Improving x-ray map resolution with image restoration techniques

1996 ◽  
Vol 54 ◽  
pp. 598-599
Author(s):  
Richard B. Mott ◽  
John J. Friel ◽  
Charles G. Waldman
Keyword(s):  
Image Restoration ◽  
Hubble Space Telescope ◽  
Extensive Literature ◽  
Small Object ◽  
X Rays ◽  
X Ray ◽  
Mapping Parameters ◽  
The Matrix ◽  
The 1960S ◽  
Map Resolution

X-rays are emitted from a relatively large volume in bulk samples, limiting the smallest features which are visible in X-ray maps. Beam spreading also hampers attempts to make geometric measurements of features based on their boundaries in X-ray maps. This has prompted recent interest in using low voltages, and consequently mapping L or M lines, in order to minimize the blurring of the maps.An alternative strategy draws on the extensive work in image restoration (deblurring) developed in space science and astronomy since the 1960s. A recent example is the restoration of images from the Hubble Space Telescope prior to its new optics. Extensive literature exists on the theory of image restoration. The simplest case and its correspondence with X-ray mapping parameters is shown in Figures 1 and 2.Using pixels much smaller than the X-ray volume, a small object of differing composition from the matrix generates a broad, low response. This shape corresponds to the point spread function (PSF). The observed X-ray map can be modeled as an “ideal” map, with an X-ray volume of zero, convolved with the PSF. Figure 2a shows the 1-dimensional case of a line profile across a thin layer. Figure 2b shows an idealized noise-free profile which is then convolved with the PSF to give the blurred profile of Figure 2c.

scholarly journals DIFFERENTIAL SENSITIVITY OF PROPHASE POLLEN TUBE CHROMOSOMES TO X-RAYS AND ULTRAVIOLET RADIATION

1943 ◽  
Vol 26 (5) ◽  
pp. 485-494 ◽  
Author(s):  
C. P. Swanson
Keyword(s):  
Nucleic Acid ◽  
Pollen Tube ◽  
Differential Sensitivity ◽  
X Rays ◽  
Relative Importance ◽  
Generative Nucleus ◽  
Acid Cycle ◽  
X Ray ◽  
Total Absence ◽  
The Matrix

1. Through use of the pollen tube technique it has been possible to study the sensitivity of prophase stages to x-rays and ultraviolet, and to correlate the varying sensitivity with changes in the generative nucleus of Tradescantia. 2. Sensitivity to ultraviolet decreases from the 2 hour stage until at 11 hours after germination there is no further production of breaks. The 0 and 1 hour stages show a decreased sensitivity over the 2 hour stage but it has been suggested that this is not due to a decreased sensitivity but to shielding by the pollen wall. 3. Sensitivity to x-rays rises to a peak at the 4 hour stage, but then subsides until no breaks are realized (at a dose of 370.8 r) after the 10 hour stage. In this respect the effects of x-rays and ultraviolet are similar. Each type of x-ray break shows its own individual trend. 4. Correlation of x-ray breaks with changes in the generative nucleus indicates that the important events determining the sensitivity of the chromosomes to breakage are the uptake of water at the time of germination and the movement involved in spiralization. The total absence of breaks after the 11 hour stage is not understood. 5. The changing sensitivity to ultraviolet may depend on any one or all of three factors: (a) the nucleic acid cycle, (b) changes in the matrix, and (c) the number of subdivisions in the chromosome. These are discussed although their relative importance is not known.

scholarly journals Optical counterparts of an ultraluminous X-Ray Source X-1 in NGC 2500

2019 ◽  
Vol 488 (4) ◽  
pp. 5935-5940 ◽  
Author(s):  
N Aksaker ◽  
A Akyuz ◽  
S Avdan ◽  
H Avdan
Keyword(s):  
Hubble Space Telescope ◽  
Optical Emission ◽  
Spectral Energy ◽  
Wide Field ◽  
Nearby Galaxy ◽  
X Rays ◽  
Energy Distributions ◽  
X Ray ◽  
Photon Index ◽  
Absolute Magnitudes

ABSTRACT We present the results of a search for optical counterparts of ultraluminous X-ray source (ULX) X-1 in the nearby galaxy NGC 2500 by using archival images taken with the Hubble Space Telescope Wide Field Camera (WFC3)/UVIS. We identified four optical sources as possible counterparts within the 2σ error radius of 0$^{\prime \prime }_{.}$3 in the images. However, only two of them were investigated as candidates for counterparts due to their point-like features and their identification in various filters. These two faint candidates have absolute magnitudes of MV ≈ −3.4 and −3.7. The spectral energy distributions of two candidates were modelled by a power-law spectrum with a photon index (α) ∼1.5, but the spectrum of one candidate shows a deviation. This may suggest that at least two components are responsible for the optical emission. The red part of the spectrum could arise from the companion star and the blue part could be interpreted as an evidence of reprocessing of the X-rays from the disc.

Stellar-Mass Black Holes

2014 ◽  
Author(s):  
Charles D. Bailyn
Keyword(s):  
Black Holes ◽  
Solar System ◽  
Empirical Study ◽  
Stellar Mass ◽  
The Sun ◽  
X Rays ◽  
X Ray ◽  
New Class ◽  
Total Luminosity ◽  
The 1960S

This chapter examines stellar-mass black holes. The empirical study of black holes began in the 1960s with the discovery of quasars and the advent of X-ray astronomy. X-ray detectors could detect X-rays coming from a particular direction—as the instrument rotated, the detector scanned the sky. It was not expected that X-ray sources from outside the solar system would be detectable. However, it was quickly discovered that there were strong X-ray sources that appeared in the same position in every scan. The inferred luminosity of the sources was hundreds or thousands of times brighter than the Sun. When coincident optical stars were identified, they proved to be relatively faint. Thus, it was clear that a new class of celestial sources must exist whose radiation is predominantly in the form of X-rays, with a total luminosity comparable to or greater than that of ordinary stars.

In the Trenches of the Solar-stellar Connection. V. High-resolution Ultraviolet and X-Ray Observations of Sun-like Stars: The Curious Case of Procyon

2021 ◽  
Vol 923 (2) ◽  
pp. 192
Author(s):  
Thomas R. Ayres
Keyword(s):  
Time Domain ◽  
Hubble Space Telescope ◽  
High Energy ◽  
High Dispersion ◽  
The Sun ◽  
X Rays ◽  
Late Type ◽  
X Ray ◽  
Imaging Spectrograph ◽  
Full Disk

Abstract A joint X-ray (0.2–2 keV) and ultraviolet (1150–3000 Å) time-domain study has been carried out on three nearby bright late-type stars, bracketing the Sun in properties. Alpha Cen A (HD 128620: G2 V) is a near twin to the Sun, although slightly more massive and luminous, slightly metal-rich, but older. Alpha Cen B (HD 128621: K1 V) is cooler than the Sun, somewhat less massive and lower in luminosity. Procyon (HD 61421: F5 IV–V) is hotter, more massive and more luminous than the Sun, half the age, but more evolved. Stellar observations were from Chandra X-ray Observatory and Hubble Space Telescope (HST). The Sun provided a benchmark through high-energy spectral scans from solar irradiance satellites and novel high-dispersion full-disk profiles of key UV species—Mg ii, C ii, and Si iv—from the Interface Region Imaging Spectrograph. Procyon’s flux history was strikingly constant at all wavelengths, in contrast to the other three cycling-dynamo stars. Procyon also displays a strong subcoronal (T ∼ 1 × 105 K) emission excess, relative to chromospheric Mg ii (T ≲ 104 K), although its X-rays (T ∼ 2 MK) appear to be more normal. At the same time, the odd sub-Gaussian shapes, and redshifts, of the subgiant’s “hot lines” (such as Si iv and C iv) are remarkably similar to the solar counterparts (and α Cen AB). This suggests a Sun-like origin, namely a supergranulation network supplied by magnetic flux from a noncycling “local dynamo.”

scholarly journals Chandra and HST studies of six millisecond pulsars in the globular cluster M13

2021 ◽  
Vol 502 (2) ◽  
pp. 1596-1604
Author(s):  
Jiaqi Zhao ◽  
Yue Zhao ◽  
Craig O Heinke
Keyword(s):  
Globular Cluster ◽  
White Dwarf ◽  
Hubble Space Telescope ◽  
X Rays ◽  
Power Law Model ◽  
Millisecond Pulsars ◽  
X Ray ◽  
V Band ◽  
Upper Limit ◽  
Single Power

ABSTRACT We analyse 55 ks of Chandra X-ray observations of the Galactic globular cluster (GC) M13. Using the latest radio timing positions of six known millisecond pulsars (MSPs) in M13 from Wang et al. (2020), we detect confident X-ray counterparts to five of the six MSPs at X-ray luminosities of LX(0.3–8 keV)∼3 × 1030–1031 erg s−1, including the newly discovered PSR J1641+3627F. There are limited X-ray counts at the position of PSR J1641+3627A, for which we obtain an upper limit LX < 1.3 × 1030 erg s−1. We analyse X-ray spectra of all six MSPs, which are well described by either a single blackbody (BB) or a single power-law model. We also incorporate optical/UV imaging observations from the Hubble Space Telescope (HST) and find optical counterparts to PSR J1641+3627D and J1641+3627F. Our colour–magnitude diagrams indicate the latter contains a white dwarf, consistent with the properties suggested by radio timing observations. The counterpart to J1641+3627D is only visible in the V band; however, we argue that the companion to J1641+3627D is also a white dwarf, since we see a BB-like X-ray spectrum, while MSPs with non-degenerate companions generally show non-thermal X-rays from shocks between the pulsar and companion winds. Our work increases the sample of known X-ray and optical counterparts of MSPs in GCs.

scholarly journals Polaris: Mass and Multiplicity

2006 ◽  
Vol 2 (S240) ◽  
pp. 102-104
Author(s):  
Nancy Remage Evans ◽  
Gail Schaefer ◽  
Howard E. Bond ◽  
Edmund Nelan ◽  
Giuseppe Bono ◽  
...  
Keyword(s):  
High Resolution ◽  
Orbital Period ◽  
Hubble Space Telescope ◽  
X Rays ◽  
Full Extent ◽  
Classical Cepheid ◽  
X Ray ◽  
Spectroscopic Binary ◽  
Advanced Camera For Surveys

AbstractPolaris, the nearest and brightest classical Cepheid, is a member of at least a triple system. It has a wide (18″) physical companion, the F-type dwarf Polaris B. Polaris itself is a single-lined spectroscopic binary with an orbital period of ∼30 years (Kamper 1996). By combining Hipparcos measurements of the instantaneous proper motion with long-term measurements and the Kamper radial-velocity orbit, Wielen et al (2000) have predicted the astrometric orbit of the close companion. Using the Hubble Space Telescope and the Advanced Camera for Surveys' High-Resolution Channel with an ultraviolet (F220W) filter, we have now directly detected the close companion. Based on the Wielen et al orbit, the Hipparcos parallax, and our measurement of the separation (0″.176 ± 0″.002), we find a preliminary mass of 5.0 ± 1.5 M⊙ for the Cepheid and 1.38 ± 0.61 M⊙ for the close companion. These values will be refined by additional HST observations scheduled for the next 3 years.We have also obtained a Chandra ACIS-I image of the Polaris field. Two distant companions C and D are not X-rays sources and hence are not young enough to be physical companions of the Cepheid. There is one additional stellar X-ray source in the field, located 253″ from Polaris A, which is a possible companion. Further investigation of such a distant companion is valuable to confirm the full extent of the system.

X-ray Fluorescence Analysis of Gold Ore

1996 ◽  
Vol 50 (5) ◽  
pp. 572-575 ◽  
Author(s):  
Benito De Celis
Keyword(s):  
Analytical Techniques ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
X Rays ◽  
Nondestructive Analysis ◽  
X Ray ◽  
Gold Ore ◽  
Large Samples ◽  
Radioisotope Source ◽  
The Matrix

A method to obtain high sensitivity and accuracy for nondestructive analysis of gold ore is proposed. The applied technique is energy-dispersive X-ray fluorescence, using a Co-57 radioisotope source to excite gold K X-rays in the sample, and a high-purity Ge (HPGe) detector with a range of energies from 1 keV to 4 MeV. The use of radioisotope sources and K X-rays gives some advantages in comparison with other analytical techniques and the usual tube excitation L X-ray analysis: the high sensitivity to concentrations of 1 ppm, the absence of interferences from other elements present in the matrix, and the possibility of performing fast and economical nondestructive analyses of large samples.

X-ray spatial resolution in electron microbeam analysis

1991 ◽  
Vol 49 ◽  
pp. 462-463
Author(s):  
John T. Armstrong ◽  
Paul K. Carpenter
Keyword(s):  
Spatial Resolution ◽  
X Rays ◽  
X Ray ◽  
Excitation Potential ◽  
Sample Density ◽  
The Matrix ◽  
Backscattered Electron ◽  
X Ray Absorption ◽  
Critical Excitation ◽  
Secondary Fluorescence

The spatial resolution of characteristic x-ray production from electron bombardment in thick specimens is dependent upon the rate of energy loss of the primary electrons, the degree of electron scattering, the degree of x-ray absorption by the matrix, and the extent of secondary fluorescence of the x-rays by higher energy characteristic and continuum x-rays. The x-ray spatial resolution in thick specimens is much coarser than the secondary or backscattered electron resolution, typically being of the order of a fraction of a μm to several μm when secondary fluorescence is not significant, or as much as 100 to 200 μm when it is. The size of the excited volume of x-ray production is dependent upon the accelerating potential of the electron beam, the critical excitation potential, and the sample density. The size of the excited volumes of different elements’ x-ray lines can be considerably different in the same matrix, due to differences in critical excitation potential; the emitting volumes can vary even more, due to differences in mass absorption.

Quantitative Evaluation of Degree of Internal Standardization in X-ray Fluorescence Analysis Using Scattered X-rays

1973 ◽  
Vol 27 (5) ◽  
pp. 352-355 ◽  
Author(s):  
D. L. Taylor ◽  
G. Andermann
Keyword(s):  
Experimental Data ◽  
Aqueous Solutions ◽  
Quantitative Evaluation ◽  
Scattered Radiation ◽  
Matrix Effects ◽  
Fluorescence Analysis ◽  
X Rays ◽  
X Ray ◽  
The Matrix ◽  
Internal Standardization

The “degree of internal standardization” for the scattered radiation method of compensation for matrix effects in x-ray fluorescence analysis is defined as the closeness of agreement between the results of analyses of specimens containing identical concentrations of analyte but with differing over-all elemental constituencies. The definition is derived in mathematical terms and is applied to experimental data of analyses of calcium in aqueous solutions containing different dissolved substances as matrix variants. The matrix compensation effectiveness of various wavelengths of scattered radiation can be clearly indicated. Interpretation of the results in terms of basic spectroscopic parameters is offered.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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