Loops and spurs: The angular power spectrum of the Galactic synchrotron background
We present a new model of the diffuse Galactic synchrotron radiation, concentrating on its angular anisotropies. While previous studies have focussed on either the variation of the emissivity on large (kpc) scales, or on fluctuations due to MHD turbulence in the interstellar medium, we unify these a...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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2013
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| _version_ | 1826277222418219008 |
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| author | Mertsch, P Sarkar, S |
| author_facet | Mertsch, P Sarkar, S |
| author_sort | Mertsch, P |
| collection | OXFORD |
| description | We present a new model of the diffuse Galactic synchrotron radiation, concentrating on its angular anisotropies. While previous studies have focussed on either the variation of the emissivity on large (kpc) scales, or on fluctuations due to MHD turbulence in the interstellar medium, we unify these approaches to match the angular power spectrum. We note that the usual turbulence cascade calculation ignores spatial correlations at the injection scale due to compression of the interstellar medium by old supernova remnants -- the 'radio loops', only four of which are visible by eye in radio maps. This new component naturally provides the otherwise missing power on intermediate and small scales in the all-sky map at 408 MHz. Our model can enable more reliable subtraction of the synchrotron foreground for studies of CMB anisotropies (both in temperature and polarisation) or searches for dark matter annihilation. We conclude with some remarks on the relevance to modelling of the polarised foreground. |
| first_indexed | 2024-03-06T23:25:40Z |
| format | Journal article |
| id | oxford-uuid:6a48cce2-c457-459c-89e5-b03e94960e99 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T23:25:40Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:6a48cce2-c457-459c-89e5-b03e94960e992022-03-26T18:56:25ZLoops and spurs: The angular power spectrum of the Galactic synchrotron backgroundJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:6a48cce2-c457-459c-89e5-b03e94960e99EnglishSymplectic Elements at Oxford2013Mertsch, PSarkar, SWe present a new model of the diffuse Galactic synchrotron radiation, concentrating on its angular anisotropies. While previous studies have focussed on either the variation of the emissivity on large (kpc) scales, or on fluctuations due to MHD turbulence in the interstellar medium, we unify these approaches to match the angular power spectrum. We note that the usual turbulence cascade calculation ignores spatial correlations at the injection scale due to compression of the interstellar medium by old supernova remnants -- the 'radio loops', only four of which are visible by eye in radio maps. This new component naturally provides the otherwise missing power on intermediate and small scales in the all-sky map at 408 MHz. Our model can enable more reliable subtraction of the synchrotron foreground for studies of CMB anisotropies (both in temperature and polarisation) or searches for dark matter annihilation. We conclude with some remarks on the relevance to modelling of the polarised foreground. |
| spellingShingle | Mertsch, P Sarkar, S Loops and spurs: The angular power spectrum of the Galactic synchrotron background |
| title | Loops and spurs: The angular power spectrum of the Galactic synchrotron
background |
| title_full | Loops and spurs: The angular power spectrum of the Galactic synchrotron
background |
| title_fullStr | Loops and spurs: The angular power spectrum of the Galactic synchrotron
background |
| title_full_unstemmed | Loops and spurs: The angular power spectrum of the Galactic synchrotron
background |
| title_short | Loops and spurs: The angular power spectrum of the Galactic synchrotron
background |
| title_sort | loops and spurs the angular power spectrum of the galactic synchrotron background |
| work_keys_str_mv | AT mertschp loopsandspurstheangularpowerspectrumofthegalacticsynchrotronbackground AT sarkars loopsandspurstheangularpowerspectrumofthegalacticsynchrotronbackground |