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HEIndividual fellowship2023–2025

FORWARD · Models of Cosmic Dawn: connecting 21cm simulations to the real world

Horizon Europe — Marie Skłodowska-Curie Actions

Duration
2023-09-01 → 2025-08-31
EU contribution
€188,590
Participants
1
Scheme
HORIZON-TMA-MSCA-PF-EF

Lines connect the coordinator with its partners.

Results in brief

Forward-Models of Cosmic Dawn: connecting 21cm simulations to the real world

The first billion years of our Universe's history are almost completely unexplored, and hold the key to answering fundamental questions about how the first massive structures in the Universe formed: dark matter halos, the first stars and galaxies, and the supermassive black holes that power quasars. More subtly, these early structures shaped the evolution of the intergalactic medium (IGM)---a diffuse gas of neutral hydrogen that fills the space between galaxies---by emitting radiation and heating the surrounding gas, leading to a complex interplay between the first galaxies and their environment. The 21cm line of neutral hydrogen is considered the most powerful probe of this epoch, with the potential to map the distribution and state of the IGM during these first billion years, and therefore indirectly inform us about the first cosmic structures. Large radio interferometers such as HERA and the upcoming SKA are designed to detect this faint signal from the early Universe. However, detecting and interpreting the 21cm signal is extremely challenging due to the presence of bright foregrounds, instrumental effects, and the complexity of the underlying astrophysical processes. The FORWARD project aimed to develop advanced forward-modeling techniques to simulate realistic 21cm observations, incorporating the effects of foregrounds, instrumental response, and noise. In particular FORWARD aimed to develop an end-to-end simulation and inference pipeline that consistently accounts for the known limiting systematics of the current world-leading 21cm experiments--HERA and EDGES--and jointly infers their effects alongside the astrophysical parameters of interest. This is the only principled way of generating robust scientific insight from this unexplored epoch, and thus represents an opportunity for huge scientific impact.

Data: CORDIS, © European Union

Project objective

FORWARD will enable a new generation of transformational probes of Cosmic Dawn (CD) to provide meaningful inference on key questions of galaxy formation. The CD contains some of the most sought-after insights into galaxy formation. Though these secrets remain locked away by a host of formidable real-world challenges, upcoming radio telescopes are optimistic. Interferometers such as HERA and future SKA, along with global experiments such as EDGES-3 are honed to observe the faint 21cm emission from neutral Hydrogen, redshifted to 50-150 MHz, in complementary ways. The dominant limitation of current experiments are spectral systematics that couple with overwhelmingly bright foregrounds. As we enter the regime in which the most extreme physical models begin to be ruled out by observations, meaningful inference of key parameters is most susceptible to inaccuracies in accounting for these systematics. Prior efforts to provide parameter constraints from CD have focused on forecasts, and treated systematics crudely and optimistically. FORWARD will synthesise the popular semi-numerical simulation code 21cmFAST and a radically overhauled parameter-inference engine, 21cmMC-2, with a series of new pluggable modules designed to efficiently forward-model the response of realistic interferometers, enabling the most direct comparison of theory to data. By applying this novel machinery jointly to observations from HERA and EDGES-3, we will (i) provide meaningful constraints on the parameters of galaxy formation during CD, (ii) build confidence in the reported detections, and (iii) enable future joint constraints from the SKA & EDGES-3. The framework developed will follow a legacy of code excellence, providing a bedrock for state-of-the-art developments over the coming years.

Original text from CORDIS.

Participants

  • SCUOLA NORMALE SUPERIORE · PisaCoordinatorItaly

Links

Data: CORDIS, © European Union