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  1. Ga la xy pr & ov Lo ed ca b l y Un HS iv C er se Yu ta ka ( NA Ko OJ mi ) ya ma

  2. I nt ro du ct io n

  3. Hyper Suprime-Cam • Hyper Suprime-Cam (HSC) • Next generation wide-field CCD Camera • 1.5~2 degree FoV covered with 100-180 red-sensitive CCDs • Conceptual design in progress • Target First Light: 2011 • Subaru will have much wider FoV among 8m class telescopes • Local objects: apparent size is large (e.g. M31 ~3deg Dia. ) • HSC: Ultimate imaging instrument for exploring the local universe

  4. M31 covered by 180 CCDs of Hyper Suprime-Cam

  5. Mt. Fuji viewed from Mauna Kea Mt. Fuji viewed from Tokyo

  6. fainter, more distant objects HSC Survey rare objects, statistics What can be done with HSC SDSS Survey Area (sq.deg) 0.1 1 10 100 1000 10000 Suprime-Cam Typical Surveys 21 22 23 24 25 26 27 28 29 30 Limiting Magnitude (mag)

  7. What can be done with HSC • Structure of nearby galaxies (M31 to nearby groups) • Structure of the Galaxy • Ultra-faint dwarf galaxies • Low surface brightness universe Many thanks to Collaborators ! M. Tanaka, M. Chiba, P. Guhathakurta, T. Morokuma, M. Yagi, M. Yoshida, N. Kashikawa

  8. S tr uc tu re o f Ga la xi es

  9. Why care about stellar halos? • Laboratory to test hierarchical galaxy formation • Tidal debris of merging galaxies survive for several Gyrs in the halo since the dynamical timescale is long there • Orbit of stream structure  strong constraint for the gravitational potential of the galaxy • How frequent do merging events occur? Bullock & Johnston. 2005.

  10. Substructures in M31’s halo Ibata et al. 2007

  11. Suprime-Cam M31 Survey (WASSHABI) NW SE Tanaka+2008

  12. Surface Brightness Profile Red: [Fe/H] > -1.1 Blue: [Fe/H] < -1.1 V < 25 I < 24 Inner halo + Outer halo + Substructures Tanaka+2008

  13. Color-Magnitude Diagram • The width of RGB gets narrower as it goes outkirts • indicating metallicity gradient exists • Our survey goes well below Red Clump North-West Tanaka+2008

  14. Features in Color-Magnitude Diagram • AGB bump (AGBb): Clustered feature of AGB stars at the beginning of He shell-burning evolution • Red Clump: Clustered feature of red HB (He core-burning) stars being metal-rich / young age  age indicator of stellar population (once metallicity is determined) • Suprime-Cam data enable us to investigate the properties of stellar population Tanaka+2007b AGBb RGBb HB AGB bump Red clump Mean Age ~ 9.6 Gyr Alves & Sarajedini 1999

  15. HSC M31 Halo Ultimate Imaging Survey • HSC can image as deep as below HB/RC in 1 hour under moderate seeing condition (~0”.7) • 81 HSC (2deg case) pointings are required to cover 254 sqrdeg (x2 the field size of Ibata et al. 2007 survey) • Total: 20 nights required • 2 color bands (V, I)

  16. DDO51 filter • With DDO51 filter, M31 RGB stars are easily discriminated from Galactic dwarf stars. giants giants dwarfs dwarfs

  17. Toward Nearby Groups • Similar investigation can be applied for galaxies in nearby groups. HSC is suitable for such observations; • 1.5deg corresponds to 130kpc @ 5Mpc • TRBG ~ 24 mag, HB ~ 28 mag @ 5Mpc • Structure of nearby galaxies (M31 to nearby groups) • More sample galaxies • Dependence on morphology • Dependence on environment N5128 Sculpter 5Mpc LG Canes1 M81 Maffei

  18. T he G al ax y

  19. “Field of Streams” in SDSS data (Belokurov+ 2006) SDSS

  20. SDSS trailing leading SDSS Tidal Structure in the Galactic Halo • Palomer 5: tidally elongated GC (extended over 10 deg) @d=25kpc (Odenkirchen+ 2003) • NGC5466: another elongated GC (extended over 4 deg)@d=16kpc (Belokurov+ 2006) • Stream structures constrain the gravitational potential of the Galaxy HSC probe the Galactic halo in deep (beyond 100kpc) for wide area Belokurov+ 2006 Odenkirchen+ 2003

  21. RR Lyrae ~ Galactic structure ~ • RR Lyrae: old stellar population (~>8Gyr)  Galactic halo (sub)structure • large amplitude (~0.5-1.0mag) and rapid (T=0.3-0.5days) variable stars • SDSS, QUEST can not effectively detect variability of RR Lyrae at the outermost region of our Galaxy (R>100kpc). • 4 RR Lyrae candidates at R>150kpc in the SXDF (~1deg2, Morokuma 2007): HSC: m~26mag, Δt:any, ~100deg2  ~500 RR Lyrae at R>100kpc Vivas & Zinn (2006): QUEST (~400deg2) Sesar et al. (2007): SDSS (~300deg2) 10 1 density [kpc-3] 0.1 0.01 10 distance [kpc] 100

  22. High proper motion objects (HPMOs) - Search for Galactic halo white dwarfs - kinematics of Halo stars - Age of WD, WD LF  age of our Galaxy - MACHO Morokuma 2007 Richer et al. (2000) reduced proper motion diagram ~20 HPMOs (>0.13arcsec) in the SDF (0.25deg2, Suprime-Cam 1 FOV, Morokuma 2007) HSC: V~28mag, delta-t>3yrs, ~10deg2  ~1000 HPWDs at d<1kpc shallower & wider might be better...? Good image quality of Subaru is the key

  23. U lt ra F ai nt Dw ar f Ga la xi es

  24. SDSS Ultra Faint Dwarf Galaxies • SDSS: discoveries of Milky Way companion dwarf “galaxies” comparable or even fainter than globular clusters! • “they might be just the first of a vast population of ultra-faint dwarf galaxies surrounding the Milky Way system that is yet to be discovered” (van den Bergh) Belokurov+ 2007 Globular Clusters

  25. Ultra Faint Dwarf Galaxies • These galaxies are metal poor and dark matter dominated • HSC : • Search for ultra faint dwarf galaxies which are companions to M31 • Relation with missing satellite problem Simon & Geha 2007

  26. L ow S ur fa ce B ri gh tn es s Un iv er se

  27. 1 degree HI map from deBlok&Walter 2002 LG Dwarf Irregular NGC 6822 • NGC6822 • Local Group dIrr • MV = -16 • 500 kpc from MW • Ongoing SF activity • Viewed in HI • Embedded in a huge HI envelope • Stellar population / SF activity in the HI envelope was unknown  Suprime-Cam is the best instrument for investigating the HI envelope Image from DSS

  28. Subaru + Suprime-Cam 2 fields B band : 24min R band : 36min I band : 22min 0”.8 PSF FWHM Limiting Mag: B~26mag MB~0.5mag 画像 Komiyama et al. 2003

  29. Intermediate-age to old population (>1Gyr) traced by red-tangle stars Spherical Distribution → main component of the galaxy Young population (<1Gyr) traced by main-sequence stars Elongate distribution • Trace the HI envelope NGC 6822: Spatial Distribution Reveals the low surface brightness star-formation activity in the HI envelope for the first time

  30. Suprime-Cam Ha Imaging of Galaxy Clusters • Extended Ha emission line region (without stellar component) found for NGC 4388 in the Virgo cluster (Yoshida et al. 2002, 2004) • Ram pressure stripping is the most plausible explanation • Environmental process special to galaxy clusters? • How rare? Dependence on environment ? Morphology/Star formation property of host galaxy ? Yoshida et al. 2002, 2004

  31. Suprime-Cam Coma Cluster Ha Imaging Survey • Narrow-band filter • lc=6714A, FWHM=130A • sample Hα line @ Coma redshift • goes as deep as 26.2 ABmag (6.0x10-18 erg/s/cm2), corresponding to SFR of 2x10-4 Ms/yr • 3 broad band filters: B, R, i’ • Continuum subtraction • Discriminate distant galaxies • 3 different fields Panchromatic data are available for this region ACS pointing

  32. Mrk60(D100) Ha cloud D100 B,NB,i composite. (B, R, NB composite is on Subaru WWW)

  33. Ha, [NII] [SII] Mrk60(D100) Ha cloud 2kpc What's this !? 60kpc Subaru FOCAS MOS observation Covers Ha and Hb lines with R~700 Measured redshift: 0.018 Same redshift as D100 confirmed D100 NB-R image Yagi et al. 2007

  34. Suprime-Cam Coma Cluster Ha Imaging Survey • >10 such faint extended emission line regions are found for 3 FoV in the Coma cluster (e.g. RB199, Yoshida et al 2008) • How rare? • Dependence on environment ? • Morphology/Star formation property of host galaxy ? • Role on galaxy evolution ? • HSC : • HSC is a powerful tool to survey such faint emission line regions • Understand the environmental effect on the galaxy evolution in dense clusters RB199 (Yoshida et al. 2008)

  35. Summary • Structure of nearby galaxies • M31 and out to galaxies in nearby groups • Structure of the Galaxy • Search substructures beyond ~100kpc • Halo structure traced by RRLyr • WDs  age of the Galaxy, IMF • Ultra faint dwarf galaxies • M>8mag dwarf galaxies around M31 • Missing satellite problem • Low surface brightness universe • Outskirts of local galaxies • Local galaxy clusters These topics are expected based on our experiences of SDSS/Suprime-Cam. Unexpected and exciting findings will be brought by HSC.