Three color composite image Color-Color diagram SED SED relative to R-band Download FITS Searching for a cosmic string through the gravitational lens effect: Japanese Virtual Observatory science use case Y. Shirasaki １,4 、 Y. Mizumoto 1 、 E. Matsuzaki 2 、 M. Ohishi 1 、 N. Yasuda 1 、 M. Tanaka 1 、 S. Honda 1 、 H.Yahagi 1 、 M.Nagashima 3 、 G.Kosugi 1 、 N.Kashikawa 1 、 F.Kakimoto 2 、 S.Ogio 2 (1) NAOJ, (2) TITech, (3) University of Durham, (4) Abstract This poster describes a method to search for a cosmic string using its unique gravitational effect which produces aligned double images. Implementation of gravitational lens search to Japanese Virtual Observatory (JVO), which is aimed at the string search, is also presented 2. Method 2.1 Procedure 1.Select closely located pair objects of similar magnitude, color, and morphology. 2.Calculate a degree of positional and directional coherence C obs for the set of pair objects. 3.Calculate 1000 sets of the degree of coherence C sim for a set of randomized pair objects and obtain C 99 so that chance probability for C obs to be larger than C 99 is 99%. 4.If C obs > C 99, the aligned pair objects are candidates of the lens events by a cosmic string. 2.2 Definition of the degree of coherence C 4. Application to the observational data We applied the method to the data of Subaru-XMM Deep Survey （ SXDS). No candidates of string lens event were detected. 5. Gravitational lens search on JVO 1. Introduction Grand Unified theory predicts that super heavy cosmic strings with linear mass density of g/cm were produced at a phase transition at the early universe. The lens effect by a long cosmic string can be characterized by undistorted double galaxies and quasars which are co-aligned in a direction of string network and are distributed in a very large scale. Because of its large scale nature, wide fied deep survey is crucial for its discovery. We have constructed a database of Subaru Suprime- Cam catalog and image for selected area and applied our search method partially through the JVO prototype. P1P1 P2P2 P3P3 Fig.1. Definition of parameters. (1) 3. Simulation Study We examined ability of the proposed method by simulating lens effect by a cosmic string. 3.1 String model Three kinds of configuration as shown in Fig.2 (left). Mass density g/cm → max separation 5’’. Perpendicular to the line of sight. 3.2 Galaxy distribution The numerical Galaxy Catalog ( GC). Calculated by a N-body numerical simulation. Cosmology  -CDM,   = 0.7,  m  = 0.3,   =1 3.3 Result Maximum redshifts, where cosmic string can produce enough lens events to prove its existence by the proposed method, are calculated according to the observational conditions (Fig. 2 Right). Fig.3. Left: Positional and directional distribution of the pair objects. Right: Degree of coherence. We developed several VO tools to implement a gravitational lens (GL) search on JVO prototype. JVO Query Language (QL) Editor (Fig. 4). VOTable Viewer (Fig 5). Candidates’ images and SED Viewer (Fig. 6). GL search engine. This field sets a restriction for a color of R-B Fig.2. Left: Assumed string configuration. Right: Detection limit of distance to a cosmic string as a function of observational condition (limiting magnitude). Fig. 4 Fig. 6 Color-Color plot and SED Sort by column value Download FITS Fig. 5 JVO QL Editor generates a query and send it to a search engine. VOTable is an output format of the search engine and can be viewed by VOTable viewer. Current version does not support morphological similarity check, so by constraining to a point like object and rejecting stellar- like color, 12 QSO GL candidates are obtained (Fig. 7). Fig. 7