The RR Lyrae distribution in the Galactic bulge

Abstract

RR Lyrae stars are important distance indicators. They are usually present in globular clusters where they were first discovered. The study of their properties and distribution in our Galaxy and in external galaxies constitutes a modern field of astrophysical research. The aim of this paper is checking the possibility that the observed distribution of RR Lyrae stars in the Galactic bulge derives from orbitally decayed globular clusters (GCs). To reach the aim of the paper I made use of the comparison of observational data of RR Lyrae in the Galactic bulge with the distribution of GCs in the Milky Way (MW) as coming from theoretical models under a set of assumptions. I obtain the expected numbers and distributions of RR Lyrae in the Galactic bulge as coming from an initial population of globular clusters at varying some characteristic parameters of the GC population and compare to observational data. The actual abundance of RR Lyrae in the Galactic bulge and their radial distribution are, likely, still too uncertain to provide a straight comparison with theoretical models. Despite this, it can be stated that a significant fraction of the ‘foreground’ RR Lyrae present in the MW originate from orbitally evolved and dissolved GCs.