dc.contributor.author | Siegert, T. | |
dc.contributor.author | Diehl, R. | |
dc.contributor.author | Khachatryan, G. | |
dc.contributor.author | Krause, M.~G.~H. | |
dc.contributor.author | Guglielmetti, F. | |
dc.contributor.author | Greiner, J. | |
dc.contributor.author | Strong, A.~W. | |
dc.contributor.author | Zhang, X. | |
dc.date.accessioned | 2017-06-28T10:51:03Z | |
dc.date.available | 2017-06-28T10:51:03Z | |
dc.date.issued | 2016-02-01 | |
dc.identifier.citation | Siegert , T , Diehl , R , Khachatryan , G , Krause , M G H , Guglielmetti , F , Greiner , J , Strong , A W & Zhang , X 2016 , ' Gamma-ray spectroscopy of positron annihilation in the Milky Way ' , Astronomy & Astrophysics , vol. 586 , pp. A84 . https://doi.org/10.1051/0004-6361/201527510 | |
dc.identifier.issn | 0004-6361 | |
dc.identifier.other | Bibtex: urn:874acafd0d8060f0f86fd90e09db886e | |
dc.identifier.other | ORCID: /0000-0002-9610-5629/work/63687379 | |
dc.identifier.uri | http://hdl.handle.net/2299/18594 | |
dc.description | T. Siegert, et al., “Gamma-ray spectroscopy of positron annihilation in the Milky Way”, Astronomy & Astrophysics, Vol. 586, January 2016, https://doi.org/10.1051/0004-6361/201527510. Reproduced with permission from Astronomy & Astrophysics, © ESO”. | |
dc.description.abstract | Context. The annihilation of positrons in the Galaxy's interstellar medium produces characteristic gamma-rays with a line at 511 keV. This gamma-ray emission has been observed with the spectrometer SPI on ESA's INTEGRAL observatory, confirming a puzzling morphology with bright emission from an extended bulge-like region, while emission from the disk is faint. Most known or plausible sources of positrons are, however, believed to be distributed throughout the disk of the Milky Way. Aims: We aim to constrain characteristic spectral shapes for different spatial components in the disk and bulge using data with an exposure that has doubled since earlier reports. Methods: We exploit high-resolution gamma-ray spectroscopy with SPI on INTEGRAL based on a new instrumental background method and detailed multi-component sky model fitting. Results: We confirm the detection of the main extended components of characteristic annihilation gamma-ray signatures, altogether at 58σ significance in the 511 keV line. The total Galactic 511 keV line intensity amounts to (2.74 ± 0.25) × 10-3 ph cm-2 s-1 for our assumed model of the spatial distribution. We derive spectra for the bulge and disk, and a central source modelled as point-like and at the position of Sgr A*, and discuss spectral differences. The bulge (56σ) shows a 511 keV line intensity of (0.96 ± 0.07) × 10-3 ph cm-2 s-1 together with ortho-positronium continuum equivalent to a positronium fraction of (1.080 ± 0.029). The two-dimensional Gaussian that represents the disk emission (12σ) has an extent of 60+10-5 degrees in longitude and a rather large latitudinal extent of 10.5+2.5-1.5 degrees; the line intensity is (1.66 ± 0.35) × 10-3 ph cm-2 s-1 with a marginal detection of the annihilation continuum and an overall diffuse Galactic continuum of (5.85 ± 1.05) × 10-5 ph cm-2 s-1 keV-1 at 511 keV. The disk shows no flux asymmetry between positive and negative longitudes, although spectral details differ. The flux ratio between bulge and disk is (0.58 ± 0.13). The central source (5σ) has an intensity of (0.80 ± 0.19) × 10-4 ph cm-2 s-1. | en |
dc.format.extent | 16 | |
dc.format.extent | 1555912 | |
dc.language.iso | eng | |
dc.relation.ispartof | Astronomy & Astrophysics | |
dc.subject | gamma rays: ISM, gamma rays: diffuse background, ISM: general, line: profiles, techniques: spectroscopic | |
dc.title | Gamma-ray spectroscopy of positron annihilation in the Milky Way | en |
dc.contributor.institution | Centre for Astrophysics Research (CAR) | |
dc.contributor.institution | School of Physics, Engineering & Computer Science | |
dc.contributor.institution | Department of Physics, Astronomy and Mathematics | |
dc.description.status | Peer reviewed | |
rioxxterms.versionofrecord | 10.1051/0004-6361/201527510 | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |