Second-order Fermi acceleration as the origin of the Fermi bubbles
Gamma-ray data from Fermi-LAT show a bi-lobular structure extending up to 50° above and below the Galactic centre, coincident with a possibly related structure in the ROSAT X-ray map which presumably originated in some energy release close to the centre a few million years ago. It has been argued th...
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| Формат: | Conference item |
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Elsevier
2012
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| _version_ | 1826268784167485440 |
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| author | Mertsch, P Sarkar, S |
| author_facet | Mertsch, P Sarkar, S |
| author_sort | Mertsch, P |
| collection | OXFORD |
| description | Gamma-ray data from Fermi-LAT show a bi-lobular structure extending up to 50° above and below the Galactic centre, coincident with a possibly related structure in the ROSAT X-ray map which presumably originated in some energy release close to the centre a few million years ago. It has been argued that the gamma-rays arise due to inverse Compton scattering of relativistic electrons accelerated at plasma shocks present in the bubbles. We explore the alternative possibility that the relativistic electrons undergo stochastic second-order Fermi acceleration in the entire volume of the bubbles by plasma wave turbulence. This turbulence is generated behind the outer shock and propagates into the bubble volume, leading to a non-trivial spatial variation of the electron spectral index. Rather than a constant volume emissivity as predicted in other models we find an almost constant surface brightness in gamma-rays and also reproduce the observed sharp edges of the bubbles. We comment on possible cross-checks in other channels. |
| first_indexed | 2024-03-06T21:14:55Z |
| format | Conference item |
| id | oxford-uuid:3f726e9c-6421-4689-bac1-61f91ea2f1ab |
| institution | University of Oxford |
| last_indexed | 2024-03-06T21:14:55Z |
| publishDate | 2012 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | oxford-uuid:3f726e9c-6421-4689-bac1-61f91ea2f1ab2022-03-26T14:32:03ZSecond-order Fermi acceleration as the origin of the Fermi bubblesConference itemhttp://purl.org/coar/resource_type/c_5794uuid:3f726e9c-6421-4689-bac1-61f91ea2f1abSymplectic Elements at OxfordElsevier2012Mertsch, PSarkar, SGamma-ray data from Fermi-LAT show a bi-lobular structure extending up to 50° above and below the Galactic centre, coincident with a possibly related structure in the ROSAT X-ray map which presumably originated in some energy release close to the centre a few million years ago. It has been argued that the gamma-rays arise due to inverse Compton scattering of relativistic electrons accelerated at plasma shocks present in the bubbles. We explore the alternative possibility that the relativistic electrons undergo stochastic second-order Fermi acceleration in the entire volume of the bubbles by plasma wave turbulence. This turbulence is generated behind the outer shock and propagates into the bubble volume, leading to a non-trivial spatial variation of the electron spectral index. Rather than a constant volume emissivity as predicted in other models we find an almost constant surface brightness in gamma-rays and also reproduce the observed sharp edges of the bubbles. We comment on possible cross-checks in other channels. |
| spellingShingle | Mertsch, P Sarkar, S Second-order Fermi acceleration as the origin of the Fermi bubbles |
| title | Second-order Fermi acceleration as the origin of the Fermi bubbles |
| title_full | Second-order Fermi acceleration as the origin of the Fermi bubbles |
| title_fullStr | Second-order Fermi acceleration as the origin of the Fermi bubbles |
| title_full_unstemmed | Second-order Fermi acceleration as the origin of the Fermi bubbles |
| title_short | Second-order Fermi acceleration as the origin of the Fermi bubbles |
| title_sort | second order fermi acceleration as the origin of the fermi bubbles |
| work_keys_str_mv | AT mertschp secondorderfermiaccelerationastheoriginofthefermibubbles AT sarkars secondorderfermiaccelerationastheoriginofthefermibubbles |