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Grand Rotation Curves & Galactic Roche Lobes in the Galaxy and M31 Yoshiaki Sofue (Meisei Uni.) at Meisei University
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Contents 1. Rotation Curve 2. Mass models 3. Grand RC 4
Contents 1. Rotation Curve 2. Mass models 3. Grand RC 4. Local DM Density 5. Roche Lobes Galactic Territory
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1. Rotation Curve
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銀河中心
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inside/outside Solar Circle
Rotation velocities inside/outside Solar Circle
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Define: Vrot =Vvirial≒ √2 VGC
Rotation curve at R>30 kpc assuming random motion of satellite galaxies Define: Vrot =Vvirial≒ √2 VGC
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Solar Circular Velocity V0=200 km/s @ R0=8kpc
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2. Mass Model
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RC Fitting by (1) Bulge: de Vaucouleurs Law (2) Disk: Exponential
(3) Dark Halo: NFW
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de V ∝ exp(-r1/4) Expo. Plummer Kepler
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(1) Bulge de Vaucouleurs: exp(-r1/4)
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Mass models: Bulge: de Vaucouleurs (r1/4)
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(2) Exponential Disk +Arm/Ring
(If Δ=0, V(R)=written by modified Bessel functions)
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Disk: Exponential
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(3) Dark Halo Density Profile (Navaro-Frenk-White 1994)
NFW Profile (Navaro-Frenk-White 1994)
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Volume Densities for Bulge, Disk, and Halo(Isoth, NFW, Burkert)
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Sofue, Honma, Omodaka 2009
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Total Masses Dark Halo Expo. Disk de Vaucl. Bulge
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3. Grand Rotation Curve
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Dark Halo Density Profiles
(X=R/h) NFW density ∝ 1/X(1+X) 2 (Navaro-Frenk-White 1994) Burkert ∝ 1/(1+X)(1+X2) Isothermal ∝ 1/(1+X2) =>X-2
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Local Group of Galaxies
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Grand Rotation Curve Sattelite’s velocity =>Virial Mass V(R)=√2 Vr
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Solar Circular Velocity V0=200 km/s @ R0=8kpc
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Grand RC
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MW ⇔ M31 border de V. Bulge Milky Way GRC Expo. Disk NFW Halo
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4. Galaxy Parameters & Locad DM Density
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Dispersion Scale radius fit Mass fit
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The Local Dark Matter Density @ Sun
ρ☉= 0.235±0.030 GeV cm-3
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M ~ RV2/G => ρ0 ~ M/R3 ~ (V/R)2 ~ Ω2
V0/R0=Ω0 (km s-1 kpc-1) ρ0 (GeV cm-3) Sofue (2012) 200/8.0 = ±0.030 ( 248/8.2 = ± ) Salucci, et al. (2011)≒Honma et al (2012) 248/8.2 = ± 0.11 ( 200/8.0 = ± 0.07 ) Weber and de Boer (2010) 0.2 ~ 0.4
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6. Galactic Roche Lobe - Territory problem –
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Grand RC of M31 √2 Vr Vrot
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GRC of M31 M31⇔ MW de V. Bulge Expo. Disk NFW Halo M31
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Grand RC of M31 ≒ Galaxy MW M31 de V. Bulge NFW Halo NFW Halo
Expo. Disk NFW Halo M31⇔ MW de V. Bulge Expo. Disk NFW Halo M31
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M31 ≒ Galaxy>> M33, dwarfs
MW+M31≒Binary
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2D Matsuda et al. 2000
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Binary (2 point masses) Roche Lobes
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Galactic Roche Lobe Φ=ΦG+ΦM31+ΦΩ Rigid rot coordi
Galactic Roche Lobe Φ=ΦG+ΦM31+ΦΩ Rigid rot coordi. = -GM1/r1 - GM2/r2 - (1/2)Ω2 r2
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NFW Roche Lobe Mh(R) = 4πρ0h3{ln(1+X)−X/(1+X)} X=R/h } :
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Galactic DM Roche Lobe MW-M31 Binary
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Local Group of Galaxies
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Galaxy + M31 =>What in future?
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Galaxy – M31
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Summary 1. Rotation Curve 2. Mass models 3. Grand RC (Log RC) 4
Summary 1. Rotation Curve 2. Mass models 3. Grand RC (Log RC) 4. Local DM Density & G-parameters 5. Roche Lobe Galactic Territory MW vs M31
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7.Grand RC (Log RC) for the Galactic Center
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Bulge is in between de Vaucouleurs and Exponential
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de V ∝ exp(-r1/4) Expo. Plummer Kepler
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MW ⇔ M31 border de V. Bulge Milky Way GRC Expo. Disk NFW Halo
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