Physics & Astronomy Faculty Publications
Document Type
Article
Publication Date
2026
Abstract
We present a crossmatch between a combined catalog of X-ray sources and the Vera C. Rubin Observatory Data Preview 1 (DP1) to identify optical counterparts. The six fields targeted as part of DP1 include the Extended Chandra Deep Field South (E-CDF-S), the Euclid Deep Field South, the Fornax Dwarf Spheroidal Galaxy (Fornax dSph), 47 Tucanae (47 Tuc), and science validation fields with low Galactic and ecliptic latitude (SV_95_-25 and SV_38_7, respectively). We find matches to 2314 of 3830 X-ray sources. We also compare our crossmatch to DP1 in the E-CDF-S field to previous efforts to identify optical counterparts. The probability of a chance coincidence match varies across each DP1 field, with overall high reliability in the E-CDF-S field, and a lower proportion of high-reliability matches in the other fields. The majority of previously known sources that we detect are, unsurprisingly, active galaxies. We plot the X-ray-to-optical flux ratio against optical magnitude and color in an effort to identify Galactic accreting compact objects using a Gaia color threshold transformed to LSST g − i, but do not find any strong candidates in these primarily extragalactic counterparts. The DP1 dataset contains high-cadence photometry collected over a number of nights. We calculate the Stetson J variability index for each object under the hypothesis that X-ray counterparts tend to exhibit higher optical variability; however, the evidence is inconclusive whether our sample is more variable over DP1 timescales when compared to field objects.
Recommended Citation
Wang, Yuankun David, Eric C. Bellm, Robert I. Hynes, Yue Zhao, Poshak Gandhi, Liliana Rivera Sandoval, Sandro Campos et al. "Optical Counterparts to X-ray sources in LSST DP1." The Astrophysical Journal Supplement Series 284, no. 1 (2026): 13. https://doi.org/10.3847/1538-4365/ae5247
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Publication Title
The Astrophysical Journal Supplement Series
DOI
10.3847/1538-4365/ae5247
Comments
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