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| Auteurs principaux: | , , , , , |
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| Format: | Preprint |
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2026
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| Accès en ligne: | https://arxiv.org/abs/2602.11356 |
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| _version_ | 1866914324034879488 |
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| author | Casassus, Simon Vidal, Matias Carcamo, Miguel Verstraete, Laurent Ysard, Nathalie Habart, Emilie |
| author_facet | Casassus, Simon Vidal, Matias Carcamo, Miguel Verstraete, Laurent Ysard, Nathalie Habart, Emilie |
| contents | The rhoOphW photo-dissociation region (PDR) is an example source of bright excess microwave emission (EME), over synchrotron, free-free, and the Rayleigh-Jeans tail of the sub-millimetre (sub-mm) dust continuum. Its filamentary morphology follows roughly that of the IR poly-cyclic aromatic hydrocarbon (PAHs) bands. The EME signal in rhoOphW drops abruptly above ~30GHz and its spectrum can be interpreted in terms of electric-dipole radiation from spinning dust grains, or ``spinning dust''. Deep and high-fidelity imaging and spectroscopy of rhoOphW may reveal the detailed morphology of the EME signal, free from imaging priors, while also enabling a search for fine structure in its spectrum. The same observations may constrain the spectral index of the high-frequency drop. An ALMA Band1 mosaic yields a deep deconvolved image of the filament at 36-44GHz, which we use as template for the extraction of a spectrum via cross-correlation in the uv-plane. Simulations and cross-correlations on near-infrared ancillary data yield estimates of flux-loss and biases. The spectrum is a power law, with no detectable fine structure. It follows a spectral index alpha=-0.78+-0.05, in frequency, with some variations along the filament. Interestingly, the Band1 power at high spatial frequencies increases relative to that of the IR signal, with a factor of two more power in Band1 at ~20'' than at ~100'' (relative to IRAC3.6um). An extreme of such radio-only structures is a compact EME source, without IR counterpart. It is embedded in strong and filamentary Band1 signal, while the IRAC maps are smooth in the same region. We provide multi-frequency intensity estimates for spectral modelling. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_11356 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | ALMA Band1 observations of the rhoOphW filament I. Enhanced power from excess microwave emission at high spatial frequencies Casassus, Simon Vidal, Matias Carcamo, Miguel Verstraete, Laurent Ysard, Nathalie Habart, Emilie Astrophysics of Galaxies Solar and Stellar Astrophysics The rhoOphW photo-dissociation region (PDR) is an example source of bright excess microwave emission (EME), over synchrotron, free-free, and the Rayleigh-Jeans tail of the sub-millimetre (sub-mm) dust continuum. Its filamentary morphology follows roughly that of the IR poly-cyclic aromatic hydrocarbon (PAHs) bands. The EME signal in rhoOphW drops abruptly above ~30GHz and its spectrum can be interpreted in terms of electric-dipole radiation from spinning dust grains, or ``spinning dust''. Deep and high-fidelity imaging and spectroscopy of rhoOphW may reveal the detailed morphology of the EME signal, free from imaging priors, while also enabling a search for fine structure in its spectrum. The same observations may constrain the spectral index of the high-frequency drop. An ALMA Band1 mosaic yields a deep deconvolved image of the filament at 36-44GHz, which we use as template for the extraction of a spectrum via cross-correlation in the uv-plane. Simulations and cross-correlations on near-infrared ancillary data yield estimates of flux-loss and biases. The spectrum is a power law, with no detectable fine structure. It follows a spectral index alpha=-0.78+-0.05, in frequency, with some variations along the filament. Interestingly, the Band1 power at high spatial frequencies increases relative to that of the IR signal, with a factor of two more power in Band1 at ~20'' than at ~100'' (relative to IRAC3.6um). An extreme of such radio-only structures is a compact EME source, without IR counterpart. It is embedded in strong and filamentary Band1 signal, while the IRAC maps are smooth in the same region. We provide multi-frequency intensity estimates for spectral modelling. |
| title | ALMA Band1 observations of the rhoOphW filament I. Enhanced power from excess microwave emission at high spatial frequencies |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2602.11356 |