Gravitational lensing science
with WISH
Masamune Oguri
Dept. of Physics & Kavli IPMU
University of Tokyo

2013/12/3 WISH science workshop @ NAOJ

Lensing benefits from space missions
A1703/HST

A1703/Subaru• sharp images lead to accurate astrometry and morphology, crucial for both strong and weak lensing!

Weak gravitational lensing• key science for Euclid/WFIRST• thought to be a main probe of dark energy andmodified gravity for these missions• what about WISH?

Weak lensing: optical vs near-IR• in ground observations the sensitivity is muchbetter in optical so that weak lensing in NIR ismuch less competitive• in space optical and NIR sensitivities are similar,so weak lensing power can be comparable

Optical/NIR depth comparison(based on HUDF photo-z by Coe et al.)• in NIR number density is slightly less, but mean
redshift is higher!

WISH and weak lensing• WISH has a potential to produce significant

weak lensing results comparable to Euclid andWFIRST• current WISH survey design is not optimizedfor cosmology• but weak lensing is not just for cosmology,
there are many applications

Galaxy-dark matter connection• stacked weak lensing provides powerful meansof studying the connection between galaxies(or clusters, quasars) and dark matter halos• with WISH we can do this at higher redshifts!

Miyatake et al. (2013)
Figure 7. Top panel: The measurements of the projected galaxy clustering signal wp rp (rp ) are shown as blue solid circles with errorbars. The one-halo and4

Dark matter density profile

M. Oguri et al.

• ΛCDM model predicts

NFW-like radial profileand very non-spherical
2D shape• stacked weak lensing

can test this at highprecision→ constraints on DM
collision cross section,coldness, ...

Oguri et al. (2012)

igure 11. The two-dimensional weak lensing shear maps obtained from stacking analysis of 25 clusters. The sticks shows
rections and strengths of weak lensing shear distortion. Colour contours are the surface density map reconstructed from the ssing the standard inversion technique (Kaiser & Squires 1993). Both the shear and density maps are smoothed for illustrative

Strong gravitational lensing• many applications− cosmology from e.g.,time delays− galaxy structure andevolution (IMF, dark
matter fraction, ...)
− study of sources withhelp of magnification(“natural telescope”)

SDSSJ1050+0017/Subaru

Oguri, Rusu & Falco arXiv:1309.5408

Stellar and dark matter distribution

straints in the αSalSPS -γDM plane for theOuter (red) contours show 1 and 2σ
the microlensing constraints (see Secer (blue) contours show the constraints
ng constraints. Values of αSalSPS correand Chabrier IMFs are indicated byFigure 4. Similar to Figure 3, but the projected constraints in
the ADM = MDM (< Re )/M∗Sal -γDM plane are shown.

• average mass profile

of elliptical galaxies
from 161 strong lens!
tan u − 1 (u > 1).
(4)• breaking degeneracy
he parameter
takes accountof
btw αstellar
and dark
MF; α= 1 means that the IMF
by correquasar
r IMF,mater
whereas αdist.
≈ 0.56
IMF. On
the other hand, we assume
microlensing
ss distribution for the dark matter#• prefer Salpeter IMFR.
(5)
andNFW-like DM
ution isprofile
simply givenby the sum ofwithoutbest-fit
dark
Figure 5. best-fit
Similar tostellar
Figure 5, but the best-fit
two-component
adiabatic
contraction
model ismatter
overplotted.
The solid line withshadingshows the bestR)
M (< R)
distribution
matterdistribution
2

SalSPSSal
SPSSalSPS

3+γDM

e+DMM∗Sal.

(6)

fit and 1σ range of the total mass profile. Dotted lines indicate
bets-fit stellar and dark matter distributions.

Lensing as a natural telescope• strong lensing

magnifies distantsources• provide a uniquetool to study
distant and/or
faint galaxiesKneib et al. (2004)

“Most distant” galaxy!
z~11 galaxy
lensed into
3 images!

Coe et al. (2013)

Hubble Frontier Fields• ultra deep imagingof 4+2 cluster coreswith HST(140 orbits per cluster)• much deeper than

HUDF with help oflensing magnification• observations started
from 2013 Oct− stay tuned!

“Frontier fields” with WISH?

• ultra deep imaging of massive cluster coreswith WISH is an interesting option• however the WISH FOV is much larger thanEinstein radii of clusters, so this might not be
an efficient use of WISH

Strong lenses in wide-field surveys• blind wide-field surveys provide an opportunity
to find very bright lensed objects• these are very useful targets for follow-up
dn/dL

deep imaging ofcluster cores→ faint end slope,
reionization

blind wide survey
for rare, bright lenses→detailed follow-up
to get physical stateL

Lessons from SDSS

“8 o’clock arc”
zs=2.73 zl=0.38(Allam et al. 2007)“clone”
zs=2.00 zl=0.422(Lin et al. 2009)“cosmic horseshoe”
zs=2.38 zl=0.446(Belokurov et al. 2007)• SDSS is a shallow survey targeting galaxies atz<0.7, yet very bright strongly lensed galaxies
at z~2-3 have been discovered!

Strongly lensed galaxies in WISH

• ~100 z~8lensed galaxies• ~10 z~10lensed galaxies

WISH wide
WISH deep (×0.1)• discovered evenin wide!

Also talk by Robert Quimby

Gravitationally lensed supernovae• for type-Ia, we canobtain magnification
factor thanks to its
standard candleness,
which can breakvarious degeneracies• first strongly lensed

SNIa PS1-10afx wasdiscovered recently!

• many more will be

discovered in WISH

Quimby, Werner, Oguri et al. (2013)

Also talk by Masayuki Tanaka

Synergy with Subaru• these gravitational lensing sciences require
deep optical images for photo-z etc• excellent synergy with Subaru Hyper Suprimecam (HSC) survey

Wide-field Imaging with Subaru HSC(anotherWISH!)
Wide-field imaging with Hyper Suprime-Cam

3

HSC-UD
HSC-D
HSC-Wide

both area and depth
are in excellent matchwith WISH survey
Figure 1: Left: The limiting magnitudes (in r) and solid angles of the HSC-Wide, Deep and Ultradeep (UD) layers,compared with other existing, on-going, and planned surveys. The three layers are complementary to each other, andeach of the three layers covers a significantly wider area than do other on-going surveys of comparable depth. The

Summary• WISH is an excellent project from the perspectiveof gravitational lensing science• its weak lensing power comparable to Euclid andWFIRST satellites, useful both for cosmology andgalaxy studies• many strongly lensed high-redshift galaxies will

be discovered in WISH, which will be interestingtargets for follow-up with TMT/JWST/...