Detalles de publicación
PP 026032
The Average Age Map of the Galactic Bulge
(1) National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China;
(2) School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China;
(3) IAC;
(4) ULL;
(5) PIFI-Visiting Scientist 2023 of Chinese Academy of Sciences at Purple Mountain Observatory, Nanjing 210023, and National Astronomical Observatories, Beijing 100012, People’s Republic of China;
(6) Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 100875, People’s Republic of China;
(7) Zhejiang Lab, Hangzhou 311121, People’s Republic of China;
(8) Local Universe and Time-Domain Astronomy Laboratory, China West Normal University, Nanchong 637002, People’s Republic of China;
(9) Luoxiahong Institute of Astronomy, China West Normal University, Nanchong 637002, People’s Republic of China;
(10) Department of Astronomy, China West Normal University, Nanchong 637002, People’s Republic of China;
(11) Shanghai Key Laboratory for Astrophysics, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, People’s Republic of China
The Galactic Bulge, as the center of the Galaxy, is the closest laboratory for studying galaxy formation and evolution. However, its study faces significant challenges due to heavy dust extinction. This paper is devoted to deriving the average age of the Galactic Bulge and investigating its spatial distribution. We utilize a high-precision PSF-fitting photometric catalogue in the J and Ks bands observed by VISTA to study the average stellar ages within the Bulge. Red giant stars are employed as tracers, with their average distances determined using red clump stars as references. The average ages are fitted with stellar models. Our analysis reveals a systematic age gradient across the Galactic Bulge (2 deg.<|b|<8 deg.). The mean stellar age increases significantly with galactic latitude, shifting from a younger population (∼4.69^{+0.97}_{−0.81} Gyr) prevalent near the plane to a predominantly older population (∼10.48^{+0.93}_{−0.85} Gyr) at higher latitudes. We hypothesize that the young stellar population at low latitudes is predominantly composed of a pseudo-bulge formed via disk/bar processes (incorporating contributions from recent star-forming activity in the Galactic center), whereas the older stellar population is associated with spheroidal bulges generated through early-stage collapse or accretion of debris from merged dwarf galaxies.