The paper is out in ApjL if you want to read it! iopscience.iop.org/article/10.3...

Supporting that this evolutionary pathway is possible. For the dynamics-minded, this system will also allow for really strong constraints on the DM halo shape and DM distribution, as the rings are clean tracers of the potential out to large radii, something we’re following up with!

Some simulations have suggested that these ring galaxies can evolve into giant low surface brightness galaxies, another enigmatic population. Here we find faded rings in the distant outskirts of the system that rival the size of such galaxies, making this the first observational evidence…

These rings formed in the aftermath of the smaller blue galaxy flying through the center of a massive spiral. We were able to measure the ring positions and spacing, and it turns out to match predictions from analytic theory extremely well over a wide range. But there’s more…

Can I be added if I defended this week? I’m clinging on to the grad status for at least a month…

Feel free to reach out to me if you have questions or want to chat about the position!

I hear i'm supposed to add a 🔭

We hope to create an "amortized" version of this framework, which would require many more simulations (think millions or more), but which then for a given survey, could produce inferences for new input galaxies in a matter of seconds. A challenge, but super useful in the upcoming era of surveys.

So what's next? At the moment, the training/fitting process is "bespoke" to every galaxy, because we fix things like sersic index/PA and survey depth/noise based on the appropriate values for every input galaxy. This takes time (~12 hr) and resources (GPU access). But...

In this paper we focus on distances, as there is a ground truth measurement of comparison. But there are some early signs that we are getting reasonable estimates for, e.g., stellar mass here as well (below: an injection/recovery test placing a logM=7.4 galaxy at many distances).

The method actually appears to be working rather well! Below is an example of one real input galaxy and three random draws from the posterior. On a sample of ~20 nearby galaxies with literature distances from TRGB/SBF, silkscreen almost always recovers the distance within the 5-95% posterior.

To do this we created Silkscreen, a code which uses neural posterior estimation and rounds of simulation and training to fit a set of galaxy properties given input images. In short, we simulate galaxy images with artpop, and use a ResNet to extract summary statistics before passing to the sbi code.

Given this fidelity, we wondered if one could "fit" the basic properties (distance/mass especially) using artpop as a simulator. Such a method would be dramatically cheaper than the gold-standard of TRGB, and might be able to marginalize over some of the uncertainties in SBF from Z/stellar pops

Our idea stems from the ability for the Artpop code to make realistic galaxy images from first principles -- i.e., create stellar populations sampling IMFs and place them "star by star" in some distribution (e.g., Sérsic), while also simulating survey depths and noise properties.

Also, I have a new textbook coming out with IOP/AAS later this year expanding on the above! You may also check out astro-330.github.io, which is the course site for a slightly higher level astro coding class I ran at Yale. Also, astro-rps.github.io has resources we're using for an intro seminar

Definitely! The exercises in the astrocodex will be open source and available publicly; the solution sets repository will be available to registered instructors.

And so I would hope the materials end up being complementary! I took part in carpentries as part of the LSST DSFP and think they're doing great work, particularly around the concepts of bootcamps and workshops. Our focus is on the "exercise"/materials portion for a classroom setting. 2/2

good q: i think the key diffs are: 1) focus on standalone exercises/materials more at the assignment level rather than workshop-style walkthroughs 2) much expanded focus on various astronomy topics 3) no (public/immediate) solutions 4) interoperability for inserting into existing curricula 1/2