QUIJOTE scientific results – V. The microwave intensity and polarization spectra of the Galactic regions W49, W51 and IC443. Issue 3 (12th January 2023)

• Record Type: Journal Article
• Authors: 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
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 519:Issue 3(2023)
• Page Start: 3432
• Page End: 3459
• Publication Date: 2023-01-12
• Subjects: radiation mechanisms: general -- ISM: individual objects: W49, W51, IC443 -- radio continuum: ISM; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac3502
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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.