Description du projet
Cartographier 13 milliards d’années d’histoire cosmique
Des radiotélescopes vont être utilisés pour détecter la raie à 21 cm de l’hydrogène neutre, afin de cartographier la structure 3D de l’Univers, couvrant 13 milliards d’années d’histoire cosmique. Le projet MapItAll, financé par l’UE, utilisera ces cartes pour répondre à certaines des questions les plus importantes de la cosmologie. Il se penchera par exemple sur la vitesse d’expansion de l’Univers et identifiera les propriétés physiques de l’énergie sombre. MapItAll permettra également de déterminer comment les premières étoiles et galaxies ont illuminé l’Univers. Le projet développera une analyse statistique qui pourra modéliser tous les degrés de liberté pertinents dans les données, de manière simultanée, une chose qui n’a jamais été tentée auparavant. Les données proviendront de deux télescopes de haute technologie (HERA et MeerKAT).
Objectif
My proposal is to map out the 3D structure of the Universe over an unprecedentedly broad swath of cosmic time, covering 13 billion years of cosmic history. I will do this by using radio telescopes to detect the 21cm emission from neutral hydrogen. The detailed statistical properties of the maps will allow us to answer some of the most pressing questions in cosmology, such as how fast space is expanding, what the physical properties of dark energy are, and how the first stars and galaxies lit up the Universe.
All experiments currently trying to make these observations are severely limited by systematic effects, exacerbated by the extremely high dynamic range between the cosmological signal and many other sources of radio emission. Even tiny calibration errors can cause huge artefacts in the data that make it extremely difficult to pick out the target signal. While a great deal of work has gone into designing methods to analyse the data, they are not yet accurate enough – by a factor of 100 by some measures.
I will develop a statistical analysis framework called “Total Calibration” that can deliver the remaining two orders of magnitude of improvement, and apply it to the most sensitive data available. The result will be precise, systematics-free maps and the most robust statistical measurements of large-scale structure ever made in the radio. Total Calibration seeks to model all of the relevant degrees of freedom in the data simultaneously, in one large global model of the signal, contaminants, and the calibration of the telescope. This is highly complex, and has never been done before.
By applying total calibration to sensitive but complex data from two cutting-edge telescopes, HERA and MeerKAT, I will obtain the most robust constraints on the 21cm signal to date, from redshifts 0–1.4 (late times) and 5–27 (reionisation/Cosmic Dawn), to constrain the physical processes that shaped the cosmic energy budget at high redshift and any possible evolution of dark energy.
Champ scientifique
Programme(s)
Thème(s)
Régime de financement
ERC-STG - Starting GrantInstitution d’accueil
M13 9PL Manchester
Royaume-Uni