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Galactic Archaeology with Subaru: Prospects for Wide-Field Surveys

Galactic Archaeology with Subaru: Prospects for Wide-Field Surveys. Masashi Chiba (Tohoku University, Sendai) with HSC and PFS science working groups. Outline. Background Wide-field photometric survey with Hyper Suprime Cam (HSC)

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Galactic Archaeology with Subaru: Prospects for Wide-Field Surveys

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  1. Galactic Archaeology with Subaru: Prospects for Wide-Field Surveys Masashi Chiba (Tohoku University, Sendai) with HSC and PFS science working groups

  2. Outline • Background • Wide-field photometric survey with Hyper Suprime Cam (HSC) • Wide-field, fiber-fed multi-object spectroscopic survey with Prime Focus Spectrograph (PFS)

  3. What do we want to know? Formation of the Galaxy in CDM theory Assembly of CDM Dark halo in the Galaxy By Moore Resolved stars provide fossil records of galaxy formation process Bright parts are centrally concentrated By Moore

  4. Then, what data do we need? Subaru/HSC • Photometry : • mag., color ( → color-mag. diagram) • Spectroscopy : • metallicity, Vrad(kinematics) • abundance pattern( → SFH & chemical evol.) • Astrometry : • proper motion, distance(→ 6d phase space) Subaru/PFS Gaia ⇒galaxy formation and evolution

  5. HSC

  6. Prime focus Funded since 2006 FOV: 1.77 sq deg (1.5 deg diameter) Pixel scale: 0”.17/pix Filters: grizy + several NB First light: Jan., 2012 HSC (Hyper Suprime Cam) International collaboration: Japan, Princeton, Taiwan

  7. HSC Wide-field FoV is essential for mapping stars

  8. Subaru Strategic Program (SSP)with HSC (to be submitted)(dedicated to a newly commissioned instrument: max: 60 nights/year x 5 years) • Wide-field survey over ~ 1,500 deg2 • cosmology: primary science driver weak lensing, strong lensing, galaxy clusters • other science incl. galactic archaeology • Deep and ultra-deep survey • galaxy and QSO/AGN evolution high-z galaxies, re-ionization, z~7 QSOs

  9. HSC white paper (July, 2011)

  10. Planned GA survey with HSC • Wide-field survey of the MW outer halo Discovery of new ultra-faint dSphs and halo streams • 3 bands (g, r, i), ~ 26 mag (3 mag deeper than SDSS) • ~1,500 deg2(fully utilizing weak-lensing survey data) • color-magnitude diagram for old MS + RGB stars in the outer halo (r = 30 – 250 kpc) • Deep and wide-field survey of the M31/M33 halo Detailed mapping of stellar halos in M31/M33 • Use (DDO51-type) NB515 filter centered @ 515 nm to distinguish halo RGBs with (g, i) + NB515 imaging • NB515 is fully optimized for z=3 BAO as well

  11. UFDs and substructures revealed by SDSS 20 < r < 22 (Belokurov+ 2006)

  12. Observed photometric properties of Galactic satellites (SDSS) Tollerud +08 Single LSST: rlim = 24.5 Co-added LSST: rlim =27.5 Subaru/HSC (wide-f. survey): rlim~26 radius satellites

  13. Survey of the MW outer halo with HSC Halo realization (Bullock & Johnston 2005) HSC HSC • HSC survey over ~1,500 deg2 • ~ 20 new UFDs @ Mv<-3 • 3~4 new streams with lim~34 mag/”

  14. Stellar halos in M31/M33 using (DDO51-type) NB515 filterCW: 5145 A, FWHM: 80 A To separate RGBs in M31/M33 from Galactic dwarfs + optimized for BAO science using z=3 LAEs Feasibility for LG science (with M.Tanaka) Requirement from BAO science (with Y. Matsuda) giants dwarfs

  15. Ibata+ Deep and wide-field survey of stellar halos in M31/M33 with HSC Metallicities and RVs of substructures and satellites with PFS (+ star clusters) ITRGB=20.5 130 HSC pointings

  16. PFS

  17. Prime focus FOV: 1.5 deg in diameter 2400 fiber positioners λ: 380~1,300 nm (3 channels: Blue, Red, IR) R: ~3,000 First light: 2016 PFS (Prime Focus Spectrograph) Led by IPMU (U. of Tokyo) + NAOJ/Subaru community + Caltech/JPL, Princeton, (JHU), LAM, UK, Brazil, Taiwan

  18. Spectrograph design By Jim Gunn Red IR Blue

  19. Key science with PFS(Science white paper, 1st ver. in Jan 2011) • Cosmology: primary science driver • BAO, lensing • Galaxy evolution • Galaxies at z ~ 2 and beyond • Galactic archaeology • Milky Way and Local Group • QSO/AGN evolution • QSOs at z < 6

  20. 1st version of PFS white paper (Jan, 2011) SuMIRe=Subaru Measurement of Images and Redshifts The project name using both HSC and PFS

  21. GA science goals with PFS Many fibers Merging history

  22. GA science goals with PFS • Formation of Galactic structures • Merging history of the Milky Way (MW)? • Formation of old MW components (thick disk, halo)? • Star-formation history of dwarf satellites? • Formation of M31: is it different from the MW? • The nature of galactic dark matter • How is dark matter distributed in the MW? • Dark matter of dwarf satellites: is CDM correct? All of these information are recorded in stars

  23. Extracting past merging history: how? Debris of building blocks • Space and velocity distributions of ancient stars • Past collapse and merging events • Tracer of dark matter profiles • Chemical abundance of ancient stars • Star formation and chemical evolution Freeman & Bland-Hawthorn 2002 Astrometry with Gaia (precise distances and proper motions) + Vrad & [Fe/H] distrib. with PFS will resolve each of blocks and its chemical evolution Phase space A building block Helmi & de Zeeuw 2000

  24. Accretion time of a satellite can be deduced from phase-space distribution of stars (McMillan & Binney 2008, Gomez+ 2010) Orbital freq. r- r-  P(k) Lz k 8.9 Gyr 7.9 Gyr 7.6 Gyr

  25. GA survey plan with PFS • The Milky Way survey • Sample: • Gaia sample: ~ 106 stars with 18<V<20 (Halo ~55%, Thick disk ~40%, Thin disk ~5%) • Faint sample: stars in 8-9 stellar streams and ~ 105 stars in the outer halo with 18<V<21.5 • Total area: 1,000 + 180 deg2 (560 + 100 pointings) • Survey time: ~30 + 20 = 50 nights • The M31 halo survey • Sample: RGBs, V < 21.5 • Total area: ~ 230 deg2 (~130 pointings) • Survey time: ~ 30 nights • Dwarf galaxy survey • Sample: RGBs, V < 21.5 • Survey time: ~ 8 nights (can be PI-led programs)

  26. Summary: GA with Subaru next decade • HSC (2012~) • 1.5 deg FOV, gri+NB515, g<26 • Discovery of new UFDs and halo substructures in the MW • Detailed halo structure in M31/M33 • PFS (2016~) • R=3,000, ~2,400 fibers, • λ=380-1300 nm, 18<V<21.5 • Discovery of kinematical substructures and merger history in the MW • Dark matter and abundance distribution in Local Group galaxies

  27. WFOS, IRIS, IRMS, HROS, NIRES etc. R~5,000 for mV<26 mag R~50,000 for mV<21 mag TMT (Thirty Meter Telescope) Japan will join TMT

  28. GA with TMTScience Working Group (Stars and Local Group) led by Wako Aoki • Exploring stellar activities and explosions • Clarifying galaxy formation with resolved stars Supernovae, GRB, Seismology, First stars, Extremely metal-poor stars, Our Galaxy, Andromeda, The Local Group and beyond … Summarized in Science Report (2011)

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