J/A+A/661/A8 eFEDS catalogue of variable X-ray sources (Boller+, 2022)
The eROSITA Final Equatorial-Depth Survey (eFEDS).
The variability catalogue and multi-epoch comparison.
Boller T., Schmitt J.H.M.M., Buchner J., Freyberg M., Georgakakis A.,
Liu T., Robrade J., Merloni A., Nandra K., Malyali A., Krumpe M.,
Salvato M., Dwelly T.
<Astron. Astrophys. 661, A8 (2022)>
=2022A&A...661A...8B 2022A&A...661A...8B (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; X-ray sources ; Stars, flare ; Active gal. nuclei
Keywords: X-rays: general - line formation - surveys
Abstract:
The 140 square degree Final Equatorial-Depth Survey (eFEDS) field,
observed with the extended ROentgen Survey with an Imaging Telescope
Array (eROSITA) aboard the Spectrum-Roentgen-Gamma (SRG) mission,
provides a first look at the variable eROSITA sky. We analyze the
intrinsic X-ray variability of the eFEDS sources, provide X-ray light
curves and tables with variability test results in the 0.2-2.3keV
(soft) and 2.3-5.0keV (hard) bands. We perform variability tests
using the normalized excess variance and maximum amplitude variability
methods as performed for the 2RXS catalogue and add results from the
Bayesian excess variance and the Bayesian block methods. In total 65
sources have been identified as being significantly variable in the
soft band. In the hard band only one source is found to vary
significantly. For the most variable sources fits to stellar flare
events reveal extreme flare properties. A few highly variable AGN have
also been detected. About half of the variable eFEDS sources have been
detected at X-rays with eROSITA for the first time. Comparison with
2RXS and XMM observations provide variability information on
timescales of years to decades.
Description:
Intrinsic X-ray variability of eFEDS sources in the 0.2-2.3keV (soft)
and 2.3-5.0keV (hard) bands has been determined. Variability tests
have been performed using the normalized excess variance, the maximum
amplitude variability method as performed for the 2RXS catalogue as
well as the Bayesian excess variance and the Bayesian block methods.
In total 65 sources have been identified as being significantly
variable in the soft band. In the hard band only one source is found
to vary significantly. For the most variable sources fits to stellar
flare events reveal extreme flare properties. A few highly variable
AGN have also been detected. About half of the variable eFEDS sources
have been detected at X-rays with eROSITA for the first time.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
efeds_va.dat 439 27910 *Variability test results, converted from
efeds_vary.fits
efeds_vary.fits 2880 3053 Original fits catalog
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Note on efeds_va.dat: Energy band 0: 0.2-5.0keV, Energy band 1: 0.2-2.3keV,
Energy band 2: 2.3-5.0keV.
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See also:
J/A+A/661/A1 : The eFEDS X-ray catalogs (V7.4) (Brunner+, 2022)
J/A+A/661/A2 : Galaxy clusters and groups in eFEDS (Liu+, 2022)
J/A+A/661/A3 : eFEDS counterparts to point-like sources (Salvato+, 2022)
J/A+A/661/A4 : eFEDS optical cluster and group catalog (Klein+, 2022)
J/A+A/661/A5 : The eFEDS AGN catalog (Liu+, 2022)
J/A+A/661/A7 : X-ray properties of eFEDS clusters and groups (Bahar+, 2022)
J/A+A/661/A10 : eFEDS galaxy clusters and groups in disguise (Bulbul+, 2022)
J/A+A/661/A23 : Exoplanet X-ray irradiation & evaporation rates (Foster+, 2022)
J/A+A/661/A24 : Corona-chromosphere connection (Fuhrmeister+, 2022)
J/A+A/661/A29 : First eROSITA study of nearby M dwarfs (Magaudda+, 2022)
J/A+A/661/A34 : eta Cha cluster eROSITA X-ray scan (Robrade+, 2022)
J/A+A/661/A35 : eROSITA study of 47 Tuc globular cluster (Saeedi+, 2022)
J/A+A/661/A38 : SRG/ART-XC 1st year all-sky X-ray survey (Pavlinsky+, 2022)
J/A+A/661/A40 : eRASS1 X-ray sources Sco-Cen members (Schmitt+, 2022)
J/A+A/661/A44 : A first eROSITA view of ultracool dwarfs (Stelzer+, 2022)
Byte-by-byte Description of file: efeds_va.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Name Source name, eFEDS JHHMMSS.s+DDMMSS
(Name)
24- 28 I5 --- ID-SRC [1/32683] Source identification number
in eFEDS catalogue (SRCID)
30- 47 F18.14 deg RAcdeg [126.24/145.66] Right ascension (ICRS)
(RA_CORR)
49- 66 F18.14 deg DEcdeg [-2.91/5.97] Declination (ICRS)
(DEC_CORR)
68- 69 I2 --- ndata0 ?=- Number of data point in
energy band 0, 0.2-5.0keV (ndata_0)
71- 79 F9.6 ct/s CRmean0 ?=- Mean count rate in energy band 0
(meancr_0)
81- 88 F8.6 ct/s e_CRmean0 ?=- Count rate error of mean count rate
in energy band 0 (meancrerr0)
90-101 E12.6 --- nev0 ?=- Normalized excess variance value
in energy band 0 (nev_0)
103-114 E12.6 --- e_nev0 ?=- Error of the normalized excess
variance value in energy band 0
(neverr0)
116-124 F9.6 --- nev0sig ?=- Normalized excess variance in units
of sigma in energy band 0 (nevsig0)
126 I1 --- nev0det [0/1] Variability flag of Normalized
excess variance in energy band 0:
1=true, 0=False (nevdet0)
128-136 F9.6 --- amplmax0 ?=- Maximum amplitude variability value
in energy band 0 (amplmax0)
138-146 F9.6 --- amplmag0sig ?=- Maximum amplitude variability in
units of sigma in energy band 0
(amplsig0)
148 I1 --- amplmax0det [0/1] Variability flag for Maximum
amplitude variability in energy band 0:
1=true, 0=False (ampldet0)
150 I1 --- nb0blocks ?=- Number of Bayesian blocks in energy
band 0 (nbblocks_0)
152 I1 --- bb0det Variability flag of Bayesian blocks in
energy band 0: 1=true, 0=False
(bbdet0)
154-158 F5.3 --- bexvar0 ?=- Bayesian excess variance value in
energy band 0 (bexvarscatt0)
160-164 F5.3 --- b_bexvar0 ?=- Bayesian excess variance lower 10
per cent quantile of the posterior in
energy band 0 (bexvarscattlo_0)
166 I1 --- bexvar0det [0/1] Variability flag of Bayesian excess
variance in energy band 0:
1=true, 0=False (bexvardet0)
168-172 F5.3 --- B_bexvar0 ?=- Bayesian excess variance upper 10
per cent quantile of the posterior in
energy band 0 (bexvarscatthi_0)
174-179 F6.3 --- bexvarrate0 ?=- Bayesian excess variance mean count
rate value in energy band 0
(bexvarrate0)
181-185 F5.3 --- e_bexvarrate0 ?=- Error of the Bayesian excess variance
mean count rate in energy band 0
(bexvarrateerr_0)
187-188 I2 --- ndata1 ?=- Number of data point in
energy band 1, 0.2-2.3keV (ndata_1)
190-198 F9.6 ct/s CRmean1 ?=- Mean count rate in energy band 1
(meancr_1)
200-207 F8.6 ct/s e_CRmean1 ?=- Count rate error of mean count rate
in energy band 1 (meancrerr1)
209-220 E12.6 --- nev1 ?=- Normalized excess variance value
in energy band 1 (nev_1)
222-233 E12.6 --- e_nev1 ?=- Error of the normalized excess
variance value in energy band 1
(neverr1)
235-243 F9.6 --- nev1sig ?=- Normalized excess variance in units
of sigma in energy band 1 (nevsig1)
245 I1 --- nev1det [0/1] Variability flag of Normalized
excess variance in energy band 1:
1=true, 0=False (nevdet1)
247-255 F9.6 --- amplmax1 ?=- Maximum amplitude variability value
in energy band 1 (amplmax1)
257-265 F9.6 --- amplmax1sig ?=- Maximum amplitude variability in
units of sigma in energy band 1
(amplsig1)
267 I1 --- amplmax1det [0/1] Variability flag for Maximum
amplitude variability in energy band 1:
1=true, 0=False (ampldet1)
269-271 F3.1 --- nb1blocks ?=- Number of Bayesian blocks in
energy band 1 (nbblocks_1)
273 I1 --- bb1det [0/1] Variability flag of Bayesian blocks
in energy band 1:
1=true, 0=False (bbdet1)
275-279 F5.3 --- bexvar1 ?=- Bayesian excess variance value in
energy band 1 (bexvarscatt1)
281-285 F5.3 --- b_bexvar1 ?=- Bayesian excess variance lower 10
per cent quantile of the posterior in
energy band 1 (bexvarscattlo_1)
287 I1 --- bexvar1det [0/1] Variability flag of Bayesian excess
variance in energy band
1: 1=true, 0=False (bexvardet1)
289-293 F5.3 --- B_bexvar1 ?=- Bayesian excess variance upper 10
per cent quantile of the posterior in
energy band 1 (bexvarscatthi_1)
295-300 F6.3 --- bexvarrate1 ?=- Bayesian excess variance mean count
rate value in energy band 1
(bexvarrate1)
302-306 F5.3 --- e_bexvarrate1 ?=- Error of the Bayesian excess variance
mean count rate in energy band 1
(bexvarrateerr_1)
308-309 I2 --- ndata2 ?=- Number of data point in
energy band 2, 2.3-5.0keV (ndata_2)
311-319 F9.6 ct/s CRmean2 ?=- Mean count rate in energy band 2
(meancr_2)
321-328 F8.6 ct/s e_CRmean2 ?=- Count rate error of mean count rate
in energy band 2 (meancrerr2)
330-341 E12.6 --- nev2 ?=- Normalized excess variance value in
energy band 2 (nev_2)
343-354 E12.6 --- e_nev2 ?=- Error of the normalized excess
variance value in energy band 2
(neverr2)
356-364 F9.6 --- nev2sig ?=- Normalized excess variance in units
of sigma in energy band 2 (nevsig2)
366 I1 --- nev2det [0/1] Variability flag of Normalized
excess variance in energy band 2:
1=true, 0=False (nevdet2)
368-376 F9.6 --- amplmax2 ?=- Maximum amplitude variability value
in energy band 2 (amplmax2)
378-386 F9.6 --- amplmax2sig ?=- Maximum amplitude variability in
units of sigma in energy band 2
(amplsig2)
388 I1 --- amplmax2det [0/1] Variability flag for Maximum
amplitude variability in energy band 2:
1=true, 0=False (ampldet2)
390 I1 --- nb2blocks ?=- Number of Bayesian blocks in
energy band 2 (nbblocks_2)
392 I1 --- bb2det [0/1] Variability flag of Bayesian blocks
in energy band 2:
1=true, 0=False (bbdet2)
394-398 F5.3 --- bexvar2 ?=- Bayesian excess variance value in
energy band 2 (bexvarscatt2)
400-404 F5.3 --- b_bexvar2 ?=- Bayesian excess variance lower 10
per cent quantile of the posterior in
energy band 2 (bexvarscattlo_2)
406 I1 --- bexvar2det [0/1] Variability flag of Bayesian excess
variance in energy band 2:
1=true, 0=False (bexvardet2)
408-412 F5.3 --- B_bexvar2 ?=- Bayesian excess variance upper 10
per cent quantile of the posterior in
energy band 2 (bexvarscatthi_2)
414-419 F6.3 --- bexvarrate2 ?=- Bayesian excess variance mean count
rate value in energy band 2
(bexvarrate2)
421-425 F5.3 --- e_bexvarrate2 ?=- Error of the Bayesian excess variance
mean count rate in energy band 2
(bexvarrateerr_2)
427 I1 --- isvariable0 [0/1] Variability flag for the 4 tests in
energy band 0: 1=true, 0=False
(isvariable_0)
429 I1 --- isvariable1 [0/1] Variability flag for the 4 tests in
energy band 1: 1=true, 0=False
(isvariable_1)
431 I1 --- isvariable2 [0/1] Variability flag for the 4 tests in
energy band 2: 1=true, 0=False
(isvariable_2)
433 I1 --- isvariable [0/1] Variability flag for all 4 tests
combined: 1=true, 0=False (isvariable)
435 I1 --- counts0-3s [0/1] Variablity for visual inspection of
the cumulative counts in band 0:
below 3 sigma = 0, above 3 sigma = 1
(counts03s)
437 I1 --- counts1-3s [0/1] Variablity for visual inspection of
the cumulative counts in band 1:
below 3 sigma = 0, above 3 sigma = 1
(counts13s)
439 I1 --- counts2-3s [0/1] Variablity for visual inspection of
the cumulative counts in band 2:
below 3 sigma = 0, above 3 sigma = 1
(counts23s)
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Acknowledgements:
Thomas Boller, bol(at)mpme.mpg.de
References:
Predehl et al., 2021A&A...647A...1P 2021A&A...647A...1P, The eROSITA X-ray telescope on SRG
The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the
SRG mission, 2022, A&A, 661, A1-A46
(End) Thomas Boller [MPE Garching, Germany], Patricia Vannier [CDS] 10-Feb-2022