The Hyper Suprime-Cam extended Point Spread Functions and applications to measuring the intra-halo light

28 Sep 2023  ·  L. P. Garate-Nuñez, A. S. G. Robotham, S. Bellstedt, L. J. M. Davies, C. Martínez-Lombilla ·

We present extended point spread function (PSF) models for the Hyper Suprime-Cam Subaru Strategic Program Public Data Release 3 (HSC-SSP PDR3) in all $\textit{g,r,i,Z}$ and $\textit{Y}$-bands. Due to its 8.2m primary mirror and long exposure periods, HSC combines deep images with wide-field coverage, making it one of the most suitable observing facilities for low surface brightness (LSB) studies. By applying a median stacking technique of point sources with different brightnesses, we show how to construct the HSC-SSP PDR3 PSF models to an extent of R $\sim$ 5.6 arcmin. These new PSFs provide the community with a crucial tool to characterise LSB properties at large angles. We apply our HSC PSFs and demonstrate that they behave reasonably in two cases: first, to generate a 2-D model of a bright star, and second, to remove the PSF-scattered light from an Ultra Deep image of the 400020 Galaxy And Mass Assembly (GAMA) group in the SXDS field. Our main focus in this second application is characterising the $\textit{r}$-band intra-halo light (IHL) component of 400020. Building on advanced source extraction techniques with careful consideration of PSF flux, we measure the IHL surface brightness (SB) group profile up to $\sim$ 31 mag arcsec$^{-2}$ and R = 300 kpc. We estimate the IHL fraction ($\mathrm{f_{IHL}}$) profile, with a mean of $\mathrm{f_{IHL}}$ $\sim$ 0.13. Our results show that not removing the PSF light can overestimate the IHL SB by $\sim$ 1.7 mag arcsec$^{-2}$ and the $\mathrm{f_{IHL}}$ by $\sim$ 30%.

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