Highlights - Volume 500-2 (June III 2009)

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HIGHLIGHTS: this week in A&A

Volume 500-2 (June III 2009)


In section 3. Cosmology (including clusters of galaxies)

“Optimal point spread function modeling for weak lensing: complexity and sparsity”, by S. Paulin-Henriksson, A. Refregier, and A. Amara, A&A 500, p. 647

The light that reaches us from the most distant galaxies has travelled billions of light years through the distribution of matter in space. According to General Relativity - by distorting the underlying structure of spacetime – matter forces light rays to deviate from a "straight" path, exactly as a lens does. This phenomenon, suitably known as gravitational lensing, induces a change in the luminosity of distant objects called magnification; in addition, it produces a distortion in the shapes of extended objects such as the galaxies. By studying this effect, cosmologists have been able to learn about many of the properties of the dark matter cosmic component, which would be very difficult to investigate otherwise. In its "weak" version, lensing experiments use large surveys to study distortions of target galaxy shapes and their correlations by the intervening matter distribution. Of course, a key point in these experiments is to control the systematic errors, such as the ones associated with the point spread function (PSF) of the instrument used for the observations. The authors of this paper present a very useful study that exploits the mathematical concepts of complexity and sparsity to derive optimal strategies to properly calibrate the PSF.  


In section 1. Letters to the Editor

“Strong [CII] emission at high redshift”, by R. Maiolino, P. Caselli, T. Nagao, C.M. Walmsley, C. De Breuck, and M. Meneghetti, A&A 500, p. L1

The CII line at 158 micron has been detected in an infrared, luminous lensed quasar at z=4.43. The CII/LFIR is larger than in local galaxies of the same infrared luminosity, and together with two other detections at high redshift, this establishes a trend that the CII line might not be as depleted as previously thought at high infrared luminosity.



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© Astronomy & Astrophysics 2009