Investigating anomalous microwave emission near G107.2+5.20 in Ku-band with the Green Bank Telescope

Abstract

Abstract Anomalous microwave emission (AME) is 30 GHz-peaking continuum emission thought to arise from spinning dust grains. Building a spatially resolved sample of regions could offer insight into environmental drivers and the grain populations that produce AME. Using the Green Bank Telescope Ku-band (12-18 GHz) receiver, we obtained a ~1 arcmin resolution map of radius 1.25○ centered on G107.2+5.20, encompassing the S140 H ii region and L1204 dark cloud. Our objectives were to (1) measure the rising edge of the AME peak to model the global emission mechanism and (2) spatially locate excess 13 GHz emission consistent with spinning dust. Using our GBT map and ancillary data, we perform matched-resolution aperture photometry to measure the SED from 408 MHz to 3 THz. We fit two emission models: one including spinning dust, the other optically thick free-free emission. We find the spinning dust model is superior, with an amplitude of 14.1 ± 1.1 Jy and a peak frequency of 27 ± 2 GHz. We compare our Ku-band map to multi-wavelength gas and dust tracers at ~4 arcmin resolution. We observe two sources of 13 GHz excess at 3σ significance consistent with spinning dust emission, though potential contributions from optically thick free-free emission remain ambiguous. “Region A” (G106.95+5.19) and “Region B” (G107.08+4.90) are spatially coincident with peak dust radiance and peak PAH abundance, respectively. If these are, indeed, sources of spinning dust emission, they are a resolved example of how AME-dust correlation varies with environment.