DoP Colloquium - Vibor Jelić

Peering towards Cosmic Dawn
(Vibor Jelić, Ruđer Bošković Institute, Laboratory for astroparticle physics and astrophysics, Zagreb)

A billion years after the Big Bang, the first stars and galaxies formed in the Universe.  Their radiation ionized most of the neutral hydrogen atoms in the intergalactic medium, marking a phase in cosmic history known as the Epoch of Reionization. This period played a key role in shaping the Universe as we know it today. To investigate it further, scientists utilize some of the most powerful radio telescopes available, aiming to detect cosmological radiation that has traveled from the time of the first stars. However,  this signal is extremely faint, making its detection comparable to finding a needle in a haystack. Complicating this endeavor is the presence of foreground emissions, particularly Galactic synchrotron radiation, which is significantly stronger than the cosmological signal and obscures observations of the cosmic dawn. Researchers must employ innovative and creative approaches to mitigate these foregrounds and capture the desired signals. This talk will provide an overview of the universe's history, the challenges of detecting cosmological radiation, and the latest findings from the LOFAR radio telescope.