J/A+A/643/A103ivo://CDS.VizieR/J/A+A/643/A103doi:10.26093/cds/vizier.36430103CDSPena-Herazo H.A.Amaya-Almazan R.A.Massaro F.de Menezes R.,Marchesini E.J.Chavushyan V.Paggi A.Landoni M.Masetti N.Ricci F.,D'Abrusco R.Cheung C.C.La Franca F.Smith H.A.Milisavljevic D.,Jimenez-Bailon E.Patino-Alvarez V.M.Tosti G.2022-09-07T09:55:36Z2020-11-09T07:35:50ZCDS support team

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

cds-question@unistra.frgamma-ray-astronomybl-lacertae-objectsactive-galactic-nucleiredshiftedA significant fraction of all gamma-ray sources detected by the Large Area Telescope aboard the Fermi satellite is still lacking a low-energy counterpart. In addition, there is still a large population of gamma-ray sources with associated low-energy counterparts that lack firm classifications. In the last 10 years we have undertaken an optical spectroscopic campaign to address the problem of unassociated or unidentified gamma-ray sources (UGSs), mainly devoted to observing blazars and blazar candidates because they are the largest population of gamma-ray sources associated to date. Here we describe the overall impact of our optical spectroscopic campaign on sources associated in Fermi-LAT catalogs, coupled with objects found in the literature. In the literature search we kept track of efforts by different teams that presented optical spectra of counterparts or potential counterparts of Fermi-LAT catalog sources. Our summary includes an analysis of additional 30 newly collected optical spectra of counterparts or potential counterparts of Fermi-LAT sources of a previously unknown nature. Methods. New spectra were acquired at the Blanco 4m and OAN-SPM 2.1m telescopes, and those available in the Sloan Digital Sky Survey (data release 15) archive. All new sources with optical spectra analyzed here are classified as blazars. Thanks to our campaign, altogether we discovered and classified 394 targets with an additional 123 objects collected from a literature search. We began our optical spectroscopic campaign between the release of the second and third Fermi-LAT source catalogs (2FGL and 3FGL, respectively), classified about 25% of the sources that had uncertain nature and discovered a blazar-like potential counterpart for ~10% of UGSs listed therein. In the 4FGL catalog, about 350 Fermi-LAT sources have been classified to date thanks to our campaign. The most elusive class of blazars are found to be BL Lacs since the largest fraction of Fermi-LAT sources targeted in our observations showed a featureless optical spectrum. The same conclusion applied to the literature spectra. Finally, we confirm the high reliability of mid-IR color-based methods to select blazar-like candidate counterparts of unassociated or unidentified gamma-ray sources.2020A&A...643A.103Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/643/A103CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/311 : WISE All-Sky Data Release (Cutri+ 2012)J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)J/ApJS/247/33 : The Fermi LAT fourth source catalog (4FGL) (Abdollahi+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/643/A103https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/643/A103http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/643/A103https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/643/A103https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/643/A103http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/643/A103GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/643/A103/tableb1 (Summary of the optical spectroscopic campaign)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/643/A103/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/643/A103/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/643/A103/tableb1?GETtext/xml+votable180.050000true1.0204583-11.81620280.005555555555555556Cone search capability for table J/A+A/643/A103/tableb2 (Summary of literature search)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/643/A103/tableb2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/643/A103/tableb2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/643/A103/tableb2?GETtext/xml+votable180.050000true0.99679178.69393060.0055555555555555566/39 50 267 730-731 739 851 893 897 968 1222 1584 1617 1915 1961 2028 2078 2094 2100 2414 2636 2646 2667 2708 2792 2879 2896 2983 3099 3338 3351 3566 3667 3876 4088 4261 4863 4940 5250 5314 5352-5353 5371 5450 5522 5556 5728 5803 5836 5891 5986 5998 6044 6062-6063 6067 6088 6306 6498 6636 6638 6815 6822 6888 6910 6937 7131 7200 7238 7248 7305 7378 7394 7758 7764 7766 7936 7947 7951 8220 8432 8438 8474 8485 8502 8955 9268 9302 9417 9731 9906 9912 10033 10046 10074 10090 10105 10183 10280 10282 10427 10526 10546 10612 10653 10798 10800 10818 10843 10921 10949 11027 11124 11185 11216 11246 11323 11326 11426 11535 11586 11652 11865 11928 11975 12164 12207 12313 12410 12444 12544 12643 12780 12902 13060 13141 13179 13278-13279 13321 13324 13334 13406 13447 13457 13476 13534 13673 13711 13720 13743 13826 13867 13929 14608 14854 14871 14943 14962 14976 14981 14986 15023 15211 15272 15300 15305 15495 15903 15917 15955 15996 16223 16480 16679 16892 17095 17154 17206 17675 17711 17819 17957 17979 17988 18119 18190 18343 18366 18444 18666 18889 19037 19071 19334 19421 19460 19517 19525 19589 19616 19789 19867 19903 19949 19999 20049 20083 20110 20136 20202 20246 20473 20478 20693 20984 21142 21164 21493 21704 21754 21764 21792 21806 21898 22186 22364 22683 22894 23009 23011 23105 23181 23402 23825 23882 23901 23932 24027 24316 24432 24566 24580 24626 24655 24818 24980 25106 25184 25387 25468 25525 25760 25781 25804 25807 25820 25865 26195 26203 26303 26363 26390 26470 26483 26513 26549 26833 26897 27053 27082 27138 27381 27423 27523 27603 27725 27776 27852 27897 27964 28015 28139 28210 28290 28388 28517 28583 28971 29018 29336 30041 30195-30196 30573 30842 30894 30999 31011 31092 31239 31599 31688 31720 32035 32050 32185 32247 32288 32311 32314 32344 32370 32475 32596 32605 32611 32729 33008 33198 33238 33243 33382 33419 33506 33528 33746 33865 33968 34123 34128 34163 34375 34437 34461 34572 34779 34871 34911 34931 35063 35074 35079 35116 35199 35227 35252 35402 35535 35594 35981 36063 36100 36133 36296 36394 36445 36614-36615 36688 36719 36795 36951 37492 37519 37568 37779 37994 38046 38112 38246 38316 38332 38369 38516 38579 38635 38797 38911 38937 39139 39208 39466 39517 39544 39570 39671 39998 40205 40323 40337 40351 40422 40470 40703 40890 40919 41073 41359 41460 41464 42188 42571 42779 42904 42914 43085 43116 43186 43228 43377 43380 43412 43422 43447 43556 43572 43597 43643 43662 43877 44011 44153 44255 44291 44308 44336 44365 44539 44543 44582 44609 44734 44913 45011 45077 45079 45242 45284 45307 45316 45330 45358 45406 45482 45774 45820 45836 45904 46040 46200 46342 46392 46445 46483 46568-46569 46613 46772 47021 47101 47130 47152 47154 47196 47288 47398 47442 47461 47630 48201 48259 48528 48580 48829 48854 48858 48868 49043 49068 49142https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/643/A103?format=asciiGamma-raydefaultJ/A+A/643/A103/tableb1Summary of the optical spectroscopic campaignu_z[?] Uncertainty flag on zmeta.code.error;src.redshiftcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameFermi designationmeta.id;meta.maincharClassFFermi classificationsrc.classcharAssocAssociated sourcemeta.id.assoccharWISEWISE counterpart (JHHMMSS.ss+DDMMSS.s)meta.id.crosscharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainClassOOptical spectral classificationsrc.classcharl_zLimit flag on zmeta.code.error;src.redshiftcharzMeasured redshift from optical spectrasrc.redshiftdoubleRefReference of the campaign paper (1)meta.bibcharTelTelescopes used to acquire the spectrummeta.id;instr.telcharLitReference in literature paper (2)meta.bibcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/643/A103/tableb2Summary of literature searchrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint3FGLFermi 3FGL designation (3FGL JHHMM.m+DDMM)meta.id;meta.maincharClass3Fermi classificationsrc.classchar4FGLFermi 3FGL designation (4FGL JHHMM.m+DDMM)meta.idcharClass4Fermi classificationsrc.classcharSimbadSimbad column added by the CDSmeta.ref.urlcharAssocAssociated sourcemeta.id.assoccharWISEWISE counterpartmeta.id.crosscharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainClassOptical spectral classificationsrc.spTypecharl_zLimit flag on zmeta.code.error;src.redshiftcharzMeasured redshift from optical spectrasrc.redshiftfloatu_z[?] Uncertainty flag on zmeta.code.error;src.redshiftcharTelTelescopes used to acquire the spectrummeta.id;instr.telcharLitReference in literature paper (1)meta.bibchar