A sharp X-ray absorption feature in the BL Lacertae object PKS 2155-304

1984 ◽  
Vol 278 ◽  
pp. L99 ◽  
Author(s):  
C. R. Canizares ◽  
J. Kruper
Keyword(s):  
Absorption Feature ◽  
X Ray ◽  
Bl Lacertae ◽  
X Ray Absorption

An X‐Ray Absorption Feature in the BL Lacertae Object H1426+428

1997 ◽  
Vol 483 (2) ◽  
pp. 774-782 ◽  
Author(s):  
Rita M. Sambruna ◽  
I. M. George ◽  
G. Madejski ◽  
C. Megan Urry ◽  
T. J. Turner ◽  
...  
Keyword(s):  
Absorption Feature ◽  
X Ray ◽  
Bl Lacertae ◽  
X Ray Absorption

X‐Ray Absorption in the BL Lacertae Object PKS 0548−322

1998 ◽  
Vol 502 (2) ◽  
pp. 630-639 ◽  
Author(s):  
Rita M. Sambruna ◽  
Richard F. Mushotzky
Keyword(s):  
X Ray ◽  
Bl Lacertae ◽  
X Ray Absorption

Martensite Transition and Microscopic Magnetism of Epitaxial Ni2MnGa Films

2007 ◽  
Vol 1050 ◽  
Author(s):  
Gerhard Jakob ◽  
Tobias Eichhorn ◽  
Michael Kallmayer ◽  
Hans-Joachim Elmers
Keyword(s):  
Magnetic Circular Dichroism ◽  
Theoretical Calculations ◽  
Magnetic Moments ◽  
Structural Phase ◽  
Absorption Feature ◽  
X Ray Diffraction ◽  
Orbital Contribution ◽  
X Ray ◽  
Transmission Geometry ◽  
X Ray Absorption

AbstractA magnetically induced shape memory effect in Ni2MnGa results in huge magnetostrictive effects of several percent. Using x-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD) we investigated element specific magnetic moments and electronic structure of single crystalline, (110) oriented Ni2MnGa films on a-plane Al2O3 substrates in the austenite and martensite state. The structural phase transition of the samples is evident from temperature dependent x-ray diffraction and magnetization measurements. The Ni XAS differ significantly for temperatures above and below the martensite transition in agreement with published ab-initio calculations. Using XAS in transmission geometry on our thin film samples we observe the corresponding reduction of the absorption feature as predicted by theoretical calculations. The XMCD analysis shows the orbital contribution of the Ni electrons to be responsible for the magnetic anisotropy.

A ubiquitous absorption feature in the X-ray spectra of BL Lacertae objects

1991 ◽  
Vol 370 ◽  
pp. 198 ◽  
Author(s):  
Greg M. Madejski ◽  
Richard F. Mushotzky ◽  
Kimberly A. Weaver ◽  
Keith A. Arnaud ◽  
C. Megan Urry
Keyword(s):  
Absorption Feature ◽  
Bl Lacertae Objects ◽  
X Ray ◽  
Bl Lacertae

CXO CDFS J033260.0-274748: A quasar with unusual spectra possibly blueshifted?1This paper is being published without benefit of authors’ corrections.

2011 ◽  
Vol 89 (10) ◽  
pp. 985-990 ◽  
Author(s):  
D. Basu
Keyword(s):  
Optical Spectrum ◽  
Optical Emission ◽  
Emission Lines ◽  
Absorption Feature ◽  
X Ray ◽  
Physical Conditions ◽  
Ejection Mechanism ◽  
X Ray Absorption ◽  
High Bulk

CXO CDFS J033260.0-274748 is a quasi-stellar object (QSO) and identification of several emission lines observed in its optical spectrum has led to the determination of its redshift as 2.579. On the other hand, the Chandra ACIS-I spectrum has detected a strong absorption feature at the observed wavelength around 6.3 keV that cannot be identified under normal physical conditions. The authors have invoked an unusually large outflow bulk velocity of 0.7c–0.8c to explain the feature. However, such extraordinarily high bulk velocities are unprecedented in the extragalactic literature. We show here that the optical emission lines and the X-ray absorption feature can be identified with search lines of longer wavelengths that have been blueshifted and do not need any unusual physical conditions to be invoked. The blueshifted spectra are explained as being due to the net motion of the QSO along with the absorbing cloud towards the observer. Two scenarios are proposed, namely, the ejection mechanism and the multiverse.

scholarly journals MULTI-WAVELENGTH STUDIES OF SPECTACULAR RAM PRESSURE STRIPPING OF A GALAXY: DISCOVERY OF AN X-RAY ABSORPTION FEATURE

2013 ◽  
Vol 777 (2) ◽  
pp. L36 ◽  
Author(s):  
Liyi Gu ◽  
Masafumi Yagi ◽  
Kazuhiro Nakazawa ◽  
Michitoshi Yoshida ◽  
Yutaka Fujita ◽  
...  
Keyword(s):  
Absorption Feature ◽  
X Ray ◽  
Ram Pressure ◽  
Multi Wavelength ◽  
X Ray Absorption

scholarly journals DETECTION OF A TRANSIENT X-RAY ABSORPTION LINE INTRINSIC TO THE BL LACERTAE OBJECT H 2356-309

2011 ◽  
Vol 731 (1) ◽  
pp. 46 ◽  
Author(s):  
Taotao Fang ◽  
David A. Buote ◽  
Philip J. Humphrey ◽  
Claude R. Canizares
Keyword(s):  
Absorption Line ◽  
X Ray ◽  
Bl Lacertae ◽  
X Ray Absorption

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

SIGMAL: A Program for Calculating L-Shell lonization Cross-Sections

1981 ◽  
Vol 39 ◽  
pp. 198-199 ◽  
Author(s):  
R.F. Egerton
Keyword(s):  
Cross Sections ◽  
Fortran Program ◽  
Absorption Data ◽  
X Ray ◽  
Atomic Electrons ◽  
Energy Dependent ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Shell Ionization

SIGMAL is a short (∼ 100-line) Fortran program designed to rapidly compute cross-sections for L-shell ionization, particularly the partial crosssections required in quantitative electron energy-loss microanalysis. The program is based on a hydrogenic model, the L1 and L23 subshells being represented by scaled Coulombic wave functions, which allows the generalized oscillator strength (GOS) to be expressed analytically. In this basic form, the model predicts too large a cross-section at energies near to the ionization edge (see Fig. 1), due mainly to the fact that the screening effect of the atomic electrons is assumed constant over the L-shell region. This can be remedied by applying an energy-dependent correction to the GOS or to the effective nuclear charge, resulting in much closer agreement with experimental X-ray absorption data and with more sophisticated calculations (see Fig. 1 ).

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