GBT26A-573

How Clumpy is the Warm Ionized Medium?

Abstract

There are two fundamental observational parameters related to the electron density of the WIM: Emission measure (EM) and dispersion measure (DM). The EM is sensitive to density squared, while DM is sensitive to density to the first power. EM is therefore biased toward the highest density plasmas along a line of sight. Although we have thousands of measurements of both parameters, we lack comparisons between them along shared lines of sight in the inner Galactic plane. We here propose a pilot project to observe radio recombination lines (RRLs), which are sensitive to EM, along a single line of sight to pulsar J1917+1353. This pulsar has a known parallax of 0.14mas and a DM of 94.5 cm^-3 pc. A RRL detection would allow us to determine the clumpiness of the ionized ISM in the inner Galactic plane.

Investigators

Name	Institution
GBT Operator	Green Bank Observatory
Dana Balser	National Radio Astronomy Observatory
Tom Bania	Boston University
Loren Anderson *	West Virginia University
Trey Wenger
Matteo Luisi	Westminster College
William Armentrout	Green Bank Observatory

* indicates the PI