Study of the Galactic structure and halo dark

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 G If a lens is a size of a star, elongation of images is an order of 100 arcsec. G Just see a star magnified observer distortion of space due to gravity

Plastic lens

Single lens

Application of microlensing l Extra galactic　 1, halo dark matter of lens galaxy(QSO variability） l 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 & dark 11 matter M~3 x 10 M (R<100 kpc) Dark Matter Kepler: v 2=GM/r

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

MACHO project Mt. Stromlo 1. 28 m telescope (1990~2000) 12 million stars

First Microlensing event by MACHO & EROS in 1993

results toward LMC MACHO 5. 7 yrs: 12 events M~0. 5 M 16% of the mass of a Standard Galactic halo. EROS 5 yrs : 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. 4 M f<11% for 0. 003 -0. 2 M 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：

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（M 31） Far side l results（preliminary)： l 14 events l f<30%

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

Super. MACHO v. s. Super Nova

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

New Zealand If. Ifyou youwanttotovisit. NZ NZfree, jointoto. MOA contact: sumi@stelab. nagoya-u. ac. jp

MOA (until ~1500) （the world largest bird in NZ） l height: 3. 5ｍ l weight: 240 kg l can not fly l Extinct 500 years ago （Maori ate them)

MOA-II 1. 8 m telescope Mirror : 1. 8 m CCD : 80 M 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 ) ~500 events/yr ( ~10 -6 ) Bulge : 　　Planetary event : ~10 -2 ８ kpc, GC 50 kpc LMC

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

Difference Image Analysis (DIA) Observed subtracted

Other constraints on MACHOs Gravitational microlensing: u EROS and MACHO (LMC) u Variability in lensed QSO Excluded (in M ): Schmidt et al ’ 98 10 -7 <M< 10 -1 Dynamical constraint (Carr & Sakellariadou ’ 99) Requiring an universality of the Galaxy! u open & globular clusters u binary stars u solar system objects u impact on Earth 103 <M<106 100 <M<107 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(WCO) 0 -1 -2 g -8 Log(M/Ms) MACHO -16 Unconstrained Black hole annihilation -16 -7 CDM = SULCOs 10 <M<10 ?

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< 104 M planetesimal, PBH primordial stars, BH, PBH

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

Galactic center

Galactic Bar θ 8 kpc lde Vaucouleur, 1964, gas kinematics l. Blitz&Spergel, 1991, 2. 4 IR luminosity asymmetry l. Weiland et al. , 1994, COBE-DIRBE, confirmed the asymmetry. l. Nakada et al. , 1991, 　 distribution of IRAS bulge stars l. Whitelock&Catchpole, 1992, distribution of Mira l. Kiraga &Paczynski, 1994 Microlening Optical depth

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

Optical Gravitational Lensing Experiment (OGLE) Las Campanas Altitude: 2300 m Seeing ~ 1. 3” OGLE-I : 1991~1996 : 1 m, 2 kx 2 k CCD OGLE-II : 1997~2000 : 1. 3 m, 2 kx 2 k CCD, 14’x 14’ OGLE-III: 2001~ : 1. 3 m, 8 kx 8 k mosaic CCD : 35’x 35’ 19 events 500 events 600 events/yr

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

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

1, the Galactic Bar structure (face on, from North) 8 kpc 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 1010 M , axis ratio (1: 0. 3: 0. 2), ~20

2. Red Clump Giants G Metal-rich horizontal branch stars G Small intrinsic width in luminosity function (~0. 2 mag) =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=~50 km/s Sumi, Eyer & Wozniak, 2003

summary２ G All three results are consistent with the Bar with G G M=1. 6 1010 M (Md=0. 7 x 1010) axis ratio (1: 0. 3: 0. 2) =20 , (Han & Gould, 1995) Vrot~50 km/s 　 • Little space for Dark Matter • Prefer Core than cusp dark matter (Binney &　Evans 2001) MOA-II constrain stronger observation Halo+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) Log(density) Simulation: Collisionless CMD reproduces nicely the observed large scale structure of the universe (r>>1 Mpc) 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(radius)

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

Cusp-core problem in dwarf spirals to giant low surface brightness galaxies (CDM dominated in center) rotation curve of dwarf spiral DDO 47 Dark halo density in ESO 116+G 12 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 image in 0047 -281 (Koopmans 2003) Observed galaxy subtracted Lensing probability with image separation Δθ (Lin & Chen 2009) 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, 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) l. 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~1 cm 2/g (10 -(21− 24) cm 2 (Mx/Ge. V)) 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. 8 x 1010 M , Rbulge=0. 5 kpc Mdisk=7 x 1010 M , Rdisk=3. 5 kpc Truncated Isothermal dark halo with h= 5. 5 kpc, vrot=200 km/s NFW(cusp) Burkert(core) Isothermal(core) (Sufue et al. 2009)

Summary l 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 l dark matter density profile in the galaxy may be core rather than cusp microlensing contribute to constrain

Microlensing by SULCOs in Galactic halo M 33 DM 33 = 790 kpc DLMC = 50 kpc Small source size 8*10 -9 (star radius /106 km) arcsec (Total event) ~103 for 10 -8 Ms, DT~103 sec 　　　　　　　~1 for 10 -11 Ms , DT~1 sec For 80 hours obs. by SUBARU/Suprime-cam

MASCOs M=103 if WMASCO=Wm 2. 5 mas N=1. 7(M/104)-1 mas-2 A B C D Inoue & Chiba Ap. J ’ 03

Distribution of surface brightness resolution＝ 0. 025 mas