HALO STREAM DETECTION IN ACTION AND ENERGY SPACES FROM GAIA DR2 DATA

• Main Author: MADE KARTIKA WIJAYANTI, NI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53925
• Institution: Institut Teknologi Bandung

In hierarchical scenario, a galaxy formed by several bounded systems. Previous studies show that Milky Way's halo has structures in its kinematics and integral of motion's coordinates because of the galaxy satellite's disruption. Kinematics and integral of motion's structures, which formed either from satellites merger or resonance, later known as stellar stream. Integral of motion is conserved over a long period so this element can be used to detect the stellar streams that formed billion years ago. In this thesis the author detect the streams using orbit's actions and energy spaces. Actions and energy are calculated by galpy package. The data used are from Gaia DR2 and substructures are analysed using a trous algorithm wavelet by MR software. In this thesis, halo sample is analysed in action and energy spaces, Lz vs Jr, Lz vs Jz, Jr vs Jz, and Lz vs E. The author detected Gaia-Enceladus stream and suggested formed by a massive galaxy satellite and has a radial orbit. In V vs p U2 + 2V 2 space, Gaia-Enceladus is detected as BB17-2, a stream found by Bajkova and Bobylev, or VelHel-6 and VelHel-7, streams found by Helmi et al. The kinematics and metallicity of BB17-2 or VelHel-6 showed that the stream are not related to !Centauri globular cluster.