Niko

A cluster of physicists @bachpropagate.bsky.social @handle.invalid

I was absolutely unaware how outstanding the Stanford campus is!!! I can only imagine how it looks when it’s not rainy&gloomy. We had a total blast with one of my fave collaborators John Franklin (and Ben, his talented PhD student)

Hi from the West Coast / SF

We did a thing.

An LSST-DESC Precursor Project: Hyper Suprime-Cam Year 1 $3\times2$pt in Harmonic Space https://arxiv.org/pdf/2609.39603 D. Sanchez-Cid et al.

@matthijs.vanderwild.com

Not sure if I ever shared but I’m obsessed with lighting (hello, photons! 😆) I have so many lamps, plugins etc it’s embarrassing at this point. But in any case I just bought a new lamp and it’s so freaking gorgeous I caaaaaant

I’m deeply honored to share I am now a builder within LSST DESC! This means I have made significant contributions to the collaboration I am in position to be added to every publication from now on (with certain caveats)

An obligatory selfie! @scipyconf.bsky.social 🐍💙

The 25th annual #SciPy2026 conference is only two weeks away! Join us in Minnesota or virtually for a plethora of scientific Python talks, including the Physics and Astronomy track 👀 see the full schedule at scipy2026.scipy.org/schedule You can sign up here 👉 ti.to/scipy/scipy2026

Conference photos are in! @perimeterinstitute.ca 🤩

Fresh on the @arxiv 💪 Check out how baryons and nonlinear galaxy bias (and scales) impact the 3x2pt analysis in the LSST scenario arxiv.org/abs/2606.10679

I’m doing science physics

Old pals catching up @marcobonici.bsky.social

I’ve been obsessed with Langewiesche’s writing since I discovered his @theatlantic.com articles. If someone had told me I’d be into a book about shipping and maritime stuff, man… He was such a master of narrative nonfiction that he can make any subject fascinating.

cloelib: A Flexible Python Library for Computing Cosmological Observables in the Euclid Era. Marco Bonici et. al. https://arxiv.org/abs/2605.23839

Over on Twitter a debate of medical doctor vs PhD and who is in the “right” is peeking its head again. I guess we have to have it at least once a year 😂 For me it’s always an excuse to pull this gem out Also: RIP Andre. What an actor he was. Pembleton forever! youtu.be/xYOK-2Q75wE?...

Ok I had to @arxiv.bsky.social

If someone told me 10 years ago that I’d be giving a talk at @scipyconf.bsky.social, I would’ve called them crazy. I’m incredibly honored that the SciPy organizers think derivkit is worthy of a talk! Thank you, SciPy team 🥹🥹🥹🥹

🚨🚨🚨 Only a few weeks left to apply for summer schools in physics (MSc / junior PhD): • Dark Universe - May 10 • Quantum Gravity & Quantum Chaos - May 10 • Scientific ML - May 15

Fresh on @arxiv 🥳🥳🥳🥳 Blinding in cosmology is especially challenging: unlike particle physics, our signal is statistical, subtle, and extracted through a long inference chain. Excited to share the official LSST DESC tool for blind analyses: arxiv.org/abs/2604.18111

@nikosarcevic.com on Modern Cosmology. Full episode on YouTube! youtube.com/shorts/idbCA...

How awesome is this?!

SBI Field Level Inference workshop at Perimeter this June Hurry up! events.perimeterinstitute.ca/event/1924/

Working on the problem from two completely different angles is the best part of this project we’ve been hammering for months Matthijs: pristine, elegant, mathematically flawless Niko: “okay but imagine the posterior is a traffic cone…” Somehow… we are both correct 🤣🤣

Apparently Matthew McConaughey was at Duke today and I missed meeting him because I was stuck in telecons/working from home This is NOT alright alright alright I’m really upset

Minor pet peeve: describing ΛCDM-based analyses as having the “potential to discover new physics.” They can reveal tensions or inconsistencies that may motivate extensions to the model — but that’s not the same as discovering new physics. Cmon my man, tone that down

Happy bday, arXiv! You are the best! Funny coincidence is that I chose to wear one of my arXiv shirts (which are top quality btw! Hoodies as well, highly recommend)

I am a science machine 💪💪💪💪 4th paper fresh on the @arxiv.bsky.social this year 🥳🥳🥳 arxiv.org/pdf/2603.09973

I was in a clusters telecon today (not my usual working group) and am so beyond impressed by the quality of plots people were showing. I find it so refreshing to see there are people out there who care about communicating their research

Impact and interplay of $Λ$CDM analysis choices for LSST cosmic shear. N. C. Robertson et. al. https://arxiv.org/abs/2602.21863

Starting the day shearing dead weeds in the forest and cutting through mountain mint — that sharp minty scent mixed with damp, rotting leaves — pure peace for the soul 🌿 And catching up with the wonderful folks over at @DukeLemurCenter is just 👌chefs kiss

Two more works on the @arxiv 🥳🥳🥳 arxiv.org/abs/2602.21863 arxiv.org/abs/2602.21280

Aaaaaand it’s officially on @arxiv.bsky.social 🥳🥳 arxiv.org/abs/2602.08078 Wanna do Fisher, XY Fisher or DALI with a chosen derivative method backend in a simple sleek Python way? Look no further, my friend. We got you! Simple examples here docs.derivkit.org/main/example...

Ok, aside that this was ten years ago (wthhhhell 😱) and I now feel ancient, it is actually nice to be reminded of good times during masters in Göttingen: Thorsten was my lecturer in cosmology and string theory courses and was super encouraging. Made me fall in love with cosmo 🤩

Actually — the first burek in the states since I moved 😱 Found the ingredients at Whole Foods Also a selfie just because

X marks the spot Happy first day of 2026! It’s cold here but nothing beats the Carolina blue 😍

There probably are a few things better than talking to Alan Heavens about a potential idea then heading to the woods and mulching sumac trees (for the lemurs!) with your best guy on a warm December morning but I can’t think of any right now. I just love the 🇺🇸 🍂🛻🪏

If you are around these parts, come and join us for a pint and a nice story about the Universe

🤣🤣🤣🤣🤣🤣

Happy Thanksgiving :) @desisurvey.bsky.social

Investigating the Dark Energy Constraint from Strongly Lensed AGN at LSST-Scale. Sydney Erickson et. al. https://arxiv.org/abs/2511.13669

I can say with full confidence I’m the happiest person on this planet right now. Seeing the Roman Space Telescope being assembled — and knowing it’ll be in orbit next year — just makes it unreal.

Hello again, DC 🤗

It’s a wrap! @nasaromantelescope.bsky.social NASA Roman HLIS Cosmology Project Infrastructure Team face to face meeting Thank you to Bhuv, Mike and the rest of UPenn folk for hosting us 🙏