Dr. Hamsa Padmanabhan

The epoch of ‘Cosmic Dawn’, when the first stars and galaxies were born-about a hundred million years after the Big Bang-is widely considered the ‘final frontier’ of research in observational cosmology today. This period is primarily accessible due to radiation from hydrogen-the most abundant element in the Universe-which emits at a wavelength of 21 cm, in the radio band. The technique of intensity mapping (IM) has emerged as a powerful tool to explore this phase of the Universe by measuring the integrated emission from sources over a broad range of frequencies. A particular advantage of IM is that it provides a tomographic, or three-dimensional picture of the Universe, unlocking several thousand times more information than available from conventional probes. Apart from hydrogen, there are also exciting prospects for using IM in the submillimetre wavelengths, from the carbon monoxide (CO), ionized carbon and oxygen ([CII] and [OIII]) lines, as tracers of large-scale structure. I will illustrate how the description of dark matter haloes can be extended to describe the abundances and clustering of molecular and ionic species in the early Universe. Combined with the information content of multi-messenger probes, this will help elucidate the properties of the first supermassive black holes at Cosmic Dawn.