Payel Das
@payeldas.bsky.social
Surrey astrophysicist. Understanding the formation history of our Milky Way through dynamics and chemistry. Talk about papers on the Starxiv.
Excited about the latest paper with collaborators! We find that in the case of missing phase-space coordinates, equilibrium dynamical models can recover the mass distribution and inclination of disc galaxies well but not the dark matter halo flattening! Find out more at arxiv.org/abs/2511.10445.
November 14, 2025 at 9:10 AM
Excited about the latest paper with collaborators! We find that in the case of missing phase-space coordinates, equilibrium dynamical models can recover the mass distribution and inclination of disc galaxies well but not the dark matter halo flattening! Find out more at arxiv.org/abs/2511.10445.
Episode 22 is out!!! With a Tolkien theme 😂
Episode 22 – ORCs, rings, and Galactic histories
In this episode, Payel and Nicole discuss what happens to the metallicity gradient of a satellite galaxy after merging, the existence of intermediate-age RR lyrae and radio rings, and much more! Have a listen at starxiv.com/2025/10/13/e....
In this episode, Payel and Nicole discuss what happens to the metallicity gradient of a satellite galaxy after merging, the existence of intermediate-age RR lyrae and radio rings, and much more! Have a listen at starxiv.com/2025/10/13/e....
Episode 22 – ORCs, rings, and Galactic histories
In this episode, Payel and Nicole discuss what happens to the metallicity gradient of a satellite galaxy after it merges with its host, the existence of intermediate-age RR lyrae and radio rings, t…
starxiv.com
October 13, 2025 at 10:17 AM
Episode 22 is out!!! With a Tolkien theme 😂
Just coming back from holiday and didn’t check arxiv? Absolutely no worries. Catch up on Starxiv! Episode 20 being recorded very soon.
Episode 19 – Peering into the Local Universe, distant blackholes, forming planets and alien signatures
In this episode, Michelle and Payel explore the chemistry of nearby M-dwarf stars and the formation of giant planets at significant distances from their hosts. They discuss supermassive black…
In this episode, Michelle and Payel explore the chemistry of nearby M-dwarf stars and the formation of giant planets at significant distances from their hosts. They discuss supermassive black…
Episode 19 – Peering into the Local Universe, distant blackholes, forming planets and alien signatures
In this episode, Michelle and Payel explore the chemistry of nearby M-dwarf stars and the formation of giant planets at significant distances from their hosts. They discuss supermassive black holes and the search for alien technosignatures. Relevant research papers discussed are also highlighted for further reading.
starxiv.com
September 8, 2025 at 7:33 AM
Just coming back from holiday and didn’t check arxiv? Absolutely no worries. Catch up on Starxiv! Episode 20 being recorded very soon.
Episode 18 is being recorded later today and for the first time I’ll be a listener! Excited to sit back and catch up with the papers I missed whilst in China.
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...
August 15, 2025 at 1:21 AM
Episode 18 is being recorded later today and for the first time I’ll be a listener! Excited to sit back and catch up with the papers I missed whilst in China.
Finding it tricky to keep up with the arxiv over the summer between holidays and childcare? Let @runningastronomer.bsky.social and i help you out with @starxiv.bsky.social!
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...
August 11, 2025 at 2:30 AM
Finding it tricky to keep up with the arxiv over the summer between holidays and childcare? Let @runningastronomer.bsky.social and i help you out with @starxiv.bsky.social!
Reposted by Payel Das
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...
August 4, 2025 at 7:00 AM
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...
In short, dynamical processes don’t quite do enough. Have we massively under-predicted the lensing effect?
In Payel's last paper, new simulations are run to trace the dynamic evolution of stellar clumps like in the Sparkler galaxy at z=1.4 using JWST, to see if their detected masses and dimensions can be reconciled with the considerably smaller values observed in Milky Way GCs.🔭☄️
arxiv.org/pdf/2507.13904
arxiv.org/pdf/2507.13904
August 5, 2025 at 7:45 AM
In short, dynamical processes don’t quite do enough. Have we massively under-predicted the lensing effect?
A neat little explanation to tie some JWST loose ends.
Can super massive stars with compact massive accretion disks form massive black hole seeds AND explain the observations of Little Red Dots? This paper claims they can! Michelle talks us through the details. 🔭☄️ arxiv.org/abs/2507.22014
August 5, 2025 at 7:44 AM
A neat little explanation to tie some JWST loose ends.
Some beautiful new artwork to help you listen to the Starxiv!
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...
August 4, 2025 at 8:07 AM
Some beautiful new artwork to help you listen to the Starxiv!
Catching up with papers after a week’s worth of work travel. It’s going to take a while…😳
July 17, 2025 at 8:46 AM
Catching up with papers after a week’s worth of work travel. It’s going to take a while…😳
If you want to join our wonderful astrophysics research group here at Surrey, please get in touch with @derkal.bsky.social!
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... 🔭
www.ukri.org/what-we-do/d... 🔭
Ernest Rutherford Fellowships
Ernest Rutherford Fellowships (ERF) enables early career researchers with clear leadership potential to establish a strong, independent research programme. They encourage talented researchers in UK un...
www.ukri.org
June 25, 2025 at 4:11 PM
If you want to join our wonderful astrophysics research group here at Surrey, please get in touch with @derkal.bsky.social!
That's some pretty big stars :)
Nicole’s last paper looked at what kind of IMF can explain the early metal-rich galaxies seen by JWST. Turns out you need stars ≥200 M☉ to match the cosmic SFRD and MZSFR at z ≈ 4–10. The best model also needs weak outflows and compact galaxies! 🔭
arxiv.org/abs/2506.06139
arxiv.org/abs/2506.06139
June 24, 2025 at 12:32 PM
That's some pretty big stars :)
What a beautiful serendipitous discovery!
Payel's favourite paper this episode was a beauty! A serendipitous discovery of the "cosmic owl" - a twin collisional ring galaxy system that looks like an owl in projection. An incredibly rare configuration with evidence for shock-induced star formation!
arxiv.org/abs/2506.10058 🔭
arxiv.org/abs/2506.10058 🔭
June 24, 2025 at 12:32 PM
What a beautiful serendipitous discovery!
Perhaps time to move on from alpha abundance ratios?
Nicole’s next paper talked about a new way to probe the high-mass end of the IMF: the ‘hex ratio’ — Hydrostatic-to-EXplosive α-elements. At fixed metallicity, a higher hex ratio means more massive stars → top-heavy IMF. Lower hex ratio? A more top-light IMF. 🔭
arxiv.org/abs/2506.08079
arxiv.org/abs/2506.08079
![Median values of the hydrostatic 𝛼-elements (namely,([Mg/Fe]+[O/Fe])/2) on the left, the explosive 𝛼-elements (namely, ([Si/Fe]+[Ca/Fe]+[Ti/Fe])/3) in the middle, and the hex ratio ([𝛼hyd/Fe]−[𝛼exp/Fe]) on the right as a function of median [Fe/H] for (first population) globular cluster stars (red circles), halo substructures (purple squares), and Milky Way satellite galaxies (yellow upside-down triangles); the running median and [16,84]th percentile range for the Galactic high-/low-𝛼 discs are also shown as dashed/dotted lines, respectively. Overall, GCs and halo substructures occupy a similar locus in all of these diagrams, which sits above the dwarf satellite galaxy sample. The difference in the hex ratio between the GCs and halo substructures with respect to the dwarf galaxies—at fixed[Fe/H]—is on the order of ≈ 0.1 dex. This implies that dwarf galaxies likely formed from a more top-light IMF when compared to Galactic GCs and halo substructures. The error bars show the average standard error for each stellar population type.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cugc4wn2mruqtvx7lm2kztiy/bafkreibonnb7lyv2kl4a3ulh7vpgbrbylfcyqsds5vma2s5dugzbf44mqi@jpeg)
June 24, 2025 at 12:31 PM
Perhaps time to move on from alpha abundance ratios?
Planetary archaeology!
Payel then discussed a planetary system not too far away from our own where the two giant plants were directly imaged by JWST. They're very misaligned! Very different from our solar system where the planets are coplanar.
arxiv.org/abs/2506.09201 🔭
arxiv.org/abs/2506.09201 🔭
June 24, 2025 at 12:30 PM
Planetary archaeology!
It was fun recording our first podcast with @nbuckley0810.bsky.social! For the astute amongst you, I've moved office (hence the boxes...).
June 24, 2025 at 12:19 PM
It was fun recording our first podcast with @nbuckley0810.bsky.social! For the astute amongst you, I've moved office (hence the boxes...).
I'm feeling very excited about reading my @starxiv.bsky.social papers for tomorrow's podcast with @runningastronomer.bsky.social. It's starting to get pretty addictive...
June 5, 2025 at 8:51 AM
I'm feeling very excited about reading my @starxiv.bsky.social papers for tomorrow's podcast with @runningastronomer.bsky.social. It's starting to get pretty addictive...
Who doesn't want to read papers on the weekend? @runningastronomer.bsky.social and I just love reading papers.
Start the weekend the right way with a quick overview of some of the most exciting papers from astronomy arxiv over the last few weeks!
It's Monday, and we are back with another episode! This time, we discuss whetherLittle Red Dots can be explained via super Eddington accretions, how high redshift galaxies and globular clusters may be linked, claims of life on a distant world and galactic graveyards. 🔭 starxiv.com/2025/05/26/e...
May 30, 2025 at 2:39 PM
Who doesn't want to read papers on the weekend? @runningastronomer.bsky.social and I just love reading papers.
My takeaway from this paper is that if we observe this planet for long enough (it might take a decade...) we will get enough signal-to-noise to more definitely exclude or claim life!
Michelle discussed the sup-Neptune world, K2-18b, which has been claimed to show a biosignature in its atmosphere, hinting at life! The paper she discusses delves into a joint analysis of multiple spectra that concludes that this claim is not supported by the data. arxiv.org/abs/2505.13407 🔭
May 27, 2025 at 7:57 AM
My takeaway from this paper is that if we observe this planet for long enough (it might take a decade...) we will get enough signal-to-noise to more definitely exclude or claim life!
Greetings from Crete! Glad we managed to squeeze this one in before both Michelle and I disappeared for holidays. A really fun bunch of papers uniting the high and low redshift universe.
It's Monday, and we are back with another episode! This time, we discuss whetherLittle Red Dots can be explained via super Eddington accretions, how high redshift galaxies and globular clusters may be linked, claims of life on a distant world and galactic graveyards. 🔭 starxiv.com/2025/05/26/e...
starxiv.com
May 26, 2025 at 8:27 AM
Greetings from Crete! Glad we managed to squeeze this one in before both Michelle and I disappeared for holidays. A really fun bunch of papers uniting the high and low redshift universe.
From Evan Davis' Made in Britain - we should be proud of our universities! Let's just hope they will get the support they need.
This, from the conclusions, hit particularly close to home.
May 20, 2025 at 8:46 AM
From Evan Davis' Made in Britain - we should be proud of our universities! Let's just hope they will get the support they need.
We finally worked out our mixer! And how to get a good signal to noise with podcasting equipment. Woohoo!
It's now also finally on Spotify, Apple Podcasts and Amazon Music! Thanks for bearing with us with this slight glitch.
May 13, 2025 at 11:17 AM
We finally worked out our mixer! And how to get a good signal to noise with podcasting equipment. Woohoo!
My first PhD student Dr Paula Gherghinescu. She’s done an amazing job trying to understand the information content encoded in phase-space data of M31-like galaxies.
April 30, 2025 at 1:04 PM
My first PhD student Dr Paula Gherghinescu. She’s done an amazing job trying to understand the information content encoded in phase-space data of M31-like galaxies.
Ok the lunar base would have to be comparable to SKA on Earth - that needs some pretty serious investment. But we would then be able to measure the 21cm line from the Dark Ages and essentially 'see' inflation!
April 28, 2025 at 1:00 PM
Ok the lunar base would have to be comparable to SKA on Earth - that needs some pretty serious investment. But we would then be able to measure the 21cm line from the Dark Ages and essentially 'see' inflation!
Was a bit out of my comfort zone talking about the Dark Ages and radio arrays but isn't that the point of learning?
Happy Monday! Episode 10 is now live! Start your week by listening to @payeldas.bsky.social and @runningastronomer.bsky.social talk about mixing dark matter, Lunar radio arrays, planet hunting, stars surviving black holes and nuclear star clusters! 🧪🔭 starxiv.com/2025/04/28/e...
Episode 10 – Mixing dark matter, surviving black holes and hunting for planets
This episode, Michelle and Payel delve into the latest constraints on mixed dark matter from the Lyman alpha forest, what happens to stars that get a little too close to a black hole, how machine l…
starxiv.com
April 28, 2025 at 12:31 PM
Was a bit out of my comfort zone talking about the Dark Ages and radio arrays but isn't that the point of learning?