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

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Presentation on theme: "Galactic Archaeology with Subaru: Prospects for Wide-Field Surveys Masashi Chiba (Tohoku University, Sendai) with HSC and PFS science working groups."— Presentation transcript:

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 Bright parts are centrally concentrated Dark halo in the GalaxyAssembly of CDM By Moore Resolved stars provide fossil records of galaxy formation process By Moore

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


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


8 HSC Wide-field FoV is essential for mapping stars

9 Subaru Strategic Program (SSP) with HSC (to be submitted) (dedicated to a newly commissioned instrument: max: 60 nights/year x 5 years) 1. Wide-field survey over ~ 1,500 deg 2 cosmology: primary science driver weak lensing, strong lensing, galaxy clusters other science incl. galactic archaeology 2. Deep and ultra-deep survey galaxy and QSO/AGN evolution high-z galaxies, re-ionization, z~7 QSOs

10 HSC white paper (July, 2011)

11 Planned GA survey with HSC 1.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 deg 2 (fully utilizing weak-lensing survey data) color-magnitude diagram for old MS + RGB stars in the outer halo (r = 30 – 250 kpc) 2.Deep and wide-field survey of the M31/M33 halo Detailed mapping of stellar halos in M31/M33 Use (DDO51-type) NB515 filter 515 nm to distinguish halo RGBs with (g, i) + NB515 imaging NB515 is fully optimized for z=3 BAO as well

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

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

14 (Bullock & Johnston 2005) Halo realization Survey of the MW outer halo with HSC HSC HSC survey over ~1,500 deg 2 ~ 20 new Mv<-3 3~4 new streams with  lim ~34 mag/  ”

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

16 130 HSC pointings Deep and wide-field survey of stellar halos in M31/M33 with HSC Metallicities and RVs of substructures and satellites with PFS (+ star clusters) I TRGB =20.5 Ibata+

17 PFS

18 (Prime Focus Spectrograph) 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 Led by IPMU (U. of Tokyo) + NAOJ/Subaru community + Caltech/JPL, Princeton, (JHU), LAM, UK, Brazil, Taiwan Prime focus

19 Spectrograph design By Jim Gunn Red Blue IR

20 Key science with PFS (Science white paper, 1 st ver. in Jan 2011) 1.Cosmology: primary science driver BAO, lensing 2.Galaxy evolution Galaxies at z ~ 2 and beyond 3.Galactic archaeology Milky Way and Local Group 4.QSO/AGN evolution QSOs at z < 6

21 1 st version of PFS white paper (Jan, 2011) SuMIRe=Subaru Measurement of Images and Redshifts The project name using both HSC and PFS

22 Many fibersMerging history GA science goals with PFS

23 1. 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? 2.The nature of galactic dark matter How is dark matter distributed in the MW? Dark matter of dwarf satellites: is CDM correct? GA science goals with PFS All of these information are recorded in stars

24 1.Space and velocity distributions of ancient stars Past collapse and merging events Tracer of dark matter profiles 2.Chemical abundance of ancient stars Star formation and chemical evolution Phase space Debris of building blocks A building block Helmi & de Zeeuw 2000 Freeman & Bland-Hawthorn 2002 Extracting past merging history: how? Astrometry with Gaia (precise distances and proper motions) + V rad & [Fe/H] distrib. with PFS will resolve each of blocks and its chemical evolution

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

26 GA survey plan with PFS 1.The Milky Way survey Sample: i.Gaia sample: ~ 10 6 stars with 18

27 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= nm, 18

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

29 GA with TMT Science Working Group (Stars and Local Group) led by Wako Aoki 1. Exploring stellar activities and explosions 2. 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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