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Yu, Fengqing ; Li, Ting S. ; Speagle, Joshua S. ; Medina, Gustavo E. ; Koposov, Sergey E. ; Bland-Hawthorn, Joss ; Cullinane, Lara R. ; Eadie, Gwendolyn M. ; Erkal, Denis ; Lewis, Geraint F. ; Limberg, Guilherme ; Zucker, Daniel B.

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 975, n. 1, p. 19-pg., 2024-11-01.

Resumo

Blue horizontal branch stars (BHBs), excellent distant tracers for probing the Milky Way's halo density profile, are distinguished in the g-r0 versus (i - z)0 color space from another class of stars, blue straggler stars. We develop a Bayesian mixture model to classify BHBs using high-precision photometry data from the Dark Energy Survey Data Release 2 (DES DR2). We select similar to 2100 highly probable BHBs based on their griz photometry and the associated uncertainties, and we use these stars to map the stellar halo over the Galactocentric radial range 20 kpc less than or similar to R less than or similar to 70 kpc. After excluding known stellar overdensities, we find that the number density n star of BHBs can be represented by a power-law density profile n star proportional to R -alpha with an index of alpha=4.34-0.12+0.13 +/- 0.52 , consistent with existing literature values. In addition, we examine the impact of systematic errors and the spatial inhomogeneity on the fitted density profile. Our work demonstrates the effectiveness of high-precision griz photometry in selecting BHBs. The upcoming photometric survey from the Rubin Observatory, expected to reach depths 2-3 mag greater than DES during its 10 yr mission, will enable us to investigate the density profile of the Milky Way's halo out to the virial radius, unraveling the complex processes of formation and evolution in our Galaxy. (AU)

• Processo FAPESP: 21/10429-0 - A estrutura quimiodinâmica do halo galáctico
• Beneficiário: Guilherme Limberg
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto