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相关论文: On the weak field approximation for CaII 8542 A

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We present and interpret new spectropolarimetric observations of the magnetic white dwarf WD 1953-011. Circular polarization and intensity spectra of the H$\alpha$ spectral line demonstrate the presence of two-component magnetic field in…

天体物理学 · 物理学 2009-11-13 G. Valyavin , G. A. Wade , S. Bagnulo , T. Szeifert , J. D. Landstreet , Inwoo Han , A. Burenkov

The distribution of magnetic field strength at different levels in the solar photosphere outside active regions was obtained on the basis of the 2D MHD simulation of magnetogranulation and the synthesis of the V profiles of the Fe I 1564.8…

太阳与恒星天体物理 · 物理学 2012-09-28 V. A. Sheminova

Besides their own intrinsic interest, correct interpretation of solar surface magnetic field observations is crucial to our ability to describe the global magnetic structure of the solar atmosphere. Photospheric magnetograms are often used…

太阳与恒星天体物理 · 物理学 2010-10-29 Gordon J. D. Petrie , Irina Patrikeeva

The measurement of Zeeman splitting in spectral lines---both in emission and absorption---can provide direct estimates of the magnetic field strength and direction in atomic and molecular clouds, both in our own Milky Way and in external…

We present a weak lensing analysis of the X-ray luminous cluster CL 0152-1357 at z~0.84 using HST/ACS observations. The unparalleled resolution and sensitivity of ACS enable us to measure weakly distorted, faint background galaxies to the…

天体物理学 · 物理学 2014-10-13 M. J. Jee , R. L. White , N. Benitez , H. C. Ford , J. P. Blakeslee , P. Rosati , R. Demarco , G. D. Illingworth

It is a common practice in the solar physics community to test whether or not measured photospheric or chromospheric vector magnetograms are force-free, using the Maxwell stress as a measure. Some previous studies have suggested that…

太阳与恒星天体物理 · 物理学 2017-01-11 X. M. Zhang , M. Zhang , J. T. Su

Weak lensing of CMB anisotropies and polarization for the power spectra and higher order statistics can be handled directly in harmonic-space without recourse to real-space correlation functions. For the power spectra, this approach not…

天体物理学 · 物理学 2009-10-31 Wayne Hu

Magnetic field strengths in objects ranging from HII regions to cosmological large scale structure can be estimated using dense grids of Rotation Measures (RMs) from polarized background radio structures. Upcoming surveys on the SKA and its…

星系天体物理 · 物理学 2019-01-29 Lawrence Rudnick

Weak gravitational lensing provides a unique method to directly map the dark matter in the universe and measure cosmological parameters. Current weak lensing surveys are limited by the atmospheric seeing from the ground and by the small…

We determined the direction and strength of the photospheric and lower chromospheric magnetic field in the umbra and penumbra of a sunspot from inversions of spectropolarimetric observations of photospheric lines at 617\,nm and 1565\,nm,…

太阳与恒星天体物理 · 物理学 2019-03-20 C. Beck , D. P. Choudhary

When observing from the ground one has to deal with the turbulence from the atmosphere and the turbulence caused by the telescope's surroundings. In order to find the best sites for future solar telescopes and develop multi-conjugate…

太阳与恒星天体物理 · 物理学 2011-03-23 Maria Tham

We use state-of-the-art, three-dimensional non-local thermodynamic equilibrium (non-LTE) radiative magnetohydrodynamic simulations of the quiet solar atmosphere to carry out detailed tests of chromospheric magnetic field diagnostics from…

太阳与恒星天体物理 · 物理学 2017-04-26 Maria Loukitcheva , Stephen M. White , Sami K. Solanki , Gregory D. Fleishman , Mats Carlsson

We present $\texttt{Miko}$, a catalog-to-cosmology pipeline for general flat-sky field-level inference, which provides access to cosmological information beyond the two-point statistics. In the context of weak lensing, we identify several…

宇宙学与河外天体物理 · 物理学 2025-05-13 Alan Junzhe Zhou , Xiangchong Li , Scott Dodelson , Rachel Mandelbaum

Field-level inference is emerging as a promising technique for optimally extracting information from cosmological datasets. Indeed, previous analyses have shown field-based inference produces tighter parameter constraints than power…

宇宙学与河外天体物理 · 物理学 2023-07-04 Supranta S. Boruah , Eduardo Rozo

On-going projects to discover Type Ia supernovae at redshifts z = 0.3 - 1, coupled with improved techniques to narrow the dispersion in SN Ia peak magnitudes, have renewed the prospects for determining the cosmic deceleration parameter q_0.…

天体物理学 · 物理学 2007-05-23 Joshua A. Frieman

Weak lensing will play an important role in future cosmological surveys, including e.g. Euclid and SKA. Sufficiently accurate theoretical predictions are important for correctly interpreting these surveys and hence for extracting correct…

宇宙学与河外天体物理 · 物理学 2019-05-07 Sofie Marie Koksbang , Chris Clarkson

Solar wind forecasting plays a crucial role in space weather prediction, yet significant uncertainties persist due to incomplete magnetic field observations of the Sun. Isolating the solar wind forecasting errors due to these effects is…

We have developed a new technique for weak lensing analysis, with which the effect of the point spread function (PSF) on small galaxy images can be corrected for accurately. Rather than relying on weighted second moments of detected images,…

天体物理学 · 物理学 2016-08-30 Konrad Kuijken

Weak gravitational lensing due to nearby structures, such as the Coma cluster, and the Local Supercluster can be expected to polarize images of distant galaxies by ${\cal O}(0.2%\Omega)$ with coherence over scales of tens of square degrees.…

凝聚态物理 · 物理学 2009-10-22 Andrew Gould , Jens Villumsen

The magnetic field is known to play a crucial role in star formation. Dust polarization is an effective tool for probing the morphology of the field, yet it does not directly trace its strength. Several methods have been developed,…

星系天体物理 · 物理学 2025-07-10 Aristeidis Polychronakis , Aris Tritsis , Raphael Skalidis , Konstantinos Tassis