TY - JOUR
T1 - The RR Lyrae projected density distribution from the Galactic centre to the halo
AU - Navarro, María Gabriela
AU - Minniti, Dante
AU - Capuzzo-Dolcetta, Roberto
AU - Alonso-García, Javier
AU - Contreras Ramos, Rodrigo
AU - Majaess, Daniel
AU - Ripepi, Vincenzo
N1 - Publisher Copyright:
© ESO 2021.
PY - 2021/2/1
Y1 - 2021/2/1
N2 - The projected density distribution of type ab RR Lyrae (RRab) stars was characterised from the innermost regions of the Milky Way to the halo, with the aim of placing constraints on the Galaxy's evolution. The compiled sample (NRRab = 64 850) stems from fundamental mode RR Lyrae variables identified by the VVV, OGLE, and Gaia surveys. The distribution is well fitted by three power laws over three radial intervals. In the innermost region (R < 2.2°) the distribution follows ςRRab[1] R-0.94 ± 0.051, while in the external region the distribution adheres to ςRRab[2] R-1.50 ± 0.019 for 2.2° < R < 8.0° and ςRRab[3] R-2.43 ± 0.043 for 8.0° < R < 30.0°. Conversely, the cumulative distribution of red clump (RC) giants exhibits a more concentrated distribution in the mean, but in the central R < 2.2° the RRab population is more peaked, whereas globular clusters (GCs) follow a density power law (ςGCs R-1.59 ± 0.060 for R < 30.0°) similar to that of RRab stars, especially when considering a more metal-poor subsample ([Fe/H] < -1.1 dex). The main conclusion emerging from the analysis is that the RRab distribution favours the star cluster infall and merger scenario for creating an important fraction (> 18%) of the central Galactic region. The radii containing half of the populations (half populations radii) are RH RRab = 6.8° (0.99 kpc), RH RC = 4.2° (0.61 kpc), and RH GCs = 11.9° (1.75 kpc) for the RRab stars, RC giants, and GCs, respectively. Finally, merely ∼1% of the stars have been actually discovered in the innermost region (R < 35 pc) out of the expected (based on our considerations) total number of RRab therein: N ∼ 1562. That deficit will be substantially ameliorated with future space missions like the Nancy Grace Roman Space Telescope (formerly WFIRST).
AB - The projected density distribution of type ab RR Lyrae (RRab) stars was characterised from the innermost regions of the Milky Way to the halo, with the aim of placing constraints on the Galaxy's evolution. The compiled sample (NRRab = 64 850) stems from fundamental mode RR Lyrae variables identified by the VVV, OGLE, and Gaia surveys. The distribution is well fitted by three power laws over three radial intervals. In the innermost region (R < 2.2°) the distribution follows ςRRab[1] R-0.94 ± 0.051, while in the external region the distribution adheres to ςRRab[2] R-1.50 ± 0.019 for 2.2° < R < 8.0° and ςRRab[3] R-2.43 ± 0.043 for 8.0° < R < 30.0°. Conversely, the cumulative distribution of red clump (RC) giants exhibits a more concentrated distribution in the mean, but in the central R < 2.2° the RRab population is more peaked, whereas globular clusters (GCs) follow a density power law (ςGCs R-1.59 ± 0.060 for R < 30.0°) similar to that of RRab stars, especially when considering a more metal-poor subsample ([Fe/H] < -1.1 dex). The main conclusion emerging from the analysis is that the RRab distribution favours the star cluster infall and merger scenario for creating an important fraction (> 18%) of the central Galactic region. The radii containing half of the populations (half populations radii) are RH RRab = 6.8° (0.99 kpc), RH RC = 4.2° (0.61 kpc), and RH GCs = 11.9° (1.75 kpc) for the RRab stars, RC giants, and GCs, respectively. Finally, merely ∼1% of the stars have been actually discovered in the innermost region (R < 35 pc) out of the expected (based on our considerations) total number of RRab therein: N ∼ 1562. That deficit will be substantially ameliorated with future space missions like the Nancy Grace Roman Space Telescope (formerly WFIRST).
KW - Galaxy: center
KW - Galaxy: general
KW - Galaxy: structure
KW - Infrared: stars
KW - Stars: variables: RR Lyrae
KW - Surveys
UR - http://www.scopus.com/inward/record.url?scp=85100545890&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202038463
DO - 10.1051/0004-6361/202038463
M3 - Article
AN - SCOPUS:85100545890
VL - 646
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A45
ER -