QUIJOTE scientific results - V. The microwave intensity and polarization spectra of the Galactic regions W49, W51 and IC443

Tramonte, D.; Génova-Santos, R. T.; Rubiño-Martín, J. A.; Vielva, P.; Poidevin, F.; López-Caraballo, C. H.; Peel, M. W.; Ashdown, M.; Artal, E.; Barreiro, R. B.; Casas, F. J.; de la Hoz, E.; Fernández-Torreiro, M.; Guidi, F.; Herranz, D.; Hoyland, R. J.; Lasenby, A. N.; Martinez-Gonzalez, E.; Piccirillo, L.; Rebolo, R.; Ruiz-Granados, B.; Vansyngel, F.; Watson, R. A.
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Monthly Notices of the Royal Astronomical Society

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We present new intensity and polarization maps obtained with the QUIJOTE experiment towards the Galactic regions W49, W51 and IC443, covering the frequency range from 10 to 20 GHz at $\sim 1\, \text{deg}$ angular resolution, with a sensitivity in the range 35-79 $\mu \text{K}\, \text{beam}^{-1}$ for total intensity and 13-23 $\mu \text{K}\, \text{beam}^{-1}$ for polarization. For each region, we combine QUIJOTE maps with ancillary data at frequencies ranging from 0.4 to 3000 GHz, reconstruct the spectral energy distribution and model it with a combination of known foregrounds. We detect anomalous microwave emission (AME) in total intensity towards W49 at 4.7σ and W51 at 4.0σ with peak frequencies $\nu _{\rm AME}=(20.0\pm 1.4)\, \text{GHz}$ and $\nu _{\rm AME}=(17.7\pm 3.6)\, \text{GHz}$, respectively; this is the first detection of AME towards W51. The contamination from ultracompact H II regions to the residual AME flux density is estimated at 10 per cent in W49 and 5 per cent in W51, and does not rule out the AME detection. The polarized SEDs reveal a synchrotron contribution with spectral indices αs = -0.67 ± 0.10 in W49 and αs = -0.51 ± 0.07 in W51, ascribed to the diffuse Galactic emission and to the local supernova remnant, respectively. Towards IC443 in total intensity we measure a broken power-law synchrotron spectrum with cut-off frequency $\nu _{\rm 0,s}=(114\pm 73)\, \text{GHz}$, in agreement with previous studies; our analysis, however, rules out any AME contribution which had been previously claimed towards IC443. No evidence of polarized AME emission is detected in this study.
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