1. Takahiro Sumi STE lab., Nagoya University
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. Gravitational “Micro”lensing
star
arcsec.
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: %
Neutral gas: %
Cluster hot gas: %
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
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 OGLE-II 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 M
f< 10% for
3.5× M
OGLE-II 4 year: 3 event (1 in SMC)
f<20% for 0.4M
f<11% for M
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: but There are lens objects towards LMC
Are they really in the halo?

17. Halo Dark Matter? or Self-lensing?

18. MEGA project results（preliminary)： 14 events f<30%
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. SuperMACHO v.s. Super Nova

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

22. New Zealand If you want to visit NZ free, join to MOA
contact:
If you want to visit NZ free, join to MOA
contact:

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

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

27. Difference Image Analysis (DIA)
Observed
subtracted

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

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

30. CDM = SULCOs 10-16<M<10-7 ?
SUb-Lunar-mass Compact Objects (SULCOs)
-16
-14
-12
-10 -8 -1 -2
Log(M/Ms)
MACHO
Log(WCO)
Unconstrained g
Black hole annihilation
CDM = SULCOs 10-16<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. Two windows (10-13) <M<10-7 M primordial stars, BH,
SUb-Lunar-mass
Compact Objects
（SULCO）
planetesimal, PBH
MAssive Stellar-mass
Compact Objects
(MASCO)
102 <M< 104M
primordial stars, BH,
PBH

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

37. Optical Gravitational Lensing Experiment (OGLE)
Las Campanas
Altitude: 2300m
Seeing ~ 1.3”
OGLE-I : 1991~1996
: 1m, 2kx2k CCD events
OGLE-II : 1997~2000
: 1.3m, 2kx2k CCD, 14’x14’ events
OGLE-III: 2001~
: 1.3m, 8kx8k mosaic CCD 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. 1,the Galactic Bar structure
(face on, from North) 
8kpc 
G.C.
Obs.

40. 1,the Galactic Bar structure
(face on, from North) 
8kpc 
G.C.
Obs.
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 RCG Sumi (Princeton) , Eyer (Geneva Obs.) & Wozniak (Los Alamos), 2003
Sun
Color Magnitude Diagram
faint
bright
Vrot=~50km/s
Sumi, Eyer & Wozniak, 2003

44. summary２ 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
　 
Little space for Dark Matter
Prefer Core than cusp
dark matter
(Binney &　Evans 2001)
MOA-II constrain stronger
ρ∝r-α
observation
Halo+disk
Halo
disk

45. Cusp-Core problem in cold dark matter (CDM) halo
Dark matter density profile at center of galaxy & galaxy cluster：
Cusp: ρ∝r 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)
disk
bulge
NFW(cusp)
Isothermal(core)
Burkert(core)

47. Cusp-core problem in dwarf spirals to giant
low surface brightness galaxies (CDM dominated in center)
rotation curve of dwarf spiral DDO47
Cusp (NFW)
Core
Dark halo density in ESO 116+G12
Observed simulation (NFW)
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 (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)

51. Cusp-core problem: solution
Barion-CDM interaction (BCDMIs)
Dynamical friction of substructure
(El-Zant et al.2001;Tonini et al., 2006;Romano-Diaz et al.2008)
Stellar bar-CDM interaction (Weinberg&Katz, 2002;Holley-Beckelmann et al.2005)
Baryon energy fedback(Mashchenko et al., 2006; Peirani et al. 2008)
Nonsingular, trancated isothermal sphere (NTIS)
Cosmological, from collapsend virialization (shapiro et al. 1999; Iliev&Shapiro, 2001)
Explain core in rotation curves, but cannot explain the
steep & cuspy center of massive galaxies favored by
Lensing and X-ray observation (just seeing cuspy baryon?).

52. the Milky Way rotation curve (HI,CO,optical, VERA)
Mbulge=1.8x1010M, Rbulge=0.5kpc
Mdisk=7x1010M , Rdisk=3.5kpc
Truncated Isothermal dark halo with h= 5.5kpc, vrot=200km/s
NFW(cusp)
Isothermal(core)
Burkert(core)
(Sufue et al. 2009)

53. MACHOs are not major component of Galactic halo dark matter (<20%)
Summary
MACHOs are not major component of Galactic halo dark matter (<20%)
except two windows (SULCO, MASCO)
but there are lens objects towards LMC, important for astrophysical point of view
dark matter density profile in the galaxy may be core rather than cusp
microlensing contribute to constrain

55. (Total event) ~103 for 10-8Ms, DT~103sec
Microlensing by SULCOs in Galactic halo
M33
DM33 = 790kpc
DLMC = 50kpc で
Small source size 8*10-9 (star radius /106 km) arcsec
(Total event) ~103 for 10-8Ms, DT~103sec
　　　　　　　~1 for 10-11Ms , DT~1sec
For 80hours obs. by SUBARU/Suprime-cam

56. A B C D MASCOs M=103 if WMASCO=Wm 2.5mas N=1.7(M/104)-1 mas-2
Inoue & Chiba ApJ ’03

57. Distribution of surface brightness
resolution＝0.025mas