on the offensive!
Here's a quick AI-written new theory on how bridges work. Has a lot of sciency-words and such, so sounds legit.
Here's a quick AI-written new theory on how bridges work. Has a lot of sciency-words and such, so sounds legit.
Today was this semester’s final session of my Dark Matter lecture. 🧪🔭
I loved how engaged these students were throughout the semester, despite the 8am time slot. We ended with an excellent student contribution on judging evidence for dark matter from the perspectives of various philosophers.
I loved how engaged these students were throughout the semester, despite the 8am time slot. We ended with an excellent student contribution on judging evidence for dark matter from the perspectives of various philosophers.
July 15, 2025 at 1:40 PM
Today was this semester’s final session of my Dark Matter lecture. 🧪🔭
I loved how engaged these students were throughout the semester, despite the 8am time slot. We ended with an excellent student contribution on judging evidence for dark matter from the perspectives of various philosophers.
I loved how engaged these students were throughout the semester, despite the 8am time slot. We ended with an excellent student contribution on judging evidence for dark matter from the perspectives of various philosophers.
All right, let’s play Trump Tariff Mad Lib (@cardsagainsthumanity.com edition).
July 13, 2025 at 10:06 AM
All right, let’s play Trump Tariff Mad Lib (@cardsagainsthumanity.com edition).
Had a nice visit to Frankfurt, albeit too short to see anything else (thanks Deutsche Bahn). The Physikalischer Verein offers an impressive range of public events. Its rooftop 🔭 might not be in the best place for astronomical observations … but the skyscraper skyline offers interesting alternatives.
July 7, 2025 at 12:31 PM
Had a nice visit to Frankfurt, albeit too short to see anything else (thanks Deutsche Bahn). The Physikalischer Verein offers an impressive range of public events. Its rooftop 🔭 might not be in the best place for astronomical observations … but the skyscraper skyline offers interesting alternatives.