J/ApJ/740/87ivo://CDS.VizieR/J/ApJ/740/87doi:10.26093/cds/vizier.17400087CDSCroft S.Tomsick J.A.Bower G.C.2017-10-02T19:28:58Z2013-03-11T16:13:59ZCDS support team

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

cds-question@unistra.frx-ray-sourcesradio-continuum-emissionWe present a 50ks Chandra/ACIS-I X-ray observation of the Bower et al. (2007ApJ...666..346B) Very Large Array archival field. The observations reach a limiting sensitivity of ~10^-4^counts/s, corresponding to a flux of a few times 10^-15^erg/s/cm^2^ for the models we explore. The Chandra observations were undertaken to search for X-ray counterparts to the eight transient sources without optical counterparts, and the two transient sources with optical counterparts seen by Bower et al. Neither of the sources with optical counterparts was detected in X-rays. One of the eight optical non-detections is associated with a marginal (2.4{sigma}) X-ray detection in our Chandra image. A second optically undetected Bower et al. transient may be associated with a z=1.29 X-ray-detected quasar or its host galaxy, or alternatively is undetected in X-rays and is a chance association with the nearby X-ray source. The X-ray flux upper limits, and the one marginal detection, are consistent with the interpretation of Ofek et al. (2010ApJ...711..517O) that the optically undetected radio transients are flares from isolated old Galactic neutron stars. The marginal X-ray detection has a hardness ratio that implies a temperature too high for a simple one-temperature neutron star model, but plausible multi-component fits are not excluded, and in any case the marginal X-ray detection may be due to cosmic rays or particle background. The X-ray flux upper limits are also consistent with flare star progenitors at >~1kpc (which would require the radio luminosity of the transient to be unusually high for such an object) or less extreme flares from brown dwarfs at distances of around 100pc.2011ApJ...740...87Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/740/87CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/chandra : The Chandra Archive Log (CXC, 1999-2012)VIII/87 : The Allen Telescope Array 20cm Survey (ATATS). I. (Croft+ 2010)J/ApJ/725/1792 : Pi Ghz Sky Survey (PiGSS). I. (Bower+, 2010)J/ApJ/698/1398 : H1743-322 2003 outburst (McClintock+, 2009)J/ApJ/663/81 : SED of hard X-ray selected AGN in XMDS (Polletta+, 2007)J/ApJ/578/405 : Neutron stars in NGC 5139 (Rutledge+, 2002)J/MNRAS/298/692 : Radio Survey of X-ray sources (Fender+ 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/740/87https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/740/87http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/740/87https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/740/87https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/740/87http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/740/87GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/740/87/table1 (VLA sources and their Chandra counterparts)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/740/87/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/740/87/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/740/87/table1?GETtext/xml+votable180.050000true225.047833378.211750.005555555555555556Cone search capability for table J/ApJ/740/87/table2 (Chandra sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/740/87/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/740/87/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/740/87/table2?GETtext/xml+votable180.050000true224.48987578.258250.0055555555555555566/12095 12138 12181 122243.313034785154005e-24 3.313034785154005e-24https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/740/87?format=asciiX-rayRadiodefaultJ/ApJ/740/87/table1VLA sources and their Chandra counterpartsNEDnameSimbad column added by the CDSmeta.idcharf_CID[NC/i ] Remarks (3)meta.codecharl_CtsLimit flag on Cts (4)meta.code.errorcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVLAVLA identification (NAN/NAN) (1)meta.id;meta.maincharprimaryRT[19840502/20010331]? Transient from B07 (G1)meta.idintnullableRAJ2000[14/15] VLA Hour of right ascension (J2000)pos.eq.ra;meta.maine_RAJ2000RAs uncertainty (2)sstat.error;pos.eq.rafloatDEJ2000[78] VLA Degree of declination (J2000)pos.eq.dec;meta.maine_DEJ2000[0.2/4] DEs uncertainty (2)arcsecstat.error;pos.eq.decfloatCIDChandra identification (as in table 2)meta.id.crosscharCts[3.2/167]? ACIS counts (0.3-10keV) (5)ctphot.count;em.X-rayfloatnullablee_Cts? Cts uncertaintyctstat.errorfloatnullablel_RateLimit flag on Ratemeta.code.errorcharRate? 0.3-10keV count ratect/ksphot.count;em.X-rayfloatnullableHR[-0.62/0.52]? Hardness constraint (G2)phot.fluxfloatnullablee_HR? HR uncertaintystat.errorfloatnullableOffset[,11]? Offset between X-ray and radio positionsarcsecpos;arith.difffloatnullablee_Offset? Offset uncertainty (6)arcsecstat.errorfloatnullablef_Offset[h] h: X-ray source is extended (7)meta.codecharz? Redshift from Bower et al. 2007ApJ...666..346Bsrc.redshiftfloatnullableOIROptical/IR identification (8)src.classcharJ/ApJ/740/87/table2Chandra sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCIDChandra identification (XNNN)meta.id;meta.maincharprimaryRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainePos[0.64/2.28] Chandra position uncertainty (1)arcsecstat.error;posfloatBin[1/4] Binning (2)instr.setupintCts[3.7/332.7] ACIS counts (0.3-10keV); background subtractedctphot.count;em.X-rayfloate_CtsCts uncertaintyctstat.errorfloatl_HRLimit flag on HR (G1)meta.code.errorcharHR[-0.62/0.89]? Hardness constraint (G1)phot.fluxfloatnullablee_HR? HR uncertaintystat.errorfloatnullableVLAVLA identification (as in table 1)meta.id.crosscharJ/ApJ/740/87/table4X-ray fluxes for radio transientsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVLAVLA identification (NAN)meta.id;meta.maincharRT[19840502/20010331] Transient from B07 (G1)meta.idintCIDChandra identificationmeta.id.crosscharl_RateLimit flag on Ratemeta.code.errorcharRate[0.000109/0.00082] 0.3-10keV count ratect/ksphot.count;em.X-rayfloatl_SnsLimit flag on Snsmeta.code.errorcharSns[3.36/25.3] Unobscured 0.3-10keV flux (neutron star model) in 10^-15^erg/s/cm2 (1)aW.m**-2phot.flux;em.X-rayfloatf_Sns[d] Remark on source (2)meta.codecharl_SfsLimit flag on Sfsmeta.code.errorcharSfsUnobscured 0.3-10keV flux (flare star model) in 10^-15^erg/s/cm2 (3)aW.m**-2phot.flux;em.X-rayfloatS5GHz[0.37/7.04] 5GHz flux density (4)mJyphot.flux.density;em.radio.3-6GHzfloat