The Infrared Glow of Galactic Outskirts: A New Window with NASIM
Abstract
The outskirts of galaxies retain fossil records of their assembly history and are dominated by old stellar populations shaped by tidal interactions, accretion events, and environmental processes. Observing these low-surface-brightness (LSB) regions in the near-infrared (NIR), particularly in the Ks band, is crucial for tracing evolved stars and minimising the effects of dust. Yet, ground-based NIR studies of faint extended structures remain challenging because of the bright and variable sky background and complex detector systematics. To overcome these limitations, we developed NASIM, the Near-infrared Automated low Surface brightness reduction In Maneage pipeline, a fully automated and reproducible framework designed to recover faint structures in VISTA/VIRCAM data. Using GNU Astronomy Utilities (Gnuastro), NASIM corrects large-scale flat-field patterns and instrumental signatures across the VIRCAM detectors while preserving LSB emission that can be strongly suppressed in conventional NIR reductions. We apply NASIM to Ks-band imaging of the Euclid Deep Field South through the KEDFS programme, a key region also targeted by Rubin/LSST and Euclid. The final reduction reaches a surface-brightness limit of μKs ≃ 27.7 mag arcsec−2, measured at 3σ over 100 arcsec2, approximately 67 times deeper than 2MASS and 11 times deeper than VHS in surface-brightness sensitivity. Direct comparisons with publicly available VISTA products show that NASIM preserves diffuse emission without substantially compromising compact-source depth. These results open a deep NIR view of faint galaxy outskirts, LSB galaxies, and intracluster light, providing a reproducible ground-based foundation for future studies of the faint Universe.
Versions
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BibTeX
@misc{saremi2026infrared,
title = {{The Infrared Glow of Galactic Outskirts: A New Window with NASIM}},
author = {Elham Saremi and Ignacio Trujillo and Mohammad Akhlaghi and Zohreh Ghaffari and Johan H. Knapen and Manda Banerji and Helmut Dannerbauer and Sébastien Comerón},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.12934},
eprint = {2609.12934},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.12934},
}
RIS
TY - UNPB
TI - The Infrared Glow of Galactic Outskirts: A New Window with NASIM
AU - Elham Saremi
AU - Ignacio Trujillo
AU - Mohammad Akhlaghi
AU - Zohreh Ghaffari
AU - Johan H. Knapen
AU - Manda Banerji
AU - Helmut Dannerbauer
AU - Sébastien Comerón
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2609.12934
UR - https://arxiv.org/abs/2609.12934
AB - The outskirts of galaxies retain fossil records of their assembly history and are dominated by old stellar populations shaped by tidal interactions, accretion events, and environmental processes. Observing these low-surface-brightness (LSB) regions in the near-infrared (NIR), particularly in the K_s band, is crucial for tracing evolved stars and minimising the effects of dust. Yet, ground-based NIR studies of faint extended structures remain challenging because of the bright and variable sky background and complex detector systematics. To overcome these limitations, we developed NASIM, the Near-infrared Automated low Surface brightness reduction In Maneage pipeline, a fully automated and reproducible framework designed to recover faint structures in VISTA/VIRCAM data. Using GNU Astronomy Utilities (Gnuastro), NASIM corrects large-scale flat-field patterns and instrumental signatures across the VIRCAM detectors while preserving LSB emission that can be strongly suppressed in conventional NIR reductions. We apply NASIM to K_s-band imaging of the Euclid Deep Field South through the KEDFS programme, a key region also targeted by Rubin/LSST and Euclid. The final reduction reaches a surface-brightness limit of μ_K_s ≃ 27.7 mag arcsec^−2, measured at 3σ over 100 arcsec^2, approximately 67 times deeper than 2MASS and 11 times deeper than VHS in surface-brightness sensitivity. Direct comparisons with publicly available VISTA products show that NASIM preserves diffuse emission without substantially compromising compact-source depth. These results open a deep NIR view of faint galaxy outskirts, LSB galaxies, and intracluster light, providing a reproducible ground-based foundation for future studies of the faint Universe.
ER -