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The cosmic shear STIS parallel program - First results

H. Haemmerle·J. -M. Miralles·P. Schneider·T. Erben·R. A. E. Fosbury·W. Freudling·N. Pirzkal·S. D. M. White
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Abstract

Since the Universe is inhomogeneous on scales well below the Hubble radius, light bundles from distant galaxies are deflected and distorted by the tidal gravitational field of the large-scale matter distribution as they propagate through the Universe. Two-point statistical measures of the observed ellipticities, like the dispersion within a finite aperture or the ellipticity cross-correlation, can be related to the power spectrum of the large-scale structure. The measurement of cosmic shear (especially on small angular scales) can thus be used to constrain cosmological parameters and to test cosmological structure formation in the non-linear regime, without any assumptions about the relation between luminous and dark matter. In this paper we will present preliminary cosmic shear measurements on sub-arcminute scales, obtained from archival STIS parallel data. The high angular resolution of HST, together with the sensitivity and PSF-stability of STIS, allows us to measure cosmic shear along many independent lines-of-sight. Ongoing STIS parallel observations, currently being carried out in the frame of a big GO program (8562+9248), will greatly increase the number of available useful fields and will enable us to measure cosmic shear with higher accuracy on sub-arcminute scales.

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H. Haemmerle, J. -M. Miralles, P. Schneider, T. Erben, R. A. E. Fosbury, W. Freudling, N. Pirzkal, S. D. M. White. 2001-10-09. The cosmic shear STIS parallel program - First results. https://arxiv.org/abs/astro-ph/0109376

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