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The search for galactic spaghetti

Starkenburg, E. (2007) The search for galactic spaghetti. Master's Thesis / Essay, Astronomy.

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We present the analysis and interpretation of the Spaghetti Survey data, a pencil-beam high latitude survey designed to test the amount of kinematic substructure in the Galactic halo. Photometrically, red giant candidates are selected which are additionally followed-up spectroscopically. The advantage of red giants is that they can be traced out to large distances up to »100 kpc. The final giant sample contains 102 giants, for which distances, radial velocities and metallicities have been determined. Using a distance measure combining spatial and velocity information we find 7 significant groups within this dataset. One group of 7 members can confidently be matched to tidal debris of the Sagittarius dwarf galaxy. Three other groups can also be associated to Sagittarius debris, provided they were stripped off relatively early. However, two of these groups as well as an additional third group also match to known Virgo structures. We discuss the limitations of linking these found groups to larger substructures. Two stars in the dataset are identified as candidate members of the Orphan Stream. One of these candidates confirms earlier radial velocity measurements from Belokurov et al. (2007). In total, we have measured 22.5% of the stars in the Spaghetti dataset to be in substructures. From comparison with substructure in smooth random sets we have derived a very conservative lower limit for the amount of stars in the halo to be in substructures of 6%. Our results are consistent with a halo entirely built up from disrupted satellites, provided the dominating features are relatively broad due to early merging processes or relatively heavy progenitor satellites.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Astronomy
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:28
Last Modified: 15 Feb 2018 07:28

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