Abstract

Invited Talk - Splinter SMBHs

Thursday, 10 September 2026, 14:18   (MW-0250)

Pushing the quasar redshift frontier with Euclid: a new era for z>7 quasar searches

Francesco Guarneri and the Euclid PU QSO WP
Hamburg University, Hamburger Sternwarte

Luminous quasars at high redshift (z ≳ 7) directly probe the buildup of supermassive black holes, the primeval galaxies hosting them, and the intergalactic medium during the epoch of reionisation. However, such objects remain rare and challenging to identify due to their faintness and scarcity. The launch of the Euclid satellite is dramatically changing this picture: the wide surveyed area, photometric depth, and wavelength coverage will allow us to push the redshift frontier well beyond z~7. In this talk, I will describe how we are actively exploiting the wealth of data made available by the Euclid collaboration, introduce our selection methods and summarise the results of discovery and follow-up campaigns. I will then focus on the Euclid DR1, presenting the sample that will be used to constrain the quasar luminosity function, highlighting the challenges we are facing and the steps undertaken to solve them. I will conclude by presenting the first preliminary estimates of the QSO LF based on the newly found Euclid quasars.