Gamma-ray emission from the Sagittarius dwarf spheroidal galaxy due to millisecond pulsars
| Autor: | Roland M. Crocker, Oscar Macias, Dougal Mackey, Mark R. Krumholz, Shin’ichiro Ando, Shunsaku Horiuchi, Matthew G. Baring, Chris Gordon, Thomas Venville, Alan R. Duffy, Rui-Zhi Yang, Felix Aharonian, J. A. Hinton, Deheng Song, Ashley J. Ruiter, Miroslav D. Filipović |
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| Přispěvatelé: | GRAPPA (ITFA, IoP, FNWI) |
| Rok vydání: | 2022 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Astrophysics::High Energy Astrophysical Phenomena Astrophysics of Galaxies (astro-ph.GA) Astrophysics::Solar and Stellar Astrophysics FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Earth and Planetary Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Astrophysics of Galaxies Astrophysics::Galaxy Astrophysics |
| Zdroj: | Nature Astronomy, 6(11), 1317-1324. Nature Publishing Group Nature astronomy |
| ISSN: | 2397-3366 |
| DOI: | 10.1038/s41550-022-01777-x |
| Popis: | The Fermi Bubbles are giant, gamma-ray emitting lobes emanating from the nucleus of the Milky Way discovered in ~1-100 GeV data collected by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. Previous work has revealed substructure within the Fermi Bubbles that has been interpreted as a signature of collimated outflows from the Galaxy's super-massive black hole. Here we show via a spatial template analysis that much of the gamma-ray emission associated to the brightest region of substructure -- the so-called cocoon -- is likely due to the Sagittarius dwarf spheroidal (Sgr dSph) galaxy. This large Milky Way satellite is viewed through the Fermi Bubbles from the position of the Solar System. As a tidally and ram-pressure stripped remnant, the Sgr dSph has no on-going star formation, but we nevertheless demonstrate that the dwarf's millisecond pulsar (MSP) population can plausibly supply the gamma-ray signal that our analysis associates to its stellar template. The measured spectrum is naturally explained by inverse Compton scattering of cosmic microwave background photons by high-energy electron-positron pairs injected by MSPs belonging to the Sgr dSph, combined with these objects' magnetospheric emission. This finding plausibly suggests that MSPs produce significant gamma-ray emission amongst old stellar populations, potentially confounding indirect dark matter searches in regions such as the Galactic Centre, the Andromeda galaxy, and other massive Milky Way dwarf spheroidals. Comment: Updated to match version accepted for publication in Nature Astronomy (2022). 14 pages main text, 3 main figures, 7 extended data figures. For published version of the paper, see https://rdcu.be/cUZ6X |
| Databáze: | OpenAIRE |
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