J/ApJS/255/28ivo://CDS.VizieR/J/ApJS/255/28doi:10.26093/cds/vizier.22550028CDSGupta N.Srianand R.Shukla G.Krogager J-.K.Noterdaeme P.Combes F.,Dutta R.Fynbo J.P.U.Hilton M.Momjian E.Moodley K.Petitjean P.2023-08-16T14:27:51Z2021-11-26T13:21:27ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiredshiftedvisible-astronomyspectroscopyradio-astronomyinfrared-sourcesWe present results from a spectroscopically blind search for associated and intervening HI 21cm and OH 18cm absorption lines toward 88 active galactic nuclei (AGN) at 2<z<5 using the uGMRT. The sample of AGN with 1.4GHz spectral luminosity in the range 10^27-29.3^W/Hz is selected using mid-infrared colors and closely resembles the distribution of the underlying quasar population. The search for associated or proximate absorption, defined to be within 3000km/s of the AGN redshift, led to one HI 21cm absorption detection (M1540-1453; z_abs_=2.1139). This is only the fourth known absorption at z>2. The detection rate (1.6_-1.4_^+3.8^%) suggests a low covering factor of the cold neutral medium (CNM; T~100K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Ly{alpha} systems (DLAs), has comoving absorption path lengths of {Delta}X=130.1 and 167.7 for HI and OH, respectively. The corresponding number of absorbers per unit comoving path length are <=0.014 and <=0.011, respectively. The former is at least 4.5 times lower than that of DLAs and consistent with the CNM cross section estimated using H_2_ and CI absorbers at z>2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path ~9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of HI 21cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z>2.2021ApJS..255...28Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/255/28CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)J/ApJ/636/610 : Damped Ly{alpha} systems at z<1.65 (Rao+, 2006)J/ApJ/675/1002 : Proximate DLA systems in SDSS-DR5 (Prochaska+, 2008)J/ApJ/757/51 : FIRST-2MASS dust-reddened QSO spectra (Glikman+, 2012)J/A+A/547/L1 : SDSS-III DR9 DLA catalogue (Noterdaeme+, 2012)J/ApJ/761/184 : IR luminosities for dusty AGNs and QSOs (Weedman+, 2012)J/MNRAS/440/696 : HI absorption in nearby radio galaxies (Allison+, 2014)J/A+A/575/A44 : HI absorption in flux-selected radio AGNs (Gereb+, 2015)J/A+A/585/A87 : Quasar composite made from bright QSOs (Selsing+, 2016)J/MNRAS/465/588 : HI 21-cm absorption survey of QSO-galaxy pairs (Dutta+, 2017)J/A+A/604/A43 : HI in nearby radio sources (Maccagni+, 2017)J/AJ/156/18 : Binary companions of evolved stars (Price-Whelan+, 2018)J/ApJS/245/3 : HI 21cm & OH 18cm absorption search with GBT (Grasha+, 2019)J/MNRAS/490/243 : ELAIS N1 field uGMRT 400MHz sources (Chakraborty+, 2019)J/A+A/648/A116 : PKS 1830-211 OH and HI spectra (Combes+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/255/28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/255/28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/255/28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/255/28https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/255/28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/255/28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/255/28/table1 (the 88 z>2 MIR-selected radio sources observed with uGMRT)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/255/28/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/255/28/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/255/28/table1?GETtext/xml+votable180.050000true10.679416712.78266670.0055555555555555566/38 172 620 8229 8253 17353 17388 17411 17925 18462 18906 19067 19323 19726 20121 20555 20561 20703 21010 21767 21917 22490 22629 22844 22978 23030 23175 24114 24759 24778 24920 24928 25071 25299 25467 25541 25574 25679 26149 26755 26853 26904 29972 30787 30870 31130 31324 31554 34276 34606 35273 36064 36177 38397 38877 38888 39669 39685 39817 40142 40217 40709 40915 43506 43717 43759 43970 44208 44243 44362 44516 44809 44812 44839 44873 44911 44944 46972 46996 47059 47971 48298 48376 48616 48732 48867 48899https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/255/28?format=asciiOpticalInfraredRadiodefaultJ/ApJS/255/28/table1the 88 z>2 MIR-selected radio sources observed with uGMRTSimbadNameSimbad column added by the CDSmeta.idcharnullableRatio[0.64/1.11]? Ratio of Fp420MHz to F420MHzphot.flux;arith.ratio;em.radio.400-750MHzfloatnullablealpha[-1.26/1.32]? Spectral index {alpha} derived using NVSS and 420MHz flux densities (3)spect.index;em.radiofloatnullablealpIn[-1.26/1.1]? In-band spectral indexspect.index;em.radio.400-750MHzfloatnullableNEDNED column added by the CDSmeta.ref.urlchardelF[1.3/11.2]? Observed spectral rms at 420MHzmJy/beamstat.stdevfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource name (MHHMMSS.ss+DDMMSS.s; J2000) based on NVSS coordinates (<NVSS JHHMMSS+DDMMSS> in Simbad)meta.id;meta.maincharf_NameFlag on Namemeta.codecharF1.4GHz[203.3/1354.9] 20cm flux density from NVSSphot.flux.density;em.radio.750-1500MHzfloatzem[2.006/5.064] Emission line redshift measured from SALT-NOT surveysrc.redshiftfloatRunObserving run (1)meta.notecharf_Runb=only M1312-2026 was also observed at Band 2meta.codecharBeam1Synthesized beam 1 (2)arcsecphys.veloc.ang;instr.beamfloatBeam2Synthesized beam 2 (2)arcsecphys.angSizefloatPA[-85/90] Position angle of the beam (2)degpos.posAng;instr.beamfloatf_PAb=Corresponds to Band 2meta.codecharFp420MHz[44.2/2554.1]? Peak of the prominent Gaussian component (2)mJy/beamphot.flux.density;em.radio.400-750MHzfloatnullableF420MHz[44.1/2577] Total flux density (2)mJyphot.flux.density;em.radio.400-750MHzfloatf_F420MHzb=Corresponds to Band 2meta.codecharNc[1/4]? Number of absorption candidatesmeta.numberintnullable_RAPositions from names (right ascension part)degpos.eq.ra;meta.main_DEPositions from names (declination part)degpos.eq.dec;meta.main