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Abstract:

High-redshift quasar pairs are expected to trace massive halos (log M ~ 12.5) and therefore pinpoint some of the densest cosmic regions, such as galaxy protoclusters. Their activity is thought to be sustained by accretion of cool gas from the cosmic web into their circumgalactic medium. I will present results from our survey of the largest sample of physically associated quasar pairs at z = 3–4, combining MUSE and SCUBA-2 observations. With MUSE, we detect extended Lyalpha emission on scales up to 100 kpc, constraining the properties of cool gas and galaxy interactions, and identify only the second known quadruple AGN candidate. With SCUBA-2, we find submillimeter galaxy overdensities in all targeted fields, peaking around the quadruple AGN system. Finally, I connect the distribution of submillimeter galaxies on megaparsec scales to the extended Lyα emission and quasar pair activity, offering a comprehensive view of protocluster cores.