Elliptical Weighted HOLICs for Weak Lensing Shear Measurement. part1:Definitions and isotropic PSF correction

We develop a new method to estimate gravitational shear by adopting an elliptical weight function to measure background galaxy images. In doing so, we introduce a new concept of "zero plane" which is an imaginal source plane where shapes of all sources are perfect circles, and regard the intrinsic shear as the result of an imaginal lensing distortion. This makes the relation between the observed shear, the intrinsic shear and lensing distortion more simple and thus higher-order calculation more easy. The elliptical weight function allows us to measure the mutiplemoment of shape of background galaxies more precisely by weighting highly to brighter parts of image and moreover to reduce systematic error due to insufficient expansion of the weight function in the original approach of KSB. Point Spread Function(PSF) correction in E-HOLICs methods becomes more complicated than those in KSB methods. In this paper we studied isotropic PSF correction in detail. By adopting the lensing distortion as the ellipticity of the weight function, we are able to show that the shear estimation in E-HOLICs method reduces to solve a polynomial in the absolute magnitude of the distortion. We compare the systematic errors between our approach and KSB using STEP2 simulation. It is confirmed that KSB method overestimate the input shear for images with large ellipticities, and E-HOLICs correctly estimate the input shear even for such images. Anisotropic PSF correction and analysis of real data will be presented in forthcoming paper.Comment: 30 pages, 8 figures, submitted to Ap

A new weak lensing shear analysis method using ellipticity defined by 0th order moments

We developed a new method that uses ellipticity defined by 0th order moments (0th-ellipticity) for weak gravitational lensing shear analysis. Although there is a strong correlation between the ellipticity calculated using this approach and the usual ellipticity defined by the 2nd order moment, the ellipticity calculated here has a higher signal-to-noise ratio because it is weighted to the central region of the image. These results were confirmed using data for Abell 1689 from the Subaru telescope. For shear analysis, we adopted the ellipticity of re-smeared artificial image (ERA) method for point spread function (PSF) correction, and we tested the precision of this 0th-ellipticity with simple simulation, then we obtained the same level of precision with the results of ellipticity defined by quadrupole moments. Thus, we can expect that weak lensing analysis using 0 shear will be improved in proportion to the statistical error.Comment: 25pages, 8figures; published by A&A 201

Weak Lensing Mass Reconstruction: Flexion vs Shear

Weak gravitational lensing has proven to be a powerful tool to map directly the distribution of dark matter in the Universe. The technique, currently used, relies on the accurate measurement of the gravitational shear that corresponds to the first-order distortion of the background galaxy images. More recently, a new technique has been introduced that relies on the accurate measurement of the gravitational flexion that corresponds to the second-order distortion of the background galaxy images. This technique should probe structures on smaller scales than that of a shear analysis. The goal of this paper is to compare the ability of shear and flexion to reconstruct the dark matter distribution by taking into account the dispersion in shear and flexion measurements. Our results show that the flexion is less sensitive than shear for constructing the convergence maps on scales that are physically feasible for mapping, meaning that flexion alone not be used to do convergence map reconstruction, even on small scales.Comment: Submitted to Ap

Financial Instability and Life Insurance Demand

This paper estimates private life insurance and Kampo demand functions using household-level data provided by the Postal Services Research Institute. The results show that income, children, pension and knowledge factors have a significant effect on the decision as to whether each household purchases life insurance products. The amount of income and financial assets also appear to have significant effect on the purchase of private life insurance and Kampo. However, pension and bankruptcy experience appear only to have an impact on Kampo, while aged (less than 40) and occupation (civil servant) factors affect only private life insurance. Dummy variables representing comparison, knowledge, and bankruptcy experience did not have any significant effect on decisions concerning private life insurance. Simultaneous estimations are also used to examine why households that already have one type of life insurance product (e.g. private life insurance) purchase the other type of life insurance product (e.g. Kampo). The results indicate that income, children, and bankruptcy experience variables are not significant factors when households with private life insurance product decide to purchase additional Kampo. The results also show that a knowledge dummy has a negative impact on additional purchases.life insurance demand, financial instability, sample selection model

Coopetition in a Mixed Oligopoly Market

In this study, we aim to investigate the impact of privatization on the degree of cooperation and competition in a mixed oligopoly market. We consider a duopoly market that comprises one semipublic firm and one private firm. Each firm is assumed to determine the level of two types of effort: the cooperative effort made to enlarge the total market size and the competitive effort made to increase market share. In a contest framework, our results show that the competitive effort level of the semipublic firm is smaller than that of the private firm. The more the semipublic firm is concerned for social welfare, the less it competes. On the basis of average costs, we then analyze the case in which only the semipublic firm undertakes cooperative effort. In this case, the private firm behaves as a free rider. Furthermore, we find that the semipublic firm expends more cooperative effort than does the private firm.Coopetition, Mixed oligopoly, Contests, Free rider