COMAP Early Science. VI. A First Look at the COMAP Galactic Plane Survey

Abstract We present early results from the CO Mapping Array Project (COMAP) Galactic Plane Survey conducted between 2019 June and 2021 April, spanning 20° < ? 40° in longitude ? b 1.°5 latitude with an angular resolution of 4.?5. initial first part survey, including diffuse emission spectral energy distributions H ii regions supernova remnants (SNRs). Using low- high-frequency surveys to constrain free–free thermal dust contributions, we find evidence excess flux density at 30 GHz six regions, which interpret as anomalous microwave emission. Furthermore model ultracompact contributions using data 5 CORNISH catalog reject these cause excess. Six known SNRs are detected GHz, measure indices consistent literature or show steepening. The SNR W44 is a power-law extrapolation lower frequencies no indication steepening contrast recent Sardinia Radio Telescope. also extract five hydrogen radio recombination lines (RRLs) map warm ionized gas, can be used estimate electron temperatures continuum full COMAP Survey, released 2023/2024, will span ? 20°–220° large-scale RRL survey 4.?5 resolution.