Active galactic nuclei and Population III stars in early galaxies

The first stars must have started the generation of heavy elements and the formation of the first galaxies in the earliest phases of the Universe.

At the same epoch, the seeds of the supermassive black holes which are detected in the centres of all nearby massive galaxies, including our own Milky Way, must have formed.

While theoretically predicted, the detection of these first stars and seed black holes is an outstanding observational challenge in modern astronomy.

With the proposed APEX project, I will capitalise on two game-changing capabilities of the James Webb Space Telescope (JWST) to deliver upon this challenge: (i) the coverage of previously inaccessible wavelengths, and (ii) the power to spectrally and spatially resolve early galaxies and, crucially, their surroundings with the integral-field unit spectrograph NIRSpec.

This is decisive to single out the locations of the first stars and black holes through their distinct spectral signatures.

With guaranteed JWST observations and the largest approved open-time programme to map galaxy spectra during the first billion years of cosmic time, the APEX team will: 1) search for and characterise the very first stars (Population III) that illuminate the Universe; 2) identify early black holes and measure the masses of active galactic nuclei to constrain supermassive black hole growth; 3) derive the physical properties of the earliest galaxies and study the role of the first stars and black holes in their evolution; 4) accurately compare our data to simulations to significantly improve models of the early Universe.

Building on these novel and cutting-edge data and my extensive expertise in integral-field observations, the APEX project comes at the right time to enable a major leap forward in our understanding of the early Universe.