Archival Diagnostics for Potential Background Contaminantsof Project Hephaistos Dyson Sphere Candidates
Abstract
We report on the diagnostic investigation of nine Project Hephaistos Dyson Sphere candidate M-dwarfs based on archival data. By comparing the Gaia DR3 positions with epoch 2016.0, propagated to the AllWISE epoch, with the mid-infrared centroids measured from the AllWISE images, together with deep archival optical/near-infrared imaging, we identified significant background contamination in candidates B and C--candidate B coincident with a radio counterpart showing a power-law-like spectrum with a radio spectral index alpha = 0.63 +/- 0.11, while candidate C has a near-infrared companion at an offset of 3.75 arcsec. Candidate A provides suggestive evidence through a radio counterpart with spectral index alpha = 0.40 +/- 0.35, while candidates E, F, H and J show marginal evidence. These systems exhibit either significant astrometric offsets or visible interlopers, indicating that the mid-infrared excess likely arises from line-of-sight contamination by hot, dust-obscured galaxies. However, candidates D and I still lack obvious signs of contamination. Dedicated observations are therefore essential to characterise these potential interlopers, eliminate false positives, and ensure that technosignature searches focus on the most robust Dyson Sphere candidates.
Versions
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BibTeX
@misc{ren2026archival,
title = {{Archival Diagnostics for Potential Background Contaminantsof Project Hephaistos Dyson Sphere Candidates}},
author = {Tongtian Ren and Michael A. Garrett and Erik Zackrisson and Andreas J. Korn and Andrew P. V. Siemion and Jason T. Wright and Alexis Brandeker},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.03619},
eprint = {2607.03619},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.03619},
}
RIS
TY - UNPB
TI - Archival Diagnostics for Potential Background Contaminantsof Project Hephaistos Dyson Sphere Candidates
AU - Tongtian Ren
AU - Michael A. Garrett
AU - Erik Zackrisson
AU - Andreas J. Korn
AU - Andrew P. V. Siemion
AU - Jason T. Wright
AU - Alexis Brandeker
PY - 2026
DA - 2026/09/12
PB - arXiv
DO - 10.48550/arxiv.2607.03619
UR - https://arxiv.org/abs/2607.03619
AB - We report on the diagnostic investigation of nine Project Hephaistos Dyson Sphere candidate M-dwarfs based on archival data. By comparing the Gaia DR3 positions with epoch 2016.0, propagated to the AllWISE epoch, with the mid-infrared centroids measured from the AllWISE images, together with deep archival optical/near-infrared imaging, we identified significant background contamination in candidates B and C--candidate B coincident with a radio counterpart showing a power-law-like spectrum with a radio spectral index alpha = 0.63 +/- 0.11, while candidate C has a near-infrared companion at an offset of 3.75 arcsec. Candidate A provides suggestive evidence through a radio counterpart with spectral index alpha = 0.40 +/- 0.35, while candidates E, F, H and J show marginal evidence. These systems exhibit either significant astrometric offsets or visible interlopers, indicating that the mid-infrared excess likely arises from line-of-sight contamination by hot, dust-obscured galaxies. However, candidates D and I still lack obvious signs of contamination. Dedicated observations are therefore essential to characterise these potential interlopers, eliminate false positives, and ensure that technosignature searches focus on the most robust Dyson Sphere candidates.
ER -