The galactic 511 keV morphology and the old stellar population

M. Ali; S. C. Ellis; S. Sharma; J. Bland-Hawthorn

doi:10.22323/1.147.0064

The galactic 511 keV morphology and the old stellar population

M. Ali^*, S. C. Ellis, S. Sharma, J. Bland-Hawthorn

^*Corresponding author for this work

Research output: Contribution to journal › Conference paper › peer-review

Abstract

The source of Galactic positron annihilation emission is a mystery. What is known is that photons produced in positron-electron annihilation are highly concentrated at the Galactic centre, with a slightly off-centred peak with respect to Galactic longitude. Using synthetic models of the Milky Way we find possible connections between age-bound stellar structures in the Milky Way and the 511 keV annihilation morphology. We find that in projection, the flux of the old tilted stellar bulge/bar can reproduce the Gaussian fit parameters and the apparent asymmetry observed in the radiation, supporting a large number of annihilation sources in an extended bulge/bar population. When looking at the same stars in the disk we were not able to reproduce the bulge to disk ratio in flux, indicating either a different class of sources in the disk or significant positron propagation out of the bulge.

Original language	English
Pages (from-to)	1-6
Number of pages	6
Journal	Proceedings of Science
DOIs	https://doi.org/10.22323/1.147.0064
Publication status	Published - 1 Dec 2011
Externally published	Yes
Event	INTEGRAL - A Science Workshop in Sardinia: The Extreme and Variable High Energy Sky, Extremesky 2011 - Cagliari, Italy Duration: 19 Sept 2011 → 23 Sept 2011

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10.22323/1.147.0064Licence: CC BY-NC-SA

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title = "The galactic 511 keV morphology and the old stellar population",

abstract = "The source of Galactic positron annihilation emission is a mystery. What is known is that photons produced in positron-electron annihilation are highly concentrated at the Galactic centre, with a slightly off-centred peak with respect to Galactic longitude. Using synthetic models of the Milky Way we find possible connections between age-bound stellar structures in the Milky Way and the 511 keV annihilation morphology. We find that in projection, the flux of the old tilted stellar bulge/bar can reproduce the Gaussian fit parameters and the apparent asymmetry observed in the radiation, supporting a large number of annihilation sources in an extended bulge/bar population. When looking at the same stars in the disk we were not able to reproduce the bulge to disk ratio in flux, indicating either a different class of sources in the disk or significant positron propagation out of the bulge.",

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T1 - The galactic 511 keV morphology and the old stellar population

AU - Ali, M.

AU - Ellis, S. C.

AU - Sharma, S.

AU - Bland-Hawthorn, J.

PY - 2011/12/1

Y1 - 2011/12/1

N2 - The source of Galactic positron annihilation emission is a mystery. What is known is that photons produced in positron-electron annihilation are highly concentrated at the Galactic centre, with a slightly off-centred peak with respect to Galactic longitude. Using synthetic models of the Milky Way we find possible connections between age-bound stellar structures in the Milky Way and the 511 keV annihilation morphology. We find that in projection, the flux of the old tilted stellar bulge/bar can reproduce the Gaussian fit parameters and the apparent asymmetry observed in the radiation, supporting a large number of annihilation sources in an extended bulge/bar population. When looking at the same stars in the disk we were not able to reproduce the bulge to disk ratio in flux, indicating either a different class of sources in the disk or significant positron propagation out of the bulge.

AB - The source of Galactic positron annihilation emission is a mystery. What is known is that photons produced in positron-electron annihilation are highly concentrated at the Galactic centre, with a slightly off-centred peak with respect to Galactic longitude. Using synthetic models of the Milky Way we find possible connections between age-bound stellar structures in the Milky Way and the 511 keV annihilation morphology. We find that in projection, the flux of the old tilted stellar bulge/bar can reproduce the Gaussian fit parameters and the apparent asymmetry observed in the radiation, supporting a large number of annihilation sources in an extended bulge/bar population. When looking at the same stars in the disk we were not able to reproduce the bulge to disk ratio in flux, indicating either a different class of sources in the disk or significant positron propagation out of the bulge.

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The galactic 511 keV morphology and the old stellar population

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