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5th of October 2022
ATNF Colloquium
Radio Selected NIR-dark sources shedding light on the dark side of high redshift SFRD
Meriem Behiri (SISSA, Italy)
Abstract: About 12 billion years ago, the Universe was first experiencing light again after the dark ages, and galaxies filled the environment with stars, metals, and dust. How efficient was this process, and how fast did these primordial galaxies form stars and dust? We can answer these questions by tracing galaxies star formation rate density (SFRD) back to its unexplored high redshift tail, traditionally observed in the Near-InfraRed (NIR), Optical, and UV-bands. This means that the dustiest objects were missing. Further, most studies on dust obscured galaxies at high redshift have been conducted in the sub-millimetre, possibly affected by dust temperature biases. In this talk, I will introduce you to the characterisation of Radio Selected NIR-dark (RS-NIRdark) sources in different fields with a panchromatic approach and new SED-fitting techniques developed by the GOThA (Galaxy Observational and Theoretical Astrophysics) group in SISSA.

The plot above shows how the Star Formation Rate per co-moving, i.e. Star Formation Rate Density (SFRD) volume evolves with time. Thus, computing the SFRD at a particular redshift for a galaxies population means finding how much that population contributes to the global production of stars at that redshift. The works cited in the picture computed the SFRD for galaxy samples selected differently, as explained in the legend. In particular, crimson shaded rectangles show the results by Behiri et al. (under submission) for Radio Selected NIR-dark galaxies in the COSMOS field, whose contribution to SFRD at z>3 is at least as large as 40% of the one estimated from UV-bright sources.

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