Kasper Elm Heintz awarded prestigious ERC Starting Grant

Congratulations to Kasper Elm Heintz, associate professor at the Cosmic Dawn Center (DAWN) at both DTU Space and the Niels Bohr Institute, who has just won an ERC Starting Grant to carry out his project “Charting Cosmic Dawn: The impact of primordial matter on galaxy assembly and reionization” (PRIMORDIAL). The grant will allow Heintz to expand his research group with two PhD students and one postdoc.

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Photo credit: Ola Jakup Joensen.

 Today, the European Research Council (ERC) announced the winners of this year’s Starting Grant competition; one of four annual ERC grant schemes. Among the winners was DAWNer Kasper Elm Heintz.

Named “Charting Cosmic Dawn: The impact of primordial matter on galaxy assembly and reionization” (PRIMORDIAL), the grant will run for five years. Over the course of the project, Heintz will expand his research group with two PhD students and one postdoc, drawing on a unique combination of new and archival data from the James Webb Space Telescope (JWST) and the Atacama Large Millimetre/sub-millimetre Array (ALMA).

The PRIMORDIAL project sets out to answer one of the most fundamental open questions in astrophysics: how did the very first stars and galaxies form, and how did they transform the early Universe from a dark, neutral gas into the bright, structured cosmos we see today?

Peering into the cosmic dawn

Roughly 13.8 billion years ago, the Universe was filled with cool, neutral hydrogen gas — the primordial material left over from the Big Bang. Over the following billion years, this gas collapsed gravitationally to form the first stars and galaxies, whose intense, ultraviolet light gradually stripped the electrons from the surrounding hydrogen atoms across the whole Universe. This process, known as the epoch of reionization, is considered the last great phase transition in the history of the cosmos.

What makes this epoch hard to study is that the same neutral hydrogen plays two opposing roles at once: it is the raw fuel that stars are made from, but it also acts as a fog that blocks most of the the very light that stars produce. The neutral gas cannot be observed directly in emission around individual galaxies at these enormous distances, and hence astronomers have lacked a way to directly connect the earliest, nearly featureless Universe (as seen in the cosmic microwave background) to the first galaxies we can actually observe.

“I am extremely excited to now have the capabilities, using some of the largest ground- and space-based telescopes every built, to start answering some of the perhaps most fundamental questions: Where did we come from? How did it all start?”, says Kasper Elm Heintz.

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Schematic illustration of the interplay between gas, star formation, and the ultraviolet radiation emitted by the first stars: in the top is an artist’s impression of a galaxy in the process of forming. The bottom right panel shows a real observation of a newly formed cluster of stars in the nearby galaxy I Zwicky 18. While this image is taken with JWST, the gas forming the stars is most easily probed with radio telescopes such as ALMA. The bottom left panel shows a computersimulation of millions of galaxies, forming a “cosmic web”. Credit: J. Olmsted (STScI), ESA/Webb, NASA, CSA, A. Hirschauer, M. Meixner et al., MPIA. Montage: Kasper Elm Heintz.

Heintz and his group have pioneered a new way around this problem. Using JWST, they have identified the clearest evidence yet of extremely dense reservoirs of this primordial gas surrounding some of the very first galaxies, seen as they were just 400 million years after the Big Bang. Combined with new methods using ALMA to trace neutral gas indirectly through far-infrared light, the PRIMORDIAL project will build the first large, statistically robust census of this primordial hydrogen: where is it located, how much is there, and how does it shape both star formation and the escape of light that ultimately reionized the Universe.

“With this dedicated project over the next five years, we will expand the current research from the first discoveries to building large, statistical samples of galaxies within the first billion years of cosmic time, largely based on the extensive data infrastructure already established at DAWN,” explains Kasper Elm Heintz. “This will allow us to investigate and robustly constrain how the first stars and galaxies emerged and »lit up« the Universe.”

The project is organized around three work packages: mapping hydrogen gas around individual galaxies in the first billion years, identifying and characterizing dense clusters of galaxies during this era, and using ALMA to “weigh” the total amount of hydrogen gas surrounding typical galaxies at these early times. Together, these studies aim to resolve some of the biggest current puzzles unveiled by JWST, including why the earliest galaxies appear brighter and more massive than expected.

The ERC Starting Grant

The ERC Starting Grant is one of Europe’s most competitive and prestigious research funding schemes, awarded by the European Research Council to outstanding early-career researchers building their first independent research team. This year’s competition was the most oversubscribed yet: a record 4807 proposals were submitted, of which only 421 were funded, for a total of EUR 705 million across Europe. Of these, only 19 grants went to researchers in Denmark.

A Starting Grant provides up to EUR 1.5 million over a maximum of five years, allowing recipients to establish their own research group, hire staff, and pursue ambitious, curiosity-driven ideas without predefined thematic constraints; the sole evaluation criterion is scientific excellence. With this grant, Heintz will now expand his team with two PhD students and a postdoc at DAWN’s section of DTU Space to carry PRIMORDIAL forward over the next five years.

We warmly congratulate Kasper Elm Heintz on this outstanding achievement, and look forward to following his group’s progress in charting the origins of the first galaxies.

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