Galaxy And Mass Assembly (GAMA): extended intragroup light in a group at z = 0.2 from deep Hyper Suprime-Cam images

ABSTRACT We present a pilot study to assess the potential of Hyper Suprime-Cam Public Data Release 2 (HSC-PDR2) images for the analysis of extended faint structures within groups of galaxies. We examine the intragroup light (IGL) of the group 400138 (Mdyn = 1. 3 ± 0. 5 × 1013 M⊙, z ∼ 0. 2) from the Galaxy And Mass Assembly (GAMA) survey using Hyper Suprime-Cam Subaru Strategic Program Public Data Release 2 (HSC-SSP PDR2) images in g, r, and i bands. We present the most extended IGL measurement to date, reaching down to ₆^ {lim}=30. 76 mag arcsec−2 (3σ; 10 × 10 arcsec2) at a semimajor axis of 275 kpc. The IGL shows mean colour values of g − i = 0. 92, g − r = 0. 60, and r − i = 0. 32 (±0. 01). The IGL stellar populations are younger (2–2. 5 Gyr) and less metal rich (Fe/H ∼ −0. 4) than those of the host group galaxies. We find a range of IGL fractions as a function of total group luminosity of 2\!-\!36 {\ per\ cent} depending on the definition of IGL, with larger fractions the bluer the observation wavelength. The early-type to late-type galaxy ratio suggests that 400138 is a more evolved group, dominated by early-type galaxies, and the IGL fraction agrees with that of other similarly evolved groups. These results are consistent with tidal stripping of the outer parts of Milky Way-like galaxies as the main driver of the IGL build-up. This is supported by the detection of substructure in the IGL towards the galaxy member 1660615 suggesting a recent interaction (1 Gyr ago) of that galaxy with the core of the group.