The ALPINE-ALMA [CII] survey: double stellar population and AGN activity in a galaxy at $z\sim5.5$

Understand

GDS J033218.92-275302.7 (here GS-14) is a $z\sim5.5$ galaxy detected in [CII] as part of the ALPINE survey with unusual UV spectral features that have been interpreted as signatures of either a double stellar population or of an active galactic nucleus (AGN).

• We exploited the multi-wavelength coverage of GS-14 to investigate the properties and the origin of its emission.
• We performed UV-to-NIR SED-fitting, with single/double stellar population and/or AGN component.
• We analyzed the VIMOS spectrum, which shows highly-ionized emission lines (Ovi, Nv, and Niv).