This likely means that UV photons from the first stars can produce extended UV bubbles around galaxies earlier and much more rapidly than previously thought, allowing Lyman-alpha and ionizing photons to escape 🌫️〰️

First, there were evidence for a prominent DLA revealing dense HI gas in and around the galaxy, which now seem common at these redshifts. More exciting, was the simultanous detection of Lyman-alpha emission! This was very unexpected, and changes the reionization history of the Universe 🤯

This galaxy, called JADES-GS-z13-1, was identified and spectroscopically observed as part of the JADES survey and showed some exciting and unexpected features!

The pairs are puzzling, because almost all models predict that such massive quiescent galaxies should only be found in pairs with number densities 10-80 times lower than observed!

The two galaxies are confirmed to spectroscopic redshifts of z~3.44 with recent JWST observations and are likely massive, M*~10^11 Msun, with surpressed star formation.

Both these galaxies show substantial mass loading factors in the outflows, likely driven by supernovae feedback or perhaps an additional AGN contribution. These results hints at a rich variety of galaxy quenching pathways at high-z 💥

But perhaps more excitingly, there is robust evidence for a significant blueshift of typical neutral ISM absorption lines in both cases, implying substantial outflows.

These recently-quenched galaxies show a wealth of stellar absorption features and are likely massive, M*>10^10 Msun.

We proposed a scenario where most of this gas originates outside the central, star-forming region, such that any estimates on the gas content of the galaxy based on the central-component only, would be severely biased against the full gas content (verified through 3 different approachs)

Carrying out our own independent analysis, together with Clara Pollock, @joriswitstok.bsky.social, and @chamillaterp.bsky.social here at DAWN/NBI @ucph.bsky.social, we confirmed the dense, massive foreground HI gas, completely enshrouding this remarkably bright nascent galaxy

Follow-up work by Schouws+24 and Carniani+24 used ALMA to accurately pin-point the redshift of the galaxy and found it to be somewhat lower, at z=14.179. This was consistent with a massive DLA, from dense HI gas in the line of sight! But puzzling in the context of no [CII] emission (Schouws+25)

The source, JADES-GS-z14-0, was originally found by Stefano Carniani and the JADES team, and spectroscopically determined to be at z~14.32 based on the Lyman-alpha break, potentially within the first ~280 Myr after the Big Bang!

Paper day 🥳 we are happy to present a new paper on ArXiv today, led by @kosmoskasper.bsky.social examing the most distant, spectroscopically confirmed galaxy to date at z=14.2 (!)

Read the paper here:
arxiv.org/abs/2502.06016
and see 🧵 below

We found that, at all redshifts z=5-14, there appeared to be a substantial fraction (+50%) of galaxies with strong DLAs. Further, evidence for prominent Lyman-alpha emission first started to appear at z<8, tracing the timeline of reionization.

Here, we specifically wanted to constrain the physical properties of 600 (!) galaxies at z>5, and provide a simple diagnostic to figure out if they were 1) Lyman-a emitters, or 2) had damped absorption profiles consistent with IGM or local dense HI gas.

Kickstarting the year, @kosmoskasper.bsky.social et al. published the JWST-PRIMAL paper in A&A 🥳

Link to paper here: ui.adsabs.harvard.edu/abs/2025A%26...