Two new magnetic cataclysmic variables discovered in the 3XMM catalogue

Webb, N.; Schwope, A. D.; Zolotukhin, I.; Lin, Dacheng; Rosen, S. R.

doi:10.1051/0004-6361/201730974

Cited by 11 publications

(4 citation statements)

References 40 publications

(47 reference statements)

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“…The X-ray spectrum is not of very high quality, but at the signal-to-noise ratio we achieved, we did not find evidence for the ubiquitous luminous soft-radiation component found in all polars prior to the XMM-Newton era. The current finding (or non-finding of a soft component) adds to several other nondetections in XMM-Newton discovered polars (see Webb et al 2018, for two recent examples and further references therein). The intrinsic X-ray spectrum of a parent polar sample remains unknown.…”

Section: Discussionsupporting

confidence: 51%

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Identification of 3XMM J000511.8+634018 as a new polar at P_orb = 133.5 min – is it inside or outside the period gap?

Schwope

Wörpel

Webb

et al. 2020

A&A

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Aims. We aimed to identify the variable X-ray source 3XMM J000511.8+634018, which was serendipitously discovered through routine inspections while the 3XMM catalogue was compiled. Methods. We analysed the archival XMM-Newton observation of the source, obtained BUSCA photometry in three colours, and performed optical spectroscopy with the LBT. These data were supplemented by archival observations from the Zwicky Transient Facility. Results. Based on its optical and X-ray properties, 3XMM J000511.8+634018 is classified as a magnetic cataclysmic variable, or polar. The flux is modulated with a period of 2.22 h (8009.1 ± 0.2 s), which we identify with the orbital period. The bright phases are highly variable in X-ray luminosity from one cycle to the next. The source shows a thermal plasma spectrum typical of polars without evidence of a luminous soft blackbody-like component. It is non-eclipsing and displays one-pole accretion. The X-ray and BUSCA light curves show a stream absorption dip, which suggests an inclination 50° < i < 75°. The phasing of this feature, which occurs at the end of the bright phase, requires a somewhat special accretion geometry with a stream running far around the white dwarf before it is magnetically channelled. The period of this polar falls within the period gap of the cataclysmic variables (2.15−3.18 h), but appears to fall just below the minimum period when only polars are considered.

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Section: Discussionsupporting

confidence: 51%

“…Their brightness, distinctive X-ray and optical light curves, and hard X-ray spectra make serendipitous discoveries relatively common (e.g. Vogel et al 2008;Ramsay et al 2009;Webb et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Identification of 3XMM J000511.8+634018 as a new polar at P_orb = 133.5 min – is it inside or outside the period gap?

Schwope

Wörpel

Webb

et al. 2020

A&A

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“…Hence, formally the source might display a soft excess, F BB /F plasma > 1 but the large uncertainties make us believe that the soft excess is mild or even insignificant. Nevertheless, this object is the first X-ray detected polar with a soft component after a long series of X-ray detected polars without soft emission at all (Vogel et al 2008;Ramsay et al 2009;Webb et al 2018;Schwope et al 2020Schwope et al , 2022bOk et al 2023).…”

Section: J0850+0443mentioning

confidence: 85%

Compact white dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey

Schwope,

Kurpas,

Baecke

et al. 2024

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X-ray surveys combined with optical follow-up observations are used to generate complete flux-limited samples of the main X-ray emitting source classes. on the Spectrum-Roentgen-Gamma (SRG) mission provides sufficient sensitivity to build significantly enhanced samples of rare X-ray emitting sources. We strive to identify and classify compact white dwarf binaries, cataclysmic variables (CVs), and related objects, which were detected in the sky area of eFEDS, the Final Equatorial Depths Survey, and they were observed in the plate program of SDSS-V. Compact white dwarf binaries were selected from spectra obtained in the early SDSS-V plate program. A dedicated set of SDSS plate observations were carried out in the eFEDS field, providing spectroscopic classifications for a significant fraction of the optically bright end ($r<22.5$) of the X-ray sample. The identification and subclassification rests on visual inspections of the SDSS spectra, spectral variability, color-magnitude and color-color diagrams involving optical and X-ray fluxes, optical variability, and literature work. Upon visual inspection of SDSS spectra and various auxiliary data products, we have identified 26 accreting compact white dwarf binaries (aCWDBs) in eFEDS, of which 24 are proven X-ray emitters. Among those 26 objects, there are 12 dwarf novae, three WZ Sge-like disk-accreting nonmagnetic CVs with low accretion rates, five likely nonmagnetic high accretion rate nova-like CVs, two magnetic CVs of the polar subcategory, and three double degenerates (AM CVn objects). Period bouncing candidates and magnetic systems are rarer than expected in this sample, but it is too small for a thorough statistical analysis. Fourteen of the systems are new discoveries, of which five are fainter than the magnitude limit. Thirteen aCWDBs have measured or estimated orbital periods, of which five were presented here. Through a Zeeman analysis, we revise the magnetic field estimate of the polar system J0926$+0105$, which is likely a low-field polar at $B=16$\,MG. We quantified the success of X-ray versus optical/UV selection of compact white dwarf binaries which will be relevant for the full SDSS-V survey. We also identified six white dwarf main sequence (WDMS) systems, among them there is one confirmed pre-CV at an orbital period of 17.6 hours and another pre-CV candidate. This work presents successful initial work in building large samples of all kinds of accreting and X-ray emitting compact white dwarf binaries that will be continued over the full hemisphere in the years to come.

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“…It may be related to a recently proposed group of hard X-ray polars (yet, these do not show high/low state changes). It may be an addition to a small number of low N H polar systems (e.g., Bernardini et al 2019;Webb et al 2018;Vogel et al 2008). It is also the only polar MCV with a soft X-ray component detected in the low state.…”

Section: Discussionmentioning

confidence: 99%

Optical identification and follow-up observations of SRGA J213151.5+491400

Balman,

Khamitov,

Kolbin

et al. 2024

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The paper is comprised of optical identification and multiwavelength studies of a new X-ray source discovered by the Spectrum Roentgen-Gamma ( observatory during the survey and its follow-up optical and X-ray observations. We aim to identify SRGA\,J213151.5+491400 in the optical wavelengths. We determine spectra and light curves in the optical high and low states to find periodicities in the light curves and resolve emission lines in the system using optical ground-based data. We intend to study the spectral and temporal X-ray characteristics of the new source using the surveys in the high and low states and data in the low state. I TAK National Observatory) and in Russia (6-m and 1-m at SAO RAS), together with the X-ray data obtained with and telescopes aboard and the observatory. Using the optical data, we performed astrometry, photometry, spectroscopy, and power spectral analysis of the optical time series. We present optical Doppler tomography along with X-ray data analysis producing light curves and spectra. We detected in a high state in 2020 (17.9 mag) that decreased by about 3 mag into a low state (21 mag) in 2021. We find only one significant period using optical photometric time series analysis, which reveals the white dwarf spin (orbital) period to be 0.059710(1) days (85.982 min). The long slit spectroscopy in the high state yields a power-law continuum increasing towards the blue with a prominent II line along with the Balmer line emissions with no cyclotron humps, which is consistent with a magnetic cataclysmic variable (MCV) nature. Doppler Tomography confirms the polar nature revealing ballistic stream accretion along with magnetic stream during the high state. These characteristics show that the new source is a polar-type MCV source. detections yield an X-ray flux of (4.0-7.0)times in the high state. detects a dominating hot plasma component max $ $>$ 21 keV in the high state) declining to (4.0-6.0)times 10$^ in 2021 (low state). The data obtained in the low state reveal a two-pole accretor showing a soft X-ray component at (6-7)sigma significance with a blackbody temperature of 15-18 eV. A soft X-ray component has never been detected for a polar in the low state before.

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Two new magnetic cataclysmic variables discovered in the 3XMM catalogue

Cited by 11 publications

References 40 publications

Identification of 3XMM J000511.8+634018 as a new polar at P_orb = 133.5 min – is it inside or outside the period gap?

Identification of 3XMM J000511.8+634018 as a new polar at P_orb = 133.5 min – is it inside or outside the period gap?

Compact white dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey

Optical identification and follow-up observations of SRGA J213151.5+491400

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Two new magnetic cataclysmic variables discovered in the 3XMM catalogue

Cited by 11 publications

References 40 publications

Identification of 3XMM J000511.8+634018 as a new polar at Porb = 133.5 min – is it inside or outside the period gap?

Identification of 3XMM J000511.8+634018 as a new polar at Porb = 133.5 min – is it inside or outside the period gap?

Compact white dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey

Optical identification and follow-up observations of SRGA J213151.5+491400

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Identification of 3XMM J000511.8+634018 as a new polar at P_orb = 133.5 min – is it inside or outside the period gap?

Identification of 3XMM J000511.8+634018 as a new polar at P_orb = 133.5 min – is it inside or outside the period gap?