Honored to receive the 2026 American Physical Society Edward A. Bouchet Award! To see how the DEI ban in Ohio influences our university, please see the OSU announcement of the award (left) vs the actual APS citation for the award (right).

We come with receipts🧾 Tidal tails are cosmic “receipts” of galactic drama, showing who collided with whom. Rubin's camera is sharp enough to catch wind of even the faintest intergalactic tea. No need to worry about "pics or it didn't happen" with Rubin keeping a close eye 😎 🔭🧪

Paper day! My PhD student Mariana Júlio, with @readdark.bsky.social, @pengfeili.bsky.social and others, studies the internal dynamics of dwarf galaxies and finds they don't agree with the Radial Acceleration Relation, challenging the dark matter alternative MOND. arxiv.org/abs/2510.06905 🔭☄️🧪 1/7

4MOST’s social media account is live! First light expected on October 21st! (1pm UK time) 🔭🧪

Let us name those who should take responsibility for this situation. The senior management of universities failed to negotiate a sustainable system of funding, and then sleep-walked into mess. But will they be held accountable? Of course not. www.theguardian.com/education/20...

Here’s the Cygnus loop with a Seestar S50. It’s so big that one mosaic won’t fit it so I stitched two of them together. The total exposure is about 4 hours. It would be cool to go even wider and deeper. 🔭

Stranded in Italy thanks to Air Canada. They say by email that they can't find any flights in the next three days and offer a refund -- ignoring EU 261/2004 regulations that they have to rebook on *any* airline. They do not answer the phone. AC has absolute contempt for its customers and employees.

Episode 17 has dropped! Tune in to hear Payel & Michelle talk about about a dark matter subhalo detection, the problem(s) with super massive black holes, massive star clusters in the Sparkler, speedy white dwarfs and more! 🔭☄️ starxiv.com/2025/08/04/e...

Anyone else notice any weird unit issues with Google lately? (3e19 m)/(1 kpc) gives 55.7 instead of ~1. Not good if you like using Google for quick unit conversions 🔭

New potential interstellar object in the South: 168 hr arc but e already 9+/-1. H=11. Follow-up encouraged! 🔭

Non-hot take: The "AI will kill us" discourse was a distraction from the real problem: it removes the young end of the skilled knowledge workforce. They are harder to train, because AI can do it for them. They can't get jobs, because AI can do it for their bosses. www.theguardian.com/business/202...

Come join us at Surrey! Please get in touch with questions on any of the fellowships (junior to senior), and if you're interested but not sure what you're eligible for, contact me. 🔭

Wow, look at that increase in depth!

Introducing...your sneak peek at the cosmos captured by NSF–DOE Vera C. Rubin Observatory! Can you guess these regions of sky? This is just a small peek...join us at 11am US EDT for your full First Look at how Rubin will #CaptureTheCosmos! 🔭🧪 #RubinFirstLook ls.st/rubin-first-look-livestream

Considering a senior UK fellowship (ERF, URF)? We have a great group at Surrey and our internal deadline for the ERF is July 8th. We are looking for a light-touch application: CV and 1 page research statement. I'm the contact person, so send questions/material to me www.ukri.org/what-we-do/d... 🔭

Really good set of slides about how Nazi scientists did very little to combat the Nazi party

An astonishing headline reporting on new observations from a team led to Nikku Madhusudhan claims they’ve found ‘hints of life’ on a planet orbiting a dwarf star some 124 light years away. What’s going on? (1/n) www.bbc.co.uk/news/article... 🔭 🧪

Bullying at Cambridge University There's a long article in today's Observer about bullying at Cambridge University, which I encourage you to read, as it shows that the scale of the bullying problem in Cambridge is very worrying. I'll just emphasize a couple of things here. One is that Cambridge…

I tried to image the Palomar 5 globular cluster with a Seestar S50 for 3 hours. The cluster is the middle of this image and some of the faintest stars have Gaia G mags of ~17.5 and the right proper motions to be Pal 5 stars. 🔭

Great book review by @chanda.bsky.social about another disappointing physicist, Roger Penrose, who didn’t treat their family or female students well.

Spent 4 hours on NGC 4631 (top galaxy, aka Whale galaxy) and NGC 4656 (bottom galaxy, aka Hockey stick galaxy) with a seestar last night. The hook in NGC 4656 is due to an interaction with other galaxies in the group. 🔭

Today’s solar eclipse from the southern UK. It was taken with a seestar 50. I was very impressed how well it kept the sun centered in the timelapse! 🔭 youtube.com/shorts/f-wsa...

Reposting to 🔭

Denis Erkal (@derkal.bsky.social), one of our contributors, is an expert in galaxy modeling at the @uniofsurrey.bsky.social He has given a talk focused on the Milky Way’s formation and dark matter properties 🌌 #ARRAKIHS #GalaxyModels #DarkMatter #MilkyWay

Paper day with a paper led by Connor Hainje: arxiv.org/abs/2503.15589. We studied how different the Sagittarius stream would look in self-interacting dark matter. In SIDM, ram pressure can evaporate Sgr's dark matter halo, leading to rapid mass loss, which changes the stream morphology. 1/ 🔭 🧪

I also got this nice image of the Orion Nebula. The framing options are quite nice on the seestar and are great for large objects on the sky. 🔭

I played a bit more with our department’s seestar and got this image of M3. The AIdenoise seems to pick out the stars resolved in the original image quite well. 🔭

Congratulations to Bob Wald for winning the Albert Einstein medal! physicalsciences.uchicago.edu/news/article...

Had some fun tonight learning how to use one of our department’s seestar telescopes. They’re super easy to set up and use. I think our students will enjoy imaging galaxies with these! 🔭

UK universities desperately need the government to wake up to the crisis unfolding in the higher education sector. Income has been throttled for a decade and now parts are dying

The ESA #Gaia mission has delivered the best Milky Way maps to date and taken its last starlight before spacecraft retirement 🔭 www.esa.int/Science_Expl...

Farewell Gaia! It’s impressive how much we’ve learned from just 33 months of data and I can’t wait to see what else is hiding in the full data!

Congratulations to my PhD student Madison Walder on her successful viva!

New submitted paper day! Led by @redshiftless.bsky.social, with me, @chrislintott.bsky.social, Simon Portegies Zwart, and four of the postgrad students in our group. We explore a beautiful new phenomena: what happens to interstellar objects as they drift out from their star & wander the Galaxy? 🔭🧪🧵

Two postdoc positions on gravitational waves at Nottingham with Stephen Green 🔭

🚀 I'm hiring--two postdocs and a research software engineer (RSE) to work with me on gravitational waves and machine learning at Nottingham! The posts are funded by my UKRI Future Leaders Fellowship. Postdocs: jobs.nottingham.ac.uk/vacancy.aspx... RSE: jobs.nottingham.ac.uk/vacancy.aspx...

Paper day! Petra Awad led this nice paper (arxiv.org/abs/2411.08991) on the outskirts of NGC 1261 and NGC 1904. NGC 1904 has two jets of stars stripped at its most recent pericenter with the Milky Way. This pericenter was only ~0.12 kpc which led to this strong stripping event. 1/3 🔭

For the Euclid release, I made a fun movie of the globular cluster M10 (NGC 6254) showing its tidal disruption in the Milky Way. The frames are every 100000 years so it’s fun to watch the stars in the outskirts of the cluster. We can detect the tidal distortion with Euclid 🔭 youtu.be/2VMycoO3oU8?...

Made this plot in ChatGPT. It shows the falloff of men’s & women’s running/swimming speed vs event duration. The y-axis shows the mean speed for each event normalized by the speed of the shortest event (100m for running, 50m for swim). It’s crazy how little the falloff is, 60% max speed for ~2 hours

Aurora over Guildford in the Southern UK! 🔭

Very excited to see my student Tariq Hilmi submit this paper https://arxiv.org/abs/2404.02953 with the S5 team. We explored how well we can recover subhalo properties from a realistic stream model. TLDR: we can do it pretty well for a 10^7 Msun perturbed even with present-day observables 1/ 🔭🧪

I wonder how flat Earthers feel about the fact that the Universe is flat

Gave a fun public talk on How to weigh the Milky Way at our Surrey Astro evening. Lots of great questions from the audience!

Lots of postdoc openings at Surrey. Come join our great group!

Hello there! Are you on the job market? Do you love astrophysics? Then how about applying for one of our 3 open Research Fellow positions at the University of Surrey? One of them is with me! Find and study dwarf galaxies with Michelle! 🔭🧪 jobs.surrey.ac.uk/Vacancy.aspx...

It's the first day of work in 2024 for me! And we're off to a great start with Eugene Vasiliev joining us as an Ernest Rutherford Fellow 🎉 I have big research plans for this year, including hiring a new postdoc to work with me! Love dwarf galaxies? Looking for work? Let me know 🔭🧪✨

Another scene from DALL-E

Exploring stellar streams with DALLE