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Mysterious Gamma-Ray Excess Traces Stars

Using a newly developed tool, SkyFACT, which is a hybrid approach between template fitting and image reconstruction, we study the gamma-ray emission from the Galactic Center. We find that the morphology of the so-called “Fermi-LAT Galactic Center Excess” is better described by the distribution of stars in the boxy bulge rather than the expected dark matter density squared. This supports the interpretation that this emission is due to millisecond pulsars instead of dark matter.
Go to the profile of Richard Bartels
Aug 02, 2018
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The quasi-linear nearby Universe

Cosmology is the science of the largest possible scales - temporal and spatial. Yet, the last two decades have seen the rise of a new approach, coined as near field cosmology, which advocates that studies of the ‘near field’, namely our local ‘patch’ of the Universe, can teach us about the Universe at large. Our paper presents a new approach to cosmography - the non-linear mapping of the total matter distribution of the local Universe, out to distances of roughly half a billion lightyears by means of constrained simulations. The paper brings the previously separated approaches: linear cosmography and massively non-linear simulations, and amalgamates them into one - the quasi-linear reconstruction of the near field. The Constrained Local UniversE Simulations (CLUES) project operates within this context. It aims at mapping - in space and time - the near field from observational data and within the framework of the standard model of cosmology. The data consists of the Cosmicflows database of galaxy distances and velocities and the essence of the standard model, namely a flat universe made of dark energy (Λ) and cold dark matter (the “ΛCDM” model). How local is ‘local’ is context dependent – for simulations such as those in the CLUES it ranges from scales as small as our Milky Way galaxy out to distances of roughly a billion lightyears from us.
Go to the profile of Noam Libeskind
Jul 09, 2018