Lunch talk on Apr. 14, 2025

A First Sample of Bright Quasars Identified with Euclid Spectroscopy

Speaker: Yuming Fu (Leiden University)

Venue: Video Conference

Time: 15:00 PM, Monday, Apr. 14, 2025

Abstract: 

The Euclid Q1 Quick Data Release contains the VIS and NIR data of one pass on each of the three Euclid deep fields (EDF-North, EDF-South, and EDF-Fornax), totaling a sky area of 63.1 square degrees. The slitless spectroscopy mode of the Near-Infrared Spectrometer and Photometer (NISP) onboard Euclid has enabled efficient spectroscopy of objects within a large field of view. Nevertheless, the relatively low spectral resolution, overlapping spectra, and contamination pose challenges to source classification and redshift determination using the NISP spectra. To facilitate spectroscopic redshift surveys of quasars with Euclid, we investigated the Euclid spectra of high-purity quasar candidates selected from Gaia (CatNorth+CatSouth) and AllWISE in Q1 fields, and identified more than 3500 bright quasars. We generated a first Euclid composite spectrum of quasars covering the rest-frame NUV-to-NIR wavelengths free of telluric lines, which will be fundamental to NIR quasar spectral analysis. We also explore the novel Euclid NIR colour space and discuss the role of these quasars in refining Euclid's AGN selection techniques for future data releases.