2008MNRAS.391..550P

We make predictions for the metallicity of diffuse stellar components in systems ranging from small spiral galaxies to rich galaxy clusters. We extend the formalism of Purcell, Bullock & Zentner, in which diffuse stellar mass is produced via galaxy disruption, and we convolve this result with the observed mass-metallicity relation for galaxies in order to analyse the chemical abundance of intrahalo light (IHL) in host haloes with virial mass 10^10.5 ≤ M_host≤ 10¹⁵M_☉. We predict a steep rise of roughly 2 dex in IHL metallicity from the scales of small to large spiral galaxies. In terms of the total dynamical mass M_host of the host systems under consideration, we predict diffuse light metallicities ranging from Z_IHL≲ -2.5 for M_host∼ 10¹¹M_☉ to Z_IHL∼ -1.0 for M_host∼ 10¹²M_☉. In larger systems, we predict a more shallow rise in this trend with Z_IHL∼ -0.4 for M_host∼ 10¹³M_☉, increasing to Z_IHL∼ 0.1 for M_host∼ 10¹⁵M_☉. This behaviour is coincident with a narrowing of the intrahalo metallicity distribution as host mass increases. The observable distinction in surface brightness between old, metal-poor IHL stars and more metal rich, dynamically younger tidal streams is of crucial importance when estimating the chemical abundance of an intrahalo population with multiple origins.