Marcin Glowacki, Jordan D. Collier, Amir Kazemi-Moridani, Bradley Frank, Hayley Roberts, Jeremy Darling, Hans-Rainer Klöckner, Nathan Adams, Andrew J. Baker, Matthew Bershady, Tariq Blecher, Sarah-Louise Blyth, Rebecca Bowler, Barbara Catinella, Laurent Chemin, Steven M. Crawford, Catherine Cress, Romeel Davé, Roger Deane, Erwin de Blok, Jacinta Delhaize, Kenneth Duncan, Ed Elson, Sean February, Eric Gawiser, Peter Hatfield, Julia Healy, Patricia Henning, Kelley M. Hess, Ian Heywood, Benne W. Holwerda, Munira Hoosain, John P. Hughes, Zackary L. Hutchens, Matt Jarvis, Sheila Kannappan, Neal Katz, Dušan Kereš, Marie Korsaga, Renée C. Kraan-Korteweg, Philip Lah, Michelle Lochner, Natasha Maddox, Sphesihle Makhathini, Gerhardt R. Meurer, Martin Meyer, Danail Obreschkow, Se-Heon Oh, Tom Oosterloo, Joshua Oppor, Hengxing Pan, D. J. Pisano, Nandrianina Randriamiarinarivo, Swara Ravindranath, Anja C. Schröder, Rosalind Skelton, Oleg Smirnov, Mathew Smith, Rachel S. Somerville, Raghunathan Srianand, Lister Staveley-Smith, Masayuki Tanaka, Mattia Vaccari, Wim van Driel, Marc Verheijen, Fabian Walter, John F. Wu, Martin A. Zwaan, European Commission, Ministerio de Ciencia e Innovación (España), Australian Research Council, and Astronomy
Full list of authors: Glowacki, Marcin; Collier, Jordan D.; Kazemi-Moridani, Amir; Frank, Bradley; Roberts, Hayley; Darling, Jeremy; Klöckner, Hans-Rainer; Adams, Nathan; Baker, Andrew J.; Bershady, Matthew; Blecher, Tariq; Blyth, Sarah-Louise; Bowler, Rebecca; Catinella, Barbara; Chemin, Laurent; Crawford, Steven M.; Cress, Catherine; Davé, Romeel; Deane, Roger; de Blok, Erwin; Delhaize, Jacinta; Duncan, Kenneth; Elson, Ed; February, Sean; Gawiser, Eric; Hatfield, Peter; Healy, Julia; Henning, Patricia; Hess, Kelley M.; Heywood, Ian; Holwerda, Benne W.; Hoosain, Munira; Hughes, John P.; Hutchens, Zackary L.; Jarvis, Matt; Kannappan, Sheila; Katz, Neal; Kereš, Dušan; Korsaga, Marie; Kraan-Korteweg, Renée C.; Lah, Philip; Lochner, Michelle; Maddox, Natasha; Makhathini, Sphesihle; Meurer, Gerhardt R.; Meyer, Martin; Obreschkow, Danail; Oh, Se-Heon; Oosterloo, Tom; Oppor, Joshua; Pan, Hengxing; Pisano, D. J.; Randriamiarinarivo, Nandrianina; Ravindranath, Swara; Schröder, Anja C.; Skelton, Rosalind; Smirnov, Oleg; Smith, Mathew; Somerville, Rachel S.; Srianand, Raghunathan; Staveley-Smith, Lister; Tanaka, Masayuki; Vaccari, Mattia; van Driel, Wim; Verheijen, Marc; Walter, Fabian; Wu, John F.; Zwaan, Martin A..--This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., In the local universe, OH megamasers (OHMs) are detected almost exclusively in infrared-luminous galaxies, with a prevalence that increases with IR luminosity, suggesting that they trace gas-rich galaxy mergers. Given the proximity of the rest frequencies of OH and the hyperfine transition of neutral atomic hydrogen (H i), radio surveys to probe the cosmic evolution of H i in galaxies also offer exciting prospects for exploiting OHMs to probe the cosmic history of gas-rich mergers. Using observations for the Looking At the Distant Universe with the MeerKAT Array (LADUMA) deep H i survey, we report the first untargeted detection of an OHM at z > 0.5, LADUMA J033046.20−275518.1 (nicknamed "Nkalakatha"). The host system, WISEA J033046.26−275518.3, is an infrared-luminous radio galaxy whose optical redshift z ≈ 0.52 confirms the MeerKAT emission-line detection as OH at a redshift zOH = 0.5225 ± 0.0001 rather than H i at lower redshift. The detected spectral line has 18.4σ peak significance, a width of 459 ± 59 km s−1, and an integrated luminosity of (6.31 ± 0.18 [statistical] ± 0.31 [systematic]) × 103 L⊙, placing it among the most luminous OHMs known. The galaxy's far-infrared luminosity LFIR = (1.576 ±0.013) × 1012 L⊙ marks it as an ultraluminous infrared galaxy; its ratio of OH and infrared luminosities is similar to those for lower-redshift OHMs. A comparison between optical and OH redshifts offers a slight indication of an OH outflow. This detection represents the first step toward a systematic exploitation of OHMs as a tracer of galaxy growth at high redshifts. © 2022. The Author(s). Published by the American Astronomical Society., M.G. acknowledges support from IDIA and was partially supported by the Australian Government through the Australian Research Council's Discovery Projects funding scheme (DP210102103). A.K.M. and A.J.B. acknowledge support from NSF grant AST-1814421. A.K.M. also thanks the LSSTC Data Science Fellowship Program, which is funded by the LSST Corporation, NSF grant OAC-1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has been helpful for this work. H.R. and Je.D. acknowledge support from NSF grant AST-1814648; M.B. and J.O. acknowledge support from NSF grant AST-1814682; R.B. acknowledges support from an STFC Ernest Rutherford Fellowship (grant No. ST/T003596/1); Ja.D. and H.P. acknowledge the financial assistance of SARAO; K.M.H. acknowledges funding from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the "Center of Excellence Severo Ochoa" awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709); from grant RTI2018-096228-B-C31 (Ministry of Science, Innovation and Universities/State Agency for Research/European Regional Development Funds, European Union); and from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and innovation (MICIN); and Z.L.H. and S.K. acknowledge support from NSF grant AST-1814486. Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013, and by the South African Research Chairs Initiative of the Department of Science and Technology and the NRF.