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Study of the Galactic structure and halo dark matter by Gravitational microlensing

Study of the Galactic structure and halo dark matter by Gravitational microlensing. Galactic halo Galactic center. Takahiro Sumi STE lab., Nagoya University. Gravitational “Macro”lensing. Gravitational “Macro”lensing.  arcsec. Gravitational “Micro”lensing. star.

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Study of the Galactic structure and halo dark matter by Gravitational microlensing

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  1. Study of the Galactic structure and halo dark matter by Gravitational microlensing • Galactic halo • Galactic center Takahiro Sumi STE lab., Nagoya University

  2. Gravitational “Macro”lensing

  3. Gravitational “Macro”lensing

  4. arcsec. Gravitational “Micro”lensing star • If a lens is a size of a star, elongation of images is an order of 100arcsec. • Just see a star magnified lens observer distortion of space due to gravity

  5. Plastic lens

  6. Single lens

  7. Application of microlensing • Extra galactic 1,halo dark matter of lens galaxy(QSO variability） • Galactic 1,Galactic halo dark matter(towards the LMC ＆ SMC) 2,Galactic center structure (towards the Bulge) 3,exoplanet (towards the Bulge)

  8. WMAP result Dark energy =0.74 Dark matter DM=0.22 • Baryon 4%: • Stars: 7% • Neutral gas: 2% • Cluster hot gas: 3% • Unknown (warm gas?): 88% B=0.04

  9. Galactic rotation curve & dark matter M~3x1011M(R<100kpc) Dark Matter Kepler: v2=GM/r

  10. Halo Dark Matter & Paczynski’s Idea （Paczynski 1986) • 20〜40 times more dark matter than visible mass. • MAssive Compact Halo Objects (MACHOs） WINPs • MACHO can be observed by Microlensing. • 〜１０−６ need to observe 1M stars！

  11. MACHO project (1990~2000) Mt. Stromlo 1.28m telescope 12 million stars

  12. First Microlensing event by MACHO & EROS in 1993

  13. results toward LMC MACHO 5.7 yrs: 12 events M~0.5M 16% of the mass of a Standard Galactic halo. EROS 5yrs : 0 event f<25% of the halo dark matter made of MACHO with 10-7-10 M f< 10% for 3.5×10-7 -100 M OGLE-II 4 year: 3 event (1 in SMC) f<20% for 0.4M f<11% for 0.003-0.2M OGLE-II (Wyrzykowski et al.2010) Tisserand et al.2006

  14. That is: • MACHOs are not major component of Galactic halo dark matter but MACHOs exist as many as visible objects!?

  15. Degeneracy in parameters Einstein crossing time：

  16. Bottom line: • There are lens objects towards LMC but Are they really in the halo?

  17. Halo Dark Matter?orSelf-lensing?

  18. MEGAproject Andromeda galaxy（M31） • results（preliminary)： • 14 events • f<30% Far side

  19. SuperMACHO • 4m telescope,1/2 nights for 3 months over 5 years. ~30events LMC Self-lensing in LMC Event rate Halo MACHO Center Outer results（preliminary）： 25events (microling+SN) Self-lensing is negligible f<30%

  20. SuperMACHOv.s.Super Nova

  21. MOA (since 1995)（Microlensing Observation in Astrophysics）（ New Zealand/Mt. John Observatory, Latitude： 44S, Alt: 1029m）

  22. New Zealand If you want to visit NZ free, join to MOA contact: sumi@stelab.nagoya-u.ac.jp If you want to visit NZ free, join to MOA contact: sumi@stelab.nagoya-u.ac.jp

  23. MOA (until ~1500)（the world largest bird in NZ） • height:3.5ｍ • weight:240kg • can not fly • Extinct 500 years ago （Maori ate them)

  24. MOA-II 1.8m telescope Mirror : 1.8m CCD : 80M pix. FOV : 2.2 deg.2 First light: 　　2005/3 Survey start:2006/4

  25. ８kpc, GC 50kpc LMC event rate: LMC,SMC : ~2events/yr (~10-7) Bulge : ~500events/yr (~10-6) Planetary event : ~10-2 Observational targets 

  26. Observation towards LMC by MOA-II ~3obs/night ~10obs/night

  27. subtracted Difference Image Analysis (DIA) Observed

  28. open & globular clusters 103 <M<106 • solar system objects 10-3<M • EROS and MACHO (LMC) • Variability in lensed QSO Schmidt et al ’98 Other constraints on MACHOs Gravitational microlensing: Excluded (in M): 10-7 <M< 10-1 Dynamical constraint (Carr & Sakellariadou ’99) Requiring an universality of the Galaxy! • binary stars 100 <M<107 M<10-13 halo M<10-12 disk • impact on Earth

  29. Microlensing of QSOs image A macrolens QSO image B microlenses

  30. -16 -14 -12 -10 -8 0 -1 -2 MACHO SUb-Lunar-mass Compact Objects (SULCOs) Log(M/Ms) Log(WCO) Unconstrained g Black hole annihilation CDM = SULCOs10-16<M<10-7 ?

  31. Constraint on MACHOs in cosmology Current limit on compact objects in universe from lensing studies • (1)microlensing of QSO Dalcanton, et al ’94 • (2,4)multiple image of compact radio sources.Wilkinson et al ’01 Augusto ’01 • (3)multiple gamma-ray bursts Nemiroff et al ’01 • (5)multiple image of QSO Nemiroff 91

  32. SUb-Lunar-mass Compact Objects （SULCO） MAssive Stellar-mass Compact Objects (MASCO) (10-13)<M<10-7 M 102 <M< 104M primordial stars, BH, PBH planetesimal, PBH Two windows

  33. Summary 1 • MACHOs are not major component of Galactic halo dark matter (<20%) • There are lens objects towards LMC • Are they really in the halo? • MOA-II is trying to solve this problem • Two windows for MACHOs (SULCO,MASCO)

  34. Galactic center

  35. Galactic Bar • de Vaucouleur,1964, gas kinematics • Blitz&Spergel,1991, 2.4 IR luminosity asymmetry • Weiland et al.,1994, COBE-DIRBE,confirmed the asymmetry. • Nakada et al.,1991, distribution of IRAS bulge stars • Whitelock&Catchpole, 1992, distribution of Mira • Kiraga &Paczynski,1994 Microlening Optical depth θ 8kpc

  36. Weiland et al.,1994, confirmed the asymmetry. COBE-DIRBE all extinction correct disk subtracted

  37. Las Campanas Altitude: 2300m Seeing ~ 1.3” Optical Gravitational Lensing Experiment(OGLE) OGLE-I : 1991~1996 : 1m, 2kx2k CCD 19 events OGLE-II : 1997~2000 : 1.3m, 2kx2k CCD, 14’x14’ 500 events OGLE-III: 2001~ : 1.3m, 8kx8k mosaic CCD 600 events/yr : 35’x35’

  38. Pieces of information • Microlensing Optical depth,  and Event Timescale, tE=RE/Vt, (Sumi et al. 2006) • Brightness of Red Clump Giant (RCG) and RRLyrae stars, (Stanek et al. 1997, Sumi 2004; Collinge, Sumi & Fabrycky, 2006) • Proper motions of RCG, (Sumi, Eyer & Wozniak, 2003; Sumi et al. 2004), Proper motion of 5M stars, I<18 mag, ~1mas/yr

  39. 8kpc   Obs. G.C. (face on, from North) 1,the Galactic Bar structure

  40. 8kpc   Obs. G.C. (face on, from North) 1,the Galactic Bar structure 1, Microlensing Optical depth,  (Alcock et al. 2000; Afonso et al.2003; Sumi et al. 2003;Popowski et al. 2004; Hamadache et al. 2006;Sumi et al. 2006) M=1.61010M, axis ratio (1:0.3:0.2), ~20

  41. 2.Red Clump Giants • Metal-rich horizontal branch stars • Small intrinsic width in luminosity function (~0.2mag) =20-30, axis ratio 1:0.4:0.3 Stanek et al. 1997

  42. RCG by IR (Babusiaux & Gilmore, 2005) Deep survery by Cambridge IR survery instrument (CIRSI) =225.5

  43. 3.Streaming motions of the bar with RCGSumi (Princeton) , Eyer (Geneva Obs.) & Wozniak (Los Alamos), 2003 Sun Color Magnitude Diagram faint bright Vrot=~50km/s Sumi, Eyer & Wozniak, 2003

  44. summary２ observation Halo+disk • All three results are consistent with the Bar with • M=1.61010M(Md=0.7x1010) • axis ratio (1:0.3:0.2) • =20, (Han & Gould, 1995) • Vrot~50km/s disk Halo •  • Little space for Dark Matter • Prefer Core than cusp • dark matter • (Binney &　Evans 2001) MOA-II constrain stronger ρ∝r-α

  45. Cusp-Core problem in cold dark matter (CDM) halo Dark matter density profile at center of galaxy & galaxy cluster： Cusp: ρ∝r -1.5 or Core: ρ∝const？ Simulation: Collisionless CMD reproduces nicely the observed large scale structure of the universe (r>>1Mpc) NFW universal density profile ρ∝r-1.5 with central cusp (Navarro, Frenk& White 1997) Observation: rotation curve for CDM dominated Dwarf and low surface brightness (LSB)galaxies high surface brightness disc galaxies (Salucci 2001) have a density profile with flat central core. Log(density) Log(radius)

  46. Density profile of Milky way (Sofue et al. 2009) NFW(cusp) Burkert(core) disk Isothermal(core) bulge

  47. Cusp-core problem in dwarf spirals to giant low surface brightness galaxies (CDM dominated in center) Dark halo density in ESO 116+G12 Observed simulation (NFW) rotation curve of dwarf spiral DDO47 Cusp (NFW) Core Prefer core (Moore et al. 1999; de Blok et al. 2000; Salucci & Burkert 2000;Salucci&Martin 2009)

  48. Cusp-core problem in giant elliptical galaxies; (Baryon dominated in center ) Lensing probability with image separation Δθ (Lin & Chen 2009) Lensing image in 0047-281 (Koopmans 2003) Observed galaxy subtracted Singular isothermal sphere Observation Cusp (NFW) Cusp, ρ∝r -1.9 Core Prefer cusp

  49. Cusp-core problem in giant elliptical galaxies & galaxy cluster; (Baryon dominated in center ) • Statistics of QSO multiple images • (Wyithe Wyithe, Turner & , Spergel 2001; Keeton & Madau 2001; • Li & Ostriker 2001; Takahashi & Chiba 2001) • Arc statistics of clusters of galaxies • (Bartelmann et al. 1998; Molikawa & Hattori 2001; • Oguri , Taruya + Suto 2001, Oguri, Lee + Suto 2003) • Time-delay statistics of QSO multiple images • (Oguri, Taruya, Suto + Turner 2002) • X-ray observation of galaxy cluster • ⇒ generally favor a steep cusp ( α～ －1.5)

  50. Cusp-core problem:solution Self interacting dark matter(Spergel & Steinhardt 1999 ): σ/m~1cm2/g (10-(21−24) cm2 (Mx/GeV)) make core and spherical halo(Yoshida etal. 2000) Weaker interaction doesn’t work; larger interaction leads to halo core collapse on Hubble time (e.g., Moore et al. 2000, 2002; Yoshida et al. 2002; Burkert 2000; Kochanek & White 2000)

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