J/MNRAS/459/220ivo://CDS.VizieR/J/MNRAS/459/220doi:10.26093/cds/vizier.74590220CDSSuess K.A.Darling J.Haynes M.P.Giovanelli R.2024-08-16T20:16:50Z2017-07-28T10:57:47ZCDS support team

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

cds-question@unistra.frradio-galaxiesh-i-line-emissionredshiftedastrophysical-masersradio-astronomyOH megamasers (OHMs) are rare, luminous molecular masers that are typically observed in (ultra) luminous infrared galaxies and serve as markers of major galaxy mergers. In blind emission line surveys such as the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) survey for neutral hydrogen (HI), OHMs at z~0.2 can mimic z~0.05 HI lines. We present the results of optical spectroscopy of ambiguous HI detections in the ALFALFA 40 per cent data release detected by the Wide Field Infrared Survey Explorer (WISE) but with uncertain optical counterparts. The optical redshifts, obtained from observations at the Apache Point Observatory, revealed five new OHMs and identified 129 HI optical counterparts. 60 candidates remain ambiguous. The new OHMs are the first detected in a blind spectral line survey. The number of OHMs in ALFALFA is consistent with predictions from the OH luminosity function. Additionally, the mid-infrared magnitudes and colours of the OHM host galaxies found in a blind survey do not seem to differ from those found in previous targeted surveys. This validates the methods used in previous IR-selected OHM surveys and indicates there is no previously unknown OHM-producing population at z~0.2. We also provide a method for future surveys to separate OH megamasers from 99 per cent of HI line emitters without optical spectroscopy by using WISE infrared colours and magnitudes. Since the fraction of OHMs found in flux-limited HI surveys is expected to increase with the survey's redshift, this selection method can be applied to future flux-limited high-redshift hydrogen surveys.2016MNRAS.459..220Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/459/220CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/142/170 : ALFALFA survey: the {alpha}.40 HI source catalog (Haynes+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/459/220https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/459/220http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/459/220https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/459/220https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/459/220http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/459/220GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/459/220/table3 (Optical counterpart redshifts of HI-emitting galaxies)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/459/220/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/459/220/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/459/220/table3?GETtext/xml+votable180.050000true0.374916731.23413890.005555555555555556Cone search capability for table J/MNRAS/459/220/table4 (Ambiguous optical counterparts)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/459/220/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/459/220/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/459/220/table4?GETtext/xml+votable180.050000true0.900083325.53444440.0055555555555555566/217 219 230 233-234 236 538 543 549 551 555 557 640 724 731-733 743 747 757 759 766-767 818 825 900 905 907 910 912 929-930 933 938 943 960 2077 2109 2131 2140 2159-2161 2183 2186 2193 2200 2210-2211 2215-2216 2220 2242 2304 2306 4841 4851 4922-4923 5003 6175 8215 8237 8291 8298 8309 8314 8333 8351 8357 8384 8390 8407 8412-8413 8432 8479 8485 8491 8686 8699 8729 8748 8984 9013 9026 10277 10285 12559 12574 12596 13333 13339 13342 13370 13411 13426 13428 13443 13467 13484 13570 18391 18410 19423 19431 19947 19954 19965 20006 20181 20185-20186 20188 20208 20218 20254 20263 20273 20283-20284 20288 20307 20318 20320 20322 20325 20356-20357 20370 20373 20387-20388 20390-20392 20396-20397 20404 20416-20417 21967 21974 21991 21997 22323-22324 22333 22398 22482 22488 26344 26358 26446 26477 26536 26552 26598 27087 27116 27824 27880 27924 28163 28210 28474 28555 31439 31450 31485 31503 31538 31620 31724https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/459/220?format=asciiRadiodefaultJ/MNRAS/459/220/table3Optical counterpart redshifts of HI-emitting galaxiesSimbadNameSimbad column added by the CDSmeta.idcharn_PosNote on Pos (2)meta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameObject namemeta.id;meta.maincharn_Name[2-6] Note on Name (1)meta.notecharRAJ2000Optical counterpart right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Optical counterpart declination (J2000)pos.eq.dec;meta.mainVoptOptical velocity (uncertainty is 130km/s)km/sphys.veloc;pos.heliocentricintVHI? HI velocity from Haynes et al. (2011, Cat. J/AJ/142/170)km/sphys.veloc;pos.heliocentricintnullablee_VHI? rms uncertainty on VHIkm/sstat.errorintnullableJ/MNRAS/459/220/table4Ambiguous optical counterpartsSimbadNameSimbad column added by the CDSmeta.idcharNameObject namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintm_Name[AB: ] Multiplicity index on Namemeta.code.multipcharn_Name[2-9] Note on Name (1)meta.notecharRAJ2000Observed right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Observed declination (J2000)pos.eq.dec;meta.mainn_PosNote on Pos (2)meta.notecharVopt? Optical velocity (uncertainty is 130km/s)km/sphys.veloc;pos.heliocentricintnullableVHI? HI velocity from Haynes et al. (2011, Cat. J/AJ/142/170)km/sphys.veloc;pos.heliocentricintnullablee_VHI? rms uncertainty on VHIkm/sstat.errorintnullableVOH? OH velocitykm/sphys.veloc;pos.heliocentricintnullablee_VOH? rms uncertainty on VOHkm/sstat.errorintnullableComComments (3)meta.notechar