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arXiv · 2607.03489

Discovery of a low surface brightness galaxy in the Zone of Avoidance using VVVX Deepstack imaging

J. L. Nilo-Castellón·L. Baravalle·D. Minniti·M. V. Alonso·G. Galaz·C. Villalon·R. Hinojosa·E. O Schmidt·C. Valotto·M. Soto·E. G. Rivera·V. Valdivia-Rojas·D. Alvarez-Rocha·P. Marchant Cortés·N. J. G. Cross
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Abstract

We report the discovery of VVVX J080705.96-273823.6, the first low-surface-brightness galaxy candidate identified in the Zone of Avoidance by the VISTA Variables in the Via Lactea eXtended Survey (VVVX). The source was detected serendipitously during a visual inspection of the new Deepstack images, reconstructed mosaics generated through an updated reprocessing and stacking procedure that significantly improves the depth and spatial uniformity of the original survey images. First-order morpho-photometric parameters were obtained using SExtractor together with PSF models derived with PSFEx, applied to star-subtracted images to minimize foreground contamination. Structural properties were derived from PSF-convolved modeling of azimuthally averaged surface-brightness profiles in the J, H, and Ks bands using exponential, Sersic, and composite models. The galaxy candidate is clearly detected in all three near-infrared bands. The profiles are consistently described by an exponential disk, with scale lengths of 32-36 arcsec and extinction-corrected central surface brightnesses of 19.82-22.35 mag arcsec^-2. The J band provides the best-constrained profile, while H and Ks show the same behavior with larger uncertainties. The projected proximity to ESO 494-25 and ESO 494-26 suggests a possible physical association. If located at the same distance (11-12 Mpc), the exponential scale length would be about 1.8-2.0 kpc, consistent with nearby LSB disk galaxies, although the lack of a spectroscopic redshift prevents confirmation. This discovery demonstrates that the new VVVX Deepstack products can reveal faint diffuse galaxies at low Galactic latitudes, opening a path toward a more complete census of the obscured nearby Universe.

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J. L. Nilo-Castellón, L. Baravalle, D. Minniti, M. V. Alonso, G. Galaz, C. Villalon, R. Hinojosa, E. O Schmidt, C. Valotto, M. Soto, E. G. Rivera, V. Valdivia-Rojas, D. Alvarez-Rocha, P. Marchant Cortés, N. J. G. Cross. 2026-07-03. Discovery of a low surface brightness galaxy in the Zone of Avoidance using VVVX Deepstack imaging. https://arxiv.org/abs/2607.03489

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