Confirmation of SRGt 062340.2-265751 as a nova-like cataclysmic variable with a possible magnetic nature

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Abstract
SRGt 062340.2-265751, a cataclysmic variable identified by SRG /eROSITA thanks to its significant X-ray variability, remains poorly characterised despite the multi-wavelength follow-up. We present spectral and timing analyses from the first dedicated X-ray and ultraviolet observations with XMM-Newton , complemented by SRG /eROSITA data from four all-sky surveys (eRASS1-4) and ASAS-SN optical photometry. Our timing analysis reveals a > 8 σ significant modulation at 3.6 ± 0.5 hours, likely representing the orbital period. Long-term ASAS-SN monitoring confirms the source as a VY Sculptoris-type nova-like system, while short-timescale X-ray and ultraviolet variability, down to a few minutes, suggests a possible underlying magnetic white dwarf. Two additional significant X-ray modulations at 43 ± 1 min and 36.0 ± 0.7 min tentatively point to the spin period of an intermediate polar. The best-fit XMM-Newton energy spectra reveal a multi-temperature thermal plasma ( kT = 0.23, 0.94, and 5.2 keV), while the SRG /eROSITA spectra are consistent with a single-temperature thermal plasma of a few keV. We estimate unabsorbed X-ray luminosities of ≳10 32 erg s −1 (0.2–12 keV). Broadband spectral energy distribution modelling, from near-ultraviolet to infrared, indicates a disc-dominated system consistent with a nova-like classification. We discuss these results in the context of the source’s confirmed nova-like classification and its possible magnetic nature, a scenario increasingly supported by discoveries of intermediate polars exhibiting VY Sculptoris-type nova-like features.
Funding Information
  • Deutsches Zentrum für Luft- und Raumfahrt (50 OR 2405)
  • Deutsches Zentrum für Luft- und Raumfahrt (50 OR 2408)
  • Deutsche Forschungsgemeinschaft (Schw536/37-1)
  • Science and Technology Facilities Council (ST/W507428/1)

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