arXiv subjects

L. Matthew Haffner

Publications and source records attributed to L. Matthew Haffner.

20 records · Page 2Linked to original sources

arXiv2008

Confirmation of a Faraday Rotation Measure Anomaly in Cygnus

We confirm the reality of a reversal of the sign of the Faraday Rotation Measure in the Galactic plane in Cygnus (Lazio et al, 1990), possibly associated with the Cygnus OB1 association. The rotation measure changes by several hundred rad/m$^2$ over an angular scale of $2-5^{\circ}$. We show that a simple model of an expanding plasma shell with an enhanced density and magnetic field, consistent with observations of H$α$ emission in this part of sky, and physically associated with a superbubble of the Cygnus OB1 association, can account for the magnitude and angular scale of this feature.

astro-ph↗

arXiv2007

Density Distribution of the Warm Ionized Medium

Observations of Halpha emission measures and pulsar dispersion measures at high Galactic latitude (|b| > 10 deg) provide information about the density and distribution of the diffuse warm ionized medium (WIM). The diffuse WIM has a lognormal distribution of EM sin |b|, which is consistent with a density structure established by isothermal turbulence. The H+ responsible for most of the emission along high-EM sin |b| sightlines is clumped in high density (> 0.1 cm^{-3}) regions that occupy only a few parsecs along the line of sight, while the H+ along low-EM sightlines occupies hundreds of parsecs with considerably lower densities.

astro-ph↗