Astro2020 Science White Paper: Construction of an L* Galaxy: the Transformative Power of Wide Fields for Revealing the Past, Present and Future of the Great Andromeda System

摘要: Author(s): Gilbert, Karoline M; Tollerud, Erik J; Anderson, Jay; Beaton, Rachael L; Bell, Eric F; Brooks, Alyson; Brown, Thomas Bullock, James; Carlin, Jeffrey Collins, Michelle; Cooper, Andrew; Crnojevic, Denija; Dalcanton, Julianne; Pino, Andres del; D'Souza, Richard; Escala, Ivanna; Fardal, Mark; Font, Andreea; Geha, Marla; Guhathakurta, Puragra; Kirby, Evan; Lewis, Geraint Marshall, Jennifer Martin, Nicolas McQuinn, Kristen; Monachesi, Antonela; Patel, Ekta; Peeples, Molly S; Pillepich, Annalisa; Quirk, Amanda CN; Rich, R Michael; Sohn, S Tony; Ting, Yuan-Sen; Marel, Roeland P van der; Wetzel, Williams, Benjamin Wojno, | Abstract: The Great Andromeda Galaxy (M31) is the nexus of near-far galaxy evolution connection and a principal data point for near-field cosmology. Due to its proximity (780 kpc), M31 can be resolved into individual stars like Milky Way (MW). Unlike MW, we have advantage global view M31, enabling observed with techniques that also apply more distant galaxies. Moreover, recent evidence suggests may survived major merger within last several Gyr, shaping morphology stellar halo triggering starburst, while leaving disk largely intact. MW thus provide complementary opportunities in-depth studies disks, halos, satellites L* Our understanding system will transformed in 2020s if they include wide field facilities both photometry (HST-like sensitivity resolution) spectroscopy (10-m class telescope, g1 sq. deg. field, highly multiplexed, R~ 3000 6000). We focus here on power these constrain past, present, future history via chemo-dynamical analyses star formation histories phase-mixed accreted at early times, as well surviving tidal debris features, M31's extended disk, intact satellite galaxies eventually tidally incorporated halo. This yield an unprecedented hierarchical subhalos built it observe today.