DETECTION OF ANOMALOUS MICROWAVE EMISSION IN THE PERSEUS MOLECULAR CLOUD WITH THE COSMOSOMAS EXPERIMENT

摘要

We present direct evidence for anomalous microwave emission in the Perseus molecular cloud, which shows a clear rising spectrum from 11 to 17 GHz in the data from the COSMOSOMAS experiment. By extending the frequency coverage using W ilkinson Microwave Anisotropy Probe maps convolved with the COSMOSOMAS scanning pattern, we reveal a peak flux density of 42 ± 4 Jy at 22 GHz integrated over an extended area of 1.65° x 1.0° centered on R.A. - 55.4°± 0.1°and decl. = +31.8°± 0.1°(J2000). The flux density that we measure at this frequency is nearly an order of magnitude higher than can be explained in terms of normal Galactic emission processes (synchrotron, free-free, and thermal dust). An extended IRAS dust feature, Gl59.6—18.5, is found near this position, and no bright unresolved source that could be an ultracompact H Ⅱ region or gigahertz-peaked source could be found. An adequate fit for the spectral density distribution can be achieved from 10 to 50 GHz by including a very significant contribution from electric dipole emission from small spinning dust grains.