Jorryt Matthee
@jorryt.bsky.social
Extragalactic astrophysicist. Assistant Prof @ IST Austria - PI of ERC StG-2022 AGENTS. PhD Leiden 2018, Zwicky fellow @ ETH Zurich,2018-2023.
One of the main conclusions so far is that a majority in the room thinks the powering engine in little red dots should be called quasars
(and that the class of objects historically known as quasars could perhaps be called DABs; disk accreting black holes).
(and that the class of objects historically known as quasars could perhaps be called DABs; disk accreting black holes).
This week, we are hosting ISSI International Team 659, “Little Red Dots, Big Open Questions”, led by Mengyuan Xiao & Rohan Naidu @rpnaidu.bsky.social.
The team brings together observers and theorists to study one of the James Webb Space Telescope’s most intriguing discoveries: Little Red Dots. 🔴🔭
The team brings together observers and theorists to study one of the James Webb Space Telescope’s most intriguing discoveries: Little Red Dots. 🔴🔭
February 6, 2026 at 2:20 PM
One of the main conclusions so far is that a majority in the room thinks the powering engine in little red dots should be called quasars
(and that the class of objects historically known as quasars could perhaps be called DABs; disk accreting black holes).
(and that the class of objects historically known as quasars could perhaps be called DABs; disk accreting black holes).
Reposted by Jorryt Matthee
Paper day!! Little Red Dots (LRDs) are seen everywhere by JWST, but even after 3 years of relentless effort we are still debating what these things actually are. We decompose LRDs to show LRD - Host Galaxy = Black Hole Star (BH*)! 🧵
arxiv.org/abs/2601.20929
🔭 🧪
arxiv.org/abs/2601.20929
🔭 🧪
February 1, 2026 at 1:04 AM
Paper day!! Little Red Dots (LRDs) are seen everywhere by JWST, but even after 3 years of relentless effort we are still debating what these things actually are. We decompose LRDs to show LRD - Host Galaxy = Black Hole Star (BH*)! 🧵
arxiv.org/abs/2601.20929
🔭 🧪
arxiv.org/abs/2601.20929
🔭 🧪
Reposted by Jorryt Matthee
Vienna has a lively astronomy department - consider applying to the below if you'd be interested in a four year (!!) position here: 🔭☄️
4-year postdoctoral fellowships for women @univie.ac.at
The application consists of a short (3-page) research statement only.
Feel free to get in touch if you’re interested or would like to discuss potential projects.
careers.univie.ac.at/en/postdoc/e...
Application deadline: 2 March 2026
The application consists of a short (3-page) research statement only.
Feel free to get in touch if you’re interested or would like to discuss potential projects.
careers.univie.ac.at/en/postdoc/e...
Application deadline: 2 March 2026
E-STEEM: Postdoctoral Positions for Women in STEM and Economics - University of Vienna
Supporting women in science: Postdoctoral positions in STEM and Economics as part of the E-STEEM programme. Apply between January and March 2026.
careers.univie.ac.at
January 5, 2026 at 8:33 AM
Vienna has a lively astronomy department - consider applying to the below if you'd be interested in a four year (!!) position here: 🔭☄️
Happy to share my introductory review article "JWST provides a new view of cosmic dawn: latest developments in studies of early galaxies" has now been published in Contemporary Physics!
www.tandfonline.com/doi/full/10....
arxiv.org/abs/2511.04843
www.tandfonline.com/doi/full/10....
arxiv.org/abs/2511.04843
JWST provides a new view of cosmic dawn: latest developments in studies of early galaxies
Studies of the distant Universe are providing key insights into our understanding of the formation of galaxies. The advent of the James Webb Space Telescope (JWST) has significantly enhanced our ob...
www.tandfonline.com
December 4, 2025 at 2:17 PM
Happy to share my introductory review article "JWST provides a new view of cosmic dawn: latest developments in studies of early galaxies" has now been published in Contemporary Physics!
www.tandfonline.com/doi/full/10....
arxiv.org/abs/2511.04843
www.tandfonline.com/doi/full/10....
arxiv.org/abs/2511.04843
Time to spotlight the first paper of my PhD student Gauri Kotiwale that appeared on arXiv last week: Rapid, out of equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy
arxiv.org/abs/2510.19959
arxiv.org/abs/2510.19959
Rapid, out of equilibrium metal enrichment indicated by a flat mass-metallicity relation at z~6 from NIRCam grism spectroscopy
We aim to characterise the mass-metallicity relation (MZR) and the 3D correlation between stellar mass, metallicity and star-formation rate (SFR) known as the fundamental metallicity relation (FMR) fo...
arxiv.org
October 31, 2025 at 10:53 AM
Time to spotlight the first paper of my PhD student Gauri Kotiwale that appeared on arXiv last week: Rapid, out of equilibrium metal enrichment indicated by a flat mass-metallicity relation at z ∼ 6 from NIRCam grism spectroscopy
arxiv.org/abs/2510.19959
arxiv.org/abs/2510.19959
Delayed paper day! In work lead by my postdoc Claudia Di Cesare as part of the ALT survey, we provide a detailed census of the so-called star formation main sequence in the early Universe. arxiv.org/pdf/2510.19044
October 28, 2025 at 11:02 AM
Delayed paper day! In work lead by my postdoc Claudia Di Cesare as part of the ALT survey, we provide a detailed census of the so-called star formation main sequence in the early Universe. arxiv.org/pdf/2510.19044
Where are you all now?
October 15, 2025 at 5:46 PM
Where are you all now?
Delayed paper day!
arxiv.org/abs/2510.00103
Led by Alberto Torralba, who is a postdoc in my group, we present the highest quality spectrum of a "Little Red Dot" yet known. This unveils new insights in the warm, dense layer of gas that is key to explain the most unusual spectral features of the LRDs!
arxiv.org/abs/2510.00103
Led by Alberto Torralba, who is a postdoc in my group, we present the highest quality spectrum of a "Little Red Dot" yet known. This unveils new insights in the warm, dense layer of gas that is key to explain the most unusual spectral features of the LRDs!
October 3, 2025 at 7:54 AM
Delayed paper day!
arxiv.org/abs/2510.00103
Led by Alberto Torralba, who is a postdoc in my group, we present the highest quality spectrum of a "Little Red Dot" yet known. This unveils new insights in the warm, dense layer of gas that is key to explain the most unusual spectral features of the LRDs!
arxiv.org/abs/2510.00103
Led by Alberto Torralba, who is a postdoc in my group, we present the highest quality spectrum of a "Little Red Dot" yet known. This unveils new insights in the warm, dense layer of gas that is key to explain the most unusual spectral features of the LRDs!
Reviving Paper Threads: Paper day for my PhD student Ivan Kramarenko at @istaresearch.bsky.social !
"Hydrogen-Alpha as a Tracer of Star Formation in the SPHINX Cosmological Simulations" arxiv.org/abs/2509.05403
1/...
"Hydrogen-Alpha as a Tracer of Star Formation in the SPHINX Cosmological Simulations" arxiv.org/abs/2509.05403
1/...
Hydrogen-Alpha as a Tracer of Star Formation in the SPHINX Cosmological Simulations
The Hydrogen-alpha (Ha) emission line in galaxies is a powerful tracer of their recent star formation activity. With the advent of JWST, we are now able to routinely observe Ha in galaxies at high red...
arxiv.org
September 9, 2025 at 4:05 PM
Reviving Paper Threads: Paper day for my PhD student Ivan Kramarenko at @istaresearch.bsky.social !
"Hydrogen-Alpha as a Tracer of Star Formation in the SPHINX Cosmological Simulations" arxiv.org/abs/2509.05403
1/...
"Hydrogen-Alpha as a Tracer of Star Formation in the SPHINX Cosmological Simulations" arxiv.org/abs/2509.05403
1/...
May 19, 2025 at 6:42 AM
More exciting measurements on the most luminous little red dot that I know of (F444W=22 at z=4.5!): an unambiguous AGN and a Balmer break in deep UNCOVER and ALT spectroscopy, led by Ivo Labbe
arxiv.org/abs/2412.04557
arxiv.org/abs/2412.04557
December 9, 2024 at 6:34 PM
More exciting measurements on the most luminous little red dot that I know of (F444W=22 at z=4.5!): an unambiguous AGN and a Balmer break in deep UNCOVER and ALT spectroscopy, led by Ivo Labbe
arxiv.org/abs/2412.04557
arxiv.org/abs/2412.04557
Yesterday was paper day!
With deep JWST data from the ALT survey we provide new independent evidence that the new population of faint AGNs in the early Universe seems to have so-called overly massive black holes compared to their stellar mass
arxiv.org/abs/2412.02846
With deep JWST data from the ALT survey we provide new independent evidence that the new population of faint AGNs in the early Universe seems to have so-called overly massive black holes compared to their stellar mass
arxiv.org/abs/2412.02846
December 6, 2024 at 2:33 PM
Yesterday was paper day!
With deep JWST data from the ALT survey we provide new independent evidence that the new population of faint AGNs in the early Universe seems to have so-called overly massive black holes compared to their stellar mass
arxiv.org/abs/2412.02846
With deep JWST data from the ALT survey we provide new independent evidence that the new population of faint AGNs in the early Universe seems to have so-called overly massive black holes compared to their stellar mass
arxiv.org/abs/2412.02846
My institute ISTA in the nice Viennese forest in Austria now calls for PhD applications, deadline Jan 8 2024. Fully funded ~5 yr US style Grad School. Multiple positions in Astronomy are available. Please distribute and contact me for details!
phd.pages.ist.ac.at
phd.pages.ist.ac.at
November 8, 2023 at 8:30 AM
My institute ISTA in the nice Viennese forest in Austria now calls for PhD applications, deadline Jan 8 2024. Fully funded ~5 yr US style Grad School. Multiple positions in Astronomy are available. Please distribute and contact me for details!
phd.pages.ist.ac.at
phd.pages.ist.ac.at
If you think MUSE is already oversubscribed, imagine that there will only be one ELT (instead of 4 UTs), which will have various instruments to commission when others can already observe. 😬
September 26, 2023 at 6:10 PM
If you think MUSE is already oversubscribed, imagine that there will only be one ELT (instead of 4 UTs), which will have various instruments to commission when others can already observe. 😬
Hello Blue Sky! Very happy and grateful to be starting a research group in extragalactic astronomy and contribute to the development of astronomy at ISTA (ista.ac.at) as of this september!
September 4, 2023 at 10:05 AM
Hello Blue Sky! Very happy and grateful to be starting a research group in extragalactic astronomy and contribute to the development of astronomy at ISTA (ista.ac.at) as of this september!