Search results for " Lens"
showing 10 items of 510 documents
Accurate modeling of weak lensing with the stochastic gravitational lensing method
2011
We revise and extend the stochastic gravitational lensing method (the sGL method) first introduced by Kainulainen and Marra [Phys. Rev. D 80, 123020 (2009)]. Here we include a realistic halo-mass function and density profiles to model the distribution of mass between and within galaxies, galaxy groups, and galaxy clusters. We also introduce a modeling of the filamentary large-scale structures and a method to embed halos into these structures. We show that the sGL method naturally reproduces the weak lensing results for the Millennium simulation. The strength of the sGL method is that a numerical code based on it can compute the lensing probability distribution function (PDF) for a given inh…
Die elektronenstreu-apparatur am mainzer 300 MeV-elektronen-linearbeschleuniger
1972
Abstract In this paper, we attempt to give a general survey and a comprehensive description of the most significant features of the facilities for electron scattering experiments at the Mainz 300 MeV Linear Accelerator, along with a list of literature, where more detailed information on certain subjects can be found. The accelerator provides energies between 80 and 300 MeV. Scattering angles are available up to 160° resulting in a momentum transfer region up to 3.0 fm −1 . The overall experimental resolution is 0.1%. Cross sections down to 10 −34 cm 2 /sr can be measured. The main features of the apparatus are: an achromatic magnet system with 90° deflection, a double focusing spectrometer,…
Integral field spectroscopy of the gravitational lens HE1104-1805
2004
We present integral field spectroscopy of the double imaged quasar HE1104-1805 taken with the optical fiber system INTEGRAL-WYFFOS at theWHT telescope. From the spectra of the two components we have measured the continuum and line emission ratios, finding an offset between them that can be related to microlensing. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffractive pulse-front tilt for low-coherence digital holography
2010
We use a diffractive lens to generate the proper pulse-front-tilt to record full-field off-axis holograms with a 10fs laser source. We experimentally demonstrate optical sectioning of three-dimensional samples with a resolution of about 5 microns.
Cosmological searches for a non-cold dark matter component
2017
We explore an extended cosmological scenario where the dark matter is an admixture of cold and additional non-cold species. The mass and temperature of the non-cold dark matter particles are extracted from a number of cosmological measurements. Among others, we consider tomographic weak lensing data and Milky Way dwarf satellite galaxy counts. We also study the potential of these scenarios in alleviating the existing tensions between local measurements and Cosmic Microwave Background (CMB) estimates of the $S_8$ parameter, with $S_8=\sigma_8\sqrt{\Omega_m}$, and of the Hubble constant $H_0$. In principle, a sub-dominant, non-cold dark matter particle with a mass $m_X\sim$~keV, could achieve…
Simbol-X Mirror Module Thermal Shields: II-Small Angle X-Ray Scattering Measurements
2009
The formation flight configuration of the Simbol-X mission implies that the X-ray mirror module will be open to Space on both ends. In order to reduce the power required to maintain the thermal stability and, therefore, the high angular resolution of the shell optics, a thin foil thermal shield will cover the mirror module. Different options are presently being studied for the foil material of these shields. We report results of an experimental investigation conducted to verify that the scattering of X-rays, by interaction with the thin foil material of the thermal shield, will not significantly affect the performances of the telescope.
Achromatic fan-out diffractive system for white-light free-space optical interconnects
2001
Abstract A simple and versatile white-light fan-out diffractive system based on the achromatization of the fractional Talbot effect is proposed. This achromatic configuration is able to interconnect a single polychromatic point source with a 2-D array of optoelectronic microdevices with low residual chromatic aberration even for white light. The whole broadband beamsplitter system is formed by two simple diffractive optical elements, a periodic diffractive lenslet array and a diffractive lens, that are made with a direct laser writing technique giving high light efficiency. The focal amplitude distribution corresponding to the lenslet array produces, by free-space propagation, self-replicas…
A Study of the Correlation between the Amplification of the Fe Kα Line and the X‐Ray Continuum of Quasars due to Microlensing
2006
The observed enhancement of the Fe Kα line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, and H1413+117) is interpreted in terms of microlensing, even when equivalent X-ray continuum amplification is not observed. In order to interpret these observations, first we studied the effects of microlensing on quasar spectra produced by a straight fold caustic crossing over a standard relativistic accretion disk. The disk emission was analyzed using the ray-tracing method, considering Schwarzschild and Kerr metrics. When the emission is separated into two regions (an inner disk corresponding to the Fe Kα line and an outer annulus corresponding to the continuum, or vice versa), …
Recurrence of the blue wing enhancements in the high ionization lines of SDSS 1004+4112 A
2006
We present integral field spectroscopic observations of the quadruple-lensed QSO SDSS 1004+4112 taken with the fiber system INTEGRAL at the William Herschel Telescope on 2004 January 19. In 2003 May, a blueward enhancement in the high-ionization lines of SDSS 1004+4112A was detected, and then it faded. Our observations are the first to note a second event of similar characteristics less than 1 year after. Although initially attributed to microlensing, the resemblance among the spectra of both events and the absence of microlensing-induced changes in the continuum of component A are puzzling. The lack of a convincing explanation under the microlensing or intrinsic variability hypotheses make…
The structure of the accretion disk in the lensed quasar SBS 0909+532
2011
We derive the size and temperature profile of the accretion disk of the lensed quasar SBS 0909+532 by measuring the wavelength dependence (chromaticity) of the microlensing magnification produced by the stars in the lens galaxy. After correcting for extinction using the flux ratios of 14 emission lines, we observe a marked change in the B-A flux ratio with wavelength, varying from -0.67 ± 0.05 mag at (rest frame) ∼1460 Åto -0.24 ± 0.07 mag at ∼6560 Å. For λ ≳ 7000 both effects, extinction and microlensing, look minimal. Simulations indicate that image B rather than A is strongly microlensed. If we model the change in disk size from 1460 Å to 6560 Å using a Gaussian source (I exp(-R 2/2r 2 s…