Constraints on OH Megamaser Excitation from a Survey of OH Satellite Lines

Abstract

We report the results of a full-Stokes survey of all four 18 cm OH lines in 77 OH megamasers (OHMs) using the Arecibo Observatory. This is the first survey of OHMs that included observations of the OH satellite lines; only 4 of the 77 OHMs have existing satellite line observations in the literature. In 5 sources, satellite line emission is detected, with 3 of the 5 sources re-detections of previously published sources. The 2 sources with new detections of satellite line emission are IRAS F10173+0829, which was detected at 1720 MHz, and IRAS F15107+0724, for which both the 1612 MHz and 1720 MHz lines were detected. In IRAS F15107+0724, the satellite lines are partially conjugate, as 1720 MHz absorption and 1612 MHz emission have the same structure at some velocities within the source, along with additional broader 1612 MHz emission. This is the first observed example of conjugate satellite lines in an OHM. In the remaining sources, no satellite line emission is observed. The detections and upper limits are generally consistent with models of OHM emission in which all of the 18 cm OH lines have the same excitation temperature. There is no evidence for a significant population of strong satellite line emitters among OHMs.

9 pages, accepted to ApJ

References in corpus (5)

• Extragalactic Zeeman Detections in OH Megamasers
• The Effect of 53 micron IR Radiation on 18 cm OH Megamaser Emission
• An Arecibo Survey for Zeeman Splitting in OH Megamaser Galaxies
• OH main line masers in the M82 starburst
• High-velocity-resolution observations of OH main line lasers in the M82 starburst

Cited by in corpus (10)

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• Apertif view of the OH Megamaser IRAS 10597+5926: OH 18 cm satellite lines in wide-area HI surveys
• Dicke's Superradiance in Astrophysics. II -- The OH 1612 MHz Line
• High-velocity OH megamasers in IRAS 20100-4156: Evidence for a Supermassive Black Hole
• LADUMA: Discovery of a luminous OH megamaser at $z>0.5$
• The radio properties of the OH megamaser galaxy IRAS 02524+2046
• Radio continuum and OH line emission of high-z OH megamaser galaxies
• FASHI: A search for extragalactic OH megamasers with FAST
• Accurate polarization calibration of FAST spectral data for measurements of Zeeman splittings of OH megamasers in IRAS 02524+2046