Looking at the Distant Universe with the MeerKAT Array: Discovery of a Luminous OH Megamaser at z > 0.5

Looking at the Distant Universe with the MeerKAT Array: Discovery of a Luminous OH Megamaser at z > 0.5

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 neutra...

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Bibliographic Details
Main Authors: Glowacki, Marcin, Collier, J.D., Kazemi-Moridani, A., Frank, B., Roberts, H., Darling, J., Klöckner, H.R., Adams, N., Baker, A.J., Bershady, M., Blecher, T., Blyth, S.L., Bowler, R., Catinella, B., Chemin, L., Crawford, S.M., Cress, C., Davé, R., Deane, R., De Blok, E., Delhaize, J., Duncan, K., Elson, E., February, S., Gawiser, E., Hatfield, P., Healy, J., Henning, P., Hess, K.M., Heywood, I., Holwerda, B.W., Hoosain, M., Hughes, J.P., Hutchens, Z.L., Jarvis, M., Kannappan, S., Katz, N., Kereš, D., Korsaga, M., Kraan-Korteweg, R.C., Lah, P., Lochner, M., Maddox, N., Makhathini, S., Meurer, G.R., Meyer, M., Obreschkow, D., Oh, S.H., Oosterloo, T., Oppor, J., Pan, H., Pisano, D.J., Randriamiarinarivo, N., Ravindranath, S., Schröder, A.C., Skelton, R., Smirnov, O., Smith, M., Somerville, R.S., Srianand, R., Staveley-Smith, L., Tanaka, M., Vaccari, M., Van Driel, W., Verheijen, M., Walter, F., Wu, J.F., Zwaan, M.A.
Format: Journal Article
Language:English
Published: IOP Publishing Ltd 2022
Subjects:
Science & Technology
Physical Sciences
Astronomy & Astrophysics
STAR-FORMATION
SKA PATHFINDER
WIDE-FIELD
H I
RADIO
GALAXY
ULTRAVIOLET
EVOLUTION
PROJECT
BLAST
Online Access:http://purl.org/au-research/grants/arc/DP210102103
http://hdl.handle.net/20.500.11937/90260
Description
Summary: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 z OH = 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 L FIR = (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.

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