Joris Witstok
@joriswitstok.bsky.social
Looking up at the stars at the Cosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen. Previously at Kavli Institute for Cosmology, University of Cambridge, University of Leiden. (He/him) 🇪🇺🇳🇱🇬🇧🇩🇰
Reposted by Joris Witstok
Come to our conference in April next year! 🧭🌌🏰
👉 Submit your abstract here: docs.google.com/forms/d/e/1F...
👉 Submit your abstract here: docs.google.com/forms/d/e/1F...
August 13, 2025 at 2:03 PM
Come to our conference in April next year! 🧭🌌🏰
👉 Submit your abstract here: docs.google.com/forms/d/e/1F...
👉 Submit your abstract here: docs.google.com/forms/d/e/1F...
Reposted by Joris Witstok
Currently watching the first light from
@vrubinobs.bsky.social’s 3200 megapixel camera 🤩
@vrubinobs.bsky.social’s 3200 megapixel camera 🤩
June 23, 2025 at 4:02 PM
Currently watching the first light from
@vrubinobs.bsky.social’s 3200 megapixel camera 🤩
@vrubinobs.bsky.social’s 3200 megapixel camera 🤩
A wonderful summary of our results on the enigmatic galaxy GS-z13-1 came out in Physics Today a few days ago!
pubs.aip.org/physicstoday...
pubs.aip.org/physicstoday...
A small ancient galaxy started reionizing its surroundings early
As the James Webb Space Telescope looks back at the universe’s first billion years, surprises continue to turn up.
pubs.aip.org
April 28, 2025 at 10:06 AM
A wonderful summary of our results on the enigmatic galaxy GS-z13-1 came out in Physics Today a few days ago!
pubs.aip.org/physicstoday...
pubs.aip.org/physicstoday...
Reposted by Joris Witstok
From Niloofar Sharei @astroneal.bsky.social : What do you get when baby galaxies crash and light up in UV? A surprising early signature of cosmic dust. 🔭✨☄️
astrobites.org/2025/04/21/dust-ahead-of-schedule-uv-bump/
astrobites.org/2025/04/21/dust-ahead-of-schedule-uv-bump/
Dust Ahead of Schedule: The Surprising UV Bump in a Galaxy at Cosmic Dawn
What do you get when baby galaxies crash and light up in UV? A surprising early signature of cosmic dust.
astrobites.org
April 21, 2025 at 10:38 PM
From Niloofar Sharei @astroneal.bsky.social : What do you get when baby galaxies crash and light up in UV? A surprising early signature of cosmic dust. 🔭✨☄️
astrobites.org/2025/04/21/dust-ahead-of-schedule-uv-bump/
astrobites.org/2025/04/21/dust-ahead-of-schedule-uv-bump/
Reposted by Joris Witstok
🧵 Today is paper day for me! Usually I don’t post about papers but I have a special soft spot for this one: the detection of the Gunn-Peterson trough in high-redshift *galaxies* !!
arxiv.org/abs/2504.02683
#astrosci #extragalactic #cosmology
arxiv.org/abs/2504.02683
#astrosci #extragalactic #cosmology
April 4, 2025 at 1:32 PM
🧵 Today is paper day for me! Usually I don’t post about papers but I have a special soft spot for this one: the detection of the Gunn-Peterson trough in high-redshift *galaxies* !!
arxiv.org/abs/2504.02683
#astrosci #extragalactic #cosmology
arxiv.org/abs/2504.02683
#astrosci #extragalactic #cosmology
Reposted by Joris Witstok
A paper in Nature reports observations from the JWST showing one of the earliest known galaxies caught in the act of reionization. The observations place the onset of cosmic reionization to at least 330 million years after the Big Bang. https://go.nature.com/4hLNK12 🧪 🔭
March 27, 2025 at 4:21 PM
A paper in Nature reports observations from the JWST showing one of the earliest known galaxies caught in the act of reionization. The observations place the onset of cosmic reionization to at least 330 million years after the Big Bang. https://go.nature.com/4hLNK12 🧪 🔭
Reposted by Joris Witstok
Paper day! And it’s a big one 🥳
Today, a team of researchers led by @joriswitstok.bsky.social — A DAWN fellow @cosmicdawncenter.bsky.social and Post-doc in the PRIMORDIAL group — published a paper in @nature.com reporting the detection of Lyman-alpha emission from a galaxy at redshift 13 (!)
🧵👇
Today, a team of researchers led by @joriswitstok.bsky.social — A DAWN fellow @cosmicdawncenter.bsky.social and Post-doc in the PRIMORDIAL group — published a paper in @nature.com reporting the detection of Lyman-alpha emission from a galaxy at redshift 13 (!)
🧵👇
Witnessing the onset of reionization through Lyman-α emission at redshift 13 - Nature
Spectroscopy from the JWST Advanced Deep Extragalactic Survey of a galaxy at redshift 13 shows a singular, bright emission line identified as Lyman-α, suggesting the onset of reionization only 330 Myr...
www.nature.com
March 26, 2025 at 7:11 PM
Paper day! And it’s a big one 🥳
Today, a team of researchers led by @joriswitstok.bsky.social — A DAWN fellow @cosmicdawncenter.bsky.social and Post-doc in the PRIMORDIAL group — published a paper in @nature.com reporting the detection of Lyman-alpha emission from a galaxy at redshift 13 (!)
🧵👇
Today, a team of researchers led by @joriswitstok.bsky.social — A DAWN fellow @cosmicdawncenter.bsky.social and Post-doc in the PRIMORDIAL group — published a paper in @nature.com reporting the detection of Lyman-alpha emission from a galaxy at redshift 13 (!)
🧵👇
Reposted by Joris Witstok
Earliest sign of the Universe becoming transparent discovered with #JamesWebb.
@joriswitstok.bsky.social et al. detected the escape of your fav UV light, Lyman α, the signature of an ionized bubble, only 330M years after the Big Bang.
🇬🇧 cosmicdawn.dk/news/james-w...
🇩🇰 cosmicdawn.dk/news-in-dani...
@joriswitstok.bsky.social et al. detected the escape of your fav UV light, Lyman α, the signature of an ionized bubble, only 330M years after the Big Bang.
🇬🇧 cosmicdawn.dk/news/james-w...
🇩🇰 cosmicdawn.dk/news-in-dani...
James Webb opdager tidligste tegn på at Universet bliver gennemsigtigt - Cosmic Dawn Center
Universets første galakser blev født indhyllet i en “tåget” gas, og kunne ikke ses tydeligt før denne tåge var lettet. Ved hjælp af rumteleskopet James Webb har et internationalt hold af forskere, led...
cosmicdawn.dk
March 27, 2025 at 6:37 AM
Earliest sign of the Universe becoming transparent discovered with #JamesWebb.
@joriswitstok.bsky.social et al. detected the escape of your fav UV light, Lyman α, the signature of an ionized bubble, only 330M years after the Big Bang.
🇬🇧 cosmicdawn.dk/news/james-w...
🇩🇰 cosmicdawn.dk/news-in-dani...
@joriswitstok.bsky.social et al. detected the escape of your fav UV light, Lyman α, the signature of an ionized bubble, only 330M years after the Big Bang.
🇬🇧 cosmicdawn.dk/news/james-w...
🇩🇰 cosmicdawn.dk/news-in-dani...
Reposted by Joris Witstok
Using the unique infrared sensitivity of #NASAWebb, researchers can examine ancient galaxies to probe secrets of the early universe. Recently, a bright hydrogen emission from a galaxy in an unexpectedly early time in the universe’s history has been identified. (1/4) 🧵 🔭 🧪
March 27, 2025 at 3:22 PM
Using the unique infrared sensitivity of #NASAWebb, researchers can examine ancient galaxies to probe secrets of the early universe. Recently, a bright hydrogen emission from a galaxy in an unexpectedly early time in the universe’s history has been identified. (1/4) 🧵 🔭 🧪
Reposted by Joris Witstok
Astronomers have identified powerful hydrogen emission in one of the most distant galaxies known — a probable sign that we are seeing some of the first hot stars from the dawn of the Universe ✨
All thanks to the NASA/ESA/CSA James #Webb Space Telescope.
Read more 👉 www.esa.int/Science_Expl...
🔭🧪☄️
All thanks to the NASA/ESA/CSA James #Webb Space Telescope.
Read more 👉 www.esa.int/Science_Expl...
🔭🧪☄️
March 26, 2025 at 4:10 PM
Astronomers have identified powerful hydrogen emission in one of the most distant galaxies known — a probable sign that we are seeing some of the first hot stars from the dawn of the Universe ✨
All thanks to the NASA/ESA/CSA James #Webb Space Telescope.
Read more 👉 www.esa.int/Science_Expl...
🔭🧪☄️
All thanks to the NASA/ESA/CSA James #Webb Space Telescope.
Read more 👉 www.esa.int/Science_Expl...
🔭🧪☄️
Unexpected, bright hydrogen emission caught astronomers by surprise 🔭😳
I'm proud to have led a study reporting this surprising result, which is now published in @nature.com. Read more in this Behind the paper post and in the thread below! 👇
I'm proud to have led a study reporting this surprising result, which is now published in @nature.com. Read more in this Behind the paper post and in the thread below! 👇
Unexpected, bright hydrogen emission caught astronomers by surprise
While the Universe right after the Big Bang was blisteringly hot, a rapid expansion and cooldown subsequently rendered it opaque to energetic ultraviolet light. This ‘fogginess’ was gradually cleared ...
communities.springernature.com
March 27, 2025 at 3:41 PM
Unexpected, bright hydrogen emission caught astronomers by surprise 🔭😳
I'm proud to have led a study reporting this surprising result, which is now published in @nature.com. Read more in this Behind the paper post and in the thread below! 👇
I'm proud to have led a study reporting this surprising result, which is now published in @nature.com. Read more in this Behind the paper post and in the thread below! 👇
Reposted by Joris Witstok
📣 Using ALMA 📡, in which ESO is a partner, astronomers have discovered oxygen in the most distant known galaxy!
This record-breaking detection is making scientists rethink how quickly galaxies formed in the early Universe 🤔
Read more: www.eso.org/public/news/...
🔭 🧪 ☄️
This record-breaking detection is making scientists rethink how quickly galaxies formed in the early Universe 🤔
Read more: www.eso.org/public/news/...
🔭 🧪 ☄️
Oxygen discovered in most distant known galaxy
Two different teams of astronomers have detected oxygen in the most distant known galaxy, JADES-GS-z14-0. The discovery, reported in two separate studies, was made possible thanks to the Atacama…
www.eso.org
March 20, 2025 at 1:07 PM
📣 Using ALMA 📡, in which ESO is a partner, astronomers have discovered oxygen in the most distant known galaxy!
This record-breaking detection is making scientists rethink how quickly galaxies formed in the early Universe 🤔
Read more: www.eso.org/public/news/...
🔭 🧪 ☄️
This record-breaking detection is making scientists rethink how quickly galaxies formed in the early Universe 🤔
Read more: www.eso.org/public/news/...
🔭 🧪 ☄️
Proud to have been part of Katherine's first PhD paper 👏👏 Her detailed study of a distant galaxy reveals what is likely an ongoing merger in a complex system containing both young and old stellar populations with new evidence for the presence of small carbonaceous grains – read more below!
March 3, 2025 at 11:51 AM
Proud to have been part of Katherine's first PhD paper 👏👏 Her detailed study of a distant galaxy reveals what is likely an ongoing merger in a complex system containing both young and old stellar populations with new evidence for the presence of small carbonaceous grains – read more below!
How do we learn about the anatomy of the most distant galaxy we currently know of? 🩻
Read more below! 👇
Read more below! 👇
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
Read the paper here:
arxiv.org/abs/2502.06016
and see 🧵 below
February 11, 2025 at 12:40 PM
How do we learn about the anatomy of the most distant galaxy we currently know of? 🩻
Read more below! 👇
Read more below! 👇
Had a wonderful time visiting the Kapteyn Astronomical Institute in Groningen last week. Congratulations to Roberto for being this year’s Blaauw professor and thanks to everyone at Kapteyn for your hospitality!
November 22, 2024 at 11:06 AM
Had a wonderful time visiting the Kapteyn Astronomical Institute in Groningen last week. Congratulations to Roberto for being this year’s Blaauw professor and thanks to everyone at Kapteyn for your hospitality!
Reminder about next year's conference on obscured star formation at the Kavli Institute for Cosmology, Cambridge (22-26 April), organised by Jan Scholtz and me. Abstract submission closes soon! sites.google.com/cam.ac.uk/sf...
November 27, 2023 at 11:02 AM
Reminder about next year's conference on obscured star formation at the Kavli Institute for Cosmology, Cambridge (22-26 April), organised by Jan Scholtz and me. Abstract submission closes soon! sites.google.com/cam.ac.uk/sf...
Looking forward to learning more about the origin and fate of cosmic dust this week in Gothenburg ✨ #CosmicDustSweden2023
September 25, 2023 at 8:51 AM
Looking forward to learning more about the origin and fate of cosmic dust this week in Gothenburg ✨ #CosmicDustSweden2023
Jan Scholtz, myself et al. are excited to announce an upcoming conference at the Kavli Institute for Cosmology. "Raising the veil on star formation near and far" is a meeting dedicated to Richard Hills, remembering his contributions to understanding obscured star formation across cosmic time:
Star Formation 2024
A hybrid (online & on-site) meeting focusing on hidden and elusive star formation, from the local Universe to high redshift, and an occasion to remember Richard Hills
sites.google.com
September 7, 2023 at 5:53 PM
Jan Scholtz, myself et al. are excited to announce an upcoming conference at the Kavli Institute for Cosmology. "Raising the veil on star formation near and far" is a meeting dedicated to Richard Hills, remembering his contributions to understanding obscured star formation across cosmic time: