A Limit on the Polarized Anomalous Microwave Emission of Lynds 1622

Abstract

The dark cloud Lynds 1622 is one of a few specific sites in the Galaxy where, relative to observed free-free and vibrational dust emission, there is a clear excess of microwave emission. In order to constrain models for this microwave emission, and to better establish the contribution which it might make to ongoing and near-future microwave background polarization experiments, we have used the Green Bank Telescope to search for linear polarization at 9.65 Ghz toward Lynds 1622. We place a 95.4% upper limit of 88 μK (123 μK at 99.7% confidence) on the total linear polarization of this source averaged over a 1farcm3 FWHM beam. Relative to the observed level of anomalous emission in Stokes I these limits correspond to fractional linear polarizations of 2.7% and 3.5%.