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
313 posts
420 followers
330 following
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Unfortunately, it lost its funding and is now supported by a company providing Astro-related software (thus excluded from grants). The town didn’t fare well after reunification either (economically+politically). But the museum and its team are fantastic, super dedicated and definitely worth a visit!
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There’s a lot of history that left an imprint at the observatory. Started before WWII, used for weather observations during the war, continued astronomy under Soviet occupation but lost many instruments, was associated to @aippotsdam.bsky.social precursor institutes a couple times.
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I also saw the library and their original bibliographic catalogue on variable stars. Each star got a card, and whenever a new publication mentioned it the reference was added to the card. This was maintained into the 1990s, got digitized and became part of the Strasbourg Astronomical Data Center.
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Consequently, it has one of the biggest archives of photographic plates, several 100k in total. With a smart filling system in which the position along the shelve corresponds to right ascension and height in the shelve to declination (and then year of observation). 85% of these have been digitized.
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The observatory’s main activity were two long-term photographic surveys, monitoring the whole visible sky and select fields whenever possible. These were used to identify variable stars, with about 11000 (a quarter of all known ones) discovered in Sonneberg.
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Back then the city seems to have had the money. It used to be a center of toy production, evidence of which can still be found in the fact that it hosts the German Toy Museum. They also produced and exported lots of Christmas decorations, with Woolworth building a major warehouse right in the city.
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Turns out they are celebrating their 100 year anniversary this year. They were founded as a municipal observatory (!), upon an initiative by local astronomer Cuno Hoffmeister, by the city of Sonneberg.
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Here is a longer video explanation of this work, illustrating the peculiarly lopsided satellite galaxy system of the Andromeda galaxy. 🧪🔭
youtu.be/xO7rTu5ADwQ?...
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If course there are infinite possibilities then, and thus one could always find something that sticks out. But as I tried to argue before, we didn’t set out to search for a weird feature,but focus on one that is established and rather fundamental.
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Of course there can be many more properties, which I think is the point Michael wants to make. To stick with the balls, that’s like suggesting to not only look for color, but also whether a ball is too big, of a different material, less massive, in fact a cube not a ball, or whatever.
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Though the analogy is limited because we need a base comparison model (isotropy in our case) to compare both the observed and simulated systems against. We need that to define what we call the isotropic frequency, which essentially quantifies the „unlikeliness“ of a given system.
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In Michael‘s example with the balls, this would count all cases of oddly-colored balls as similarly rare. So if there are 20 single balls each with a different color and 80 red ones, observing e.g. a purple one would result in a simulation analog frequency of 20%. We wouldn’t call that a challenge.
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Yes that’s what we try here. Generalize the property we investigate (asymmetry) by quantifying it via how rare a given arrangement is for an isotropic model. We then test how often similarly rare systems are found in sims; no requiring a specific arrangement, just having the same isotropic frequency
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So now we tested whether the known lopsidedness in M31, which is remarkable if you compare it to isotropy, is also special compared to cosmological expectations. We could have found that such an arrangement is common in the simulations, and would have reported that. But it turns out it isn’t.
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Furthermore, lopsidedness is a quite active field and was already studied independently of this work for external galaxies for years. Both @cosmicwebmaster.bsky.social and I published on it, in fact in 2017 I showed that for stacked satellite systems, there does not seem to be any tension with LCDM.
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Thanks for your explanation, but I have to disagree. We didn’t pick a weirdness to ensure that we find a disagreement with LCDM.
For one, a global asymmetry is a much more fundamental quality than other „weirdnesses“ you suggest, like a distribution in a triangle.
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That’s a bit harsh given that we account for this look-elsewhere effect: we don’t just search for similarly asymmetric distributions in the simulations, but for ones that are similarly unlikely compared to an isotopic one. See this paragraph and the following ones, and Fig 5.
🧪🔭
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If you want to know more, read the article or our related Nature Astronomy research briefing written for a broader audience: www.nature.com/articles/s41...
Of course we have also prepared a press release: www.aip.de/news/androme...
And feel free to contact me if you have any questions!
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I am super thrilled that I can finally share Jamie's fantastic work publicly, after we've been working on it for two years. Jamie will present this at a few upcoming conferences, too, and we are working on follow-up projects already … though he also needs to focus on wrapping up his PhD soon.
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So, either M31 is an extreme outlier to cosmological expectations, or an outright challenge to the cold dark matter model of cosmology. What speaks for the latter is that the unexpected lopsidedness is on top of the existence of a plane of satellites around M31, which already challenges the model.
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Interestingly the observed M31 system (open black circle) also shows the most population-wide asymmetry. Analogs in the simulations that are similarly extreme (black crosses) are cases where fewer satellites (smaller cone population, vertical) are more clustered (smaller opening angles, horizontal).
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We tested for the first time whether such an arrangement is common for analogs in cosmological simulations (TNG & EAGLE). Turns out that no, the observed system is highly unexpected. At a level of 0.3%! Even considering the look-elsewhere effect (that analogs might be weird in some other sense).
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Here is a video summary Jamie made, showing the distribution of satellite galaxies around Andromeda (M31). You can see that the observed satellite system is highly lopsided: most dwarf galaxies lie towards the Milky Way. In fact, 40% of the volume around M31 contains only 1 out of 37 satellites! 🔭🧪☄️
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Oh, and I got to meet a special guest who traveled from far away to attend the event. 😂
Which ChatGPT turned into a neat action figure set, including a little telescope. 🔭
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As an astronomer, another neat thing on this trip was that the hotel they reserved for us had nice space-themed decorations. 🤩🔭
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Some tickets are still available, but for those who aren’t in Nürnberg there are also plans to record the talks for the „Urknall, Weltall und das Leben“ YouTube Channel.
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I will talk late this afternoon about Astronomy, its challenges as an observational science, and how we can decide between dark matter and modified gravity.
kortizes.de/event/05-04-...
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... They were founded in 1947, and are on the top floors of an old WW2 bunker. Makes the place somewhat small, but gives the telescope great stability. And despite sitting in the city of Munich, they have an impressive 80cm reflector – with which they even managed to follow and photograph the ISS! 🔭
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Of course, I was just joking. Also, kids have to be in school at that time anyway.
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Wow, congrats, this is so cool!
Though what did you say that this got labelled as "for adults only"? 😂