J/A+A/644/A163ivo://CDS.VizieR/J/A+A/644/A163doi:10.26093/cds/vizier.36440163CDSCanameras R.Schuldt S.Suyu S. H.Taubenberger S.Meinhardt T.,Leal-Taixe L.Lemon C.Rojas K.Savary E.2021-09-06T08:03:19Z2020-12-15T07:43:41ZCDS support team

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

cds-question@unistra.frsurveysgravitational-lensingredshiftedinfrared-photometryvisible-astronomybroad-band-photometryWe present a systematic search for wide-separation (with Einstein radius ~1.5"), galaxy-scale strong lenses in the 30000 sq.deg of the Pan-STARRS 3pi survey on the Northern sky. With long time delays of a few days to weeks, these types of systems are particularly well-suited for catching strongly lensed supernovae with spatially-resolved multiple images and offer new insights on early-phase supernova spectroscopy and cosmography. We produced a set of realistic simulations by painting lensed COSMOS sources on Pan-STARRS image cutouts of lens luminous red galaxies (LRGs) with redshift and velocity dispersion known from the sloan digital sky survey (SDSS). First, we computed the photometry of mock lenses in gri bands and applied a simple catalog-level neural network to identify a sample of 1050207 galaxies with similar colors and magnitudes as the mocks. Second, we trained a convolutional neural network (CNN) on Pan-STARRS gri image cutouts to classify this sample and obtain sets of 105760 and 12382 lens candidates with scores of pCNN>0.5 and >0.9, respectively. Extensive tests showed that CNN performances rely heavily on the design of lens simulations and the choice of negative examples for training, but little on the network architecture. The CNN correctly classified 14 out of 16 test lenses, which are previously confirmed lens systems above the detection limit of Pan-STARRS. Finally, we visually inspected all galaxies with pCNN>0.9 to assemble a final set of 330 high-quality newly-discovered lens candidates while recovering 23 published systems. For a subset, SDSS spectroscopy on the lens central regions proves that our method correctly identifies lens LRGs at z~0.1-0.7. Five spectra also show robust signatures of high-redshift background sources, and Pan-STARRS imaging confirms one of them as a quadruply-imaged red source at z_s_=1.185, which is likely a recently quenched galaxy strongly lensed by a foreground LRG at z_d_=0.3155. In the future, high-resolution imaging and spectroscopic follow-up will be required to validate Pan-STARRS lens candidates and derive strong lensing models. We also expect that the efficient and automated two-step classification method presented in this paper will be applicable to the ~4 mag deeper gri stacks from the Rubin Observatory Legacy Survey of Space and Time (LSST) with minor adjustments.2020A&A...644A.163Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/644/A163CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/644/A163https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/644/A163http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/644/A163https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/644/A163https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/644/A163http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/644/A163GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/644/A163/table1 (Complete list of strong lens candidates from visual inspection of the highest neural network scores)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/644/A163/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/644/A163/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/644/A163/table1?GETtext/xml+votable180.050000true336.53750.6950.0055555555555555566/2 594 598 619 704 2704 4153 4220 4245 4268 4472 4489 4513 4590 4629 4732 4777 4882 4914 4967 5081 5133 5228 5352 5369 5523 5533 5599 5626 5635 5778 5803 5825 5890 5968-5969 5978 6011 6080 6102 6214 6277 6300 6370 6500 6586 6684 6725 6739 6926 6962 6990 7193 7284 7442 7589 7634 7759 7824 7999 8326 8349 8462 8485 8507 8645-8646 8662 8693 8707 8711 8761 8815 8870 8897-8898 8910 8932 9198 9227 9287 9297 9330 9332 9389 9403 9489 9632 9833 9909 9941 9946 10099 10159 10229 10303 10386 10439 10606 10698 10801 10852 10918 11007 11307 11479 11698 11854 12088 12312 12337 12391 12549 12620 12720 12748 12751 12755 12779 13317 13368 13418 13433 15047 15105 15166 15287 15337 15982 16054 16104 16110 16688 16832 16841 16844 16855 16861 17075 17115 17134 17275 17281 17287 17389 17412 17415 17450 17477 17560 17585 17617 17622 17681 17724 17853-17854 17868 18061 18065 18106 18181 18208 18353 18397 18485 18488 18516 18555 18596 18605 18620 18652 18656 18752 18757 18761 18776 18783 18828 18830 18883 18901 18960 18975 19003 19013 19031 19053 19072 19207 19242 19329 19336 19442 19521 19570 19587 19712 19716 19755 19924 19974 19987 20066 20107 20219 20236 20268 20353 20425 20461 20649 21096 21840 21863 22395 22565 22570 22634 22642 22704 22716 22774 22789 22915 22938 23062 23086 23174 23312 25346 25382 25515 25714 25724 25747 25811 25823 25830 25842 25865 25880 25927 25929 25979 26000 26010 26053 26078 26085 26134 26137 26206 26367 26434 26481 26509 26767 26912 26924 26939 27074 27183 27190 27222 27235 27286 27321 27326 27547 27775 27875 27939 27964 28030 28068 28152-28153 28218 28227 28233 28306 28434 28462 28469 28514 30897 31146 31165 31330 31348 31350 31355 31425 31471 31597 31608 31678 31684 32309 32425 32488 32505 32536 32547 32686 32736 32752 34650-34651 34716 34776 35737 35807 35988 36020 36025 36031 36034 36097 36121 36179 36200 36293 36301 36310 36380 36396 36403 36469 36476 36501 36517 36527 36535 36562 36628 36654 36685 36696 36755 36771 40875 40912 44280 44450 44483 44564 44805 45041 47003 48121 48739 49028https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/644/A163?format=asciiOpticalInfrareddefaultJ/A+A/644/A163/table1Complete list of strong lens candidates from visual inspection of the highest neural network scoresrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameCandidate identifier (PS1JHHMM+DDMM)meta.id;meta.maincharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainpCNNOutput score from the neural networkmeta.code.qualfloatGradeAverage of the visual grades from four authorsmeta.code.qualfloatgKron? PS1 catalog g band Kron magnitude (1)magphot.mag;em.opt.BfloatnullablerKron? PS1 catalog r band Kron magnitudemagphot.mag;em.opt.RfloatnullableiKron? PS1 catalog i band Kron magnitudemagphot.mag;em.opt.IfloatnullablegAperPS1 catalog g band Aper magnitude (2)magphot.mag;em.opt.BfloatrAperPS1 catalog r band Aper magnitudemagphot.mag;em.opt.RfloatiAperPS1 catalog i band Aper magnitudemagphot.mag;em.opt.Ifloatz? Redshift (3)src.redshiftfloatnullablef_z[*] * for spectroscopic redshift, else photometricmeta.codecharRefReference(s) for candidates in the literature (4)meta.ref;pos.framechar