J/A+A/651/A55ivo://CDS.VizieR/J/A+A/651/A55doi:10.26093/cds/vizier.36510055CDSSchuldt S.Suyu S.H.Canameras R.Taubenberger S.Meinhard T.,Leal-Taixe L.Hsieh B.C.2021-09-29T11:39:39Z2021-07-13T08:17:25ZCDS support team

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

cds-question@unistra.frastronomical-modelsgalaxiesredshiftedThe redshifts of galaxies are a key attribute that is needed for nearly all extragalactic studies. Since spectroscopic redshifts require additional telescope and human resources, millions of galaxies are known without spectroscopic redshifts. Therefore, it is crucial to have methods for estimating the redshift of a galaxy based on its photometric properties, the so-called photo-z. We developed NetZ, a new method using a Convolutional Neural Network (CNN) to predict the photo-z based on galaxy images, in contrast to previous methods which often used only the integrated photometries of galaxies without their images. We use data from the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP) in five different filters as training data. The network over the whole redshift range between 0 and 4 performs well overall and especially in the high-z range better than other methods on the same data. We obtain an accuracy |zpred-zref| of sigma=0.12 (68% confidence interval) with a CNN working for all galaxy types averaged over all galaxies in the redshift range of 0 to ~4. By limiting to smaller redshift ranges or to Luminous Red Galaxies (LRGs), we find a further notable improvement. We publish more than 34 million new photo-z values predicted with NetZ here. This shows that the new method is very simple and fast to apply, and, importantly, covers a wide redshift range limited only by the available training data. It is broadly applicable and beneficial to imaging surveys, particularly upcoming surveys like the Rubin Observatory Legacy Survey of Space and Time which will provide images of billions of galaxies with similar image quality as HSC.2021A&A...651A..55Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/651/A55CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/651/A55https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/651/A55http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/651/A55https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/651/A55https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/651/A55http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/651/A55GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/651/A55/catalog (Catalog of photometric redshifts predicted with our newly developed code NetZ)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/651/A55/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/651/A55/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/651/A55/catalog?GETtext/xml+votable180.050000true29.12345-6.774850.0055555555555555564/256 1105-1107 1173-1174 1177-1179 1189 1191 1200-1202 1365 1621-1622 1625 1641-1642 1685 1702 1705-1707 5/1028-1030 2048 2455 2459-2460 2470-2471 2475-2476 2480 2496 2647 2651-2652 2672 2816 2856 4351 4417 4419 4432 4434 4449 4452 4501-4503 4508 4520 4522-4523 4544 4671 4687 4691 4700-4702 4707 4720-4722 4755 4761 4789 4812 4816 4832 4864-4866 5459 5465 5468-5470 6398-6399 6477-6479 6481 6483 6492 6497-6499 6504-6505 6507-6508 6512 6543 6554 6561 6563 6572 6576 6737 6739 6748 6798-6799 6803-6804 6806 6812 6814 6817-6819 6832-6833 6836 6912 9199 10237 10239 11262-11263 6/4124-4126 4128-4130 4133 4144-4145 4160-4162 8196 8198 8200-8202 9641-9644 9646 9813-9815 9817-9819 9829-9831 9833-9835 9844-9846 9848-9850 9877-9879 9893-9895 9897-9899 9908-9910 9912-9914 9924-9926 9928-9930 9988 9990 9992-9994 10581-10583 10585-10587 10597-10599 10601-10603 10612-10614 10616-10618 10645 10647 10692-10694 10696-10697 10741 10743 11268-11270 11272-11274 11402-11403 17399 17403 17525-17527 17533 17535 17621 17662-17663 17673-17675 17732 17734 17740 17742 17760-17762 17768 17792-17793 17795 17801 17804-17805 17812 17814 17816-17817 17834 17997-17999 18001-18003 18020-18021 18036-18038 18040-18041 18044 18086-18087 18104 18106 18679 18683 18743 18747 18759 18763 18812 18814 18823 18827 18892-18894 18896 18912-18914 18920 18922-18923 19015 19019 19041 19043 19053 19055 19153 19155 19252 19256 19272 19332 19336 19468-19470 19472 19474 19488 21827 21829-21831 21833 21835 21857 21869 21884-21885 25583 25587 25589-25591 25903 25907 25923 25929-25931 25972-25974 25976-25978 25987 26036-26038 26040-26042 26052-26054 26056-26058 26159 26166-26167 26169-26171 26192 26194-26195 26198 26204 26210-26211 26214 26220 26222 26243 26249-26251 26292-26294 26296-26298 26308 26310 26312-26314 26947 26953 26955 26977 26980-26981 26983 26989 26996-26998 27000-27001 27183 27187 27189-27191 27203 27205-27207 27209-27211 27222 27228 27230-27231 27252 27254 27260 27262-27263 27267 27336-27338 27348-27350 27368 27370-27371 27652-27654 27656-27658 31400 31402-31403 36783 36790-36791 36793-36795 36840 36842-36843 40927 40947 40953-40955 45039 45043 45046-45047https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/651/A55?format=asciidefaultJ/A+A/651/A55/catalogCatalog of photometric redshifts predicted with our newly developed code NetZrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDGalaxy identification number from the HSC PDR2meta.id;meta.mainzpred? photometric redshift estimated from NetZ (1)src.redshift.photdoublenullableRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainindexedDEJ2000Declination in (J2000)degpos.eq.dec;meta.mainindexed