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arXiv · 2401.12371

Investigating the Ultra-Compact X-ray Binary Candidate SLX 1735-269 with NICER and NuSTAR

David Moutard·Renee Ludlam·Malu Sudha·Douglas Buisson·Edward Cackett·Nathalie Degenaar·Andrew Fabian·Poshak Gandhi·Javier Garcia·Aarran Shaw·John Tomsick
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Abstract

We present two simultaneous NICER and NuSTAR observations of the ultra-compact X-ray binary (UCXB) candidate SLX 1735-269 while the source was in two different spectral states. Using various reflection modeling techniques, we find that xillverCO, a model used for fitting X-ray spectra of UCXBs with high carbon and oxygen abundances is an improvement over relxill or relxillns, which instead contains solar-like chemical abundances. This provides indirect evidence in support of the source being ultra-compact. We also use this reflection model to get a preliminary measurement of the inclination of the system, $i = 57^{+23}_{-7}$ degrees. This is consistent with our timing analysis, where a lack of eclipses indicates an inclination of $i<80^{\circ}$. The timing analysis is otherwise inconclusive, and we can not confidently measure the orbital period of the system.

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David Moutard, Renee Ludlam, Malu Sudha, Douglas Buisson, Edward Cackett, Nathalie Degenaar, Andrew Fabian, Poshak Gandhi, Javier Garcia, Aarran Shaw, John Tomsick. 2024-01-22. Investigating the Ultra-Compact X-ray Binary Candidate SLX 1735-269 with NICER and NuSTAR. https://arxiv.org/abs/2401.12371

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