Detecting damped Ly{alpha} absorbers J/MNRAS/472/1850 ivo://CDS.VizieR/J/MNRAS/472/1850 doi:10.26093/cds/vizier.74721850 CDS Garnett R. Ho S. Bird S. Schneider J. 2024-08-17T20:20:47Z 2020-08-11T10:00:09Z CDS support team CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France cds-question@unistra.fr quasars redshifted We develop an automated technique for detecting damped Ly{alpha} absorbers (DLAs) along spectroscopic lines of sight to quasi-stellar objects (QSOs or quasars). The detection of DLAs in large-scale spectroscopic surveys such as SDSS III sheds light on galaxy formation at high redshift, showing the nucleation of galaxies from diffuse gas. We use nearly 50000 QSO spectra to learn a novel tailored Gaussian process model for quasar emission spectra, which we apply to the DLA detection problem via Bayesian model selection. We propose models for identifying an arbitrary number of DLAs along a given line of sight. We demonstrate our method's effectiveness using a large-scale validation experiment, with excellent performance. We also provide a catalogue of our results applied to 162858 spectra from SDSS-III data release 12. 2017MNRAS.472.1850G https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/472/1850 Catalog Research IsServedBy TAP VizieR generic service IsServedBy Conesearch service related-to VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017) https://cds.unistra.fr/vizier-org/licences_vizier.html https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/472/1850 https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/472/1850 http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/472/1850 https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/472/1850 https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/472/1850 http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/472/1850 GET text/xml+votable https://tapvizier.cds.unistra.fr/TAPVizieR/tap Cone search capability for table J/MNRAS/472/1850/table1 (The 297301 objects in the SDSS-III DR12Q catalog, and the results of our cuts) https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/472/1850/table1? https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/472/1850/table1? http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/472/1850/table1? 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Should Not be used for identification. meta.record int ID SDSS Thing id meta.id;meta.main long SDSS SDSS name (HHMMSS.ss+DDMMSS.s) meta.id char Plate SDSS plate number meta.id;instr.plate int MJD SDSS MJD number meta.id int RAJ2000 Right ascension (J2000) deg pos.eq.ra;meta.main indexed DEJ2000 Declination (J2000) deg pos.eq.dec;meta.main indexed zQSO QSO redshift src.redshift;pos.heliocentric float SNR Signal-to-noise stat.snr double FCut Cut flags meta.code int Sp Interactive spectrum from SDSS meta.ref.url char
J/MNRAS/472/1850/table2 The 162858 objects in the SDSS-III DR12Q catalog processed by our proposed GP DLA detection method, and a summary of derived quantities of interest ID Thing id meta.id;meta.main long recno Record number assigned by the VizieR team. Should Not be used for identification. meta.record int zmin Redshift search range, lower value src.redshift float zmax Redshift search range, upper value src.redshift float logPr1A Prior probability of the MDLA model, logPr(-DLA|zQSO) stat.probability;meta.modelled double logPr1B Prior probability of the MDLA(1) model, logPr(DLA|zQSO) stat.probability;meta.modelled double logpA Model evidence for MDLA model, logp(y|lambda,v,zSAO,M-DLA) stat.fit.param double logpB Model evidence for MDLA(1) model, logp(y|lambda,v,zSAO,M-DLA(1)) stat.fit.param double Pr2A Posterior probability of the MDLA model, Pr(tMDLA|DzQQSO) stat.probability;meta.modelled double Pr2B Posterior probability of the MDLA(1) model, Pr(MDLA|DzQQSO) stat.probability;meta.modelled double zSLA SLA redshift src.redshift;pos.heliocentric float logNHI HI column density log(cm**-2) phys.columnDensity float