J/A+A/687/A37ivo://CDS.VizieR/J/A+A/687/A37doi:10.26093/cds/vizier.36870037CDSBogensberger D.Nandra K.Salvato M.Liu T.Wolf J.Croom S.,Starck H.Buchner J.Ponti G.Ider Chitham J.Maitra C.Robrade J.,Merloni A.Krumpe M.2024-11-29T20:04:16Z2024-06-28T08:06:48ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frx-ray-sourcesredshiftedDuring the Spectrum Roentgen Gamma (SRG)/eROSITA all-sky surveys, X-ray sources close to the South Ecliptic Pole (SEP) are observed almost every 4h. We aim to identify the sources exhibiting the most significant long-term X-ray variability within 3{deg} of the SEP in the first three surveys, and investigate their properties. We determined the variability significance of ~10^4^ sources observed by eROSITA within 3{deg} of the SEP by using thresholds on the Bayesian excess variance (SCATT_LO) and the maximum amplitude deviation (AMPL_SIG). Sources exhibiting a variability significance above 3{sigma} were subdivided into likely Galactic and extragalactic sources, by using spectral and photometric information of their optical counterparts. We quantified the X-ray normalised excess variances of all variable sources, and also calculated the periodograms of the brightest ones. Out of more than 104 X-ray sources detected by eROSITA within 3{deg} of the SEP, we identified 453 that exhibit significant X-ray variability. SCATT_LO is significantly more sensitive to detecting variable sources in this field, but AMPL_SIG helps to provide a more complete variability sample. Of those variable sources, 168 were classified as likely extragalactic, and 235 as likely Galactic. The periodograms of most bright and variable extragalactic sources are approximately described by an aliased power law (P{prop.to}{nu}^-{alpha}^) with an index of {alpha}~=1. We identified a potential tidal disruption event, and long-term transient sources. The stellar X-ray variability was predominantly caused by bright X-ray flares from coronally active stars.2024A&A...687A..37Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/687/A37CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/682/A34 : SRG/eROSITA all-sky survey catalogs (eRASS1) (Merloni+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/687/A37https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/687/A37http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/687/A37https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/687/A37https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/687/A37http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/687/A37GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/687/A37/catalog (Catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/687/A37/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/687/A37/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/687/A37/catalog?GETtext/xml+votable180.050000true82.70774-67.098750.0055555555555555565/8276-8277 8448 9384 9386 9728 6/33093 33095 33101 33112-33113 33116-33117 33796-33798 37514-37515 37518 37540 37542 37548 37550 38920-38922https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/687/A37?format=asciiX-raydefaultJ/A+A/687/A37/catalogCatalogCReRASS3? Average eRASS3 count rate (Countrate_eRASS3)ct/sphot.count;em.X-rayfloatnullableSigniSLeRASS3[0/3]? SCATT_LO variability significance in eRASS3 (SCATT_LO_sig_eRASS3a (1))meta.code;src.varintnullableSigniASeRASS3[0/3]? AMPL_SIG variability significance in eRASS3 (AMPL_SIG_sig_eRASS3a (1))meta.code;src.varintnullableNEVbGeometric mean normalised excess variance NEVb of all 20-bin segments (NEV_b)stat.variancefloate_NEVb[] NEVb measurement error in - direction (NEV_b_error-)stat.errorfloatE_NEVbNEVb measurement error in + direction (NEV_b_error+)stat.error;stat.maxfloatNEVbSct-Intrinsic scatter in NEVb in - direction (NEV_b_scatter-)stat.variancefloatNEVbSct+Intrinsic scatter in NEVb in + direction (NEV_b_scatter+)stat.variancefloatPeriodIndex? Index of power-law fit to periodogram (Periodogram_index)spect.indexfloatnullablee_PeriodIndex? Error of periodogram index (Periodogram_index_error)stat.errorfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameeRASSt Name (eRASSt JHHMMSS.s+DDMMSS) (Name)meta.id;meta.maincharRAJ2000Right ascension (J2000) of the X-ray source (RAdeg_x)degpos.eq.ra;meta.mainDEJ2000Declination (J2000) of the X-ray source (DEdeg_x)degpos.eq.dec;meta.mainRAodeg? Right ascension (J2000) of the most likely optical counterpart (RAdeg_o)degpos.eq.ranullableDEodeg? Declination (J2000) of the most likely optical counterpart (DEdeg_o)degpos.eq.decnullableExtragalactic[0/1]? Is the source likely extragalactic (1), or likely Galactic (0)? (Extragalactic)meta.codeintnullableDGalactic-extragalactic distinction parameter (D)meta.codeintz? AAT optical redshifts (Redshift)src.redshiftfloatnullableExtended[0/1] Is the X-ray source extended (1), or point-like (0)? (Extended)meta.codeintCReRASS1? Average eRASS1 count rate (Countrate_eRASS1)ct/sphot.count;em.X-rayfloatnullableSigniSLeRASS1[0/3]? SCATT_LO variability significance in eRASS1 (SCATT_LO_sig_eRASS1)a (1)meta.code;src.varintnullableSigniASeRASS1[0/3]? AMPL_SIG variability significance in eRASS1 (AMPL_SIG_sig_eRASS1a (1))meta.code;src.varintnullableCReRASS2? Average eRASS2 count rate (Countrate_eRASS2)ct/sphot.count;em.X-rayfloatnullableSigniSLeRASS2[0/3]? SCATT_LO variability significance in eRASS2 (SCATT_LO_sig_eRASS2a (1))meta.code;src.varintnullableSigniASeRASS2[0/3]? AMPL_SIG variability significance in eRASS2 (AMPL_SIG_sig_eRASS2a (1))meta.code;src.varintnullable