J/PASP/137/A4201 CVs and AM CVn binaries eRASS1/Gaia X-match (Rodriguez+, 2025)
Cataclysmic Variables and AM CVn Binaries in SRG/eROSITA + Gaia:
Volume Limited Samples, X-Ray Luminosity Functions, and Space Densities.
Rodriguez A.C., El-Badry K., Suleimanov V., Pala A.F., Kulkarni S.R.,
Gaensicke B., Mori K., Rich R.M., Sarkar A., Bao T., Lopes de Oliveira R.,
Ramsay G., Szkody P., Graham M., Prince T.A., Caiazzo I., Vanderbosch Z.P.,
van Roestel J., Das K.K., Qin Y.-J., Kasliwal M.M., Wold A., Groom S.L.,
Reiley D., Riddle R.
<Publ. Astron. Soc. Pac. 137, A4201 (2025)>
=2025PASP..137a4201R 2025PASP..137a4201R (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Stars, double and multiple ; Stars, variable ;
Optical
Keywords: X-ray astronomy - binary stars - cataclysmic variable stars -
AM Canum Venaticorum variable stars - variable stars -
astronomy data visualization - X-ray stars
Abstract:
We present volume-limited samples of cataclysmic variables (CVs) and
AM CVn binaries jointly selected from SRG/eROSITA eRASS1 and Gaia DR3
using an X-ray + optical color-color diagram (the "X-ray Main Sequence").
This tool identifies all CV subtypes, including magnetic and low-accretion
rate systems, in contrast to most previous surveys. We find 23 CVs, 3 of
which are AM CVns, out to 150 pc in the Western Galactic Hemisphere.
Our 150 pc sample is spectroscopically verified and complete down to
LX=1.3x1029erg/s in the 0.2-2.3keV band, and we also present
CV candidates out to 300pc and 1000pc.
We discovered two previously unknown systems in our 150pc sample: the
third nearest AM CVn and a magnetic period bouncer. We find the mean
LX of CVs to be ∼4.6x1030erg/s, in contrast to previous surveys
which yielded ∼1031-1032erg/s. We construct X-ray luminosity
functions that, for the first time, flatten out at LX∼1030erg/s. We
infer average number, mass, and luminosity densities of
ρN,CV=(3.7±0.7)x10-6pc-3,
ρM=(5.0±1.0)x10-5M☉-1, and
ρLX=(2.3+.-0.4)x1026erg/s/M☉, respectively, in the solar
neighborhood. Our uniform selection method also allows us to place
meaningful estimates on the space density of AM CVns,
ρN,AM-CVn=(5.5±3.7)x10-7pc-3. Magnetic CVs and period
bouncers make up 35% and 25% of our sample, respectively. This work,
through a novel discovery technique, shows that the observed number
densities of CVs and AM CVns, as well as the fraction of period
bouncers, are still in tension with population synthesis estimates.
Description:
Cross-match of SRG/eROSITA eRASS1 (Cat. J/A+A/682/A34) and Gaia DR3
(Cat. I/355) for CVs and AM CVn binaries.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
cv_300.dat 432 122 Catalog of candidate CVs and AM CVns out to 300c
cv_1000.dat 432 590 Catalog of candidate CVs and AM CVns out to 1000pc
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/A+A/682/A34 : SRG/eROSITA all-sky survey catalogs (eRASS1) (Merloni+, 2024)
Byte-by-byte Description of file: cv_300.dat cv_1000.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- IAUName eROSITA name, 1eRASS JHHMMSS.s+DDMMSS
(IAUNAME)
25- 44 F20.16 deg RAdeg eROSITA right ascension (J2000) (RA_1)
46- 65 F20.16 deg DEdeg eROSITA declination (J2000) (DEC_1)
67- 76 F10.8 arcsec posErr X-ray positional error (POS_ERR)
78- 95 F18.14 deg GLON Galactic longitude (LII)
97-116 F20.16 deg GLAT Galactic latitude (BII)
118-120 F3.1 arcsec EXT X-ray extent (arcsec) (EXT)
122-134 F13.7 --- DetLike0 X-ray detection likelihood (DETLIKE0)
136-149 E14.8 mW/m2 MLFlux1 X-ray (0.2-2.3keV) flux (erg/s/cm2)
(MLFLUX1)
151-164 E14.8 mW/m2 e_MLFlux1 X-ray (0.2-2.3keV) flux error (MLFLUXERR_1)
166-180 F15.11 deg RAGdeg Gaia right ascension (J2000) (ra_epoch2000)
182-196 F15.11 deg DEGdeg Gaia declination (J2000) (dec_epoch2000)
198-216 I19 --- GaiaDR3 Gaia source id (source_id)
218-232 F15.11 deg RAIdeg Gaia right ascension (ICRS) at Ep=2016.0
(ra_x)
234-248 F15.11 deg DEIdeg Gaia declination (ICRS) at Ep=2016.0
(dec_x)
250-256 F7.4 mas Plx Parallax (parallax)
258-263 F6.4 mas e_Plx Parallax error (parallax_error)
265-273 F9.4 --- RPlx Parallax over error (parallaxovererror)
275-281 F7.3 mas/yr PM Total proper motion (pm)
283-290 F8.3 mas/yr pmRA Proper motion in right ascension,
(pmRA*cosDE (pmra)
292-296 F5.3 mas/yr e_pmRA Proper motion in right ascension error
(pmra_error)
298-305 F8.3 mas/yr pmDE Proper motion in declination (pmdec)
307-311 F5.3 mas/yr e_pmDE Proper motion in declination error
(pmdec_error)
313-317 F5.3 --- RUWE Gaia RUWE (ruwe)
319-327 F9.6 mag Gmag Gaia G magnitude (photgmean_mag)
329-337 F9.6 mag BPmag Gaia BP magnitude (photbpmean_mag)
339-347 F9.6 mag RPmag Gaia RP magnitude (photrpmean_mag)
349-357 F9.6 --- BP-RP Gaia BP-RP colour (bp_rp)
359-366 F8.6 arcsec Sep Separation between X-ray and optical
(angDist)
368-389 F22.19 --- Fx/Fopt X-ray to optical flux ratio (Fx/Fopt)
391-409 F19.16 mag GMAG Absolute G magnitude (Gabs)
411-432 E22.16 10-7W LX X-ray luminosity (erg/s) (L_X)
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Acknowledgements:
Antonio Rodriguez, acrodrig(at)caltech.edu
(End) Patricia Vannier [CDS] 28-Feb-2025