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dc.contributor.authorAllison, J R
dc.contributor.authorSadler, E M
dc.contributor.authorBellstedt, S
dc.contributor.authorDavies, L J M
dc.contributor.authorDriver, S P
dc.contributor.authorEllison, S L
dc.contributor.authorHuynh, M
dc.contributor.authorKapińska, A D
dc.contributor.authorMahony, E K
dc.contributor.authorMoss, V A
dc.contributor.authorRobotham, A S G
dc.contributor.authorWhiting, M T
dc.contributor.authorCurran, S J
dc.contributor.authorDarling, J
dc.contributor.authorHotan, A W
dc.contributor.authorHunstead, R W
dc.contributor.authorKoribalski, B S
dc.contributor.authorLagos, C D P
dc.contributor.authorPettini, M
dc.contributor.authorPimbblet, K A
dc.contributor.authorVoronkov, M A
dc.identifier.citationAllison , J R , Sadler , E M , Bellstedt , S , Davies , L J M , Driver , S P , Ellison , S L , Huynh , M , Kapińska , A D , Mahony , E K , Moss , V A , Robotham , A S G , Whiting , M T , Curran , S J , Darling , J , Hotan , A W , Hunstead , R W , Koribalski , B S , Lagos , C D P , Pettini , M , Pimbblet , K A & Voronkov , M A 2020 , ' FLASH Early Science – discovery of an intervening HI 21-cm absorber from an ASKAP survey of the GAMA 23 field ' , Monthly Notices of the Royal Astronomical Society , vol. 494 , no. 3 , pp. 3627-3641 .
dc.identifier.othercrossref: 10.1093/mnras/staa949
dc.description.abstractWe present early science results from the First Large Absorption Survey in H i (FLASH), a spectroscopically blind survey for 21-cm absorption lines in cold hydrogen (H i) gas at cosmological distances using the Australian Square Kilometre Array Pathfinder (ASKAP). We have searched for H i absorption towards 1253 radio sources in the GAMA 23 field, covering redshifts between z = 0.34 and 0.79 over a sky area of approximately 50 deg2. In a purely blind search, we did not obtain any detections of 21-cm absorbers above our reliability threshold. Assuming a fiducial value for the H i spin temperature of Tspin = 100 K and source covering fraction cf = 1, the total comoving absorption path-length sensitive to all Damped Lyman α Absorbers (DLAs; NH i ≥ 2 × 1020 cm−2) is ΔX = 6.6 ± 0.3 (Δz = 3.7 ± 0.2) and super-DLAs (NH i ≥ 2 × 1021 cm−2) is ΔX = 111 ± 6 (Δz= 63 ± 3). We estimate upper limits on the H i column density frequency distribution function that are consistent with measurements from prior surveys for redshifted optical DLAs, and nearby 21-cm emission and absorption. By cross-matching our sample of radio sources with optical spectroscopic identifications of galaxies in the GAMA 23 field, we were able to detect 21-cm absorption at z = 0.3562 towards NVSS J224500−343030, with a column density of NHI=(1.2±0.1)×1020(Tspin/100K) cm−2. The absorber is associated with GAMA J22450.05−343031.7, a massive early-type galaxy at an impact parameter of 17 kpc with respect to the radio source and which may contain a massive (MH i ≳ 3 × 109 M⊙) gas disc. Such gas-rich early types are rare, but have been detected in the nearby Universe.
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen
dc.subjectGalaxies: evolutionen
dc.subjectGalaxies: high redshiften
dc.subjectGalaxies: ISMen
dc.subjectGalaxies: strucutreen
dc.subjectRadio: lines galaxiesen
dc.subjectQB Astronomyen
dc.titleFLASH Early Science – discovery of an intervening HI 21-cm absorber from an ASKAP survey of the GAMA 23 fielden
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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