2:00–2:30 pm
ERC 401 Giant low surface brightness galaxy found in DES Y6 survey: A photometry study of Silhouette 1 Low-surface-brightness galaxies (LSBGs) provide important constraints on galaxy formation and evolution, particularly in the low-density regime. In this work, we analyze the DES Y6 LSBG catalog to investigate their large-scale spatial distribution. The catalog provides a large sample that enables the study of environmental trends, confirming that LSBGs trace large-scale structures and exhibit distinct clustering behaviors. In particular, red LSBGs are preferentially associated with denser environments, while blue systems are more uniformly distributed, consistent with previous studies of diffuse galaxy populations. Within the DES Y6 catalog, an LSBG is identified as part of an extremely extended and diffuse disk belonging to a much larger system, Silhouette 1. This peculiar object exhibits a multi-component structure, consisting of a relatively bright central region embedded within a faint, extended disk, resembling the morphology of the well-known giant LSBG Malin 1. We perform a detailed photometric analysis on this object using a two-component Sérsic model. The disk component exhibits an exceptionally low central surface brightness around u-0 = 25.316 in the g band, whereas its large angular extent suggests a physical size comparable to that of known extreme systems. To estimate its distance and physical scale, we combine photometric and spectroscopic constraints. The photometric redshift from the DNF places Silhouette 1 at z ∼ 0.13, and the bright galaxies associated with the LSBG catalog suggest a more conservative value of z ∼ 0.1. A preliminary spectroscopy analysis using its Ha emission line yields the redshift of z ∼ 0.14. Together, these estimations imply the physical size of Silhouette 1 ∼ 60 − 70 kpc. More complex structural analysis and detailed spectroscopic studies in the future will be essential to account for the spiral remnant in the residual of the Sérsic fit and to get a more accurate estimate of the physical size. Advisor: Alex Drlica-Wagner
May
21
