Hypernovae/GRB in the Galactic Center as possible sources of Galactic Positrons
| Autor: | Cass��, M., Cordier, B., Paul, J., Schanne, S. |
|---|---|
| Přispěvatelé: | Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), arXiv, Import |
| Jazyk: | angličtina |
| Rok vydání: | 2003 |
| Předmět: |
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
[PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO] Astrophysics::High Energy Astrophysical Phenomena Astrophysics (astro-ph) FOS: Physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Astrophysics::Galaxy Astrophysics |
| Zdroj: | The Astrophysical Journal The Astrophysical Journal, American Astronomical Society, 2004, 602, pp.L17-L20 The Astrophysical Journal, 2004, 602, pp.L17-L20 |
| ISSN: | 0004-637X 1538-4357 |
| Popis: | The observation of a strong and extended positron-electron line annihilation emission in the central regions of the Galaxy by INTEGRAL-SPI, consistent with the Galactic bulge geometry, without any counterpart in the gamma-ray range, neither at high energy nor in the 1809 keV $^{26}$Al decay line, is challenging. Leaving aside the geometrical question, we address the problem of the adequate positron sources, showing the potentiality of a new category of SN Ic, exemplified by SN2003dh, which is associated to a gamma-ray burst. This kind of supernova/hypernova/GRB event is interpreted as the result of a bipolar Wolf-Rayet explosion, which produces a large amount of $^{56}$Ni and ejects it at high velocity along the rotation axis. The bulk of positrons resulting from $^{56}$Co decay escapes in the surrounding medium due to the rapid thinning of the ejecta in the polar direction. We show that a rate of about 0.02 SN2003dh-like events per century in the central region of the Galaxy is sufficient to explain the positron flux detected by INTEGRAL-SPI. In order to explain this flux by SN Ia events alone, a rate of 0.5 per century is necessary, much higher than indicated by Galactic evolutionary models applied to the bulge. Further observations of late light curves of SNe Ia and SNe Ic in the bulge of spiral galaxies, together with 3D hydrodynamic calculations of anisotropic ejections of $^{56}$Ni in SN Ic/GRB events, will allow to estimate the separate contributions of SNe Ia and SNe Ic to positron injection. 7 pages, 0 figures, accepted for publication in Astrophysical Journal Letters, 2003 12 08 |
| Databáze: | OpenAIRE |
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