J/A+A/698/A321 eROSITA, XMM, Swift and ROSAT cataclysmic variables (Wang+, 2025)
Cataclysmic variable candidates identified in eROSITA-DE DR1, XMM-Newton, Swift,
and ROSAT catalogs.
Wang X., Takata J.
<Astron. Astrophys. 698, A321 (2025)>
=2025A&A...698A.321W 2025A&A...698A.321W (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, cataclysmic ; X-ray sources ; Gamma rays
Keywords: novae - cataclysmic variables
Abstract:
The cataclysmic variable (CV) is a binary system composed of a
white-dwarf (WD) primary and a low-mass main-sequence star. The
accretion onto the WD surface causes an X-ray emission, and the CVs
are one of the major Galactic X-ray sources. The eROSITA observation
offers a new opportunity to identify numerous X-ray-emitting CVs and
advance our understanding of its Galactic population.
We aim to search for candidates of the X-ray-emitting CVs in the four
catalogs of eROSITA, XMM-Newton, Swift, and ROSAT observations. We
also intend to examine how the eROSITA survey can enhance the search
for new X-ray-emitting CVs.
In this study, we identified the candidates of the X-ray-emitting CVs
by cross-matching among the four X-ray catalogs and the Gaia sources
that are selected from the bridge region between the main sequence and
the WD's cooling sequence in the Hertzsprung-Russell diagram. For
the selected candidates, we searched for the periodic modulation in
the photometry light curves taken by the ZTF and/or TESS observations.
The cross-matching selects 444 candidates of the X-ray-emitting CVs,
in which 267 sources are the identified CVs. In the other 177
candidates of the X-ray-emitting CVs, we identify possible orbital
modulation for 56 sources in ZTF/TESS light curves. About 51% of the
candidates are exclusively selected from the eROSITA catalog, while
about 36%, 9%, and 4% are selected from the XMM-Newton, Swift, and
ROSAT catalogs, respectively. In the color-color diagram, most of the
selected CV candidates are distinguished from the active stars, while
some sources are likely classified as eclipsing binary systems rather
than CVs.
Combining the cross-matching process between X-ray catalogs and Gaia
sources with the timing analysis of the ZTF/TESS data is an effective
tool to identify the candidates of X-ray-emitting CVs. In particular,
the eROSITA observation successfully identified the sources that have
been missed in the other three catalogs because of its wide coverage
on the sky region and high flux sensitivity. On the other hand, the
current flux sensitivity of eROSITA is limited to on the order of
∼10-14erg/cm-2/s. As the first eROSITA catalog is result of
the operation in the first six months, it is expected that the future
operation will further increase the population of known X-ray-emitting
CVs.
Description:
The sky survey of eROSITA offers a new opportunity to identify
numerous X-ray-emitting CVs. In this study, therefore, we searched for
candidates of the X-ray-emitting CVs by cross-matching four X-ray
catalogs (eROSITA, XMM-Newton, Swift, and ROSAT) with Gaia's
sources. We demonstrate how the eROSITA survey is more efficient in
searching for X-ray-emitting CVs. We selected 264 sources, including
176 identified CVs and 91 CV candidates from the eROSITA catalog.
Among 91 CV candidates, we identified a periodic signal from 40
sources in ZTF and/or TESS photometric light curves.
Tables of identified CVs and CV candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
cvs.dat 251 367 Cataclysmic variable sources
cand.dat 251 186 Cataclysmic variable candidates
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
IX/30 : Second ROSAT PSPC Catalog (ROSAT, 2000)
IX/58 : 2SXPS Swift X-ray tel. point source catalogue (Evans+, 2020)
B/swift : Swift Master Catalog (HEASARC, 2004-)
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-)
J/A+A/682/A34 : SRG/eROSITA all-sky survey catalogs (eRASS1) (Merloni+, 2024)
J/A+A/687/A305 : CV eROSITA-enhanced multi-wavelength cat.
(Munoz-Giraldo+, 2024)
Byte-by-byte Description of file: cvs.dat cand.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Tel Source identified in which telescope
(eROSITA, XMM-Newton, Swift or ROSAT)
15- 33 I19 --- GaiaDR3 Source ID in Gaia DR3
35- 57 A23 --- 1eRASS Name of the X-ray source (from the X-ray
catalog, 1eRASS JHHMMSS.s+DDMMSS)
59- 76 E18.13 deg RAdeg Right Ascension (ICRS) at Ep=2016.0 of the
source in Gaia DR3
78- 96 E19.13 deg DEdeg Declination (ICRS) at Ep=2016.0 of the source
in Gaia DR3
98-126 A29 --- Name Name of the source in the SIMBAD astronomical
database
128-157 A30 --- VSX Name of the source in the Variable Star Index
(VSX) catalog
158-175 E18.13 mag BP-RP Difference between the Gaia blue photometric
band (G_bp) and the red photometric band
(G_rp) magnitudes in Gaia DR3
177-194 E18.13 mag GMAG Absolute magnitude of the source in Gaia DR3
196-213 E18.13 mas plx Parallax of the source in Gaia DR3
215-232 E18.13 mW/m2 FX ?=- X-ray flux of the source in X-ray catalogs
(in erg/cm2/s) (1)
234-251 E18.13 d Per ?=- Period of the source based on light curve
of ZTF/TESS or recored in VSX
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Note (1): "Flux" column represents the X-ray flux in erg/cm2/s and can be
used to assess the source's brightness in the X-ray band
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Acknowledgements:
Xiangxiang Wang, wangxx(at)hust.edu.cn
(End) Patricia Vannier [CDS] 16-Apr-2025