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
“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.”
Vera’s Rotation CurvesVera’s Rotation Curves
M/L
Kaptyen (Local) 1920’s
Zwicky (Clusters) 1930s
Rubin (Galaxies) 1970s ( M/L ~ R )
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
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]]
M/L(R) (Davis etal 1980)M/L(R) (Davis etal 1980)
Galaxies
Groups
Clusters
Ωm=1
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
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
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)
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
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
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
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
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
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
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
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
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
“ 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
Dedication to Women in ScienceGreat Wall, China 1986 (Margaret, Anna, Vera, Neta)
Dedication to Women in ScienceGreat Wall, China 1986 (Margaret, Anna, Vera, Neta)