A CMB Gibbs sampler for localized secondary anisotropies
As well as primary fluctuations, CMB temperature maps contain a wealth of additional information in the form of secondary anisotropies. Secondary effects that can be identified with individual objects, such as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are d...
| Váldodahkkit: | , , , , , , |
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| Materiálatiipa: | Journal article |
| Almmustuhtton: |
2014
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| _version_ | 1826288196581851136 |
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| author | Bull, P Wehus, I Eriksen, H Ferreira, P Fuskeland, U Gorski, K Jewell, J |
| author_facet | Bull, P Wehus, I Eriksen, H Ferreira, P Fuskeland, U Gorski, K Jewell, J |
| author_sort | Bull, P |
| collection | OXFORD |
| description | As well as primary fluctuations, CMB temperature maps contain a wealth of additional information in the form of secondary anisotropies. Secondary effects that can be identified with individual objects, such as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are difficult to unambiguously disentangle from foreground contamination and the primary CMB, which currently inhibits their use as precision cosmological probes. We develop a Bayesian formalism for rigorously characterising anisotropies that are localised on the sky, taking the TSZ and KSZ effects as an example. Using a Gibbs sampling scheme, we are able to efficiently sample from the joint posterior distribution for a multi-component model of the sky with many thousands of correlated physical parameters. The posterior can then be exactly marginalised to estimate properties of the secondary anisotropies, fully taking into account degeneracies with the other signals in the CMB map. We show that this method is computationally tractable using a simple implementation based on the existing Commander component separation code, and also discuss how other types of secondary anisotropy can be accommodated within our framework. |
| first_indexed | 2024-03-07T02:10:03Z |
| format | Journal article |
| id | oxford-uuid:a0520a3a-b413-4fa6-9d9d-c5217ddbf2e4 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T02:10:03Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | oxford-uuid:a0520a3a-b413-4fa6-9d9d-c5217ddbf2e42022-03-27T02:04:34ZA CMB Gibbs sampler for localized secondary anisotropiesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:a0520a3a-b413-4fa6-9d9d-c5217ddbf2e4Symplectic Elements at Oxford2014Bull, PWehus, IEriksen, HFerreira, PFuskeland, UGorski, KJewell, JAs well as primary fluctuations, CMB temperature maps contain a wealth of additional information in the form of secondary anisotropies. Secondary effects that can be identified with individual objects, such as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are difficult to unambiguously disentangle from foreground contamination and the primary CMB, which currently inhibits their use as precision cosmological probes. We develop a Bayesian formalism for rigorously characterising anisotropies that are localised on the sky, taking the TSZ and KSZ effects as an example. Using a Gibbs sampling scheme, we are able to efficiently sample from the joint posterior distribution for a multi-component model of the sky with many thousands of correlated physical parameters. The posterior can then be exactly marginalised to estimate properties of the secondary anisotropies, fully taking into account degeneracies with the other signals in the CMB map. We show that this method is computationally tractable using a simple implementation based on the existing Commander component separation code, and also discuss how other types of secondary anisotropy can be accommodated within our framework. |
| spellingShingle | Bull, P Wehus, I Eriksen, H Ferreira, P Fuskeland, U Gorski, K Jewell, J A CMB Gibbs sampler for localized secondary anisotropies |
| title | A CMB Gibbs sampler for localized secondary anisotropies |
| title_full | A CMB Gibbs sampler for localized secondary anisotropies |
| title_fullStr | A CMB Gibbs sampler for localized secondary anisotropies |
| title_full_unstemmed | A CMB Gibbs sampler for localized secondary anisotropies |
| title_short | A CMB Gibbs sampler for localized secondary anisotropies |
| title_sort | cmb gibbs sampler for localized secondary anisotropies |
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