takahiro sumi ste lab., nagoya university
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Study of the Galactic structure and halo dark matter by
Gravitational microlensing
Takahiro Sumi STE lab., Nagoya University
•Galactic haloGalactic halo
•Galactic centerGalactic center
Gravitational “Macro”lensing
Gravitational “Macro”lensing
Gravitational “Micro”lensing
starstar
observerobserver lenslens
distortion of space due to gravity distortion of space due to gravity
arcsec.arcsec. If a lens is a size of a star, elongation of images is an order of 100arcsec.
Just see a star magnified
Plastic lensPlastic lens
Single lensSingle lens
Application of Application of microlensingmicrolensing
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 resultWMAP result
Dark Dark mattermatter DMDM=0.22=0.22 Baryon 4%:Baryon 4%:
Stars: 7%
Neutral gas: 2%
Cluster hot gas: 3%
Unknown (warm gas?): 88%
Dark energy Dark energy =0.74=0.74
BB=0.04=0.04
Galactic rotation curve & dark matter
Kepler: v2=GM/r
Dark Matter
M~3x1011M(R<100kpc)
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!
( Paczynski 1986)
MACHO project (1990~2000)
12 million stars Mt. Stromlo 1.28m telescope
First Microlensing event by MACHO & EROS in 1993
results toward LMC
Tisserand et al.2006
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)
That is:
• MACHOs are not major component of Galactic halo dark matter
MACHOs exist as many as visible objects!?
but
Degeneracy in parameters
tE RE (M,D)v t
Einstein crossing time :
Bottom line:
• There are lens objects towards LMC
Are they really in the halo?
but
Halo Dark Matter?or
Self-lensing?
MEGAMEGA projectproject
results( preliminary) :
14 eventsf<30%
Andromeda galaxy ( M31 )
Far side
SuperMACHO 4m telescope, 1/2 nights for 3 months over 5 years. ~30events
Center OuterCenter OuterE
vent
rate
Eve
nt ra
te
Halo MACHOHalo MACHO
Self-lensing in LMCSelf-lensing in LMC
results ( preliminary ):25events (microling+SN)Self-lensing is negligiblef<30%
LMC
SuperMACHOv.s.
Super Nova
MOA (since 1995)
( Microlensing Observation in Astrophysics)
( New Zealand/Mt. John Observatory, Latitude: 44S, Alt: 1029m )
If you want to visit NZ free, join to MOA If you want to visit NZ free, join to MOA contact: contact: sumi@stelab.nagoya-u.ac.jp
New Zealand
If you want to visit NZ free, join to MOA If you want to visit NZ free, join to MOA contact: contact: sumi@stelab.nagoya-u.ac.jp
MOA (until ~1500) ( the world largest bird in NZ)
height:3.5height:3.5 mmweight:240kgweight:240kgcan not flycan not flyExtinct 500 years Extinct 500 years agoago
(( MaoriMaori ate ate them)them)
MOA-II 1.8m telescope
First light: First light: 2005/32005/3Survey start:Survey start: 2006/42006/4
Mirror : 1.8mCCD : 80M pix. FOV : 2.2 deg.2
Observational targets
LMCLMC
50kpc50kpc
event rate:event rate: LMC,SMC : LMC,SMC : ~2~2 events/yr (events/yr (~10~10-7-7 ))
Bulge : Bulge : ~500~500events/yr (events/yr (~10~10-6-6 )) Planetary event : Planetary event : ~10~10-2-2
88 kpc, GCkpc, GC
Observation towards LMC by MOA-II
~3obs/night~3obs/night
~10obs/night~10obs/night
Difference Image Analysis (DIA)
Observed Observed subtractedsubtracted
Dynamical constraint Dynamical constraint ((Carr & Sakellariadou ’99Carr & Sakellariadou ’99))
open & globular clusters open & globular clusters 10103 3 <M<10<M<1066
binary stars binary stars 101000 <M<10 <M<107 7
solar system objects 1010-3-3<M <M
impact on EarthEarth M<10M<10-13-13 halo halo M<10M<10-12 -12 disk disk
Requiring an universality of the Galaxy!Requiring an universality of the Galaxy!
Variability in lensed QSO Variability in lensed QSO EROS and MACHO (LMC)EROS and MACHO (LMC)
Schmidt et al ’98 Schmidt et al ’98 Excluded (in MExcluded (in M):):1010-7-7 <M< <M< 1010-1-1
Gravitational microlensingGravitational microlensing::
Other constraints on MACHOsOther constraints on MACHOs
Microlensing of QSOs
QSOmacrolens
microlenses
image A
image B
SUb-Lunar-mass Compact Objects (SULCOs)
-16 -14 -12 -10 -80
-1
-2
Log(M/Ms)
Log
CO
MACHOUnconstrained
CDM = SULCOs 10-16<M<10-7 ? Black hole annihilation
Current limit on compact objects Current limit on compact objects in universe from lensing studiesin 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
Constraint on MACHOs in cosmologyConstraint on MACHOs in cosmology
(10-13) <M<10-7 M
SUb-Lunar-mass Compact Objects
( SULCO )
planetesimal, PBH
MAssive Stellar-massCompact Objects
(MASCO)
102 <M< 104M
primordial stars, BH, PBH
Two windows
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 centerGalactic center
Galactic Bar
de Vaucouleur,1964, gas kinematicsBlitz&Spergel,1991, 2.4 IR luminosity asymmetryWeiland et al.,1994, COBE-DIRBE,confirmed the asymmetry.Nakada et al.,1991, distribution of IRAS bulge starsWhitelock&Catchpole, 1992, distribution of MiraKiraga &Paczynski,1994 Microlening Optical depth
m
θ
8kpc
COBE-DIRBE Weiland et al.,1994, confirmed the asymmetry.
3030 l
all extinction correct disk subtracted
1010 b
Optical Gravitational Optical Gravitational Lensing ExperimentLensing Experiment
(OGLE)(OGLE)Las Campanas Altitude: 2300mSeeing ~ 1.3”
)'4270,'0029( ES
OGLE-I : 1991~1996 : 1m, 2kx2k CCD 19 eventsOGLE-II : 1997~2000 : 1.3m, 2kx2k CCD, 14’x14’ 500 eventsOGLE-III: 2001~ : 1.3m, 8kx8k mosaic CCD 600 events/yr : 35’x35’
Pieces of informationMicrolensing 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
G.C.Obs.
1,the Galactic Bar structure
(face on, from North)
8kpc
G.C.Obs.
1, 1, Microlensing Optical depth, Microlensing Optical depth, (Alcock et al. 2000; Afonso et al.2003; Sumi et al. 2003;Popowski (Alcock et al. 2000; Afonso et al.2003; Sumi et al. 2003;Popowski et al. 2004; et al. 2004; HamadacheHamadache et al. 2006;Sumi et al. 2006) et al. 2006;Sumi et al. 2006)
M=1.61010M,
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)
Stanek et al. 1997=20-30=20-30, axis ratio 1:0.4:0.3, axis ratio 1:0.4:0.3
RCG by IR (Babusiaux & Gilmore, 2005)
Deep survery by Cambridge IR survery instrument (CIRSI)
=225.5
3.Streaming motions of the bar with RCG
Sumi (Princeton) , Eyer (Geneva Obs.) & Wozniak (Los Alamos), 2003
Sun
faint
Vrot=~50km/s
Color Magnitude Diagram
Sumi, Eyer & Wozniak, 2003
bright
summary2All three results are consistent with the Bar with
M=1.61010M(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 strongerρ r∝ -α
observation Halo+disk
Halo
disk
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 dominatedDwarf and low surface brightness (LSB)galaxieshigh surface brightness disc galaxies (Salucci 2001) have a density profile with flat central core.
Cusp-Core problem in cold dark matter (CDM) halo
Log(radius)
Log(
dens
ity)
Density profile of Milky way (Sofue et al. 2009)
disk
bulge
NFW(cusp)
Isothermal(core)
Burkert(core)
(Moore et al. 1999; de Blok et al. 2000; Salucci & Burkert 2000;Salucci&Martin 2009)
Dark halo density in ESO 116+G12Observed simulation (NFW)
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
Prefer core
Lensing probability with image separation Δθ (Lin & Chen 2009)
Lensing image in 0047-281 (Koopmans 2003)
Observed galaxy subtracted
Cusp-core problem in giant elliptical galaxies;(Baryon dominated in center )
Core
Prefer cusp
Cusp, ρ r ∝ -1.9
Observation
Cusp (NFW)
Singular isothermal sphere
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:solutionSelf 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; largerinteraction leads to halo core collapse onHubble time (e.g., Moore et al. 2000, 2002; Yoshidaet 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?).
Mbulge=1.8x1010M, Rbulge=0.5kpcMdisk=7x1010M , Rdisk=3.5kpcTruncated Isothermal dark halo with h= 5.5kpc, vrot=200km/s
the Milky Way rotation curve (HI,CO,optical, VERA)
NFW(cusp)
Isothermal(core)
Burkert(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
DM33 = 790kpc
Small source size 8*10-9 (star radius /106 km) arcsec
DLMC = 50kpc
M33
(Total event) ~103 for 10-8Ms, sec ~1 for 10-11Ms , secFor 80hours obs. by SUBARU/Suprime-cam
A B
C D
MASCOs M=103 if MASCO=m
2.5mas
N=1.7(M/104)-1 mas-2 Inoue & Chiba ApJ ’03
Distribution of surface brightness
resolution= 0.025mas
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