The discovery of a z = 0.7092 OH megamaser with the MIGHTEE survey
Journal article, 2024
We present the discovery of the most distant OH megamaser (OHM) to be observed in the main lines, using data from the MeerKAT International Giga-Hertz Tiered Extragalactic Exploration (MIGHTEE) survey. At a newly measured redshift of z = 0.7092, the system has strong emission in both the 1665 MHz (L ≈ 2500 L-) and 1667 MHz (L ≈ 4.5 × 104 L-) transitions, with both narrow and broad components. We interpret the broad line as a high-velocity-dispersion component of the 1667 MHz transition, with velocity v ∼330 km s-1 with respect to the systemic velocity. The host galaxy has a stellar mass of M = 2.95 × 1010 M- and a star formation rate of SFR = 371 M- yr-1, placing it ∼1.5 dex above the main sequence for star-forming galaxies at this redshift, and can be classified as an ultraluminous infrared galaxy. Alongside the optical imaging data, which exhibit evidence for a tidal tail, this suggests that the OHM arises from a system that is currently undergoing a merger, which is stimulating star formation and providing the necessary conditions for pumping the OH molecule to saturation. The OHM is likely to be lensed, with a magnification factor of ∼2.5, and perhaps more if the maser emitting region is compact and suitably offset relative to the centroid of its host galaxy's optical light. This discovery demonstrates that spectral line mapping with the new generation of radio interferometers may provide important information on the cosmic merger history of galaxies.
galaxies: ISM
galaxies: starburst
ISM: molecules
masers
Author
M.J. Jarvis
University of Oxford
University of the Western Cape
I. Heywood
South African Radio Astronomy Observatory (SARAO)
Rhodes University
University of Oxford
Sophie M. Jewell
University of Oxford
Royal Observatory
R. P. Deane
University of Pretoria
University of Witwatersrand
H. R. Klockner
Max Planck Society
Anastasia A. Ponomareva
University of Oxford
Natasha Maddox
University of Bristol
A. J. Baker
Rutgers University
University of the Western Cape
Alessandro Bianchetti
University of Padua
Istituto nazionale di astrofisica (INAF)
Kelley Michelle Hess
Chalmers, Space, Earth and Environment, Onsala Space Observatory
H. Roberts
University of Minnesota
G. Rodighiero
University of Padua
Istituto nazionale di astrofisica (INAF)
Ilaria Ruffa
Cardiff University
Francesco Sinigaglia
Istituto nazionale di astrofisica (INAF)
University of Geneva
University of Padua
Rohan G. Varadaraj
University of Oxford
Imogen H. Whittam
University of Oxford
Elizabeth A.K. Adams
University of Groningen
Netherlands Institute for Radio Astronomy (ASTRON)
Maarten Baes
Ghent university
Eric J. Murphy
National Radio Astronomy Observatory
Hengxing Pan
University of Oxford
M. Vaccari
University of the Western Cape
Istituto di Radioastronomia
Monthly Notices of the Royal Astronomical Society
00358711 (ISSN) 13652966 (eISSN)
Vol. 529 4 3484-3494Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.1093/mnras/stad3821