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

D Tramonte, RT Genova-Santos, JA Rubino-Martin, P Vielva, F Poidevin, CH Lopez-Caraballo, MW Peel, M Ashdown, E Artal, RB Barreiro, FJ Casas, E de la Hoz, M Fernandez-Torreiro, F Guidi, D Herranz, RJ Hoyland, AN Lasenby, E Martinez-Gonzalez, L Piccirillo, R ReboloB Ruiz-Granados, F Vansyngel, RA Watson

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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 ∼ 1 deg angular resolution, with a sensitivity in the range 35-79 μ K beam-1 for total intensity and 13-23 μ K 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 ν AME =(20.0 ± 1.4) GHz and ν AME=(17.7 ± 3.6) 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 ν 0,s =(114 ± 73) 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.

Original languageEnglish
Pages (from-to)3432-3459
Number of pages28
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date12 Jan 2023
Publication statusPublished - 1 Mar 2023


  • ISM: individual objects: W49, W51, IC443
  • radiation mechanisms: general
  • radio continuum: ISM


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