Euclid preparation. TBD. Using mock Low Surface Brightness dwarf galaxies to probe Wide Survey detection capabilities

Local Universe dwarf galaxies are both cosmological and mass assembly probes. Deep surveys have enabled the study of these objects downto the low surface brightness (LSB) regime. In this paper, we estimate Euclid’s dwarf detection capabilities and limits of its MERge processingfunction (MER pipeline), responsible of producing the stacked tiles and final catalogues. To do this, we inject mock dwarf galaxies in a real EuclidWide Survey (EWS) field in the VIS band and compare the input catalogue to the final MER catalogue. The mock dwarf galaxies are generatedwith the help of simple Sérsic models and structural parameters extracted from observed dwarf galaxy property catalogues. In the following, tocharacterize the detected dwarfs, we use the mean surface brightness inside the effective radius SBe (in mag arcsec−2). The final MER cataloguesachieve completenesses of 91 % for SBe ∈ [21, 24], and 54 % for SBe ∈ [24, 28]. These numbers do not take into account possible contaminants,including confusion with background galaxies at the location of the dwarfs. After taking into account this effect, they become respectively 86 %and 38 %. The MER pipeline performs a final local background subtraction with small mesh size, leading to a flux loss for galaxies with Re > 10′′.By using the final MER tiles and reinjecting this local background, we obtain an image in which we recover reliable photometric properties forobjects under the arcminute scale. This background-reinjected product is thus suitable for the study of Local Universe dwarf galaxies. Euclid’sdata reduction pipeline serves as a test bed for other deep surveys, particularly regarding background subtraction methods, a key issue in LSBscience.Key words. Galaxies: dwarf – Techniques: image processing – Catalogues