The New Extragalactic Magnetometer: Zeeman Splitting in OH Megamasers


A recent Arecibo Zeeman survey of OH megamasers has provided 16 line-of-sight magnetic eld detections across 4 of 6 observed ULIRGs. The most amazing result was found in the archetypal ULIRG Arp 220: a total of 7 magnetic eld measurements with 3 elds pointing away from us and 4 towards. While the single-dish observations allow us to estimate the strength and direction of the magnetic eld throughout each ULIRG, they cannot address whether the elds are characteristic of each masing site or of the ISM as a whole. VLBA observations of the Zeeman e ect in the maser spots are crucial to our understanding of the structure and origin of large-scale elds in ULIRGs. We propose to use 48 hours of High-Sensitivity Array time in order to detect Zeeman splitting of the 1667 MHz OH megamaser emission in 4 ULIRGs.

Name Other * Institution Email Phone
Tim Robishaw PI T University of California at Berkeley 510 643-8530
Carl Heiles University of California 510-642-4510
Anuj Sarma Depaul U
Geoff Bower UC Berkeley 510 642-4075
Eliot Quataert University of California at Berkeley
* PI = Principal Investigator; CO = Contact author; T = Thesis observations; S = Student

Front Ends
Gregorian L(1.15 to 1.73 GHz)

Back Ends
VLBA recorder and DAR Mark 5 recorder (disks)

Type of Observing
Very Long Baseline Interferometry Zeeman line splitting

Switching Type

Processor (correlator)

Allotted time 28.00 hours

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Updated 09/19/2007