Weak Lensing Study of DM sub halos in Coma Cluster T. Futamase Astronomical Institute, Tohoku University, Sendai, Japan 29 th Apr. Collaborators: N. Okabe (ASIAA, Taiwan), Y. Okura(NAO, Japan)

Relation between Gerhard and Japan(and me) On the behalf of all Japanese cosmologists I would like to celebrate 70 th birthday of Prof. G. Boerner His first post-doc was at Yukawa Institute, Kyoto University in 1969 where he worked with Profs. K. Sato and H. Bethe on Nuclear matter in Neutron star. In his popular book, Yukawa mentioned a young German physicist at the Institute with photograph. Since then he repeatedly visited and stayed various part of Japan including Kyoto, Tokyo, Sendai, and has collaborated with Prof. K. Sato and Y. Suto group, given many talks and encouraged many young scientists to study cosmology I first met him at 1982 when I was a post-doc. in relativity group at Garching. Since then his group at MPA has a nice relation with me and many of his students came to Japan as JSPS post-doc.. I attended his 60 th birthday meeting at Shanghai. Until that time I did not know his age because his looking was not changed since I first met him (I mentioned this as “age problem”. At that time another age problem was popular in cosmology ). Today his looking is same as 10 years ago. I am sure he will be the same in next 10 years and more

Weak Lensing Search of substructures in Coma cluster Is it possible to determine the mass function of substructure in cluster of galaxies by weak lensing using Hyper Suprime Cam? Observational verification of CDM scenario of structure formation as well as formation dynamics of cluster

Suprime-Cam on Subaru Prime Focus Camera 34’×27’FOV

1: Hyper Suprime Camera for Subaru New wide field prime focus camera for high –z galaxy survey Main purpose is to measure the cosmic equation of state(Dark energy) by observing cosmic shear and BAO( Baryon Acoustic Oscillation) Wide FOV (~10 times of S-Cam) High resolution （ 3 times better than the present at 1 micrometer ） Project started at 2006 and will finish 2011( 科研費特定領域 )

HSC and SC S-cam

Substructures in Coma cluster (z=0.0236) Statistics of sub halos (spatial distribution, mass function) in clusters reflects the history of formation of clusters Thus if we can observe many sub halos in cluster, we may be able to test CDM scenario of structure formation One of the most massive relaxed clusters near us HSC is able to observe whole region of Coma in 1 night !! Let’s observe! Is it possible?

As a preliminary study we made weak lensing analysis of small region in coma cluster by S-Cam with old CCD(present S-Cam has new CCD) Two R-band image data from SMOKA(Subaru Archive Data) Central region of r<30’ from CD galaxy NGC4874 (exp.time:42min) Outskirts region of r~30-60’ (exp.time: 6min) Seeing was ~ 0.8” Source galaxies AB mag ~23 arcmin^-2 background galaxies This is just ~10% of the whole area of the cluster N. Okabe, Y. Okura and TF, ApJ (2010) Not really perfect data for weak lensing

~400 /h kpc 1 2 CD galaxies A B C D E

8 A B C D E

Mass Profile of Substructure

Effect of LSS

March Observation 5 half nights observation proposal were accepted in last Dec Observation were performed in early March and 4 half nights were perfect condition with seeing ~0.5” and n~70/arcmin^2 Two bands(Rc and V) observation to make a clear separation between member galaxies and background galaxies Archive Data March Observation

Preliminary results Earth quake with mag. 9 has hit around Sendai area at 11 th of March, and we have to stop every scientific activities for a month or so Background selection: AB mag, smoothing scale FWHM=3.3 arcmin FOV of HSC S/N>4 peaks

If we change smoothing scale to FWHM=2 arcmin, but some of peaks may be LSS origin FWHM=3.3 arcmin FWHM=2 arcmin 23 peaks ~100 peaks

Comparison between galaxies and DM sub halos Luminosity map of member galaxies by SDSS photo-z selection

Mass function of DM sub halos (very preliminary)

Soon we will do More detailed analyses separation between member and background using color information Accurate determination of mass and mass profile of DM sub halos Determination of mass and mass profile of main halo Effect of LSS Use our V-band images and SDSS data as we did before (N. Okabe, Y. Okura and TF, 2010) Use higher-order weak lensing effect Flexion detection using HOLICs technique (Y. Okura.K. Umetsu and TF,2008; Y. Okura and TF, 2010) Statistical properties of DM sub halos such as number, radial distribution, mass function et al. and relation of distribution between baryon and DM

Mass and Light in A1689 (Subaru) Mass + Light Mass + Light contours from Shear+Magbias data (Umetsu & Broadhurst 07) Mass map from Fleixon in a 4’x4’ region (Okura, Umetsu, & Futamase 2007b) 15 arcmin (2Mpc/h)

Using HSC By observing nearby clusters z<0.05 with various stage of evolution, we will know the detail of cluster formation process Since gravity is scale-free, we will also have some information of galaxy formation Statistical properties of DM sub halos will give us not only an observational test of CDM structure formation scenario, but also important information of the nature of DM We have been observing ~50 clusters (LoCuss) with 0.15<z<0.3 by Subaru for about 5 years, HSC will be able to observe ~50 clusters less than 1 year