MOAIIプロジェクトステータス

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
Gravitational “Micro”lensing
star
arcsec.
lens
 If a lens is a size of a star,
elongation of images is an
order of 100arcsec.
 Just see a star magnified
observer
distortion of space due to gravity
Plastic lens
Single lens
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)
WMAP result
Dark energy
=0.74
Dark matter
DM=0.22
B=0.04
Baryon 4%:
Stars:
7%
Neutral gas:
2%
Cluster hot gas:
3%
Unknown (warm gas?): 88%
Galactic rotation curve & dark11matter
M~3x10 M(R<100kpc
)
Dark Matter
Kepler: v2=GM/r
Halo Dark Matter & Paczynski’s Idea
 20〜40 times more dark matter than visible mass.
（Paczynski 1986)
 MAssive Compact Halo Objects (MACHOs）  WINPs
•MACHO can be observed by Microlensing.
•〜１０−６ 
need to observe 1M stars！
MACHO project (1990~2000)
Mt. Stromlo
1.28m telescope
12 million stars
First Microlensing event
by MACHO & EROS in 1993
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
That is:
• MACHOs are not major component of Galactic
halo dark matter
but
MACHOs exist as many as visible objects!?
Degeneracy in parameters
Einstein crossing time：
RE (M,D)
tE 
vt
Bottom line:
• There are lens objects towards LMC
but
Are they really in the halo?
Halo Dark Matter?
or
Self-lensing?
MEGA
project
Andromeda galaxy（M31）
 results（preliminary)：
 14 events
Far side
 f<30%
SuperMACHO
 4m telescope, 1/2 nights for 3 months over 5 years. ~30events
LMC
Event rate
Self-lensing in LMC
Halo MACHO
Center
Outer
results（preliminary）：
25events (microling+SN)
Self-lensing is negligible
f<30%
SuperMACHO
v.s.
Super Nova
MOA (since 1995)
（Microlensing Observation in Astrophysics）
（ New Zealand/Mt. John Observatory, Latitude： 44S, Alt:
1029m ）
New Zealand
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youwant
wanttotovisit
visitNZ
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contact:
contact:[email protected]
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MOA (until ~1500)
（the world largest bird in NZ）
 height:3.5ｍ
 weight:240kg
 can not fly
 Extinct 500 years ago
（Maori ate them)
MOA-II 1.8m telescope
Mirror : 1.8m
CCD : 80M pix.
FOV : 2.2 deg.2
First light:
2005/3
Survey start: 2006/4
Observational targets
event rate:
LMC,SMC :
~2 events/yr (~10-7 )
~500events/yr (~10-6 )
Bulge
:
Planetary event : ~10-2
８kpc, GC

50kpc
LMC
Observation towards LMC by MOA-II
~3obs/night
~10obs/night
Difference Image Analysis (DIA)
Observed
subtracted
Other constraints on MACHOs
Gravitational microlensing:
 EROS and MACHO (LMC)
 Variability in lensed QSO
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
 impact on Earth
10-3<M
M<10-13 halo
M<10-12 disk
Microlensing of QSOs
image A
macrolens
QSO
image B
microlenses
SUb-Lunar-mass Compact Objects (SULCOs)
-14
-12
-10
Log(CO)
0
-1
-2
g
-8 Log(M/Ms)
Unconstrained
Black hole annihilation
CDM = SULCOs 10-16<M<10-7 ?
MACHO
-16
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
Two windows
SUb-Lunar-mass
Compact Objects
（SULCO）
MAssive Stellar-mass
Compact Objects
(MASCO)
(10-13) <M<10-7 M
102 <M< 104M
planetesimal, PBH
primordial stars, BH,
PBH
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)
Galactic center
Galactic Bar
θ
8kpc
de Vaucouleur,1964,
gas kinematics
Blitz&Spergel,1991, 2.4 m
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
COBE-DIRBE
all
 10  b  10
Weiland et al.,1994,
confirmed the asymmetry.
extinction correct
disk subtracted
 30  l  30
Optical Gravitational Lensing Experiment
(OGLE)
Las Campanas
Altitude: 2300m
Seeing ~ 1.3”
(2900' S ,70 42' E)
OGLE-I : 1991~1996
: 1m, 2kx2k CCD
OGLE-II : 1997~2000
: 1.3m, 2kx2k CCD, 14’x14’
OGLE-III: 2001~
: 1.3m, 8kx8k mosaic CCD
: 35’x35’
19 events
500 events
600 events/yr
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
1,the Galactic Bar structure
(face on, from North)
8kpc


Obs.
G.C.
1,the Galactic Bar structure
(face on, from North)
8kpc


Obs.
G.C.
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
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
RCG by IR
(Babusiaux & Gilmore, 2005)
Deep survery by Cambridge IR
survery instrument (CIRSI)
=225.5
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
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
observation
Halo+disk
disk
Halo
ρ∝r-α
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？
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)
Simulation: Collisionless CMD reproduces
nicely the observed large scale structure
of the universe (r>>1Mpc)
Log(radius)
Density profile of Milky way (Sofue et al. 2009)
NFW(cusp)
Burkert(core)
disk
Isothermal(core)
bulge
Cusp-core problem in dwarf spirals to giant
low surface brightness galaxies (CDM dominated in center)
rotation curve of dwarf spiral DDO47
Dark halo density in ESO 116+G12
Observed
simulation (NFW)
Cusp (NFW)
Core
Prefer core
(Moore et al. 1999; de Blok et al. 2000; Salucci & Burkert 2000;Salucci&Martin 2009)
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
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)
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)
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?).
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)
Burkert(core)
Isothermal(core)
(Sufue et al. 2009)
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
Microlensing by SULCOs in Galactic halo
M33
DM33 = 790kpc
DLMC = 50kpc
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
MASCOs M=103 if MASCO=m
2.5mas
N=1.7(M/104)-1 mas-2
A
B
C
D
Inoue & Chiba ApJ ’03
Distribution of surface brightness
resolution＝0.025mas

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