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We present a statistical analysis of halo emission for a sample of 1047 edge-on disc galaxies imaged in five bands by the Sloan Digital Sky Survey (SDSS). Stacking the homogeneously rescaled images of the galaxies, we can measure surface brightnesses as deep as μr∼ 31 mag arcsec−2. The results strongly support the almost ubiquitous presence of stellar haloes around disc galaxies, whose spatial distribution is well described by a power law ρ∝r−3, in a moderately flattened spheroid (c/a∼ 0.6). The colour estimates in g–r and r–i, although uncertain, give a clear indication for extremely red stellar populations, hinting at old ages and/or non-negligible metal enrichment. These results support the idea of haloes being assembled via early merging of satellite galaxies.
Zibetti et al. (Sun,) studied this question.