Beyond 31 mag/arcsec^2: the low surface brightness frontier with the largest optical telescopes

TL;DR

This paper demonstrates that current 10-meter class telescopes can image extremely faint surface brightness structures, reaching depths of 31.5 mag/arcsec^2, enabling detailed studies of galaxy stellar halos at significant distances.

Contribution

The study shows how existing large telescopes can achieve unprecedented surface brightness depths, allowing exploration of galaxy halos beyond local groups with shorter observation times.

Findings

Achieved surface brightness limit of 31.5 mag/arcsec^2 with GTC in 8.1 hours.

Measured the stellar halo mass of galaxy UGC00180 as ~4x10^9 Msun.

Halo mass aligns with theoretical models for similar galaxies.

Abstract

The detection of optical surface brightness structures in the sky with magnitudes fainter than 30 mag/arcsec^2 (3sigma in 10x10 arcsec boxes; r-band) has remained elusive in current photometric deep surveys. Here we show how present-day 10 meter class telescopes can provide broadband imaging 1.5-2 mag deeper than most previous results within a reasonable amount of time (i.e. <10h on source integration). In particular, we illustrate the ability of the 10.4 m Gran Telescopio de Canarias (GTC) telescope to produce imaging with a limiting surface brightness of 31.5 mag/arcsec^2 (3sigma in 10x10 arcsec boxes; r-band) using 8.1 hours on source. We apply this power to explore the stellar halo of the galaxy UGC00180, a galaxy analogous to M31 located at ~150 Mpc, by obtaining a surface brightness radial profile down to mu_r~33 mag/arcsec^2. This depth is similar to that obtained using star counts techniques of Local Group galaxies, but is achieved at a distance where this technique is unfeasible. We find that the mass of the stellar halo of this galaxy is ~4x10^9 Msun, i.e. 3+-1% of the total stellar mass of the whole system. This amount of mass in the stellar halo is in agreement with current theoretical expectations for galaxies of this kind.