A search for substructures near the Galactic plane and bulge using RR Lyrae stars as tracers
Loading...
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Usando estrellas pulsantes de tipo RR Lyrae, hacemos una búsqueda de subestructuras Galácticas ("stellar streams" y cúmulos globulares) en la región del plano Galáctico. Construimos una muestra de estrellas RR Lyrae con valores de distancia y metalicidades. Estudiamos esta muestra con un algoritmo de "clustering" para encontrar grupos de estrellas cercanas y con propiedades similares. Mediante esta búsqueda, recuperamos estructuras conocidas y encontramos posibles nuevas estructuras.
Context. Stellar streams and globular clusters (GCs) provide crucial insights into galaxy formation and the history of the Milky Way. Although many of these substructures have been identified in the Galaxy, the Galactic plane remains largely devoid of known stellar streams, and the population of Galactic GCs is estimated to be incomplete. RR Lyrae stars, as standard candles and tracers ofold populations, hold immense potential in the search for such substructures. Aims. We aim to build a sample of RR Lyrae stars with positions, kinematics, and metallicities in the Galactic plane and bulge, and use it to search for new Galactic substructures. Methods. We build a sample of fundamental-mode RR Lyrae stars in the Galactic plane and bulge with distances, proper motions, and metallicity estimates. Using a clustering algorithm combined with a Monte Carlo technique, we detect andcharacterize RRab groups with similar positions, kinematics, and metallicities. We inspect these groups to identify known GCs and stellar streams, and constrain their distances and metallicities. Finally, we search for the most promising new substructure candidates among our groups.Results. We find several RRab groups associated with the Sagittarius dwarf spheroidal galaxy and known Galactic GCs. We obtain the first distance estimates obtained with RR Lyrae stars for the GCs BH 140 (4.74 ± 0.32 kpc), VVV-CL160 (7.4 ± 0.2 kpc), and NGC 6544 (2.59 ± 0.08 kpc), on top of finding the first metallicity estimate for BH 140 (−1.54 ± 0.20 dex). Additionally, we identify 26 possible new GC members within 12 Galactic GCs. Furthermore, we explored possible new GC and stellar stream candidates within our RRab groups. Conclusions. RR Lyrae stars are excellent tracers of old Galactic substructures, allowing for metallicity and distance estimates at several kiloparsecs from the Sun, even in challenging regions of the Galaxy with large amounts of dust and gas. Using clustering algorithms on RR Lyrae samples shows a huge potential to detect and study old substructures within our Galaxy. Access to radial velocity measurements would be useful for detecting new globular clusters and (especially) stellar streams within the Milky Way
Context. Stellar streams and globular clusters (GCs) provide crucial insights into galaxy formation and the history of the Milky Way. Although many of these substructures have been identified in the Galaxy, the Galactic plane remains largely devoid of known stellar streams, and the population of Galactic GCs is estimated to be incomplete. RR Lyrae stars, as standard candles and tracers ofold populations, hold immense potential in the search for such substructures. Aims. We aim to build a sample of RR Lyrae stars with positions, kinematics, and metallicities in the Galactic plane and bulge, and use it to search for new Galactic substructures. Methods. We build a sample of fundamental-mode RR Lyrae stars in the Galactic plane and bulge with distances, proper motions, and metallicity estimates. Using a clustering algorithm combined with a Monte Carlo technique, we detect andcharacterize RRab groups with similar positions, kinematics, and metallicities. We inspect these groups to identify known GCs and stellar streams, and constrain their distances and metallicities. Finally, we search for the most promising new substructure candidates among our groups.Results. We find several RRab groups associated with the Sagittarius dwarf spheroidal galaxy and known Galactic GCs. We obtain the first distance estimates obtained with RR Lyrae stars for the GCs BH 140 (4.74 ± 0.32 kpc), VVV-CL160 (7.4 ± 0.2 kpc), and NGC 6544 (2.59 ± 0.08 kpc), on top of finding the first metallicity estimate for BH 140 (−1.54 ± 0.20 dex). Additionally, we identify 26 possible new GC members within 12 Galactic GCs. Furthermore, we explored possible new GC and stellar stream candidates within our RRab groups. Conclusions. RR Lyrae stars are excellent tracers of old Galactic substructures, allowing for metallicity and distance estimates at several kiloparsecs from the Sun, even in challenging regions of the Galaxy with large amounts of dust and gas. Using clustering algorithms on RR Lyrae samples shows a huge potential to detect and study old substructures within our Galaxy. Access to radial velocity measurements would be useful for detecting new globular clusters and (especially) stellar streams within the Milky Way
Description
Tesis (MSc degree in Astrophysics)--Pontificia Universidad Católica de Chile, 2024