Revealing the Hidden Universe: Low-Surface-Brightness Astronomy in the Big-Survey Era

The faint outskirts of galaxies preserve some of the most sensitive tracers of their assembly histories. Diffuse stellar halos, shells, stellar streams, tidal tails, and other tidal features encode the cumulative imprint of galaxy interactions. On larger scales, intracluster and intragroup light reveal the environmental settings for galaxy evolution. Moreover, low-surface-brightness galaxies and ultra-diffuse galaxies add to the growing inventory of diffuse structures that probe the faintest regimes of galaxy formation. Low-surface-brightness (LSB) structures, often orders of magnitude fainter than the night sky, provide a unique archaeological record of the dynamical lives of galaxies, yet their detection and interpretation have long been hindered by observational limitations.

We are now entering a transformative period in LSB astronomy. Deep, wide-area surveys conducted by the Vera C. Rubin Observatory’s LSST, the Euclid mission, and the forthcoming Nancy Grace Roman Space Telescope will enable systematic exploration of the diffuse Universe on an unprecedented scale. Taken together, these surveys will open a new frontier in the study of the LSB Universe.

Despite these advances, significant challenges remain. Recovering extremely faint structures requires stringent control of instrumental systematics, scattered light, sky-background modeling, and Galactic cirrus separation, along with new data-processing pipelines tailored for such extremely faint features. Interpreting the wealth of upcoming detections will demand sophisticated simulations capable of predicting the fine-grained morphology of tidal debris, the evolution of ultra-diffuse galaxies, and the spatial distribution of stellar halos and intracluster light. The community must also confront the question of how best to link these observations with hierarchical galaxy formation models and environmental processes across cosmic time.

This research topic aims to bring together observational, theoretical, and methodological efforts to illuminate the LSB frontier. We welcome contributions on topics including, but not limited to:

• Detection and characterization of diffuse stellar halos and tidal features
• Formation pathways of ultra-diffuse galaxies
• Mapping and modeling intracluster and intragroup light
• Morphological diversity of tidal streams and their dynamical implications
• Advanced sky-subtraction and scattered-light mitigation techniques
• Machine-learning approaches designed to reveal faint, structured signals in survey data
• Comparisons with cosmological hydrodynamical simulations.

The research topic aims to lay the groundwork for the scientific discoveries that LSST, Euclid, Roman, and future deep-imaging programs will make possible, bringing the hidden Universe into view as never before.

Article types and fees

This Research Topic accepts the following article types, unless otherwise specified in the Research Topic description:

• Brief Research Report
• Curriculum, Instruction, and Pedagogy
• Data Report
• Editorial
• FAIR² Data
• General Commentary
• Hypothesis and Theory
• Methods
• Mini Review
• ... View all formats

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Article types

This Research Topic accepts the following article types, unless otherwise specified in the Research Topic description:

• Brief Research Report
• Curriculum, Instruction, and Pedagogy
• Data Report
• Editorial
• FAIR² Data
• General Commentary
• Hypothesis and Theory
• Methods
• Mini Review
• Opinion
• Original Research
• Perspective
• Review
• Study Protocol
• Technology and Code

Keywords: Intracluster Light, Galaxies, Ultra-diffuse galaxies, Diffuse stellar halos, Low-surface brightness, Survey, LSST, Euclid mission, Nancy Grace Roman Space Telescope

Important note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.