mass-to-light function: from galaxies to superclusters mass-to-light function: from galaxies to...
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MASS-TO-LIGHT FUNCTION: MASS-TO-LIGHT FUNCTION: from Galaxies to Superclustersfrom Galaxies to Superclusters
MASS-TO-LIGHT FUNCTION: MASS-TO-LIGHT FUNCTION: from Galaxies to Superclustersfrom Galaxies to Superclusters
Celebrating Vera RubinCelebrating Vera Rubin
Neta A. BahcallPrinceton University
Celebrating Vera RubinCelebrating Vera Rubin
Neta A. BahcallPrinceton University
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“In a spiral galaxy, the ratio of dark-to-light matter is about a factor of ten. That's probably a good number for the ratio of our ignorance-to-knowledge. We're out of kindergarten,
but only in about third grade.”
“In a spiral galaxy, the ratio of dark-to-light matter is about a factor of ten. That's probably a good number for the ratio of our ignorance-to-knowledge. We're out of kindergarten,
but only in about third grade.”
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Vera’s Rotation CurvesVera’s Rotation Curves
M/L
Kaptyen (Local) 1920’s
Zwicky (Clusters) 1930s
Rubin (Galaxies) 1970s ( M/L ~ R )
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Mass-to-Light FunctionMass-to-Light FunctionM/L(R)M/L(R)
Mass-to-Light FunctionMass-to-Light FunctionM/L(R)M/L(R)
How does M/L depend on scale?How does M/L depend on scale? How and where is the mass distributed?How and where is the mass distributed? How use it to weigh Universe?How use it to weigh Universe?
<M/L><M/L>rep rep LLunivuniv(L(Loo/Vol) = /Vol) = mm(M(Moo/Vol)/Vol)
Determine M, <M/L> of clusters, SCs, LSS
<M/L><M/L> rep rep [[≈ 300h≈ 300h ]
m m ~ 0.2 +-0.05~ 0.2 +-0.05
How does M/L depend on scale?How does M/L depend on scale? How and where is the mass distributed?How and where is the mass distributed? How use it to weigh Universe?How use it to weigh Universe?
<M/L><M/L>rep rep LLunivuniv(L(Loo/Vol) = /Vol) = mm(M(Moo/Vol)/Vol)
Determine M, <M/L> of clusters, SCs, LSS
<M/L><M/L> rep rep [[≈ 300h≈ 300h ]
m m ~ 0.2 +-0.05~ 0.2 +-0.05
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Weighing ClustersWeighing Clusters
3 Basic Methods 3 Basic Methods
Motion of galaxiesMotion of galaxies [M[MRR ~ v ~ v22R]R]
Temperature of hot gasTemperature of hot gas [M[MRR~TR]~TR] Gravitational lensingGravitational lensing [M[MRR]]
3 Basic Methods 3 Basic Methods
Motion of galaxiesMotion of galaxies [M[MRR ~ v ~ v22R]R]
Temperature of hot gasTemperature of hot gas [M[MRR~TR]~TR] Gravitational lensingGravitational lensing [M[MRR]]
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M/L(R) (Davis etal 1980)M/L(R) (Davis etal 1980)
Galaxies
Groups
Clusters
Ωm=1
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Mass-to-Light Function Mass-to-Light Function (Bahcall, Lubin & Dorman ‘95; Bahcall and Fan ‘98)
Mass-to-Light Function Mass-to-Light Function (Bahcall, Lubin & Dorman ‘95; Bahcall and Fan ‘98)
1. M/L flattens on large-scales: M ~ L. End of Dark Matter. 2. Sp + E produce M/L of groups, clusters; Clusters: ~ no excess DM !3. Most of the DM is in huge halos around galaxies ( ~200-300 Kpc)
Ωm = 1.0
Ωm = 0.3Ωm=0.25
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Mass-to-Light Function Mass-to-Light Function (Bahcall, Lubin & Dorman ‘95; Bahcall and Fan ‘98)
Mass-to-Light Function Mass-to-Light Function (Bahcall, Lubin & Dorman ‘95; Bahcall and Fan ‘98)
SDSSSDSS Ωm=0.2
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M/L(R) Function: simulations (Bahcall, Yu, etal ’01)M/L(R) Function: simulations (Bahcall, Yu, etal ’01)
1. Same shape as observed: FLAT on large-scales (M ~ L)
2. Cluster M/L increases with Mcl. Explains M/L Groups to Clusters
3. Anti-Bias of Rich Clusters: their M/LB larger than average (LB low)
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Cluster M/L versus T (or M) (Bahcall and Comerford ’02)
Cluster M/L versus T (or M) (Bahcall and Comerford ’02)
M/L=(173+-29) Tkev0.30+-0.08M/L=(173+-29) Tkev0.30+-0.08
Due to mergers (lowers L at a fixed Mass)?Increase in E-fraction; Older systems (L fades)?
Due to mergers (lowers L at a fixed Mass)?Increase in E-fraction; Older systems (L fades)?
Data vs Sims Data vs Sims
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Theory vs. ObservationsTheory vs. ObservationsTheory vs. ObservationsTheory vs. Observations
(Bahcall, Yu, et al ‘01)(Bahcall, Yu, et al ‘01)
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SDSS Cluster Mass Profile: Weak Lensing 2x104 SDSS clusters, N=3 to 220. (Sheldon et al 2008)SDSS Cluster Mass Profile: Weak Lensing 2x104 SDSS clusters, N=3 to 220. (Sheldon et al 2008)
X = R200
NFW
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Cluster M/Li(R) Profile (SDSS, weak lensing
2x104 clusters N= 3 to 220 (Sheldon etal 2008)
Cluster M/Li(R) Profile (SDSS, weak lensing
2x104 clusters N= 3 to 220 (Sheldon etal 2008)
X=R(vir)
Flat >~ 1MpcM ~ L
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Cluster (M/L)200 versus M200 Cluster (M/L)200 versus M200
M/L ~ M0.33+-0.02M/L ~ M0.33+-0.02
M/L~M0.33+-0.02
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M/Li(r=22Mpc) vs. Mcl (SDSS; Sheldon etal ‘08)M/Li(r=22Mpc) vs. Mcl (SDSS; Sheldon etal ‘08)
Flat M/L on large scales; SAME for ALL clusters!Flat M/L on large scales; SAME for ALL clusters!
Ωm= 0.2 +- .03
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M/L Function: ConclusionsM/L Function: ConclusionsM/L Function: ConclusionsM/L Function: Conclusions
M/L Function Flattens on Large ScalesM/L Function Flattens on Large Scales M ~ LM ~ L (reaching end of Dark-Matter)
Dark Matter located mostly in large galactic halos ~300s Kpc) Group/Clusters: made up of Sp+E; no significant additional DM
Cluster M/L increases slightly with M (mergers?) Rich clusters M/LB is ‘Anti-biased’ (M/LB>mean)
Asymptotic Cluster M/Li(22Mpc) is same for ALL Groups and Clusters, 362+-54h !
Mass-Density of Univers: Mass-Density of Univers: mm = 0.2 +- 0.04 = 0.2 +- 0.04
M/L Function Flattens on Large ScalesM/L Function Flattens on Large Scales M ~ LM ~ L (reaching end of Dark-Matter)
Dark Matter located mostly in large galactic halos ~300s Kpc) Group/Clusters: made up of Sp+E; no significant additional DM
Cluster M/L increases slightly with M (mergers?) Rich clusters M/LB is ‘Anti-biased’ (M/LB>mean)
Asymptotic Cluster M/Li(22Mpc) is same for ALL Groups and Clusters, 362+-54h !
Mass-Density of Univers: Mass-Density of Univers: mm = 0.2 +- 0.04 = 0.2 +- 0.04
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Improved Cluster Mass Tracer from SDSS(R. Reyes etal 2008)
Improved Cluster Mass Tracer from SDSS(R. Reyes etal 2008)
Improved optical cluster mass tracer from SDSS, using weak-lensing calibration Tested M200 versus N200 (richness), L200, LBCG, and
combinations (avail in many surveys) Best tracer (least scatter, highest Mcl):
Combination of Richness and LBCG: M ~ N1.2 LBCG0.7
M200 = (1.27+-0.08) (N200/20)1.20+-0.09
x [LBCG/<LBCG>(N200)]0.71+-0.14
LBCG important second parameter.
Consistent with merger picture: At fixed Mcl mergers produce Lower N and Brighter LBCG
Improved optical cluster mass tracer from SDSS, using weak-lensing calibration Tested M200 versus N200 (richness), L200, LBCG, and
combinations (avail in many surveys) Best tracer (least scatter, highest Mcl):
Combination of Richness and LBCG: M ~ N1.2 LBCG0.7
M200 = (1.27+-0.08) (N200/20)1.20+-0.09
x [LBCG/<LBCG>(N200)]0.71+-0.14
LBCG important second parameter.
Consistent with merger picture: At fixed Mcl mergers produce Lower N and Brighter LBCG
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M200 vs. LBCG [at fixed N200] (Reyes etal ‘08)M200 vs. LBCG [at fixed N200] (Reyes etal ‘08)
M200 = (1.27+-0.08) (N200/20)1.20+-0.09
x [LBCG/<LBCG>(N200)]0.71+-0.14
M200 = (1.27+-0.08) (N200/20)1.20+-0.09
x [LBCG/<LBCG>(N200)]0.71+-0.14
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Weighing the UniverseWeighing the UniverseWeighing the UniverseWeighing the Universe M/L Function M/L Function mm= 0.2 +- 0.04= 0.2 +- 0.04 Baryon Fraction 0.24 +- 0.04Baryon Fraction 0.24 +- 0.04 Cluster Abundance 0.2 +- 0.05Cluster Abundance 0.2 +- 0.05
and Evolution [and Evolution [8 8 == 0.9 +- 0.1]0.9 +- 0.1] Supernovae Ia + Flat 0.25 +- 0.05Supernovae Ia + Flat 0.25 +- 0.05 CMB + LSS + h + Flat 0.24 +- 0.04CMB + LSS + h + Flat 0.24 +- 0.04
m m ≈ 0.23 +- 0.05≈ 0.23 +- 0.05
4% Baryons + ~20% Dark Matter4% Baryons + ~20% Dark Matter Mass ~ LightMass ~ Light
M/L Function M/L Function mm= 0.2 +- 0.04= 0.2 +- 0.04 Baryon Fraction 0.24 +- 0.04Baryon Fraction 0.24 +- 0.04 Cluster Abundance 0.2 +- 0.05Cluster Abundance 0.2 +- 0.05
and Evolution [and Evolution [8 8 == 0.9 +- 0.1]0.9 +- 0.1] Supernovae Ia + Flat 0.25 +- 0.05Supernovae Ia + Flat 0.25 +- 0.05 CMB + LSS + h + Flat 0.24 +- 0.04CMB + LSS + h + Flat 0.24 +- 0.04
m m ≈ 0.23 +- 0.05≈ 0.23 +- 0.05
4% Baryons + ~20% Dark Matter4% Baryons + ~20% Dark Matter Mass ~ LightMass ~ Light
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“ The joy and fun of understanding the universe is what we bequeath to our grandchildren and their grandchildren.
With over 90% of the matter in the universe still to play with, even the sky will not be the limit.”
Vera C. RubinVera C. Rubin
“ The joy and fun of understanding the universe is what we bequeath to our grandchildren and their grandchildren.
With over 90% of the matter in the universe still to play with, even the sky will not be the limit.”
Vera C. RubinVera C. Rubin
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Dedication to Women in ScienceGreat Wall, China 1986 (Margaret, Anna, Vera, Neta)
Dedication to Women in ScienceGreat Wall, China 1986 (Margaret, Anna, Vera, Neta)