Scientists believe that the shape of the dark matter halo is key to understanding the hierarchical formation of the Milky Way. Despite extensive efforts in recent decades, its shape remains a matter of debate, with suggestions ranging from strongly oblate to prolate. Based on observational data fro...
Reports on evidence which suggests that the halo, the envelope of material that extends to the outskirts of the Milky Way, consists mostly of exotic material unlike ordinary atoms. Findings reported by Kem H. Cook and his colleagues in the April 10, 1995 issue of 'Physical Review Letters'; ...
Astronomers believe that the baryon (stellar) halo of the Milky Way retains a fossil imprint of how it was formed. But a vast literature shows that we are still struggling to interpret the observations within a consistent framework. The evidence indicates that the halo has built up through a ...
RR Lyrae stars are ideal massless tracers that can be used to study the total mass and dark matter content of the outer halo of the Milky Way (MW). This is because they are easy to find in the light-curve databases of large stellar surveys and their distances can be determined with onl...
Halo substructure on spatial scales of >3 degrees is revealed as an excess in the local density of sub-giant stars. With an appropriate assumption of a model stellar isochrone it is possible for us to then derive distances to the sub-giant population. We describe three new candidate halo ...
Many stars in the halo that surrounds the Milky Way travel in groups. This is the outcome of a recent analysis of data for millions of stars from the Gaia space mission. Astronomers report their discovery today in the international journal Astronomy & As
We present a spectroscopic study of a sample of 238 RR Lyrae stars, from the QUEST survey, located in the Galactic halo at distances between 4 and 20 kpc from the Sun. Combining their spatial position and kinematics we were able to identify sub-structures in this part of the halo. Some ...
The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way1,2,3,4; however, the origin...
We present results from our survey of RR Lyrae stars in the halo of the Milky Way. Since these stars are standard candles, the survey is capable of finding spatial structures in the halo, such as streams of debris left by the destruction of small satellites by the tidal forces of the ...
The gravitational wave detectors have shown a population of massive black holes that do not resemble those observed in the Milky Way1–3 and whose origin is debated4–6. According to a possible explanation, these black holes may have formed from density