Critical image depth required to expand extragalactic tidal stream detections

Determine the critical image depth, expressed as a surface brightness limit (mag arcsec−2), required to significantly increase the number of detectable extragalactic stellar tidal streams in wide-field imaging surveys of nearby galaxies, so that survey design and planning (e.g., for Euclid and LSST) can be quantitatively informed by the expected detection rates.

Background

Within the hierarchical galaxy formation framework, extragalactic stellar tidal streams are expected to be common yet are challenging to detect due to their extremely low surface brightness. While future facilities are anticipated to produce deeper images than currently available surveys, the precise image depth at which stream detections begin to grow substantially remains uncertain.

Clarifying the surface brightness threshold that materially increases the number of known streams is essential for optimizing survey strategies and instrumentation, particularly for forthcoming missions such as Euclid and LSST. This paper compares observed stream frequencies to predictions from cosmological simulations across varying surface brightness limits, highlighting the need for a definitive, empirically grounded threshold value.