Fermat's Principle and Gravitational Lensingstar.herts.ac.uk/ewass/talks/sym6/saha.pdf · 1979...
Transcript of Fermat's Principle and Gravitational Lensingstar.herts.ac.uk/ewass/talks/sym6/saha.pdf · 1979...
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Sjur Refsdal
1979 Quasar microlensing
1970 Numerical ray-tracing in cosmology
1966 Galactic microlensing
1964 Time delays ∝ H−10
1964 Wavefront picture of lensing
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Sjur Refsdal
1979 Quasar microlensing
1970 Numerical ray-tracing in cosmology
1966 Galactic microlensing
1964 Time delays ∝ H−10
1964 Wavefront picture of lensing
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Sjur Refsdal
1979 Quasar microlensing
1970 Numerical ray-tracing in cosmology
1966 Galactic microlensing
1964 Time delays ∝ H−10
1964 Wavefront picture of lensing
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Sjur Refsdal
1979 Quasar microlensing
1970 Numerical ray-tracing in cosmology
1966 Galactic microlensing
1964 Time delays ∝ H−10
1964 Wavefront picture of lensing
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
The Wavefront
The wavefront picture of lensingseems unique to Refsdal. . .
. . . and his students, includingChang and Kayser.
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
The Wavefront
The wavefront picture of lensingseems unique to Refsdal. . .
. . . and his students, includingChang and Kayser.
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefront and Time Delays
From the wavefront Refsdalshowed
∆t ∝ H−10
Soon after, he realized ∆t alsodepends on the cosmologicalmodel.
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefront and Time Delays
From the wavefront Refsdalshowed
∆t ∝ H−10
Soon after, he realized ∆t alsodepends on the cosmologicalmodel.
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefront and Time Delays
From the wavefront Refsdalshowed
∆t ∝ H−10
Soon after, he realized ∆t alsodepends on the cosmologicalmodel.
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefront and Time Delays
From the wavefront Refsdalshowed
∆t ∝ H−10
Soon after, he realized ∆t alsodepends on the cosmologicalmodel.
In 1964–66 Sjur Refsdal
1 Independently derived theShapiro time delay
2 and connected it to the ageof the Universe
3 and the cosmological model.
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefronts and Moving Sources
Then Refsdal considered theGalactic microlensing regime.
. . . if the lens can be observedfrom the Earth and from at leastone distant space observatory.(Refsdal 1966)
MACHO parallaxes from a singlesatellite (Gould 1995)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefronts and Moving Sources
Then Refsdal considered theGalactic microlensing regime.
. . . if the lens can be observedfrom the Earth and from at leastone distant space observatory.(Refsdal 1966)
MACHO parallaxes from a singlesatellite (Gould 1995)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Wavefronts and Moving Sources
Then Refsdal considered theGalactic microlensing regime.
. . . if the lens can be observedfrom the Earth and from at leastone distant space observatory.(Refsdal 1966)
MACHO parallaxes from a singlesatellite (Gould 1995)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Fermat’s Principle
=4πG
c2
H0
c DL
× surf dens
=H0
(1 + zL) DL
× arrival time
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Fermat’s Principle
=4πG
c2
H0
c DL
× surf dens
=H0
(1 + zL) DL
× arrival time
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Fermat’s Principle
∇2 =
=DS
DLS
× −
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
The Earliest Lens Models
P.J. Young et al. (1980)
Nine-parameter (galaxy+cluster)model for Q0957+561.
. . . We settled upon the followingrepresentative case; it must notbe looked upon as a unique orwell-determined solution at thistime, but merely an example. . .
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
The Earliest Lens Models
P.J. Young et al. (1980)
Nine-parameter (galaxy+cluster)model for Q0957+561.
. . . We settled upon the followingrepresentative case; it must notbe looked upon as a unique orwell-determined solution at thistime, but merely an example. . .
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Some Recent Lens-Model Topics
1 Use stellar velocity field as a mass constraint.
Talks by Koopmans, Czoske
2 Compare with stellar population to map dark matter.
Poster by Leier
3 Explore the model-space satisfying (i) data and (ii) minimalassumptions about mass distribution.
Liesenborgs et al. arXiv:0904.2382PixeLens
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Model Ensembles
∇2 =
=DS
DLS
× −
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Model Ensembles
∇2 =
=DS
DLS
× −
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Model Ensembles
∇2 =
=DS
DLS
× −
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Model Ensembles
∇2 =
=DS
DLS
× −
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
ACO 1703
Inner profile like N-body CDM
(thanks to DS/DLS contrast)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
ACO 1703
Inner profile weakly constrained
(without DS/DLS contrast)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Time-delay lenses and H−10
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Time-delay lenses and H−10
10
20
30
10 20
50100
Hubble time (Gyr)
Hubble constant (legacy units)
num
ber o
f mod
els
H−10 = 15.3+1.8
−1.7 Gyr
13.6± 0.6 (WMAP)
13.6± 1.5 (HST key proj)
15.7± 0.3± 1.2 (SN Ia)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Time-delay lenses and H−10
10
20
30
10 20
50100
Hubble time (Gyr)
Hubble constant (legacy units)
num
ber o
f mod
els
H−10 = 15.3+1.8
−1.7 Gyr
13.6± 0.6 (WMAP)
13.6± 1.5 (HST key proj)
15.7± 0.3± 1.2 (SN Ia)
Sjur Refsdal Wavefronts Fermat’s Principle Lens modelling Clusters Time Delays
Time-delay lenses and H−10
10
20
30
10 20
50100
Hubble time (Gyr)
Hubble constant (legacy units)
num
ber o
f mod
els
H−10 = 15.3+1.8
−1.7 Gyr
13.6± 0.6 (WMAP)
13.6± 1.5 (HST key proj)
15.7± 0.3± 1.2 (SN Ia)