An extreme case of X-ray reflection in the symbiotic V648 Car

[2608.00266] An extreme case of X-ray reflection in the symbiotic V648 Car Skip to main content Search Submit Donate Log in Astrophysics > Solar and Stellar Astrophysics arXiv:2608.00266 (astro-ph) [Submitted on 31 Jul 2026 ( v1 ), last revised 25 Aug 2026 (this version, v2)] Title: An extreme case of X-ray reflection in the symbiotic V648 Car Authors: Jherssica Freitas , Raimundo Lopes de Oliveira , Koji Mukai View PDF HTML (experimental) Abstract: V648 Car is a $\delta$-type symbiotic star known for its strong hard thermal X-ray emission, heavy local photoelectric absorption, and stochastic variability. We analyze NuSTAR observations, complemented by nearly contemporaneous Swift/XRT observations, to check for the expected presence and physical implications of Compton reflection in its X-ray spectrum. The spectra were fitted with X-ray models that accounted for thermal plasma components, different prescriptions to quantify the intrinsic absorption, the presence of the fluorescent iron line at 6.4 keV, and a reflection component. Our results reveal a strong Compton reflection contribution, accounting for approximately 37% of the total unabsorbed flux in the 3-50 keV band. The inclusion of reflection significantly improves the spectral fits and reduces the value for the maximum plasma temperature by a factor of 2 (from about 49 keV to 25 keV). If the maximum temperature is attributed to strong shock of a Keplerian flow, the inferred white dwarf mass decreases from about 20% (from $1.2$ to $0.95\,M_{\odot}$), demonstrating that neglecting reflection can lead to significant overestimates of this parameter. Reflection models yield high reflection scaling factors ($R \sim 2$), inconsistent with a simple picture of a primary X-ray source above a reflecting disk. The timing analysis reveals stochastic flickering variability with no evidence for coherent periodic modulations, thus the accreting object is likely a non-magnetic white dwarf. We propose a multiple-reflection model to explain the extraordinary strength of reflection features in V648 Car. Comments: Accepted for publication in ApJ Subjects: Solar and Stellar Astrophysics (astro-ph.SR) ; High Energy Astrophysical Phenomena (astro-ph.HE) Cite as: arXiv:2608.00266 [astro-ph.SR] (or arXiv:2608.00266v2 [astro-ph.SR] for this version) https://doi.org/10.48550/arXiv.2608.00266 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Raimundo Lopes de Oliveira Filho [ view email ] [v1] Fri, 31 Jul 2026 20:16:07 UTC (522 KB) [v2] Tue, 25 Aug 2026 04:35:54 UTC (522 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.SR < prev | next > new | recent | 2026-08 Change to browse by: astro-ph astro-ph.HE References & Citations INSPIRE HEP SciX Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab)

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