Analysis of the Central X-ray Source in DG Tau

NASA Astrophysics Data System (ADS)

Schneider, P. Christian; Schmitt, Jürgen H. M. M.

As a stellar X-ray source DG Tau shows two rather unusual features: A resolved X-ray jet [2] and an X-ray spectrum best described by two thermal components with different absorbing column densities, a so called "two-absorber X-ray (TAX)" morphology [1, 2]. In an effort to understand the properties of the central X-ray source in DG Tau a detailed position analysis was carried out.

Optimization of X-ray Absorbers for TES Microcalorimeters

NASA Technical Reports Server (NTRS)

Iyomoto, Naoko; Sadleir, John E.; Figueroa-Feliciano, Enectali; Saab, Tarek; Bandler, Simon; Kilbourne, Caroline; Chervenak, James; Talley, Dorothy; Finkbeiner, Fred; Brekosky, Regis

2004-01-01

We have investigated the thermal, electrical, and structural properties of Bi and BiCu films that are being developed as X-ray absorbers for transition-edge sensor (TES) microcalorimeter arrays for imaging X-ray spectroscopy. Bi could be an ideal material for an X-ray absorber due to its high X-ray stopping power and low heat capacity, but it has a low thermal conductivity, which can result in position dependence of the pulses in the absorber. In order to improve the thermal conductivity, we added Cu layers in between the Bi layers. We measured electrical and thermal conductivities of the films around 0.1 K(sub 1) the operating temperature of the TES calorimeter, to examine the films and to determine the optimal thickness of the Cu layer. From the electrical conductivity measurements, we found that the Cu is more resistive on the Bi than on a Si substrate. Together with an SEM picture of the Bi surface, we concluded that the rough surface of the Bi film makes the Cu layer resistive when the Cu layer is not thick enough t o fill in the roughness. From the thermal conductivity measurements, we determined the thermal diffusion constant to be 2 x l0(exp 3) micrometers squared per microsecond in a film that consists of 2.25 micrometers of Bi and 0.1 micrometers of Cu. We measured the position dependence in the film and found that its thermal diffusion constant is too low to get good energy resolution, because of the resistive Cu layer and/or possibly a very high heat capacity of our Bi films. We show plans to improve the thermal diffusion constant in our BiCu absorbers.

Multi-Absorber Transition-Edge Sensors for X-Ray Astronomy Applications

NASA Technical Reports Server (NTRS)

Smith, S. J.; Adams, J. S.; Bandler, S. R.; Busch, S. E.; Chervenak, J. A.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kelly, D. P.;

Microstructure Analysis of Bismuth Absorbers for Transition-Edge Sensor X-ray Microcalorimeters

NASA Astrophysics Data System (ADS)

Yan, Daikang; Divan, Ralu; Gades, Lisa M.; Kenesei, Peter; Madden, Timothy J.; Miceli, Antonino; Park, Jun-Sang; Patel, Umeshkumar M.; Quaranta, Orlando; Sharma, Hemant; Bennett, Douglas A.; Doriese, William B.; Fowler, Joseph W.; Gard, Johnathon D.; Hays-Wehle, James P.; Morgan, Kelsey M.; Schmidt, Daniel R.; Swetz, Daniel S.; Ullom, Joel N.

2018-03-01

Given its large X-ray stopping power and low specific heat capacity, bismuth (Bi) is a promising absorber material for X-ray microcalorimeters and has been used with transition-edge sensors (TESs) in the past. However, distinct X-ray spectral features have been observed in TESs with Bi absorbers deposited with different techniques. Evaporated Bi absorbers are widely reported to have non-Gaussian low-energy tails, while electroplated ones do not show this feature. In this study, we fabricated Bi absorbers with these two methods and performed microstructure analysis using scanning electron microscopy and X-ray diffraction microscopy. The two types of material showed the same crystallographic structure, but the grain size of the electroplated Bi was about 40 times larger than that of the evaporated Bi. This distinction in grain size is likely to be the cause of their different spectral responses.

DISCOVERY OF RAPIDLY MOVING PARTIAL X-RAY ABSORBERS WITHIN GAMMA CASSIOPEIAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamaguchi, K.; Oskinova, L.; Russell, C. M. P.

2016-12-01

Gamma Cassiopeiae is an enigmatic Be star with unusually strong hard X-ray emission. The Suzaku observatory detected six rapid X-ray spectral hardening events called “softness dips” in a ∼100 ks observation in 2011. All the softness dip events show symmetric softness-ratio variations, and some of them have flat bottoms apparently due to saturation. The softness dip spectra are best described by either ∼40% or ∼70% partial covering absorption to kT  ∼ 12 keV plasma emission by matter with a neutral hydrogen column density of ∼(2−8) × 10{sup 21} cm{sup −2}, while the spectrum outside these dips is almost free of absorption. This resultmore » suggests the presence of two distinct X-ray-emitting spots in the γ  Cas system, perhaps on a white dwarf (WD) companion with dipole mass accretion. The partial covering absorbers may be blobs in the Be stellar wind, the Be disk, or rotating around the WD companion. Weak correlations of the softness ratios to the hard X-ray flux suggest the presence of stable plasmas at kT  ∼ 0.9 and 5 keV, which may originate from the Be or WD winds. The formation of a Be star and WD binary system requires mass transfer between two stars; γ  Cas may have experienced such activity in the past.« less

Establishment of new design criteria for GlidCop ® X-ray absorbers

DOE PAGES

Collins, Jeff T.; Nudell, Jeremy; Navrotski, Gary; ...

2017-02-20

Here, an engineering research program has been conducted at the Advanced Photon Source (APS) in order to determine the thermomechanical conditions that lead to crack formation in GlidCop ®, a material commonly used to fabricate X-ray absorbers at X-ray synchrotron facilities. This dispersion-strengthened copper alloy is a proprietary material and detailed technical data of interest to the synchrotron community is limited. The results from the research program have allowed new design criteria to be established for GlidCop ® X-ray absorbers based upon the thermomechanically induced fatigue behavior of the material. X-ray power from APS insertion devices was used to exposemore » 30 GlidCop ® samples to 10000 thermal loading cycles each under various beam power conditions, and all of the samples were metallurgically examined for crack presence/geometry. In addition, an independent testing facility was hired to measure temperature-dependent mechanical data and uniaxial mechanical fatigue data for numerous GlidCop ® samples. Data from these studies support finite element analysis (FEA) simulation and parametric models, allowing the development of a thermal fatigue model and the establishment of new design criteria so that the thermomechanically induced fatigue life of X-ray absorbers may be predicted. It is also demonstrated how the thermal fatigue model can be used as a tool to geometrically optimize X-ray absorber designs.« less

Establishment of new design criteria for GlidCop ® X-ray absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, Jeff T.; Nudell, Jeremy; Navrotski, Gary

Here, an engineering research program has been conducted at the Advanced Photon Source (APS) in order to determine the thermomechanical conditions that lead to crack formation in GlidCop ®, a material commonly used to fabricate X-ray absorbers at X-ray synchrotron facilities. This dispersion-strengthened copper alloy is a proprietary material and detailed technical data of interest to the synchrotron community is limited. The results from the research program have allowed new design criteria to be established for GlidCop ® X-ray absorbers based upon the thermomechanically induced fatigue behavior of the material. X-ray power from APS insertion devices was used to exposemore » 30 GlidCop ® samples to 10000 thermal loading cycles each under various beam power conditions, and all of the samples were metallurgically examined for crack presence/geometry. In addition, an independent testing facility was hired to measure temperature-dependent mechanical data and uniaxial mechanical fatigue data for numerous GlidCop ® samples. Data from these studies support finite element analysis (FEA) simulation and parametric models, allowing the development of a thermal fatigue model and the establishment of new design criteria so that the thermomechanically induced fatigue life of X-ray absorbers may be predicted. It is also demonstrated how the thermal fatigue model can be used as a tool to geometrically optimize X-ray absorber designs.« less

Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

NASA Technical Reports Server (NTRS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-01-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show

Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Nemmen, R. S.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-04-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60 per cent, consistent with previous studies. The fraction of sources with UFOs is >34 per cent, >67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show

Automated Hybridization of X-ray Absorber Elements-A Path to Large Format Microcalorimeter Arrays

NASA Technical Reports Server (NTRS)

Moseley, S.; Kelley, R.; Allen, C.; Kilbourne, C.; Costen, N.; Miller, T.

2007-01-01

In the design of microcalorimeters, it is often desirable to produce the X-ray absorber separately from the detector element. In this case, the attachment of the absorber to the detector element with the required thermal and mechanical characteristics is a major challenge. In such arrays, the attachment has been done by hand. This process is not easily extended to the large format arrays required for future X- ray astronomy missions such as the New x-ray Telescope or NeXT. In this paper we present an automated process for attaching absorber tiles to the surface of a large-scale X-ray detector array. The absorbers are attached with stycast epoxy to a thermally isolating polymer structure made of SU-8. SU-8 is a negative epoxy based photo resist produced by Microchem. We describe the fabrication of the X-ray absorbers and their suspension on a handle die in an adhesive matrix. We describe the production process for the polymer isolators on the detector elements. We have developed a new process for the alignment, and simultaneous bonding of the absorber tiles to an entire detector array. This process uses equipment and techniques used in the flip-chip bonding industry and approaches developed in the fabrication of the XRS-2 instrument. XRS-2 was an X-ray spectrometer that was launched on the Suzaku telescope in July 10, 2005. We describe the process and show examples of sample arrays produced by this process. Arrays with up to 300 elements have been bonded. The present tests have used dummy absorbers made of Si. In future work, we will demonstrate bonding of HgTe absorbers.

Unification of X-ray Winds in Seyfert Galaxies: From Ultra-fast Outflows to Warm Absorbers

NASA Astrophysics Data System (ADS)

Tombesi, Francesco; Cappi, M.; Reeves, J.; Nemmen, R.; Braito, V.; Gaspari, M.; Reynolds, C. S.

2013-04-01

The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is >60%, consistent with previous studies. The fraction of sources with UFOs is >34%, >67% of which also show WAs. The large dynamic range obtained when considering all the absorbers together allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. The absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. This strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The observed parameters and correlations are consistent with both radiation pressure through Compton scattering and MHD processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, have a sufficiently high mechanical power to significantly contribute to the AGN feedback.

X-ray filter for x-ray powder diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinsheimer, John Jay; Conley, Raymond P.; Bouet, Nathalie C. D.

Technologies are described for apparatus, methods and systems effective for filtering. The filters may comprise a first plate. The first plate may include an x-ray absorbing material and walls defining first slits. The first slits may include arc shaped openings through the first plate. The walls of the first plate may be configured to absorb at least some of first x-rays when the first x-rays are incident on the x-ray absorbing material, and to output second x-rays. The filters may comprise a second plate spaced from the first plate. The second plate may include the x-ray absorbing material and wallsmore » defining second slits. The second slits may include arc shaped openings through the second plate. The walls of the second plate may be configured to absorb at least some of second x-rays and to output third x-rays.« less

A partial eclipse of the heart: the absorbed X-ray low state in Mrk 1048

NASA Astrophysics Data System (ADS)

Parker, M. L.; Schartel, N.; Komossa, S.; Grupe, D.; Santos-Lleó, M.; Fabian, A. C.; Mathur, S.

2014-11-01

We present two new XMM-Newton observations of an unprecedented low-flux state in the Seyfert 1 Mrk 1048 (NGC 985), taken in 2013. The X-ray flux below 1 keV drops by a factor of 4-5, whereas the spectrum above 5 keV is essentially unchanged. This points towards an absorption origin for the low state, and we confirm this with spectral fitting, finding that the spectral differences can be well modelled by the addition of a partial covering neutral absorber, with a column density of ˜3 × 1022 cm-2 and a covering fraction of ˜0.6. The optical and UV fluxes are not affected, and indeed are marginally brighter in the more recent observations, suggesting that only the inner regions of the disc are affected by the absorption event. This indicates either that the absorption is due to a cloud passing over the inner disc, obscuring the X-ray source but leaving the outer disc untouched, or that the absorber is dust-free so the UV continuum is unaffected. We use arguments based on the duration of the event and the physical properties of the absorber to constrain its size and location, and conclude that it is most likely a small cloud at ˜1018 cm from the source.

Eliminating the non-Gaussian spectral response of X-ray absorbers for transition-edge sensors

NASA Astrophysics Data System (ADS)

Yan, Daikang; Divan, Ralu; Gades, Lisa M.; Kenesei, Peter; Madden, Timothy J.; Miceli, Antonino; Park, Jun-Sang; Patel, Umeshkumar M.; Quaranta, Orlando; Sharma, Hemant; Bennett, Douglas A.; Doriese, William B.; Fowler, Joseph W.; Gard, Johnathon D.; Hays-Wehle, James P.; Morgan, Kelsey M.; Schmidt, Daniel R.; Swetz, Daniel S.; Ullom, Joel N.

2017-11-01

Transition-edge sensors (TESs) as microcalorimeters for high-energy-resolution X-ray spectroscopy are often fabricated with an absorber made of materials with high Z (for X-ray stopping power) and low heat capacity (for high resolving power). Bismuth represents one of the most compelling options. TESs with evaporated bismuth absorbers have shown spectra with undesirable and unexplained low-energy tails. We have developed TESs with electroplated bismuth absorbers over a gold layer that are not afflicted by this problem and that retain the other positive aspects of this material. To better understand these phenomena, we have studied a series of TESs with gold, gold/evaporated bismuth, and gold/electroplated bismuth absorbers, fabricated on the same die with identical thermal coupling. We show that the bismuth morphology is linked to the spectral response of X-ray TES microcalorimeters.

Ionized absorbers, ionized emitters, and the X-ray spectrum of active galactic nuclei

NASA Technical Reports Server (NTRS)

Netzer, Hagai

1993-01-01

Broad absorption features are common in the X-ray spectrum of low-luminosity AGNs. The features have been modeled by leaky neutral absorbers or by highly ionized gas that completely occult the continuum source. Such models are incomplete since they do not take into account all the physical processes in the gas. In particular, no previous model included the X-ray emission by the ionized absorbing gas and the reflection of the continuum source radiation. The present work discusses the emission, absorption, and reflection properties of photoionized gases with emphasis on conditions thought to prevail in AGNs. It shows that such gas is likely to produce intense X-ray line and continuum radiation and to reflect a sizable fraction of the nonstellar continuum at all energies. If such gas is indeed responsible for the observed X-ray absorption, then absorption edges are much weaker than commonly assumed, and some residual X-ray continuum is likely to be observed even if the line of sight is completely blocked. Moreover, X-ray emission features may show up in sources not showing X-ray absorption. This has immense consequences for medium-resolution X-ray missions, such as BBXRT and Astro-D, and for the planned high-resolution experiments on board XMM and AXAF.

On the relation of optical obscuration and X-ray absorption in Seyfert galaxies

NASA Astrophysics Data System (ADS)

Burtscher, L.; Davies, R. I.; Graciá-Carpio, J.; Koss, M. J.; Lin, M.-Y.; Lutz, D.; Nandra, P.; Netzer, H.; Orban de Xivry, G.; Ricci, C.; Rosario, D. J.; Veilleux, S.; Contursi, A.; Genzel, R.; Schnorr-Müller, A.; Sternberg, A.; Sturm, E.; Tacconi, L. J.

2016-02-01

The optical classification of a Seyfert galaxy and whether it is considered X-ray absorbed are often used interchangeably. There are many borderline cases, however, and also numerous examples where the optical and X-ray classifications appear to be in disagreement. In this article we revisit the relation between optical obscuration and X-ray absorption in active galactic nuclei (AGNs). We make use of our "dust colour" method to derive the optical obscuration AV, and consistently estimated X-ray absorbing columns using 0.3-150 keV spectral energy distributions. We also take into account the variable nature of the neutral gas column NH and derive the Seyfert subclasses of all our objects in a consistent way. We show in a sample of 25 local, hard-X-ray detected Seyfert galaxies (log LX/ (erg / s) ≈ 41.5-43.5) that there can actually be a good agreement between optical and X-ray classification. If Seyfert types 1.8 and 1.9 are considered unobscured, the threshold between X-ray unabsorbed and absorbed should be chosen at a column NH = 1022.3 cm-2 to be consistent with the optical classification. We find that NH is related to AV and that the NH/AV ratio is approximately Galactic or higher in all sources, as indicated previously. However, in several objects we also see that deviations from the Galactic ratio are only due to a variable X-ray column, showing that (1) deviations from the Galactic NH/AV can be simply explained by dust-free neutral gas within the broad-line region in some sources; that (2) the dust properties in AGNs can be similar to Galactic dust and that (3) the dust colour method is a robust way to estimate the optical extinction towards the sublimation radius in all but the most obscured AGNs.

Absorbed dose determination using experimental and analytical predictions of x-ray spectra

NASA Astrophysics Data System (ADS)

Edwards, David Lee

1999-10-01

Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate radiation shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) to measure the radiation dose. The TLD's were exposed to x- ray radiation generated by operation of the ISWE in- vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during

Simultaneous X-ray and Far-Ultraviolet Spectra of AGN with ASCA and HUT

NASA Technical Reports Server (NTRS)

Kriss, Gerard A.

1997-01-01

We obtained ASCA spectra of the Seyfert 1 galaxy NGC 3516 in March 1995. Simultaneous far-UV observations were obtained with the Hopkins Ultraviolet Telescope on the Astro-2 shuttle mission. The ASCA spectrum shows a lightly absorbed power law of energy index 0.78. The low energy absorbing column is significantly less than previously seen. Prominent 0 VII and 0 VIII absorption edges are visible, but, consistent with the much lower total absorbing column, no Fe K absorption edge is detectable. A weak, narrow Fe K(alpha) emission line from cold material is present as well as a broad Fe K(alpha) line. These features are similar to those reported in other Seyfert 1 galaxies. A single warm absorber model provides only an imperfect description of the low energy absorption. In addition to a highly ionized absorber with ionization parameter U = 1.66 and a total column density of 1.4 x 10(exp 22)/sq cm, adding a lower ionization absorber with U = 0.32 and a total column of 6.9 x 10(exp 21)/sq cm significantly improves the fit. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to less than 160 km/s at 90% confidence. Turbulence at the sound speed of the photoionized gas provides the best fit. None of the warm absorber models fit to the X-ray spectrum can match the observed equivalent widths of all the UV absorption lines. Accounting for the X-ray and UV absorption simultaneously requires an absorbing region with a broad range of ionization parameters and column densities.

Eliminating the non-Gaussian spectral response of X-ray absorbers for transition-edge sensors

DOE PAGES

Divan, Ralu; Gades, Lisa M.; Kenesei, Peter; ...

2017-11-08

Transition-edge sensors (TESs) as microcalorimeters for high-energy-resolution X-ray spectroscopy are often fabricated with an absorber made of materials with high Z (for X-ray stopping power) and low heat capacity (for high resolving power). Bismuth represents one of the most compelling options. TESs with evaporated bismuth absorbers have shown spectra with undesirable and unexplained low-energy tails. We have developed TESs with electroplated bismuth absorbers over a gold layer that are not afflicted by this problem and that retain the other positive aspects of this material. To better understand these phenomena, we have studied a series of TESs with gold, gold/evaporated bismuth,more » and gold/electroplated bismuth absorbers, fabricated on the same die with identical thermal coupling. Lastly, we show that the bismuth morphology is linked to the spectral response of X-ray TES microcalorimeters.« less

Eliminating the non-Gaussian spectral response of X-ray absorbers for transition-edge sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Divan, Ralu; Gades, Lisa M.; Kenesei, Peter

Transition-edge sensors (TESs) as microcalorimeters for high-energy-resolution X-ray spectroscopy are often fabricated with an absorber made of materials with high Z (for X-ray stopping power) and low heat capacity (for high resolving power). Bismuth represents one of the most compelling options. TESs with evaporated bismuth absorbers have shown spectra with undesirable and unexplained low-energy tails. We have developed TESs with electroplated bismuth absorbers over a gold layer that are not afflicted by this problem and that retain the other positive aspects of this material. To better understand these phenomena, we have studied a series of TESs with gold, gold/evaporated bismuth,more » and gold/electroplated bismuth absorbers, fabricated on the same die with identical thermal coupling. Lastly, we show that the bismuth morphology is linked to the spectral response of X-ray TES microcalorimeters.« less

Complex X-ray Absorption and the Fe K(alpha) Profile in NGC 3516

NASA Technical Reports Server (NTRS)

Turner, T. J.; Kraemer, S. B.; George, I. M.; Reeves, J. N.; Botorff, M. C.

2004-01-01

We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and November. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of approximately 1100 kilometers per second, has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (approximately 2.5 x 10(exp 23) per square centimeter) of highly ionized gas with a covering fraction approximately 50%. This low covering fraction suggests that the absorber lies within a few 1t-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two new components are too highly ionized to be radiatively accelerated, which we suggest is evidence for a hydromagnetic origin for the outflow. Applying our model to the November dataset, we can account for the spectral variability primarily by a drop in the ionization states of the absorbers, as expected by the change in the continuum flux. When this complex absorption is accounted for we find the underlying continuum to be typical of Seyfert 1 galaxies. The spectral curvature attributed to the high column absorber, in turn, reduces estimates of the flux and extent of any broad Fe emission line from the accretion disk.

X-ray wind tomography of IGR J17252-3616

NASA Astrophysics Data System (ADS)

Manousakis, Antonios; Walter, Roland

IGR J17252-3616 is an heavily absorbed and eclipsing High Mass X-ray Binary with an ab-sorbing hydrogen column density >1023 cm-2 . We have observed it with XMM-Newton to understand the geometry of the absorbing material. Observations were scheduled in order to cover as many orbital phases as possible. Timing analysis is constraining the orbital solution and the physical parameters of the system. Spectral analysis reveals remarkable variations of the absorbing column density and of the Iron Kα fluorescence line around the eclipse. These variations allow to map the geometry of the absorbing and reflection material. Very large accretion structures could be imaged for the first time.

Dynamical and Radiative Properties of X-Ray Pulsar Accretion Columns: Phase-averaged Spectra

NASA Astrophysics Data System (ADS)

West, Brent F.; Wolfram, Kenneth D.; Becker, Peter A.

2017-02-01

The availability of the unprecedented spectral resolution provided by modern X-ray observatories is opening up new areas for study involving the coupled formation of the continuum emission and the cyclotron absorption features in accretion-powered X-ray pulsar spectra. Previous research focusing on the dynamics and the associated formation of the observed spectra has largely been confined to the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface, while the dynamical effect of gas pressure is ignored. In a companion paper, we have presented a detailed analysis of the hydrodynamic and thermodynamic structure of the accretion column obtained using a new self-consistent model that includes the effects of both gas and radiation pressures. In this paper, we explore the formation of the associated X-ray spectra using a rigorous photon transport equation that is consistent with the hydrodynamic and thermodynamic structure of the column. We use the new model to obtain phase-averaged spectra and partially occulted spectra for Her X-1, Cen X-3, and LMC X-4. We also use the new model to constrain the emission geometry, and compare the resulting parameters with those obtained using previously published models. Our model sheds new light on the structure of the column, the relationship between the ionized gas and the photons, the competition between diffusive and advective transport, and the magnitude of the energy-averaged cyclotron scattering cross-section.

Absorbed Dose Determination Using Experimental and Analytical Predictions of X-Ray Spectra

NASA Technical Reports Server (NTRS)

Edwards, D. L.; Carruth, Ralph (Technical Monitor)

2001-01-01

Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the U.S. Space Shuttle. This series of experiments was named the international space welding experiment (ISWE). The hardware associated with the ISWE was leased to NASA by the Paton Welding Institute (PWI) in Ukraine for ground-based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used thermoluminescence dosimeters (TLD's) shielded with material currently used by astronauts during extravehicular activities to measure the radiation dose. The TLD's were exposed to x-ray radiation generated by operation of the ISWE in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure, then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the ISWE in-vacuum electron beam welding tool. The calculated absorbed dose

The O VI Mystery: Mismatch between X-Ray and UV Column Densities

NASA Astrophysics Data System (ADS)

Mathur, S.; Nicastro, F.; Gupta, A.; Krongold, Y.; McLaughlin, B. M.; Brickhouse, N.; Pradhan, A.

2017-12-01

The UV spectra of Galactic and extragalactic sightlines often show O VI absorption lines at a range of redshifts, and from a variety of sources from the Galactic circumgalactic medium to active galactic nuclei (AGN) outflows. Inner shell O VI absorption is also observed in X-ray spectra (at λ =22.03 Å), but the column density inferred from the X-ray line was consistently larger than that from the UV line. Here we present a solution to this discrepancy for the z = 0 systems. The O II Kβ line {}4{S}0\\to {(}3D)3{p}4P at 562.40 eV (≡22.04 Å) is blended with the O VI Kα line in X-ray spectra. We estimate the strength of this O II line in two different ways, and show that in most cases the O II line accounts for the entire blended line. The small amount of O VI equivalent width present in some cases has column density entirely consistent with the UV value. This solution to the O VI discrepancy, however, does not apply to high column-density systems like AGN outflows. We discuss other possible causes to explain their UV/X-ray mismatch. The O VI and O II lines will be resolved by gratings on board the proposed mission Arcus and the concept mission Lynx, and would allow the detection of weak O VI lines not just at z = 0, but also at higher redshift.

Are There Intrinsically X-Ray Quiet Quasars

NASA Technical Reports Server (NTRS)

Gallagher, S. C.; Brandt, W. N.; Laor, A.; Elvis, Martin; Mathur, S.; Wills, Beverly J.; Iyomoto, N.; White, Nicholas (Technical Monitor)

2000-01-01

Recent ROSAT studies have identified a significant population of Active Galactic Nuclei (AGN) that are notably faint in soft X-rays relative to their optical fluxes. Are these AGN intrinsically X-ray weak or are they just highly absorbed? Brandt, Laor & Wills have systematically examined the optical and UV spectral properties of a well-defined sample of these soft X-ray weak (SXW) AGN drawn from the Boroson & Green sample of all the Palomar Green AGN 00 with z < 0.5. We present ASCA observations of three of these SXW AGN: PG 1011-040, PG 1535+547 (Mrk 486), and PG 2112+059. In general, our ASCA observations support the intrinsic absorption scenario for explaining soft X-ray weakness; both PG 1535+547 and PG 2112+059 show significant column densities (NH is approximately 10(exp 22) - 10(exp 23)/sq cm) of absorbing gas. Interestingly, PG 1011-040 shows no spectral evidence for X-ray absorption. The weak X-ray emission may result from very strong absorption of a partially covered source, or this AGN may be intrinsically X-ray weak. PG 2112+059 is a Broad Absorption Line (BAL) QSO, and we find it to have the highest X-ray flux known of this class. It shows a typical power-law X-ray continuum above 3 keV; this is the first direct evidence that BAL QSOs indeed have normal X-ray continua underlying their intrinsic absorption. Finally, marked variability between the ROSAT and ASCA observations of PG 1535+547 and PG 2112+059 suggests that the soft X-ray weak designation may be transient, and multi-epoch 0.1-10.0 KeV X-ray observations are required to constrain variability of the absorber and continuum.

A New Two-fluid Radiation-hydrodynamical Model for X-Ray Pulsar Accretion Columns

NASA Astrophysics Data System (ADS)

West, Brent F.; Wolfram, Kenneth D.; Becker, Peter A.

2017-02-01

Previous research centered on the hydrodynamics in X-ray pulsar accretion columns has largely focused on the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface. This type of model has been relatively successful in describing the overall properties of the accretion flows, but it does not account for the possible dynamical effect of the gas pressure. On the other hand, the most successful radiative transport models for pulsars generally do not include a rigorous treatment of the dynamical structure of the column, instead assuming an ad hoc velocity profile. In this paper, we explore the structure of X-ray pulsar accretion columns using a new, self-consistent, “two-fluid” model, which incorporates the dynamical effect of the gas and radiation pressures, the dipole variation of the magnetic field, the thermodynamic effect of all of the relevant coupling and cooling processes, and a rigorous set of physical boundary conditions. The model has six free parameters, which we vary in order to approximately fit the phase-averaged spectra in Her X-1, Cen X-3, and LMC X-4. In this paper, we focus on the dynamical results, which shed new light on the surface magnetic field strength, the inclination of the magnetic field axis relative to the rotation axis, the relative importance of gas and radiation pressures, and the radial variation of the ion, electron, and inverse-Compton temperatures. The results obtained for the X-ray spectra are presented in a separate paper.

Dynamical and Radiative Properties of X-Ray Pulsar Accretion Columns: Phase-averaged Spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, Brent F.; Wolfram, Kenneth D.; Becker, Peter A., E-mail: bwest@usna.edu, E-mail: kswolfram@gmail.com, E-mail: pbecker@gmu.edu

The availability of the unprecedented spectral resolution provided by modern X-ray observatories is opening up new areas for study involving the coupled formation of the continuum emission and the cyclotron absorption features in accretion-powered X-ray pulsar spectra. Previous research focusing on the dynamics and the associated formation of the observed spectra has largely been confined to the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface, while the dynamical effect of gas pressure is ignored. In a companion paper, we have presented a detailed analysis of the hydrodynamic and thermodynamicmore » structure of the accretion column obtained using a new self-consistent model that includes the effects of both gas and radiation pressures. In this paper, we explore the formation of the associated X-ray spectra using a rigorous photon transport equation that is consistent with the hydrodynamic and thermodynamic structure of the column. We use the new model to obtain phase-averaged spectra and partially occulted spectra for Her X-1, Cen X-3, and LMC X-4. We also use the new model to constrain the emission geometry, and compare the resulting parameters with those obtained using previously published models. Our model sheds new light on the structure of the column, the relationship between the ionized gas and the photons, the competition between diffusive and advective transport, and the magnitude of the energy-averaged cyclotron scattering cross-section.« less

Bright X-ray transient in the LMC

NASA Astrophysics Data System (ADS)

Saxton, R.; Read, A. M.; Li, D. Y.

2018-01-01

We report a bright X-ray transient in the LMC from an XMM-Newton slew made on 5th January 2018. The source, XMMSL2 J053629.4-675940, had a soft X-ray (0.2-2 keV) count rate in the EPIC-pn detector, medium filter of 1.82+/-0.56 c/s, equivalent to a flux Fx=2.3+/-0.7E-12 ergs/s/cm2 for a nominal spectrum of a power-law of slope 2 absorbed by a column NH=3E20 cm^-2.

High-Resolution Hard X-Ray and Gamma-Ray Spectrometers Based on Superconducting Absorbers Coupled to Superconducting Transition Edge Sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

van den Berg, M.; Chow, D.; Loshak, A.

2000-09-21

We are developing detectors based on bulk superconducting absorbers coupled to superconducting transition edge sensors (TES) for high-resolution spectroscopy of hard X-rays and soft gamma-rays. We have achieved an energy resolution of 70 eV FWHM at 60 keV using a 1 x 1 x 0.25 mm{sup 3} Sn absorber coupled to a Mo/Cu multilayer TES with a transition temperature of 100 mK. The response of the detector is compared with a simple model using only material properties data and characteristics derived from IV-measurements. We have also manufactured detectors using superconducting absorbers with a higher stopping power, such as Pb andmore » Ta. We present our first measurements of these detectors, including the thermalization characteristics of the bulk superconducting absorbers. The differences in performance between the detectors are discussed and an outline of the future direction of our detector development efforts is given.« less

X-Ray Characteristics of Megamaser Galaxies

NASA Astrophysics Data System (ADS)

Leiter, K.; Kadler, M.; Wilms, J.; Braatz, J.; Grossberger, C.; Krauss, F.; Kreikenbohm, A.; Langejahn, M.; Litzinger, E.; Markowitz, A.

2017-10-01

Water megamaser galaxies are a rare subclass of Active Galactic Nuclei (AGN). They play a key role in modern cosmology, providing a significant improvement for measuring geometrical distances with high precision. Megamaser studies presently measure H_{0} to about 5%. The goal of modern programs is to reach 3%, which strongly constrains the equation of state of dark energy. An increasing number of independent measurements of suitable water masers is providing the statistics necessary to decrease the uncertainties. X-ray studies of maser galaxies yield important constraints on target-selection criteria for future surveys, increasing their detection rate. We studied the X-ray properties of a homogeneous sample of Type 2 AGN with water maser activity observed by XMM-Newton to investigate the properties of megamaser-hosting galaxies compared to a control sample of non-maser galaxies. Comparing the luminosity distributions confirm previous results that water maser galaxies appear more luminous than non-maser sources. The maser phenomenon goes along with more complex X-ray spectra, higher column densities and higher equivalent widths of the Fe Kα line. Both a sufficiently luminous X-ray source and a high absorbing column density in the line of sight are necessary prerequisites to favour the appearance of the water megamaser phenomenon in AGN.

X-Rays

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X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat ...

X-ray counterpart candidates for six new γ-ray pulsars

NASA Astrophysics Data System (ADS)

Zyuzin, Dmitry A.; Karpova, Anna V.; Shibanov, Yuriy A.

2018-05-01

Using archival X-ray data, we have found point-like X-ray counterpart candidates positionally coincident with six γ-ray pulsars discovered recently in the Fermi Gamma-ray Space Telescope data by the Einstein@Home project. The candidates for PSRs J0002+6216, J0554+3107, J1844-0346, and J1105-6037 are detected with Swift, and those for PSRs J0359+5414 and J2017+3625 are detected with Chandra. Despite a low count statistics for some candidates, assuming plausible constraints on the absorbing column density towards the pulsars, we show that X-ray spectral properties for all of them are consistent with those observed for other pulsars. J0359+5414 is the most reliably identified object. We detect a nebula around it, whose spectrum and extent suggest that this is a pulsar wind nebula powered by the pulsar. Associations of J0002+6216 and J1844-0346 with supernova remnants CTB 1 and G28.6-0.1 are proposed.

A Suzaku X-ray Observation of One Orbit of the Supergiant Fast X-ray Transient IGR J16479-4514

NASA Technical Reports Server (NTRS)

Sidoli, L.; Esposito, P.; Sguera, V.; Bodaghee, A.; Tomsick, J. A.; Pottschmidt, K.; Rodriguez, J.; Ramano, P.; Wilms, J.

2013-01-01

We report on a 250 ks long X-ray observation of the supergiant fast X-ray transient (SFXT) IGR J16479-4514 performed with Suzaku in 2012 February. During this observation, about 80% of the short orbital period (P(sub orb) approximates 3.32 days) was covered as continuously as possible for the first time. The source light curve displays variability of more than two orders of magnitude, starting with a very low emission state (10(exp -13) erg / sq cm/s; 1-10 keV) lasting the first 46 ks, consistent with being due to the X-ray eclipse by the supergiant companion. The transition to the uneclipsed X-ray emission is energy dependent. Outside the eclipse, the source spends most of the time at a level of 6-7X10)(exp-12) erg/sq. cm/s) punctuated by two structured faint flares with a duration of about 10 and 15 ks, respectively, reaching a peak flux of 3-4X10(exp -11) erg/sq. cm./S, separated by about 0.2 in orbital phase. Remarkably, the first faint flare occurs at a similar orbital phase of the bright flares previously observed in the system. This indicates the presence of a phase-locked large scale structure in the supergiant wind, driving a higher accretion rate onto the compact object. The average X-ray spectrum is hard and highly absorbed, with a column density, NH, of 10*exp 23)/sq cm, clearly in excess of the interstellar absorption. There is no evidence for variability of the absorbing column density, except that during the eclipse, where a less absorbed X-ray spectrum is observed. A narrow Fe K-alpha emission line at 6.4 keV is viewed along the whole orbit, with an intensity which correlates with the continuum emission above 7 keV. The scattered component visible during the X-ray eclipse allowed us to directly probe the wind density at the orbital separation, resulting in rho(sub w)=7X10(exp -14) g/cubic cm. Assuming a spherical geometry for the supergiant wind, the derived wind density translates into a ratio M(sub w)/v(sub infinity) = 7X10(exp -17) Solar M

X-ray Luminosity and Absorption Column Fluctuations in the H2O Maser Galaxy NGC 4258 from Weeks to Years

DOE Office of Scientific and Technical Information (OSTI.GOV)

Argon, A.

2004-07-30

The authors report monitoring of the 0.3-10 keV spectrum of NGC 4258 with the XMM-Newton observatory at five epochs over 1.5 years. They also report reprocessing of an overlapping four epoch series of archival Chandra observations (0.5-10 keV). By including earlier ASCA and Beppo-SAX observations, they present a new, nine year time-series of models fit to the X-ray spectrum of NGC 4258. They model the Chandra and XMM-Newton data self-consistently with partially absorbed, hard power-law, soft thermal plasma, and soft power-law components. Over the nine years, the photo-electric absorbing column ({approx} 10{sup 23} cm{sup -2}) did not vary detectably, exceptmore » for a {approx} 40% drop between two ASCA epochs separated by 3 years (in 1993 and 1996) and a {approx} 60% rise between two XMM-Newton epochs separated by just 5 months (in 2001 and 2002). In contrast, factor of 2-3 changes are seen in absorbed flux on the timescale of years. These are uncorrelated with changes in absorbing column and indicative of central engine variability. The most rapid change in luminosity (5-10 keV) that the authors detect (with XMM-Newton and Chandra) is on the order of 30% over 19 days. The warped disk that is a known source of H{sub 2}O maser emission in NGC 4258 is believed to cross the line of sight to the central engine. They propose that the variations in absorbing column arise from inhomogeneities in the rotating disk, as they sweep across the line of sight. They estimate that the inhomogeneities are {approx} 10{sup 15} cm in size.« less

Modelling of TES X-ray Microcalorimeters with a Novel Absorber Design

NASA Technical Reports Server (NTRS)

Iyomoto, Naoko; Bandler, Simon; Brefosky, Regis; Brown, Ari; Chervenak, James; Figueroa-Feliciano, Enectali; Finkbeiner, Frederick; Kelley, Richard; Kilbourne, Caroline; Lindeman, Mark;

The Nature of the Torus in the Heavily Obscured AGN Markarian 3: an X-Ray Study

NASA Technical Reports Server (NTRS)

Guainazzi, M.; Risaliti, G.; Awaki, H.; Arevalo, P.; Bauer, F. E.; Bianchi, S.; Boggs, S.E; Brandt, W. N.; Brightman, M.; Christensen, F. E.;

X-ray Absorbers as Probes of AGN Unification

NASA Astrophysics Data System (ADS)

Kazannas, Demosthenes

We have developed, over the past few years, models of photoionized MHD winds off black hole accretion disks and showed that their properties are consistent with those of the AGN warm absorbers and those of the tori invoked in AGN unification schemes. Furthermore, we have shown that these models are sufficiently robust to reproduce the absorber properties (UV and X-ray) in AGN classes as diverse as Seyferts and BAL QSOs.With this proposal we request funding to model archival spectroscopic data of eighteen AGN with photoionized MHD winds. Successful implementation of this program will provide for the first time an association of the properties of warm absorbers with the parameters of a well-defined physical model, namely their density profiles, mass fluxes and inclination angles. Furthermore, determination of these parameters for our AGN sample will allow a statistical analysis of their properties and, as such, a better understanding of the properties of AGN structure. The value of our models lies in their simplicity: the winds are essentially analytic with only a small number of parameters. This simplicity makes possible the generation of a large grid of models which will be made available to the community through XSPEC/mtable for analysis of similar data by the observers.

X-Ray Modeling of the Intrinsic Absorption in NGC 4151

NASA Astrophysics Data System (ADS)

Denes Couto, Jullianna; Kraemer, Steven; Turner, T. Jane; Crenshaw, D. Michael

2017-01-01

We have investigated the relationship between the long term X-ray spectral variability in the Seyfert 1.5 galaxy NGC 4151 and its intrinsic absorption, by comparing our 2014 simultaneous ultraviolet/X-Ray observations taken with Hubble STIS Echelle and Chandra HETGS with archival observations from Chandra, XMM-Newton and Suzaku. The observations were divided into "high" and "low" states, with the low states showing strong and unabsorbed extended emission at energies below 2 keV. Our X-ray model consists of a broken powerlaw, neutral reflection and the two dominant absorption components identified by Kraemer et al (2005), X-High and D+Ea, which are present in all epochs. The model fittings suggest that the absorbers are very stable, with the principal changes in the intrinsic absorption resulting from variations in the ionization state of the gas in response to the variable strength of the ionizing continuum. However, the low states show evidence of larger column densities in one or both of the absorbers. Among plausible explanations for the column increase, we discuss the possibility of an expanding/contracting X-ray corona. X-High is consistent with being part of a magnetohydrodynamic (MHD) wind, while D+Ea is possibly radiatively driven, which suggests that at a sufficiently large radial distance there could be a break point between MHD-dominated and radiatively driven outflows. Preliminary results on the analysis of the AGN mass outflow rates and kinematics of the ionized gas in the extended emission region of NGC 4151 will also be presented.

X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN

NASA Technical Reports Server (NTRS)

Winter, Lisa M.; Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig

2007-01-01

The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) < 3 x 10(exp 25)/sq cm), local (< z >= 0.03), AGN sample. We find 9/22 low absorption (n(sub H) < 10(exp 23)/sq cm), simple power law model sources, where 4 of these sources have a statistically significant soft component. Among these sources, we find the presence of a warm absorber statistically significant for only one Seyfert 1 source, contrasting with the ASCA results of Reynolds (1997) and George et al. (1998), who find signatures of warm absorption in half or more of their Seyfert 1 samples at similar redshifts. Additionally, the remaining sources (13122) have more complex spectra, well-fit by an absorbed power law at E > 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.

Atomic Calculations and Laboratory Measurements Relevant to X-ray Warm Absorbers

NASA Technical Reports Server (NTRS)

Kallman, Tim; Bautista, M.; Palmeri, P.

2007-01-01

This viewgraph document reviews the atomic calculations and the measurements from the laboratory that are relevant to our understanding of X-Ray Warm Absorbers. Included is a brief discussion of the theoretical and the experimental tools. Also included is a discussion of the challenges, and calculations relevant to dielectronic recombination, photoionization cross sections, and collisional ionization. A review of the models is included, and the sequence that the models were applied.

Characterization of New Hard X-ray Cataclysmic Variables

NASA Technical Reports Server (NTRS)

Bernardini, F.; deMartino, D.; Falanga, M.; Mukai, K.; Matt, G.; Bonnet-Bidaud, J.-M.; Masetti, N.; Mouchet, M.

2012-01-01

Aims. We aim at characterizing a sample of nine new hard X-ray selected Cataclysmic Variable (CVs), to unambiguously identify them as magnetic systems of the Intermediate Polar (IP) type. Methods. We performed detailed timing and spectral analysis by using X-ray, and simultaneous UV and optical data collected by XMM-Newton, complemented with hard X-ray data provided by INTEGRAL and Swift. The pulse arrival time were used to estimate the orbital periods. The broad band X-ray spectra were fitted using composite models consisting of different absorbing columns and emission components. Results. Strong X-ray pulses at the White Dwarf (WD) spin period are detected and found to decrease with energy. Most sources are spin-dominated systems in the X-rays, though four are beat dominated at optical wavelengths. We estimated the orbital period in all system (except for IGR J16500-3307), providing the first estimate for IGRJ08390-4833, IGRJ18308-1232, and IGR J18173-2509. All X-ray spectra are multi-temperature. V2069 Cyg and RX J0636+3535 poses a soft X-ray optically thick component at kT approx. 80 eV. An intense K (sub alpha) Fe line at 6.4 keV is detected in all sources. An absorption edge at 0.76 keV from OVII is detected in IGR J08390-4833. The WD masses and lower limits to the accretion rates are also estimated. Conclusions. We found all sources to be IPs. IGR J08390-4833, V2069 Cyg, and IGR J16500-3307 are pure disc accretors, while IGR J18308-1232, IGR J1509-6649, IGR J17195-4100, and RX J0636+3535 display a disc-overflow accretion mode. All sources show a temperature gradient in the post-shock regions and a highly absorbed emission from material located in the pre-shock flow which is also responsible for the X-ray pulsations. Reflection at the WD surface is likely the origin of the fluorescent iron line. There is an increasing evidence for the presence of a warm absorber in IPs, a feature that needs future exploration. The addition of two systems to the subgroup of

Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-Ray Observations of NGC 4945

NASA Technical Reports Server (NTRS)

Madejski, G.; Zycki, P.; Done, C.; Valinia, A.; Blanco, P.; Rothschild, R.; Turek, B.

2000-01-01

NGC 4945 is one of the brightest Se.yfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV, implying an optical depth of the absorber to electron scattering of a few; its absorption column is probably the largest which still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with Solar abundances implies a column of 4.5(sup 0.4, sub -0.4) x 10(exp 24) /sq cm. Using a a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of approximately 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on time scales shorter than the light travel time through it. The rapid (with a time scale of approximately a day) hard X-ray variability of NGC 4945 we observed with the RXTE implies that the bulk of the extreme absorption in this object does not originate in a parsec-size, geometrically thick molecular torus. Limits on the amount of scattered flux require that the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle < 10 deg. This is only marginally consistent with the recent determinations of the obscuring column in hard X-rays, where only a quarter of Seyfert 2s have columns which are optically thick, and presents a problem in accounting for the Cosmic X-ray Background primarily with AGN possessing the geometry as that inferred by us. The small solid angle of the obscuring material, together with the black hole mass (of approximately 1.4 x 10(exp 6) solar mass) from megamaser measurements. allows a robust determination of the source luminosity, which in turn implies that the source radiates at approximately 10% of the Eddington limit.

X-Ray Wind Tomography of IGR J17252-3616

NASA Astrophysics Data System (ADS)

Manousakis, Antonios; Walter, Roland

2010-07-01

IGR J17252-3616, a highly absorbed High Mass X-ray Binary (HMXB) with Hydrogen column density NH~(2-4)×1023 cm-2, has been observed with XMM-Newton for about one month. Observations were scheduled in order to cover the orbital-phase space as much as possible. IGR J17252-3616 shows a varying column density NH and Fe Kα line when fit with simple phenomenological models. A refined orbital solution can be derived. Spectral timing analysis allows derivation of the wind properties of the massive star.

Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

NASA Astrophysics Data System (ADS)

Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

2014-07-01

We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5absorber flow is probably constituted by a clumpy distribution of discrete clouds. The distribution of the WA column densities for the sources with broad Fe K-alpha lines are similar to those sources which do not have broadened emission lines. Therefore the detected broad Fe K lines are bonafide and not artefacts of ionised absorption in the soft X-rays. The WA parameters show no correlation among themselves, except for one case. The shallow slope of the logξ versus logv_{out} linear regression (0.12± 0.03) is inconsistent with the scaling laws predicted by radiation or magneto-hydrodynamic-driven winds. Our results suggest also that WA and Ultra Fast Outflows (UFOs) do not represent extreme manifestation of the same astrophysical system.

Dissecting Diffuse X-ray Emission in 30 Doradus with T-ReX

NASA Astrophysics Data System (ADS)

Townsley, Leisa K.; Broos, Patrick

2017-08-01

30 Doradus (the Tarantula Nebula) offers us a microscope on starburst astrophysics, having endured 25 Myrs of the birth and death of the most massive stars known. Across 30 Dor's 250-pc extent, stellar winds and supernovae have carved its ISM into an amazing display of arcs, pillars, and bubbles. For over 40 years, we have also known that 30 Dor is a bright X-ray emitter, so its familiar stars and cold ISM structures suffer irradiation by multi-million-degree plasmas. The 2-Ms Chandra X-ray Visionary Project ``The Tarantula -- Revealed by X-rays'' (T-ReX) exploits Chandra's fine spatial resolution and the ACIS-I field of view to study ISM interfaces on 1--10 pc scales across the entire 30 Dor complex. Here we give preliminary results from ongoing analyses of these data, focusing on the diffuse X-ray emission. Massive star winds and cavity supernovae over the millenia have contributed to a broad mix of X-ray-emitting plasmas and absorbing columns, showing that 30 Dor's hot ISM is just as complex and confusing as that seen at colder temperatures.

Why do we see Broad Lines in X-ray Absorbed, Red AGN?

NASA Astrophysics Data System (ADS)

Wilkes, B. J.; Ghosh, Himel; Cutri, R.; Hines, D.; Nelson, B.; Schmidt, G. D.; Smith, P. S.

2003-05-01

The Two Micron All-Sky Survey (2MASS) red AGN catalog has revealed a previously unknown population whose number density rivals that of optically-selected AGN as found in the many, relatively shallow surveys (e.g. PG, Hamburg). The Chandra X-ray spectra of these red, mostly broad-line AGN are hard. This, combined with their unusually high optical polarization, suggests substantial obscuration (log NH = 21-23 cm-2) toward the nuclear energy source, despite a clear view of the broad emission line region. We have expanded our Chandra-observed sub-sample to include 20 more 2MASS AGN yielding a set of 46 which includes all available optical classes. This sample is thus pre-selected for complex absorption and sufficient to study the relative X-ray and optical obscuration for each AGN class. Those observed to date continue the lack of a relation between the X-ray hardness ratio and optical class noted in our earlier sample. Combining this with X-ray spectral fits where we have sufficient counts and with our multi-wavelength data, we compare the spectral energy distributions with those of normal and other red AGN and investigate possible scenarios for the absorbing material. We gratefully ackowledge the financial support of NASA grant: GO1-2112A

Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert galaxies - I. A global view and frequency of occurrence of warm absorbers.

NASA Astrophysics Data System (ADS)

Laha, Sibasish; Guainazzi, Matteo; Dewangan, Gulab C.; Chakravorty, Susmita; Kembhavi, Ajit K.

2014-07-01

We present results from a homogeneous analysis of the broad-band 0.3-10 keV CCD resolution as well as of the soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal is to characterize warm absorbers (WAs) along the line of sight to the active nucleus. We significantly detect WAs in 65 per cent of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates. We find a gap in the distribution of the ionization parameter in the range 0.5 < log ξ < 1.5 which we interpret as a thermally unstable region for WA clouds. This may indicate that the WA flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe Kα lines are similar to those sources which do not have broadened emission lines. Therefore, the detected broad Fe Kα emission lines are bona fide and not artefacts of ionized absorption in the soft X-rays. The WA parameters show no correlation among themselves, with the exception of the ionization parameter versus column density. The shallow slope of the log ξ versus log vout linear regression (0.12 ± 0.03) is inconsistent with the scaling laws predicted by radiation or magnetohydrodynamic-driven winds. Our results also suggest that WA and ultra fast outflows do not represent extreme manifestation of the same astrophysical system.

ASCA Observation of the Dipping X-Ray Source X1916-053

NASA Technical Reports Server (NTRS)

Ko, Yuan-Kuen; Makai, Koji; Smale, Alan P.; White, Nick E.

1997-01-01

We present the results of timing and spectral studies of the dipping X-ray source X1916-053, observed by ASCA during its Performance Verification phase. The detected dipping activity is consistent with previous observations, with a period of 3008s and an intermittent secondary dip observed roughly 0.4 out of phase with the primary dip. The energy spectra of different intensity states are fitted with a power law with partial covering fraction absorption and interstellar absorption. The increase in the hardness ratio during the primary and secondary dips, and the increase in the covering fraction and column density with decreasing X-ray intensity, all imply that the dipping is caused by the photo-absorbing materials which have been suggested to be where the accreted flow hits the outer edge of the disk materials. The spectra at all intensity levels show no apparent evidence for Fe or Ne emission lines. This may be due to the low metal abundance in the accretion flow. Alternatively, the X-ray luminosity of the central source may be too weak to excite emission lines, which are assumed to be produced by X-ray photoionization of the disk materials.

Atmospheric electron x-ray spectrometer

NASA Technical Reports Server (NTRS)

Feldman, Jason E. (Inventor); George, Thomas (Inventor); Wilcox, Jaroslava Z. (Inventor)

2002-01-01

The present invention comprises an apparatus for performing in-situ elemental analyses of surfaces. The invention comprises an atmospheric electron x-ray spectrometer with an electron column which generates, accelerates, and focuses electrons in a column which is isolated from ambient pressure by a:thin, electron transparent membrane. After passing through the membrane, the electrons impinge on the sample in atmosphere to generate characteristic x-rays. An x-ray detector, shaping amplifier, and multi-channel analyzer are used for x-ray detection and signal analysis. By comparing the resultant data to known x-ray spectral signatures, the elemental composition of the surface can be determined.

Discovery of Associated Absorption Lines in an X-Ray Warm Absorber: Hubble Space Telescope Faint Object Spectrograph Observations of MR 2251-178

NASA Technical Reports Server (NTRS)

Monier, Eric M.; Mathur, Smita; Wilkes, Belinda; Elvis, Martin

2001-01-01

The presence of a 'warm absorber' was first suggested to explain spectral variability in an X-ray spectrum of the radio-quiet quasi-stellar object (QSO) MR 2251-178. A unified picture, in which X-ray warm absorbers and 'intrinsic' UV absorbers are the same, offers the opportunity to probe the nuclear environment of active galactic nuclei. To test this scenario and understand the physical properties of the absorber, we obtained a UV spectrum of MR 2251-178 with the Faint Object Spectrograph on board the Hubble Space Telescope (HST). The HST spectrum clearly shows absorption due to Lyalpha, N v, and C IV, blueshifted by 300 km s(exp -1) from the emission redshift of the QSO. The rarity of both X-ray and UV absorbers in radio-quiet QSOs suggests these absorbers are physically related, if not identical. Assuming the unified scenario, we place constraints on the physical parameters of the absorber and conclude the mass outflow rate is essentially the same as the accretion rate in MR 2251-178.

The Swift Burst Alert Telescope Detected Seyfert 1 Galaxies: X-Ray Broadband Properties and Warm Absorbers

NASA Technical Reports Server (NTRS)

Winter, Lisa M.; Veilleux, Sylvain; McKernan, Barry; Kallman, T.

2012-01-01

We present results from an analysis of the broadband, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased toward both obscuration and host galaxy properties. Our detailed and uniform model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral absorption, direct power-law, reflected emission, soft excess, warm absorption, and narrow Fe I K[alpha] emission properties for the entire sample. We significantly detect O VII and O VIII edges in 52% of our sample. The strength of these detections is strongly correlated with the neutral column density measured in the spectrum. Among the strongest detections, X-ray grating and UV observations, where available, indicate outflowing material. The ionized column densities of sources with O VII and O VIII detections are clustered in a narrow range with Nwarm [approx] 1021 cm-2, while sources without strong detections have column densities of ionized gas an order of magnitude lower. Therefore, we note that sources without strong detections likely have warm ionized outflows present but at low column densities that are not easily probed with current X-ray observations. Sources with strong complex absorption have a strong soft excess, which may or may not be due to difficulties in modeling the complex spectra of these sources. Still, the detection of a flat [Gamma] [approx] 1 and a strong soft excess may allow us to infer the presence of strong absorption in low signal-to-noise active galactic nucleus spectra. Additionally, we include a useful correction from the Swift BAT luminosity to bolometric luminosity, based on a comparison of our spectral fitting results with published spectral energy distribution fits from 33 of our sources.

A detailed analysis of the high-resolution X-ray spectra of NGC 3516: variability of the ionized absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huerta, E. M.; Krongold, Y.; Jimenez-Bailon, E.

2014-09-20

The 1.5 Seyfert galaxy NGC 3516 presents a strong time variability in X-rays. We re-analyzed the nine observations performed in 2006 October by XMM-Newton and Chandra in the 0.3 to 10 keV energy band. An acceptable model was found for the XMM-Newton data fitting the EPIC-PN and RGS spectra simultaneously; later, this model was successfully applied to the contemporary Chandra high-resolution data. The model consists of a continuum emission component (power law + blackbody) absorbed by four ionized components (warm absorbers), and 10 narrow emission lines. Three absorbing components are warm, producing features only in the soft X-ray band. Themore » fourth ionization component produces Fe XXV and Fe XXVI in the hard-energy band. We study the time response of the absorbing components to the well-detected changes in the X-ray luminosity of this source and find that the two components with the lower ionization state show clear opacity changes consistent with gas close to photoionization equilibrium. These changes are supported by the models and by differences in the spectral features among the nine observations. On the other hand, the two components with higher ionization state do not seem to respond to continuum variations. The response time of the ionized absorbers allows us to constrain their electron density and location. We find that one component (with intermediate ionization) must be located within the obscuring torus at a distance 2.7 × 10{sup 17} cm from the central engine. This outflowing component likely originated in the accretion disk. The three remaining components are at distances larger than 10{sup 16}-10{sup 17} cm. Two of the absorbing components in the soft X-rays have similar outflow velocities and locations. These components may be in pressure equilibrium, forming a multi-phase medium, if the gas has metallicity larger than the solar one (≳ 5 Z {sub ☉}). We also search for variations in the covering factor of the ionized absorbers (although

The Variable Fast Soft X-Ray Wind in PG 1211+143

NASA Astrophysics Data System (ADS)

Reeves, J. N.; Lobban, A.; Pounds, K. A.

2018-02-01

The analysis of a series of seven observations of the nearby (z = 0.0809) QSO PG 1211+143, taken with the Reflection Grating Spectrometer (RGS) onboard XMM-Newton in 2014, are presented. The high-resolution soft X-ray spectrum, with a total exposure exceeding 600 ks, shows a series of blueshifted absorption lines from the He and H-like transitions of N, O, and Ne, as well as from L-shell Fe. The strongest absorption lines are all systematically blueshifted by ‑0.06c, originating in two absorption zones from low- and high-ionization gas. Both zones are variable on timescales of days, with the variations in absorber opacity effectively explained by either column density changes or the absorber ionization responding directly to the continuum flux. We find that the soft X-ray absorbers probably exist in a two-phase wind at a radial distance of ∼1017–1018 cm from the black hole with the lower-ionization gas as denser clumps embedded within a higher-ionization outflow. The overall mass outflow rate of the soft X-ray wind may be as high as 2{M}ȯ yr‑1, close to the Eddington rate for PG 1211+143 and similar to that previously deduced from the Fe K absorption.

X-Ray Spectroscopy of the Nearby, Classical T Tauri Star TW Hydrae

NASA Astrophysics Data System (ADS)

Kastner, Joel H.; Huenemoerder, David P.; Schulz, Norbert S.; Weintraub, David A.

1999-11-01

We present ASCA and ROSAT X-ray observations of the classical T Tauri star TW Hya, the namesake of a small association that, at a distance of ~50 pc, represents the nearest known region of recent star formation. Analysis of ASCA and ROSAT spectra indicates characteristic temperatures of ~1.7 and ~9.7 MK for the X-ray-emitting region(s) of TW Hya, with emission lines of highly ionized Fe dominating the spectrum at energies of ~1 keV. The X-ray data show variations in X-ray flux on timescales of <~1 hr as well as indications of changes in the X-ray-absorbing column on timescales of several years, suggesting that flares and variable obscuration are responsible for the large-amplitude optical variability of TW Hya on short and long timescales, respectively. Comparison with model calculations suggests that TW Hya produces sufficient hard X-ray flux to produce significant ionization of molecular gas within its circumstellar disk; such X-ray ionization may regulate both protoplanetary accretion and protoplanetary chemistry.

The density and location of the X-ray absorbing gas in AGN

NASA Astrophysics Data System (ADS)

Netzer, H.

Chandra and XMM-Newton have opened the era of real X-ray spectroscopy. The launch of these spacecraft was followed with great expectations to solve some of the mysteries of AGN, including the determination of the accurate profile of the iron Kα line, the ionization and location of the warm absorbing gas (the "warm absorber", hereafter WA) and the AGN-starburst connection. So far, only a small subset of those big questions have been answered. In particular, new observations of several type-I AGN are providing the first clues about the nature of the various soft X-ray spectral components and the location of the WA. Perhaps the best example regarding the WA location and the various spectral components is the new Chandra observation of NGC 3516. This is a well known Seyfert 1 galaxy that happened to be in a very low state at the time of observations (October 2000). The analysis by Netzer et al (2002) gives the following new results: The X-ray continuum is extremely hard (Γ < 1) and is very different from a single power-law continuum. Its shape is entirely consistent with the fading of the source by a factor of ~8 between 1994 (ASCA observation) and 2000 assuming a 1022 cm-2 line-of sight WA which reacts to the flux of the central ionizing source. A correlation between the observed changes in the source spectral energy distribution (SED) and the hard (E>5 keV) energy luminosity of the source. This can be used to set an upper limit of about 6 × 1017 cm on the WA location. There is a significant contribution, at high energies, from a cold reflecting remote gas which is constant in time and is producing most of the narrow component of the Kα line. The combination of a highly variable central source and a constant far-away ``reflector'' is required to explain the time dependent SED of NGC 3516. The generalization of these results (assuming they are typical) to other type I AGN is very important. They suggest that in many sources much (or even most) of the apparent

Thermalization of X-rays in evaporated tin and bismuth films used as the absorbing materials in X-ray calorimeters

NASA Astrophysics Data System (ADS)

Stahle, C. K.; Kelley, R. L.; Moseley, S. H.; Szymkowiak, A. E.; Juda, M.; McCammon, D.; Zhang, J.

1993-11-01

We have investigated the use of evaporated tin and bismuth films as the absorbing materials in X-ray calorimeters. When the films were deposited directly on monolithic silicon calorimeters, the output signal from both Sn and Bi devices was strongly dependent on the location of the absorption event relative to the ion-implanted thermistors, presumably indicating thermistor sensitivity to a non-thermal spectrum of phonons. With Sn films we also observed that a component of the thermalization proceeded slowly, relative to a complete thermalization reference. The thermalization function could be modified by trapping magnetic flux within the film. In order to distinguish thermalization effects in the films from the thermistor sensitivity to energetic phonons, we deposited Sn and Bi films on thin Si substrates which we then affixed to calorimeters using epoxy. With glued Sn films, we were able to attain as good as 13.6 eV resolution of 6 keV X-rays with no excess broadening of the line beyond the width of the baseline, while similarly made Bi devices showed excess broadening.

A logNHI = 22.6 Damped Lyα Absorber in a Dark Gamma-Ray Burst: The Environment of GRB 050401

NASA Astrophysics Data System (ADS)

Watson, D.; Fynbo, J. P. U.; Ledoux, C.; Vreeswijk, P.; Hjorth, J.; Smette, A.; Andersen, A. C.; Aoki, K.; Augusteijn, T.; Beardmore, A. P.; Bersier, D.; Castro Cerón, J. M.; D'Avanzo, P.; Diaz-Fraile, D.; Gorosabel, J.; Hirst, P.; Jakobsson, P.; Jensen, B. L.; Kawai, N.; Kosugi, G.; Laursen, P.; Levan, A.; Masegosa, J.; Näränen, J.; Page, K. L.; Pedersen, K.; Pozanenko, A.; Reeves, J. N.; Rumyantsev, V.; Shahbaz, T.; Sharapov, D.; Sollerman, J.; Starling, R. L. C.; Tanvir, N.; Torstensson, K.; Wiersema, K.

2006-12-01

The optical afterglow spectrum of GRB 050401 (at z=2.8992+/-0.0004) shows the presence of a damped Lyα absorber (DLA), with logNHI=22.6+/-0.3. This is the highest column density ever observed in a DLA and is about 5 times larger than the strongest DLA detected so far in any QSO spectrum. From the optical spectrum, we also find a very large Zn column density, implying an abundance of [Zn/H]=-1.0+/-0.4. These large columns are supported by the early X-ray spectrum from Swift XRT, which shows a column density (in excess of Galactic) of logNH=22.21+0.06-0.08 assuming solar abundances (at z=2.9). The comparison of this X-ray column density, which is dominated by absorption due to α-chain elements, and the H I column density derived from the Lyα absorption line allows us to derive a metallicity for the absorbing matter of [α/H]=-0.4+/-0.3. The optical spectrum is reddened and can be well reproduced with a power law with SMC extinction, where AV=0.62+/-0.06. But the total optical extinction can also be constrained independent of the shape of the extinction curve: from the optical to X-ray spectral energy distribution, we find 0.5<~AV<~4.5. However, even this upper limit, independent of the shape of the extinction curve, is still well below the dust column that is inferred from the X-ray column density, i.e., AV=9.1+1.4-1.5. This discrepancy might be explained by a small dust content with high metallicity (low dust-to-metals ratio). ``Gray'' extinction cannot explain the discrepancy, since we are comparing the metallicity to a measurement of the total extinction (without reference to the reddening). Little dust with high metallicity may be produced by sublimation of dust grains or may naturally exist in systems younger than a few hundred megayears. Based in part on observations made at the European Southern Observatory, Paranal, Chile under program 075.D-0270, with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland

NUCLEAR X-RAY PROPERTIES OF THE PECULIAR RADIO-LOUD HIDDEN AGN 4C+29.30

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobolewska, M. A.; Siemiginowska, Aneta; Migliori, G.

2012-10-20

We present results from a study of nuclear emission from a nearby radio galaxy, 4C+29.30, over a broad 0.5-200 keV X-ray band. This study used new XMM-Newton ({approx}17 ks) and Chandra ({approx}300 ks) data, and archival Swift/BAT data from the 58 month catalog. The hard (>2 keV) X-ray spectrum of 4C+29.30 can be decomposed into an intrinsic hard power law ({Gamma} {approx} 1.56) modified by a cold absorber with an intrinsic column density N {sub H,z} {approx} 5 Multiplication-Sign 10{sup 23} cm{sup -2}, and its reflection (|{Omega}/2{pi}| {approx} 0.3) from a neutral matter including a narrow iron K{alpha} emission linemore » at a rest-frame energy {approx}6.4 keV. The reflected component is less absorbed than the intrinsic one with an upper limit on the absorbing column of N {sup refl} {sub H,z} < 2.5 Multiplication-Sign 10{sup 22} cm{sup -2}. The X-ray spectrum varied between the XMM-Newton and Chandra observations. We show that a scenario invoking variations of the normalization of the power law is favored over a model with variable intrinsic column density. X-rays in the 0.5-2 keV band are dominated by diffuse emission modeled with a thermal bremsstrahlung component with temperature {approx}0.7 keV, and contain only a marginal contribution from the scattered power-law component. We hypothesize that 4C+29.30 belongs to a class of 'hidden' active galactic nuclei containing a geometrically thick torus. However, unlike the majority of hidden AGNs, 4C+29.30 is radio-loud. Correlations between the scattering fraction and Eddington luminosity ratio, and between black hole mass and stellar velocity dispersion, imply that 4C+29.30 hosts a black hole with {approx}10{sup 8} M {sub Sun} mass.« less

The X-ray monitoring of the long-period colliding wind binaries

NASA Astrophysics Data System (ADS)

Sugawara, Y.; Maeda, Y.; Tsuboi, Y.

2017-10-01

We present the first results from XMM-Newton and Swift observations of two long-period colliding wind binaries WR19 and WR125 around periastron passages. Mass-loss is one of the most important and uncertain parameters in the evolution of a massive star. The X-ray spectrum off the colliding wind binary is the best measure of conditions in the hot postshock gas. By monitoring the changing of the X-ray luminosity and column density along with the orbital phases, we derive the mass-loss rates of these stars. It is known that WR19 (WC5+O9; P=10.1 yr) and WR125 (WC7+O9; P> 24.3 yr) are the dust-making binaries. Each periastron is expected to come in 2016-2017. Since 2016, we carry out on-going monitoring campaigns of WR19 and WR125 with XMM-Newton and Swift. On these observations, the X-rays from WR19 and WR125 were detected for the first time. In the case of WR19, as periastron approached, the column density increased, which indicates that the emission from the wind-wind collision plasma was absorbed by the dense Wolf-Rayet wind.

Search for correlated UV and x ray absorption of NGC 3516

NASA Technical Reports Server (NTRS)

Martin, Christopher; Halpern, Jules P.; Kolman, Michiel

1991-01-01

NGC 3516, a low-luminosity Seyfert galaxy, is one of a small fraction of Seyfert galaxies that exhibit broad absorption in a resonance line. In order to determine whether the UV and x ray absorption in NGC 3516 are related, 5 IUE observations were obtained, quasi-simultaneously with 4 Ginga observations. The results are presented and discussed. The following subject areas are covered: short-term UV variability; emission lines; galactic absorption lines; the C IV, N V, and Si IV absorption features; lower limit on the carbon column density; estimate of the distance from the absorber to the continuum source; variability in the continuum and absorption; a comparison with BAL QSO's; and the x ray-UV connection.

A graphite calorimeter for absolute measurements of absorbed dose to water: application in medium-energy x-ray filtered beams.

PubMed

Pinto, M; Pimpinella, M; Quini, M; D'Arienzo, M; Astefanoaei, I; Loreti, S; Guerra, A S

2016-02-21

The Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI) has designed and built a graphite calorimeter that, in a water phantom, has allowed the determination of the absorbed dose to water in medium-energy x-rays with generating voltages from 180 to 250 kV. The new standard is a miniaturized three-bodies calorimeter, with a disc-shaped core of 21 mm diameter and 2 mm thickness weighing 1.134 g, sealed in a PMMA waterproof envelope with air-evacuated gaps. The measured absorbed dose to graphite is converted into absorbed dose to water by means of an energy-dependent conversion factor obtained from Monte Carlo simulations. Heat-transfer correction factors were determined by FEM calculations. At a source-to-detector distance of 100 cm, a depth in water of 2 g cm(-2), and at a dose rate of about 0.15 Gy min(-1), results of calorimetric measurements of absorbed dose to water, D(w), were compared to experimental determinations, D wK, obtained via an ionization chamber calibrated in terms of air kerma, according to established dosimetry protocols. The combined standard uncertainty of D(w) and D(wK) were estimated as 1.9% and 1.7%, respectively. The two absorbed dose to water determinations were in agreement within 1%, well below the stated measurement uncertainties. Advancements are in progress to extend the measurement capability of the new in-water-phantom graphite calorimeter to other filtered medium-energy x-ray qualities and to reduce the D(w) uncertainty to around 1%. The new calorimeter represents the first implementation of in-water-phantom graphite calorimetry in the kilovoltage range and, allowing independent determinations of D(w), it will contribute to establish a robust system of absorbed dose to water primary standards for medium-energy x-ray beams.

The New BeppoSAX Observation of the Brightest X-Ray Quasar at Redshift

NASA Technical Reports Server (NTRS)

Nicastro, Fabrizio; Oliversen, Ronald J. (Technical Monitor)

2001-01-01

This grant was to support the reduction and analysis of our approved SAX observation of the high redshift (z=3.2) blazar PKS 2126-158. This is the brightest quasar at z greater than 3 and has been intensively studied in X-ray, since the first Einstein detection. In 1994 Elvis et al., discovered a strong low energy cutoff in this object, which could imply either quasar frame photoelectric absorption by a column of 0.8-2.7 x 1e22 cm-2 cold gas, or a lower column of cold gas at z=0. Subsequent ASCA observations of this object, could not definitely address this issue, nor could establish whether the curvature of the low energy portion of the spectrum was due to pure photoelectric absorption (considerably exceeding the Galactic value along the line of sight) or to an intrinsic continuum curvature. We proposed to observe PKS 2126-158 with BeppoSAX, to try to solve this puzzle (thanks to the broadband of BeppoSAX: 0.1-250 keV). PKS 2126 was observed by BeppoSAX on May 1999, with a MECS exposure of 100 ks. We have reduced and analyzed the BeppoSAX data, and compared them with a Chandra ACIS observation of the same object, taken only 6 months apart (Nov. 1999). We have recently finished to write a paper on the BeppoSAX data only, that concentrate on the properties of the X-ray absorber, which is highly requested by our SAX data, independently on the continuum model adopted. The paper (P.I.F. Fiore) will be submitted to APJ in the next few days. A second paper on the combined BeppoSAX and Chandra data, and based on the broad band spectral energy distribution of this quasar, is currently in preparation. Our main results, on the X-ray absorber, are: (a) the presence of an X-ray absorber is confirmed, indipendently on the continuum adopted (simple power law, or curved continuum); (b) if the absorber is not significantly ionized, then the BeppoSAX data do prefer a low redshift absorber; (c) if the gas is ionized, then it can be located in the quasar environment, but its metal

A Unified View of X-ray Absorbers in AGNs and XRBs with MHD Winds

NASA Astrophysics Data System (ADS)

Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Behar, Ehud; Contopoulos, John

2016-01-01

The presence of UV and X-ray absorbers (aka. warm absorbers or WAs) has been long known for decades from extensive spectroscopic studies across diverse AGN populations such as nearby Seyfert galaxies and distant quasars. Furthermore, another class of seemingly distinct type of absorbers, ultra-fast outflows or UFOs, is becoming increasingly known today. Nonetheless, a physical identification of such absorbers, such as geometrical property and physical conditions, is very elusive to date despite the recent state-of-the-art observations. We develop a coherent scenario in which the detected absorbers are driven primarily (if not exclusively) by the action of global magnetic fields originating from a black hole accretion disk. In the context of MHD disk-wind of density profile of n~1/r, it is found that the properties of the observed WAs/UFOs are successfully described assuming a characteristic SED. As a case study, we analyze PG1211+143 and GRO J1655-40 to demonstrate that our wind model can systematically unify apparently diverse absorbers in both AGNs and XRBs in terms of explaining their global behavior as well as individual spectral lines.

Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

PubMed

Mathur; Green; Arav; Brotherton; Crenshaw; deKool; Elvis; Goodrich; Hamann; Hines; Kashyap; Korista; Peterson; Shields; Shlosman; van Breugel W; Voit

2000-04-20

We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

Primary DNA damage assessed with the comet assay and comparison to the absorbed dose of diagnostic X-rays in children.

PubMed

Milkovic, Durdica; Garaj-Vrhovac, Vera; Ranogajec-Komor, Mária; Miljanic, Saveta; Gajski, Goran; Knezevic, Zeljka; Beck, Natko

2009-01-01

The aim of this work is to assess DNA damage in peripheral blood lymphocytes of children prior to and following airway X-ray examinations of the chest using the alkaline comet assay and to compare data with the measured absorbed dose. Twenty children with pulmonary diseases, between the ages of 5 and 14 years, are assessed. Absorbed dose measurements are conducted for posterior-anterior projection on the forehead, thyroid gland, gonads, chest, and back. Doses are measured using thermoluminescent and radiophotoluminescent dosimetry systems. Differences between tail lengths, tail intensity, and tail moments as well as for the long-tailed nuclei before and after exposures are statistically significant and are dependent on the individual. The results demonstrate the usefulness of the comet assay as a measure of X-ray damage to lymphocytes in a clinical setting. Doses measured with both dosimeters show satisfactory agreement (0.01 mSv) and are suitable for dosimetric measurements in X-ray diagnostics.

Observation of soft X-ray spectra from a Seyfert 1 and a narrow emission-line galaxy

NASA Technical Reports Server (NTRS)

Singh, K. P.; Garmire, G. P.; Nousek, J.

1985-01-01

The 0.2-40 keV X-ray spectra of the Seyfert 1 galaxy Mrk 509 and the narrow emission-line galaxy NGC 2992 are analyzed. The results suggest the presence of a steep soft X-ray component in Mrk 509 in addition to the well-known Gamma = 1.7 component found in other active galactic nuclei in the 2-40 keV energy range. The soft X-ray component is interpreted as due to thermal emission from a hot gas, probably associated with the highly ionized gas observed to be outflowing from the galaxy. The X-ray spectrum of NGC 2992 does not show any steepening in the soft X-ray band and is consistent with a single power law (Gamma = 1.78) with very low absorbing column density of 4 x 10 to the 21st/sq cm. A model with partial covering of the nuclear X-ray source is preferred, however, to a simple model with a single power law and absorption.

An X-Ray Counterpart of HESS J1427-608 Discovered with Suzaku

NASA Astrophysics Data System (ADS)

Fujinaga, Takahisa; Mori, Koji; Bamba, Aya; Kimura, Shoichi; Dotani, Tadayasu; Ozaki, Masanobu; Matsuta, Keiko; Pülhofer, Gerd; Uchiyama, Hideki; Hiraga, Junko S.; Matsumoto, Hironori; Terada, Yukikatsu

2013-06-01

We report on the discovery of an X-ray counterpart of the unidentified very high-energy gamma-ray source HESS J1427-608. In the sky field coincident with HESS J1427-608, an extended source was found in the 2-8 keV band, and was designated as Suzaku J1427-6051. Its X-ray radial profile has an extension of σ = 0.'9 ± 0.'1 if approximated by a Gaussian. The spectrum was well fitted by an absorbed power-law with NH = (1.1 ± 0.3) × 1023 cm-2, Γ = 3.1+0.6-0.5, and the unabsorbed flux FX = (9+4-2) × 10-13 erg s-1 cm-2 in the 2-10 keV band. Using XMM-Newton archive data, we found seven point sources in the Suzaku source region. However, because their total flux and absorbing column densities are more than an order of magnitude lower than those of Suzaku J1427-6051, we consider that they are unrelated to the Suzaku source. Thus, Suzaku J1427-6051 is considered to be a truly diffuse source and an X-ray counterpart of HESS J1427-608. The possible nature of HESS J1427-608 is discussed based on the observational properties.

X-ray transmissive debris shield

DOEpatents

Spielman, R.B.

1996-05-21

An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

X-ray transmissive debris shield

DOEpatents

Spielman, Rick B.

1996-01-01

An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

The Variable Warm Absorber in Circinus X-1

NASA Astrophysics Data System (ADS)

Schulz, N. S.; Kallman, T. E.; Galloway, D. K.; Brandt, W. N.

2008-01-01

We observed Circinus X-1 twice during a newly reached low-flux phase near zero orbital phase using the High-Energy Transmission Grating Spectrometer (HETGS) onboard Chandra. In both observations the source did not show the P Cygni lines we observed during the high-flux phases of the source in 2000 and 2001. During the prezero phase the source did not exhibit significant variability but did exhibit an emission-line spectrum rich in H- and He-like lines from high-Z elements such as Si, S, Ar, and Ca. The light curve in the postdip observation showed quiescent and flaring episodes. Only in these flaring episodes was the source luminosity significantly higher than observed during the prezero phase. We analyzed all high-resolution X-ray spectra by fitting photoionization and absorption models from the most recent version of the XSTAR code. The prezero-phase spectrum could be fully modeled with a very hot photoionized plasma with an ionization parameter of log ξ = 3.0, down from log ξ = 4.0 in the high-flux state. The ionization balances we measure from the spectra during the postzero-phase episodes are significantly different. Both episodes feature absorbers with variable high columns, ionization parameters, and luminosity. While cold absorption remains at levels quite similar to that observed in previous years, the new observations show unprecedented levels of variable warm absorption. The line emissivities also indicate that the observed low source luminosity is inconsistent with a static hot accretion disk corona (ADC), an effect that seems common to other near-edge-on ADC sources as well. We conclude that unless there exists some means of coronal heating other than X-rays, the true source luminosity is likely much higher, and we observe obscuration in analogy to the extragalactic Seyfert 2 sources. We discuss possible consequences and relate cold, lukewarm, warm, and hot absorbers to dynamic accretion scenarios.

Oxygen, Neon, and Iron X-Ray Absorption in the Local Interstellar Medium

NASA Technical Reports Server (NTRS)

Gatuzz, Efrain; Garcia, Javier; Kallman, Timothy R.; Mendoza, Claudio

2016-01-01

We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer. Methods. By modeling the continuum with a simple broken power-law and by implementing the new ISMabs X-ray absorption model, we have estimated the total H, O, Ne, and Fe column densities towards the observed sources. Results. We have determined the absorbing material distribution as a function of source distance and galactic latitude longitude. Conclusions. Direct estimates of the fractions of neutrally, singly, and doubly ionized species of O, Ne, and Fe reveal the dominance of the cold component, thus indicating an overall low degree of ionization. Our results are expected to be sensitive to the model used to describe the continuum in all sources.

Normal incidence x-ray mirror for chemical microanalysis

DOEpatents

Carr, M.J.; Romig, A.D. Jr.

1987-08-05

An x-ray mirror for both electron column instruments and micro x-ray fluorescence instruments for making chemical, microanalysis comprises a non-planar mirror having, for example, a spherical reflecting surface for x-rays comprised of a predetermined number of alternating layers of high atomic number material and low atomic number material contiguously formed on a substrate and whose layers have a thickness which is a multiple of the wavelength being reflected. For electron column instruments, the wavelengths of interest lie above 1.5nm, while for x-ray fluorescence instruments, the range of interest is below 0.2nm. 4 figs.

The X-ray footprint of the circumnuclear disc

NASA Astrophysics Data System (ADS)

Mossoux, Enmanuelle; Eckart, Andreas

2018-03-01

We studied the central regions of the Galactic Centre to determine if the circumnuclear disc (CND) acts as an absorber or a barrier for the central X-rays diffuse emission. After reprocessing 4.6 Ms of Chandra observations, we were able to detect, for the first time, a depression in the X-ray luminosity of the diffuse emission whose size and location correspond to those of the CND. We extracted the X-ray spectra for various regions inside the CND footprint as well as for the region where the footprint is observed and for a region located outside the footprint. We simultaneously fitted these spectra as an optically thin plasma whose absorption by the interstellar medium (ISM) and by the local plasma were fitted independently using the Markov chain Monte Carlo method. The hydrogen column density of the ISM is 7.5 × 1022 cm-2. The X-ray diffuse emission inside the CND footprint is formed by a 2T plasma of 1 and 4 keV with slightly super-solar abundances except for the iron and carbon that are sub-solar. The plasma from the CND, in turn, is better described by a 1T model with abundances and local hydrogen column density that are very different from those of the innermost regions. The large iron abundance in this region confirms that the CND is dominated by the shock-heated ejecta of the Sgr A East supernova remnant. We deduced that the CND rather acts as a barrier for the Galactic Centre plasma and that the plasma located outside the CND may correspond to the collimated outflow possibly created by Sgr A* or the interaction between the wind of massive stars and the mini-spiral material.

X-Ray Properties of the Youngest Radio Sources and Their Environments

NASA Astrophysics Data System (ADS)

Siemiginowska, Aneta; Sobolewska, Małgosia; Migliori, Giulia; Guainazzi, Matteo; Hardcastle, Martin; Ostorero, Luisa; Stawarz, Łukasz

2016-05-01

We present the first results from our X-ray study of young radio sources classified as compact symmetric objects (CSOs). Using the Chandra X-ray Observatory we observed six CSOs for the first time in X-rays, and re-observed four CSOs already observed with XMM-Newton or BeppoSAX. We also included six other CSOs with archival data to built a pilot study of a sample of the 16 CSO sources observed in X-rays to date. All the sources are nearby, z\\lt 1, and the age of their radio structures (\\lt 3000 yr) has been derived from the expansion velocity of their hot spots. Our results show the heterogeneous nature of the CSOs’ X-ray emission, indicating a complex environment associated with young radio sources. The sample covers a range in X-ray luminosity, {L}2{--10{keV}}˜ {10}41-1045 erg s-1, and intrinsic absorbing column density of {N}{{H}}≃ {10}21-1022 cm-2. In particular, we detected extended X-ray emission in 1718-649 a hard photon index of {{Γ }}≃ 1 in 2021+614 and 1511+0518 consistent with either a Compton-thick absorber or non-thermal emission from compact radio lobes, and in 0710+439 an ionized iron emission line at {E}{rest}=(6.62+/- 0.04) keV and EW ˜ 0.15-1.4 keV, and a decrease by an order of magnitude in the 2-10 keV flux since the 2008 XMM-Newton observation in 1607+26. We conclude that our pilot study of CSOs provides a variety of exceptional diagnostics and highlights the importance of deep X-ray observations of large samples of young sources. This is necessary in order to constrain theoretical models for the earliest stage of radio source evolution and to study the interactions of young radio sources with the interstellar environment of their host galaxies.

Study on the quality assurance of diagnostic X-ray machines and assessment of the absorbed dose to patients

NASA Astrophysics Data System (ADS)

Hassan, G. M.; Rabie, N.; Mustafa, K. A.; Abdel-Khalik, S. S.

2012-09-01

Radiation exposure and image quality in X-ray diagnostic radiology provide a clear understanding of the relationship between the radiation dose delivered to a patient and image quality in optimizing medical diagnostic radiology. Because a certain amount of radiation is unavoidably delivered to patients, this should be as low as reasonably achievable. Several X-ray diagnostic machines were used at different medical diagnostic centers in Egypt for studying the beam quality and the dose delivered to the patient. This article studies the factors affecting the beam quality, such as the kilo-volt peak (kVp), exposure time (mSc), tube current (mAs) and the absorbed dose in (μGy) for different examinations. The maximum absorbed dose measured per mAs was 594±239 and 12.5±3.7 μGy for the abdomen and the chest, respectively, while the absorbed dose at the elbow was 18±6 μGy, which was the minimum dose recorded. The compound and expanded uncertainties accompanying these measurements were 4±0.35% and 8±0.7%, respectively. The measurements were done through quality control tests as acceptance procedures.

Absorption in X-ray spectra of high-redshift quasars

NASA Technical Reports Server (NTRS)

Elvis, Martin; Fiore, Fabrizio; Wilkes, Belinda; Mcdowell, Jonathan; Bechtold, Jill

1994-01-01

We present evidence that X-ray absorption is common in high-redshift quasars. We have studied six high-redshift (z approximately 3) quasars with the ROSAT Position Sensitive Proportional Counter (PSPC) of which four are in directions of low Galactic N(sub H). Three out of these four show excess absorption, while only three in approximately 50 z approximately less than 0.4 quasars do, indicating that such absorption must be common, but not ubiquitous, at high redshifts, and that the absorbers must lie at z greater than 0.4. The six quasars were: S5 0014+81, Q0420-388, PKS 0438-436, S4 0636+680. PKS 2000-330, PKS 2126-158, which have redshifts between 2.85 and 3.78. PKS 0438-436 and PKS 2126-158 show evidence for absorption above the local Galactic value at better than 99.999% confidence level. If the absorber is at the redshift of the quasar, then values of N(sub H) = (0.86(+0.49, -0.28)) x 10(exp 22) atoms/sq cm for PKS 0438-436, and N(sub H) = (1.45(+1.20, -0.64)) x 10(exp 22) atoms/ sq cm for PKS 2126-158, are implied, assuming solar abundances. The spectrum of S4 0636+680 also suggests the presence of a similarly large absorption column density at the 98% confidence level. This absorption reverses the trend for the most luminous active galactic nuclei (AGN) to have the least X-ray absorption, so a new mechanism is likely to be responsible. Intervening absorption due to damped Lyman(alpha) systems is a plausible cause. We also suggest, as an intrinsic model, that intracluster material, e.g., a cooling flow, around the quasar could account for both the X-ray spectrum and other properties of these quasars. All the quasars are radio-loud and three are gigahertz peaked (two of the three showing absorption). No excess absorption above the Galactic value is seen toward Q0420-388. This quasar has two damped Lyman(alpha) systems at z = 3.08. The limit on the X-ray column density implies a low ionization fraction, N(H I)/N(H) approximately greater than 4 x 10(exp -3) (3

X-Ray Spectroscopy of the Low-Mass X-Ray Binaries 2S 0918-549 and 4U 1543-624: Evidence for Neon-rich Degenerate Donors

NASA Astrophysics Data System (ADS)

Juett, Adrienne M.; Chakrabarty, Deepto

2003-12-01

We present high-resolution spectroscopy of the neutron star/low-mass X-ray binaries 2S 0918-549 and 4U 1543-624 with the High Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory and the Reflection Grating Spectrometer on board XMM-Newton. Previous low-resolution spectra of both sources showed a broad, linelike feature at 0.7 keV that was originally attributed to unresolved line emission. We recently showed that this feature could also be due to excess neutral Ne absorption, and this is confirmed by the new high-resolution Chandra and XMM spectra. The Chandra spectra are each well fitted by an absorbed-power-law+blackbody model with a modified Ne/O number ratio of 0.52+/-0.12 for 2S 0918-549 and 1.5+/-0.3 for 4U 1543-624, compared to the interstellar medium value of 0.18. The XMM spectrum of 2S 0918-549 is best fitted by an absorbed-power-law model with a Ne/O number ratio of 0.46+/-0.03, consistent with the Chandra result. On the other hand, the XMM spectrum of 4U 1543-624 is softer and less luminous than the Chandra spectrum and has a best-fit Ne/O number ratio of 0.54+/-0.03. The difference between the measured abundances and the expected interstellar ratio, as well as the variation of the column densities of O and Ne in 4U 1543-624, supports the suggestion that there is absorption local to these binaries. We propose that the variations in the O and Ne column densities of 4U 1543-624 are caused by changes in the ionization structure of the local absorbing material. It is important to understand the effect of ionization on the measured absorption columns before the abundance of the local material can be determined. This work supports our earlier suggestion that 2S 0918-549 and 4U 1543-624 are ultracompact binaries with Ne-rich companions.

Si K EDGE STRUCTURE AND VARIABILITY IN GALACTIC X-RAY BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schulz, Norbert S.; Corrales, Lia; Canizares, Claude R.

2016-08-10

We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 10{sup 22} cm{sup −2}. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edgemore » absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s{sup −1}. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.« less

Scattered radiation doses absorbed by technicians at different distances from X-ray exposure: Experiments on prosthesis.

PubMed

Chiang, Hsien-Wen; Liu, Ya-Ling; Chen, Tou-Rong; Chen, Chun-Lon; Chiang, Hsien-Jen; Chao, Shin-Yu

2015-01-01

This work aimed to investigate the spatial distribution of scattered radiation doses induced by exposure to the portable X-ray, the C-arm machine, and to simulate the radiologist without a shield of lead clothing, radiation doses absorbed by medical staff at 2 m from the central exposure point. With the adoption of the Rando Phantom, several frequently X-rayed body parts were exposed to X-ray radiation, and the scattered radiation doses were measured by ionization chamber dosimeters at various angles from the patient. Assuming that the central point of the X-ray was located at the belly button, five detection points were distributed in the operation room at 1 m above the ground and 1-2 m from the central point horizontally. The radiation dose measured at point B was the lowest, and the scattered radiation dose absorbed by the prosthesis from the X-ray's vertical projection was 0.07 ±0.03 μGy, which was less than the background radiation levels. The Fluke biomedical model 660-5DE (400 cc) and 660-3DE (4 cc) ion chambers were used to detect air dose at a distance of approximately two meters from the central point. The AP projection radiation doses at point B was the lowest (0.07±0.03 μGy) and the radiation doses at point D was the highest (0.26±0.08 μGy) .Only taking the vertical projection into account, the radiation doses at point B was the lowest (0.52 μGy), and the radiation doses at point E was the highest (4 μGy).The PA projection radiation at point B was the lowest (0.36 μGy) and the radiation doses at point E was the highest(2.77 μGy), occupying 10-32% of the maximum doses. The maximum dose in five directions was nine times to the minimum dose. When the PX and the C-arm machine were used, the radiation doses at a distance of 2 m were attenuated to the background radiation level. The radiologist without a lead shield should stand at point B of patient's feet. Accordingly, teaching materials on radiation safety for radiological interns and clinical

Determination of Lateral Diffusivity in Single Pixel X-ray Absorbers with Implications for Position Dependent Excess Broadening

NASA Technical Reports Server (NTRS)

Saab, T.; Figueroa-Feliciano, E.; Iyomoto, N.; Bandler, S. R.; Chervenak, J.; Finkbeiner, F.; Kelley, R.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J.

2005-01-01

An ideal microcalorimeter is characterized by a constant energy resolution across the sensor's dynamic range. Any dependence of pulse shape on the position within the absorber where an event occurs leads to a degradation in resolution that is linear with event s energy (excess broadening). In this paper we present a numerical simulation that was developed to model the variation in pulse shape with position based on the thermal conductivity within the absorber and between the absorber, sensor, and heat bath, for arbitrarily shaped absorbers and sensors. All the parameters required for the simulation can be measured from actual devices. We describe how the thermal conductivity of the absorber material is determined by comparing the results of this model with data taken from a position sensitive detector in which any position dependent effect is purposely emphasized by making a long, narrow absorber that is read out by sensors on both end. Finally, we present the implications for excess broadening given the measured parameters of our X-ray microcalorimeters.

Investigating Dueling Scenarios in NGC 7582 with Broadband X-ray Spectroscopy

NASA Astrophysics Data System (ADS)

Rivers, E.

2015-09-01

NGC 7582 is a well-studied X-ray bright Seyfert 2 with moderately heavy (NH = 10^{23} - 10^{24} cm^{-2}), highly variable absorption and unusually strong reflection spectral features. The spectral shape changed around the year 2000, dropping in observed flux and becoming much more highly absorbed. Two scenarios have been put forth to explain this spectral change: 1) the source "shut off" around this time, decreasing in intrinsic luminosity, with a delayed decrease in reflection features due to the light crossing time of the Compton-thick material or 2) the source is a "hidden nucleus" which has recently become more heavily obscured, with only a portion of the power law continuum leaking through. NuSTAR observed NGC 7582 twice in 2012 two weeks apart in order to quantify the reflection using high-quality data above 10 keV. We analyze both NuSTAR observations placing them in the context of historical X-ray, infrared and optical observations, including re-analysis of RXTE data from 2003-2005. We find that the most plausible scenario is that NGC 7582 has a hidden nucleus which has recently become more heavily absorbed by a patchy torus with a covering fraction of 80-90% and a column density of 3.6 x 10^{24} cm^{-2}. We find the need for an additional highly variable full-covering absorber with NH= 4-6 x 10^{23} cm^{-2}, possibly associated with a hidden broad line region or a dust lane in the host galaxy.

Weak Hard X-Ray Emission from Two Broad Absorption Line Quasars Observed with NuStar: Compton-Thick Absorption or Intrinsic X-Ray Weakness?

NASA Technical Reports Server (NTRS)

Luo, B.; Brandt, W. N.; Alexander, D. M.; Harrison, F. A.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W..;

WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, B.; Brandt, W. N.; Alexander, D. M.

We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain Almost-Equal-To 400-600 hard X-ray ({approx}> 10 keV) photons with NuSTAR, provided that these photons are not significantlymore » absorbed (N{sub H} {approx}< 10{sup 24} cm{sup -2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N{sub H} Almost-Equal-To 7 Multiplication-Sign 10{sup 24} cm{sup -2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe K{alpha} line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.« less

X-Ray Dust Tomography: Mapping the Galaxy one X-ray Transient at a Time

NASA Astrophysics Data System (ADS)

Heinz, Sebastian; Corrales, Lia

2018-01-01

Tomography using X-ray light echoes from dust scattering by interstellar clouds is an accurate tool to study the line-of-sight distribution of dust. It can be used to measure distances to molecular clouds and X-ray sources, it can map Galactic structure in dust, and it can be used for precision measurements of dust composition and grain size distribution. Necessary conditions for observing echoes include a suitable X-ray lightcurve and sufficient dust column density to the source. I will discuss a tool set for studying dust echoes and show results obtained for some of the brightest echoes detected to date.

Luminescence properties after X-ray irradiation for dosimetry

NASA Astrophysics Data System (ADS)

Hong, Duk-Geun; Kim, Myung-Jin

2016-05-01

To investigate the luminescence characteristics after exposure to X-ray radiation, we developed an independent, small X-ray irradiation system comprising a Varian VF-50J mini X-ray generator, a Pb collimator, a delay shutter, and an Al absorber. With this system, the apparent dose rate increased linearly to 0.8 Gy/s against the emission current for a 50 kV anode potential when the shutter was delayed for an initial 4 s and the Al absorber was 300 µm thick. In addition, an approximately 20 mm diameter sample area was irradiated homogeneously with X rays. Based on three-dimensional (3D) thermoluminescence (TL) spectra, the small X-ray irradiator was considered comparable to the conventional 90Sr/90Y beta source even though the TL intensity from beta irradiation was higher than that from X-ray irradiation. The single aliquot regenerative (SAR) growth curve for the small X-ray irradiator was identical to that for the beta source. Therefore, we concluded that the characteristics of the small X-ray irradiator and the conventional 90Sr/90Y beta source were similar and that X ray irradiation had the potential for being suitable for use in luminescence dosimetry.

A Chandra X-ray Study of Cygnus A. 2; The Nucleus

NASA Technical Reports Server (NTRS)

Young, Andrew J.; Wilson, Andrew; Terashima, Yuichi; Arnaud, Keith A.; Smith, David A.; White, Nicholas E. (Technical Monitor)

2002-01-01

We report Chandra Advanced CCD Imaging Spectrometer and quasi-simultaneous Rossi X-Ray Timing Explorer (RXTE) observations of the nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the properties of the active nucleus. In the Chandra observation, the hard (less than a few keV) X-ray emission is spatially unresolved with a size is approximately 1" (1.5 kpc, H(sub 0) = 50 km/s/Mpc) and coincides with the radio and near-infrared nuclei. In contrast, the soft (less than 2 keV) emission exhibits a bipolar nebulosity that aligns with the optical bipolar continuum and emission-line structures and approximately with the radio jet. In particular, the soft X-ray emission corresponds very well with the [O III] (lambda)5007 and H(alpha) + [N II] lambda(lambda)6548, 6583 nebulosity imaged with Hubble Space Telescope. At the location of the nucleus, there is only weak soft X-ray emission, an effect that may be intrinsic or result from a dust lane that crosses the nucleus perpendicular to the source axis. The spectra of the various X-ray components have been obtained by simultaneous fits to the six detectors. The compact nucleus is detected to 100 keV and is well described by a heavily absorbed power-law spectrum with Gamma(sub h) = 1.52(sup + 0.12, sub -0.12) (similar to other 0.12 narrow-line radio galaxies) and equivalent hydrogen column N(sub H)(nuc) = 2.0(sup +0.1, sub -0.1) x 10(exp 23)/sq cm. This 0.2 column is compatible with the dust obscuration to the near-infrared source for a normal gas-to-dust ratio. The soft (less than 2 keV) emission from the nucleus may be described by a power-law spectrum with the same index (i.e., Gamma(sub l) = Gamma(sub h), although direct fits suggest a slightly larger value for Gamma(sub l). Narrow emission lines from highly ionized neon and silicon, as well as a "neutral" Fe K(alpha) line, are detected in the nucleus and its vicinity (r approximately less than 2 kpc). The equivalent width (EW) of the Fe K(alpha) line

History of Chandra X-Ray Observatory

NASA Image and Video Library

2004-09-24

Astronomers have used an x-ray image to make the first detailed study of the behavior of high-energy particles around a fast moving pulsar. This image, from NASA's Chandra X-Ray Observatory (CXO), shows the shock wave created as a pulsar plows supersonically through interstellar space. These results will provide insight into theories for the production of powerful winds of matter and antimatter by pulsars. Chandra's image of the glowing cloud, known as the Mouse, shows a stubby bright column of high-energy particles, about four light years in length, swept back by the pulsar's interaction with interstellar gas. The intense source at the head of the X-ray column is the pulsar, estimated to be moving through space at about 1.3 million miles per hour. A cone-shaped cloud of radio-wave-emitting particles envelopes the x-ray column. The Mouse, a.k.a. G359.23-0.82, was discovered in 1987 by radio astronomers using the National Science Foundation's Very Large Array in New Mexico. G359.23-0.82 gets its name from its appearance in radio images that show a compact snout, a bulbous body, and a remarkable long, narrow, tail that extends for about 55 light years. NASA’s Marshall Space Flight Center in Huntsville, Alabama manages the Chandler program.

X-Ray Detection Visits the Classroom

ERIC Educational Resources Information Center

Peralta, Luis; Farinha, Ana; Pinto, Ana

2008-01-01

Film has been used to detect x-rays since the early days of their discovery by Rontgen. Although nowadays superseded by other techniques, film still provides a cheap means of x-ray detection, making it attractive in high-school or undergraduate university courses. If some sort of quantitative result is required, the film's optical absorbance or…

Correlations in the three-dimensional Lyman-alpha forest contaminated by high column density absorbers

NASA Astrophysics Data System (ADS)

Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris

2018-05-01

Correlations measured in three dimensions in the Lyman-alpha forest are contaminated by the presence of the damping wings of high column density (HCD) absorbing systems of neutral hydrogen (H I; having column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}), which extend significantly beyond the redshift-space location of the absorber. We measure this effect as a function of the column density of the HCD absorbers and redshift by measuring three-dimensional (3D) flux power spectra in cosmological hydrodynamical simulations from the Illustris project. Survey pipelines exclude regions containing the largest damping wings. We find that, even after this procedure, there is a scale-dependent correction to the 3D Lyman-alpha forest flux power spectrum from residual contamination. We model this residual using a simple physical model of the HCD absorbers as linearly biased tracers of the matter density distribution, convolved with their Voigt profiles and integrated over the column density distribution function. We recommend the use of this model over existing models used in data analysis, which approximate the damping wings as top-hats and so miss shape information in the extended wings. The simple `linear Voigt model' is statistically consistent with our simulation results for a mock residual contamination up to small scales (|k| < 1 h Mpc^{-1}). It does not account for the effect of the highest column density absorbers on the smallest scales (e.g. |k| > 0.4 h Mpc^{-1} for small damped Lyman-alpha absorbers; HCD absorbers with N(H I) ˜ 10^{21} atoms cm^{-2}). However, these systems are in any case preferentially removed from survey data. Our model is appropriate for an accurate analysis of the baryon acoustic oscillations feature. It is additionally essential for reconstructing the full shape of the 3D flux power spectrum.

A Comprehensive Spectral Analysis of the X-Ray Pulsar 4U 1907+09 from Two Observations with the Suzaku X-Ray Observatory

NASA Technical Reports Server (NTRS)

Rivers, Elizabeth; Markowitz, Alex; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Furst, Felix; Suchy, Slawomir; Kreykenbohm, Ingo; Wilms, Jorn; Rothschild, Richard

2009-01-01

We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku observatory, The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx. 19 keV. Additionally, using the narrow CCD response of Suzaku near 6 ke V allows us to study in detail the Fe K bandpass and to quantify the Fe Kp line for this source for the first time. The source is absorbed by fully-covering material along the line of sight with a column density of N(sub H) approx. 2 x 10(exp 22)/sq cm, consistent with a wind accreting geometry, and a high Fe abundance (approx. 3 - 4 x solar). Time and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in NH along the line of sight, perhaps indicating clumpiness in the stellar wind

Short-term X-ray spectral variability of the quasar PDS 456 observed in a low-flux state

NASA Astrophysics Data System (ADS)

Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

2016-05-01

We present a detailed analysis of a recent, 2013 Suzaku campaign on the nearby (z = 0.184) luminous (Lbol ˜ 1047 erg s-1) quasar PDS 456. This consisted of three observations, covering a total duration of ˜1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was unusually low, suppressed by a factor of >10 in the soft X-ray band when compared to previous observations. We investigated the broad-band continuum by constructing a spectral energy distribution (SED), making use of the optical/UV photometry and hard X-ray spectra from the later simultaneous XMM-Newton and NuSTAR campaign in 2014. The high-energy part of this low-flux SED cannot be accounted for by physically self-consistent accretion disc and corona models without attenuation by absorbing gas, which partially covers a substantial fraction of the line of sight towards the X-ray continuum. At least two layers of absorbing gas are required, of column density log (NH,low/cm-2) = 22.3 ± 0.1 and log (NH,high/cm-2) = 23.2 ± 0.1, with average line-of-sight covering factors of ˜80 per cent (with typical ˜5 per cent variations) and 60 per cent (±10-15 per cent), respectively. During these observations PDS 456 displays significant short-term X-ray spectral variability, on time-scales of ˜100 ks, which can be accounted for by variable covering of the absorbing gas along the line of sight. The partial covering absorber prefers an outflow velocity of v_pc = 0.25^{+0.01}_{-0.05} c at the >99.9 per cent confidence level over the case where vpc = 0. This is consistent with the velocity of the highly ionized outflow responsible for the blueshifted iron K absorption profile. We therefore suggest that the partial covering clouds could be the denser, or clumpy part of an inhomogeneous accretion disc wind. Finally estimates are placed upon the size-scale of the X-ray emission region from the source variability. The radial extent of the X-ray emitter is found to be of the order ˜15-20Rg

A Search for H I Lyα Counterparts to Ultrafast X-Ray Outflows

NASA Astrophysics Data System (ADS)

Kriss, Gerard A.; Lee, Julia C.; Danehkar, Ashkbiz

2018-06-01

Prompted by the H I Lyα absorption associated with the X-ray ultrafast outflow at ‑17,300 km s‑1 in the quasar PG 1211+143, we have searched archival UV spectra at the expected locations of H I Lyα absorption for a large sample of ultrafast outflows identified in XMM-Newton and Suzaku observations. Sixteen of the X-ray outflows have predicted H I Lyα wavelengths falling within the bandpass of spectra from either the Far Ultraviolet Spectroscopic Explorer or the Hubble Space Telescope, although none of the archival observations were simultaneous with the X-ray observations in which ultrafast X-ray outflows (UFOs) were detected. In our spectra broad features with FWHM of 1000 km s‑1 have 2σ upper limits on the H I column density of generally ≲2 × 1013 cm‑2. Using grids of photoionization models covering a broad range of spectral energy distributions (SEDs), we find that producing Fe XXVI Lyα X-ray absorption with equivalent widths >30 eV and associated H I Lyα absorption with {N}{{H}{{I}}}< 2× {10}13 {cm}}-2 requires total absorbing column densities {N}{{H}}> 5× {10}22 {cm}}-2 and ionization parameters log ξ ≳ 3.7. Nevertheless, a wide range of SEDs would predict observable H I Lyα absorption if ionization parameters are only slightly below peak ionization fractions for Fe XXV and Fe XXVI. The lack of Lyα features in the archival UV spectra indicates that the UFOs have very high ionization parameters, that they have very hard UV-ionizing spectra, or that they were not present at the time of the UV spectral observations owing to variability.

NICER observations of MAXI J1820+070 suggest a rapidly-brightening black hole X-ray binary in the hard state

NASA Astrophysics Data System (ADS)

Uttley, P.; Gendreau, K.; Markwardt, C.; Strohmayer, T. E.; Bult, P.; Arzoumanian, Z.; Pottschmidt, K.; Ray, P. S.; Remillard, R.; Pasham, D.; Steiner, J.; Neilsen, J.; Homan, J.; Miller, J. M.; Iwakiri, W.; Fabian, A. C.

2018-03-01

NICER observed the new X-ray transient MAXI J1820+070 (ATel #11399, #11400, #11403, #11404, #11406, #11418, #11420, #11421) on multiple occasions from 2018 March 12 to 14. & nbsp;During this time the source brightened rapidly, from a total NICER mean count rate of 880 count/s on March 12 to 2800 count/s by March 14 17:00 & nbsp;UTC, corresponding to a change in 2-10 keV modelled flux (see below) from 1.9E-9 to 5E-9 erg cm-2 s-1. & nbsp; The broadband X-ray spectrum is absorbed by a low column density (fitting the model given below, we obtain 1.5E21 cm-2), in keeping with the low Galactic column in the direction of the source (ATel #11418; Dickey & Lockman, 1990, ARAA, 28, 215; Kalberla et al. 2005, A &A, 440, 775) and consists of a hard power-law component with weak reflection features (broad iron line and narrow 6.4 keV line core) and an additional soft X-ray component.

Extragalactic Hard X-ray Surveys: From INTEGRAL to Simbol-X

NASA Astrophysics Data System (ADS)

Paltani, S.; Dwelly, T.; Walter, R.; McHardy, I. M.; Courvoisier, T. J.-L.

2009-05-01

We present some results of the deepest extragalactic survey performed by the INTEGRAL satellite. The fraction of very absorbed AGN is quite large. The sharp decrease in the absorption fraction with X-ray luminosity observed at lower-energy X-rays is not observed. The current lack of truly Compton-thick objects, with an upper limit of 14% to the size of this population, is just compatible with recent modeling of the cosmic X-ray background. We also study the prospects for a future hard X-ray serendipitous survey with Simbol-X. We show that Simbol-X will easily detect a large number of serendipitous AGN, allowing us to study the evolution of AGN up to redshifts about 2, opening the door to the cosmological study of hard X-ray selected AGN, which is barely possible with existing satellites like Swift and INTEGRAL.

Variable X-Ray Absorption in the Mini-BAL QSO PG 1126-041

NASA Technical Reports Server (NTRS)

Giustini, M.; Cappi, M.; Chartas, G.; Dadina, M.; Eracleous, M.; Ponti, G.; Proga, D.; Tombesi, F.; Vignali, C.; Palumbo, G. G. C.

2011-01-01

Context. X-ray studies of AGN with powerful nuclear winds are important to constrain the physics of the inner accretion/ejection flow around SMBH, and to understand the impact of such winds on the AGN environment. Aims. Our main scientific goal is to constrain the properties of a variable outflowing absorber that is thought to be launched near the SMBH of the mini-BAL QSO PG 1126-041 using a multi-epoch observational campaign performed with XMM-Newton. Methods. We performed temporally resolved X-ray spectroscopy and simultaneous UV and X-ray photometry on the most complete set of observations and on the deepest X-ray exposure of a mini-BAL QSO to date. Results. We found complex X-ray spectral variability on time scales of both months and hours, best reproduced by means of variable massive ionized absorbers along the line of sight. As a consequence, the observed optical-to-X-ray spectral index is found to be variable with time. In the highest signal-to-noise observation we detected highly ionized X-ray absorbing material outflowing much faster (u(sub X) approx. 16 500 km/s) than the UV absorbing one (u(sub uv) approx. 5,000 km/s). This highly ionized absorber is found to be variable on very short (a few kiloseconds) time scales. Conclusions. Our findings are qualitatively consistent with line driven accretion disk winds scenarios. Our observations have opened the time-resolved X-ray spectral analysis field for mini-BAL QSOs; only with future deep studies will we be able to map the dynamics of the inner flow and understand the physics of AGN winds and their impact on the environment.

Pinhole X-ray fluorescence imaging of gadolinium and gold nanoparticles using polychromatic X-rays: a Monte Carlo study

PubMed Central

Jung, Seongmoon; Sung, Wonmo; Ye, Sung-Joon

2017-01-01

This work aims to develop a Monte Carlo (MC) model for pinhole K-shell X-ray fluorescence (XRF) imaging of metal nanoparticles using polychromatic X-rays. The MC model consisted of two-dimensional (2D) position-sensitive detectors and fan-beam X-rays used to stimulate the emission of XRF photons from gadolinium (Gd) or gold (Au) nanoparticles. Four cylindrical columns containing different concentrations of nanoparticles ranging from 0.01% to 0.09% by weight (wt%) were placed in a 5 cm diameter cylindrical water phantom. The images of the columns had detectable contrast-to-noise ratios (CNRs) of 5.7 and 4.3 for 0.01 wt% Gd and for 0.03 wt% Au, respectively. Higher concentrations of nanoparticles yielded higher CNR. For 1×1011 incident particles, the radiation dose to the phantom was 19.9 mGy for 110 kVp X-rays (Gd imaging) and 26.1 mGy for 140 kVp X-rays (Au imaging). The MC model of a pinhole XRF can acquire direct 2D slice images of the object without image reconstruction. The MC model demonstrated that the pinhole XRF imaging system could be a potential bioimaging modality for nanomedicine. PMID:28860750

The X-ray spectrum and spectral energy distribution of FIRST J155633.8+351758: a LoBAL quasar with a probable polar outflow

NASA Astrophysics Data System (ADS)

Berrington, Robert C.; Brotherton, Michael S.; Gallagher, Sarah C.; Ganguly, Rajib; Shang, Zhaohui; DiPompeo, Michael; Chatterjee, Ritaban; Lacy, Mark; Gregg, Michael D.; Hall, Patrick B.; Laurent-Muehleisen, S. A.

2013-12-01

We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e. an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Γ = 1.7 or flatter at a >99 per cent confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 1023 cm-2, with both partially ionized models and partially covering neutral hydrogen models providing good fits. We present several lines of argument that suggest the fraction of X-ray emissions associated with the radio jet is not large. We combine our Chandra data with observations from the literature to construct the spectral energy distribution of FIRST J1556+3517 from radio to X-ray energies. We make corrections for Doppler beaming for the pole-on radio jet, optical dust reddening and X-ray absorption, in order to recover a probable intrinsic spectrum. The quasar FIRST J1556+3517 seems to be an intrinsically normal radio-quiet quasar with a reddened optical/UV spectrum, a Doppler-boosted but intrinsically weak radio jet and an X-ray absorber not dissimilar from that of other broad absorption line quasars.

High-resolution X-Ray Spectroscopy of the Seyfert 1 Galaxy Mrk 1040. Revealing the Failed Nuclear Wind with Chandra

NASA Astrophysics Data System (ADS)

Reeves, J. N.; Braito, V.; Behar, E.; Fischer, T. C.; Kraemer, S. B.; Lobban, A.; Nardini, E.; Porquet, D.; Turner, T. J.

2017-03-01

High-resolution X-ray spectroscopy of the warm absorber in the nearby X-ray bright Seyfert 1 galaxy Mrk 1040 is presented. The observations were carried out in the 2013-2014 timeframe using the Chandra High Energy Transmission Grating with a total exposure of 200 ks. A multitude of absorption lines from Ne, Mg, and Si are detected from a wide variety of ionization states. In particular, the detection of inner K-shell absorption lines from Ne, Mg, and Si, from charge states ranging from F-like to Li-like ions, suggests the presence of a substantial amount of low-ionization absorbing gas, illuminated by a steep soft X-ray continuum. The observations reveal at least three warm absorbing components ranging in ionization parameter from {log}(ξ /{erg} {cm} {{{s}}}-1)=0{--}2 and with column densities of {N}{{H}}=1.5{--}4.0× {10}21 cm-2. The velocity profiles imply that the outflow velocities of the absorbing gas are low and within ±100 km s-1 of the systemic velocity of Mrk 1040, which suggests that any outflowing gas may have stalled in this AGN on large enough scales. The warm absorber is likely located far from the black hole, within 300 pc of the nucleus, and is spatially coincident with emission from an extended narrow-line region as seen in the Hubble Space Telescope images. The iron K-band spectrum reveals only narrow emission lines, with Fe Kα at 6.4 keV consistent with originating from reflection off Compton-thick pc-scale reprocessing gas.

X-ray emission from high temperature plasmas

NASA Technical Reports Server (NTRS)

Harries, W. L.

1974-01-01

X-rays from a 25-hJ plasma focus apparatus were observed with pinhole cameras. The cameras consist of 0.4 mm diameter pinholes in 2 cm thick lead housing enclosing an X-ray intensifying screen at the image plane. Pictures recorded through thin aluminum foils or plastic sheets for X-ray energies sub gamma smaller than 15 keV show distributed X-ray emissions from the focussed plasma and from the anode surface. However, when thick absorbers are used, radial filamentary structure in the X-ray emission from the anode surface is revealed. Occasionally larger structures are observed in addition to the filaments. Possible mechanisms for the filamentary structure are discussed.

Discovery of X-ray pulsations in the Be/X-ray binary IGR J06074+2205

NASA Astrophysics Data System (ADS)

Reig, P.; Zezas, A.

2018-05-01

Context. IGR J06074+2205 is a poorly studied X-ray source with a Be star companion. It has been proposed to belong to the group of Be/X-ray binaries (BeXBs). In BeXBs, accretion onto the neutron star occurs via the transfer of material from the Be star's circumstellar disk. Thus, in the absence of the disk, no X-ray should be detected. Aims: The main goal of this work is to study the quiescent X-ray emission of IGR J06074+2205 during a disk-loss episode. Methods: We obtained light curves at different energy bands and a spectrum covering the energy range 0.4-12 keV. We used Fourier analysis to study the aperiodic variability and epoch folding methods to study the periodic variability. Model fitting to the energy spectrum allowed us to identify the possible physical processes that generated the X-rays. Results: We show that at the time of the XMM-Newton observation, the decretion disk around the Be star had vanished. Still, accretion appears as the source of energy that powers the high-energy radiation in IGR J06074+2205. We report the discovery of X-ray pulsations with a pulse period of 373.2 s and a pulse fraction of 50%. The 0.4-12 keV spectrum is well described by an absorbed power law and blackbody components with the best fitting parameters: NH = (6.2 ± 0.5) × 1021 cm-2, kTbb = 1.16 ± 0.03 keV, and Γ = 1.5 ± 0.1. The absorbed X-ray luminosity is LX = 1.4 × 1034 erg s-1 assuming a distance of 4.5 kpc. Conclusions: The detection of X-ray pulsations confirms the nature of IGR J06074+2205 as a BeXB. We discuss various scenarios to explain the quiescent X-ray emission of this pulsar. We rule out cooling of the neutron star surface and magnetospheric emission and conclude that accretion is the most likely scenario. The origin of the accreted material remains an open question.

NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-Ray Source Candidate in NGC 5643

NASA Astrophysics Data System (ADS)

Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Arévalo, P.; Ballantyne, D. R.; Baloković, M.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Del Moro, A.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Matt, G.; Puccetti, S.; Ricci, C.; Rigby, J. R.; Stern, D.; Walton, D. J.; Zappacosta, L.; Zhang, W.

2015-12-01

We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (˜0.5-100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X-1, have left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X-1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of NH ≳ 5 × 1024 cm-2. The range of 2-10 keV absorption-corrected luminosity inferred from the best-fitting models is L2-10,int = (0.8-1.7) × 1042 erg s-1, consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X-1 and show that it exhibits evidence of a spectral cutoff at energy E ˜ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3-8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X-1.

High resolution, multiple-energy linear sweep detector for x-ray imaging

DOEpatents

Perez-Mendez, Victor; Goodman, Claude A.

1996-01-01

Apparatus for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels.

High resolution, multiple-energy linear sweep detector for x-ray imaging

DOEpatents

Perez-Mendez, V.; Goodman, C.A.

1996-08-20

Apparatus is disclosed for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels. 12 figs.

5.8 X-ray Calorimeters

NASA Technical Reports Server (NTRS)

Porter, F. Scott

2008-01-01

X-ray calorimeter instruments for astrophysics have seen rapid development since they were invented in 1984. The prime instrument on all currently planned X-ray spectroscopic observatories is based on calorimeter technology. This relatively simple detection concept that senses the energy of an incident photon by measuring the temperature rise of an absorber material at very low temperatures, can form the basis of a very high performance, non-dispersive spectrometer. State-of-the-art calorimeter instruments have resolving powers of over 3000, large simultaneous band-passes, and near unit efficiency. This coupled with the intrinsic imaging capability of a pixilated x-ray calorimeter array, allows true spectral-spatial instruments to be constructed. In this chapter I briefly review the detection scheme, the state-of-the-art in X-ray calorimeter instruments and the future outlook for this technology.

The second ROSAT All-Sky Survey source catalogue: the deepest X-ray All-Sky Survey before eROSITA

NASA Astrophysics Data System (ADS)

Boller, T.; Freyberg, M.; Truemper, J.

2014-07-01

We present the second ROSAT all-sky survey source catalogue (RASS2, (Boller, Freyberg, Truemper 2014, submitted)). The RASS2 is an extension of the ROSAT Bright Source Catalogue (BSC) and the ROSAT Faint Source Catalogue (FSC). The total number of sources in the second RASS catalogue is 124489. The extensions include (i) the supply of new user data products, i.e., X-ray images, X-ray spectra, and X-ray light curves, (ii) a visual screening of each individual detection, (iii) an improved detection algorithm compared to the SASS II processing. This results into an as most as reliable and as most as complete catalogue of point sources detected during the ROSAT Survey observations. We discuss for the first time the intra-day timing and spectral properties of the second RASS catalogue. We find new highly variable sources and we discuss their timing properties. Power law fits have been applied which allows to determine X-ray fluxes, X-ray absorbing columns, and X-ray photon indices. We give access to the second RASS catalogue and the associated data products via a web-interface to allow the community to perform further scientific exploration. The RASS2 catalogue provides the deepest X-ray All-Sky Survey before eROSITA data will become available.

The X-ray Spectral Evolution of eta Carinae as Seen by ASCA

NASA Technical Reports Server (NTRS)

Corcoran, M. F.; Fredericks, A. C.; Petre, R.; Swank, J. H.; Drake, S. A.; White, Nicholas E. (Technical Monitor)

2000-01-01

Using data from the ASCA X-ray observatory, we examine the variations in the X-ray spectrum of the supermassive star nu Carinae with an unprecedented combination of spatial and spectral resolution. We include data taken during the recent X-ray eclipse in 1997-1998, after recovery from the eclipse, and during and after an X-ray flare. We show that the eclipse variation in the X-ray spectrum is apparently confined to a decrease in the emission measure of the source. We compare our results with a simple colliding wind binary model and find that the observed spectral variations are only consistent, with the binary model if there is significant high-temperature emission far from the star and/or a substantial change in the temperature distribution of the hot plasma. If contamination in the 2-10 keV band is important, the observed eclipse spectrum requires an absorbing column in excess of 10(exp 24)/sq cm for consistency with the binary model, which may indicate an increase in the first derivative of M from nu Carinae near the time of periastron passage. The flare spectra are consistent with the variability seen in nearly simultaneous RXTE observations and thus confirm that nu Carinae itself is the source of the flare emission. The variation in the spectrum during the flare seems confined to a change in the source emission measure. By comparing 2 observations obtained at the same phase in different X-ray cycles, we find that the current, X-ray brightness of the source is slightly higher than the brightness of the source during the last cycle perhaps indicative of a long-term increase in the first derivative of M, not associated with the X-ray cycle.

X-Ray Shadowing Experiments Toward Infrared Dark Clouds

NASA Technical Reports Server (NTRS)

Anderson, L. E.; Snowden, S.; Bania, T. M.

2009-01-01

We searched for X-ray shadowing toward two infrared dark clouds (IRDCs) using the MOS detectors on XMM-Newton to learn about the Galactic distribution of X-ray emitting plasma. IRDCs make ideal X-ray shadowing targets of 3/4 keY photons due to their high column densities, relatively large angular sizes, and known kinematic distances. Here we focus on two clouds near 30 deg Galactic longitude at distances of 2 and 5 kpc from the Sun. We derive the foreground and background column densities of molecular and atomic gas in the direction of the clouds. We find that the 3/4 ke V emission must be distributed throughout the Galactic disk. It is therefore linked to the structure of the cooler material of the ISM, and to the birth of stars.

The Ultra-Luminous X-ray Source Population from the Chandra Archive of Galaxies

NASA Technical Reports Server (NTRS)

Swartz, Douglas A.; Ghosh, Kajal K.; Tennant, Allen F.; Wu, Kinwah

2004-01-01

One hundred fifty-four discrete non-nuclear Ultra-Luminous X-ray (ULX) sources, with spectroscopically-determined intrinsic X-ray luminosities greater than 1 e39 ergs/s, are identified in 82 galaxies observed with Chandra's Advanced CCD Imaging Spectrometer. Source positions, X-ray luminosities, and spectral and timing characteristics are tabulated. Statistical comparisons between these X-ray properties and those of the weaker discrete sources in the same fields (mainly neutron star and stellar-mass black hole binaries) are made. Sources above approximately le38 ergs per second display similar spatial, spectral, color, and variability distributions. In particular, there is no compelling evidence in the sample for a new and distinct class of X-ray object such as the intermediate-mass black holes. 83% of ULX candidates have spectra that can be described as absorbed power laws with index = 1.74 and column density = 2.24e21 l per square centimeter, or approximately 5 times the average Galactic column. About 20% of the ULX's have much steeper indices indicative of a soft, and likely thermal, spectrum. The locations of ULXs in their host galaxies are strongly peaked towards their galaxy centers. The deprojected radial distribution of the ULX candidates is somewhat steeper than an exponential disk, indistinguishable from that of the weaker sources. About 5--15% of ULX candidates are variable during the Chandra observations (which average 39.5 ks). Comparison of the cumulative X-ray luminosity functions of the ULXs to Chandra Deep Field results suggests approximately 25% of the sources may be background objects including 14% of the ULX candidates in the sample of spiral galaxies and 44% of those in elliptical galaxies implying the elliptical galaxy ULX population is severely compromised by background active galactic nuclei. Correlations with host galaxy properties confirm the number and total X-ray luminosity of the ULXs are associated with recent star formation

X-ray atlas of rheumatic diseases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dihlmann, W.

1986-01-01

This atlas comprises instructive X-rays of the various inflammatory rheumatic joint diseases in all stages at the extremities and the spinal column. In addition, the complex pattern of the wide range of arthroses, also known as degenerative rheumatic disease is included. Besides the instructive pointers to X-ray diagnosis, the book is also a guide to differential diagnosis. Hence, this book is actually an X-ray atlas of joint diseases in general. Selected Contents: Introduction: What Does ''Rheumatism'' Actually Mean./Radiographic Methodology in Rheumatic Diseases of the Locomotor System/The Mosaic of Arthritis/Adult Rheumatoid Arthritis/Seronegative Spondylarthritis/Classic Collagen Diseases/Enthesiopathies/Gout-Pseudogout

X-ray View of Four High-Luminosity Swift-BAT AGN: Unveiling Obscuration and Reflection with Suzaku

NASA Technical Reports Server (NTRS)

Fiorettil, V.; Angelini, L.; Mushotzky, R. F.; Koss, M.; Malaguti, G.

2013-01-01

Aims. A complete census of obscured Active Galactic Nuclei (AGN) is necessary to reveal the history of the super massive black hole (SMBH) growth and galaxy evolution in the Universe given the complex feedback processes and the fact that much of this growth occurs in an obscured phase. In this context, hard X-ray surveys and dedicated follow-up observations represent a unique tool for selecting highly absorbed AGN and for characterizing the obscuring matter surrounding the SMBH. Here we focus on the absorption and reflection occurring in highly luminous, quasar-like AGN, to study the relation between the geometry of the absorbing matter and the AGN nature (e.g. X-ray, optical, and radio properties), and to help to determine the column density dependency on the AGN luminosity. Methods. The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10(exp -11) erg per square centimeter and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 less than LogLBAT less than 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis, adding an original spectral analysis when non was available from the literature. Results. Of our sample, 3C 452 is the only certain Compton-thick AGN candidate because of i) the high absorption (N(sub H) approximately 4 × 10(exp 23) per square centimeter) and strong Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e. the low scattering fraction (less than 0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C 105 is not reflection-dominated, despite the comparable column density

SoilJ - An ImageJ plugin for semi-automatized image-processing of 3-D X-ray images of soil columns

NASA Astrophysics Data System (ADS)

Koestel, John

2016-04-01

3-D X-ray imaging is a formidable tool for quantifying soil structural properties which are known to be extremely diverse. This diversity necessitates the collection of large sample sizes for adequately representing the spatial variability of soil structure at a specific sampling site. One important bottleneck of using X-ray imaging is however the large amount of time required by a trained specialist to process the image data which makes it difficult to process larger amounts of samples. The software SoilJ aims at removing this bottleneck by automatizing most of the required image processing steps needed to analyze image data of cylindrical soil columns. SoilJ is a plugin of the free Java-based image-processing software ImageJ. The plugin is designed to automatically process all images located with a designated folder. In a first step, SoilJ recognizes the outlines of the soil column upon which the column is rotated to an upright position and placed in the center of the canvas. Excess canvas is removed from the images. Then, SoilJ samples the grey values of the column material as well as the surrounding air in Z-direction. Assuming that the column material (mostly PVC of aluminium) exhibits a spatially constant density, these grey values serve as a proxy for the image illumination at a specific Z-coordinate. Together with the grey values of the air they are used to correct image illumination fluctuations which often occur along the axis of rotation during image acquisition. SoilJ includes also an algorithm for beam-hardening artefact removal and extended image segmentation options. Finally, SoilJ integrates the morphology analyses plugins of BoneJ (Doube et al., 2006, BoneJ Free and extensible bone image analysis in ImageJ. Bone 47: 1076-1079) and provides an ASCII file summarizing these measures for each investigated soil column, respectively. In the future it is planned to integrate SoilJ into FIJI, the maintained and updated edition of ImageJ with selected

X-ray-bright optically faint active galactic nuclei in the Subaru Hyper Suprime-Cam wide survey

NASA Astrophysics Data System (ADS)

Terashima, Yuichi; Suganuma, Makoto; Akiyama, Masayuki; Greene, Jenny E.; Kawaguchi, Toshihiro; Iwasawa, Kazushi; Nagao, Tohru; Noda, Hirofumi; Toba, Yoshiki; Ueda, Yoshihiro; Yamashita, Takuji

2018-01-01

We construct a sample of X-ray-bright optically faint active galactic nuclei by combining Subaru Hyper Suprime-Cam, XMM-Newton, and infrared source catalogs. Fifty-three X-ray sources satisfying i-band magnitude fainter than 23.5 mag and X-ray counts with the EPIC-PN detector larger than 70 are selected from 9.1 deg2, and their spectral energy distributions (SEDs) and X-ray spectra are analyzed. Forty-four objects with an X-ray to i-band flux ratio FX/Fi > 10 are classified as extreme X-ray-to-optical flux sources. Spectral energy distributions of 48 among 53 are represented by templates of type 2 AGNs or star-forming galaxies and show the optical signature of stellar emission from host galaxies in the source rest frame. Infrared/optical SEDs indicate a significant contribution of emission from dust to the infrared fluxes, and that the central AGN is dust obscured. The photometric redshifts determined from the SEDs are in the range of 0.6-2.5. The X-ray spectra are fitted by an absorbed power-law model, and the intrinsic absorption column densities are modest (best-fit log NH = 20.5-23.5 cm-2 in most cases). The absorption-corrected X-ray luminosities are in the range of 6 × 1042-2 × 1045 erg s-1. Twenty objects are classified as type 2 quasars based on X-ray luminsosity and NH. The optical faintness is explained by a combination of redshifts (mostly z > 1.0), strong dust extinction, and in part a large ratio of dust/gas.

Discovery of X-ray emission associated with the Gum Nebula

NASA Technical Reports Server (NTRS)

Leahy, D. A.; Nousek, J.; Garmire, G.

1992-01-01

The Gum Nebula was observed by the A-2 LED proportional counters on the HEAO-1 satellite as part of the all-sky survey. The first detection of X-ray emission associated with the Gum Nebula is reported. Soft X-ray spectra were constructed from the A-2 LED PHA data. Single temperature Raymond-Smith models were fitted to the observed spectra to yield temperature, column density and emission measure. The temperature is 6 x 10 exp 5 K, the column density 4 x 10 exp 20/sq cm, and the emission measure 5 cm exp-6 pc. The X-ray and optical properties of the Gum Nebula are consistent with a supernova remnant in the shell stage of evolution, which was the product of an energetic (3 x 10 exp 51 ergs) supernova explosion which occurred about 2 x 10 exp 6 yr ago.

High-redshift Extremely Red Quasars in X-Rays

NASA Astrophysics Data System (ADS)

Goulding, Andy D.; Zakamska, Nadia L.; Alexandroff, Rachael M.; Assef, Roberto J.; Banerji, Manda; Hamann, Fred; Wylezalek, Dominika; Brandt, William N.; Greene, Jenny E.; Lansbury, George B.; Pâris, Isabelle; Richards, Gordon; Stern, Daniel; Strauss, Michael A.

2018-03-01

Quasars may have played a key role in limiting the stellar mass of massive galaxies. Identifying those quasars in the process of removing star formation fuel from their hosts is an exciting ongoing challenge in extragalactic astronomy. In this paper, we present X-ray observations of 11 extremely red quasars (ERQs) with L bol ∼ 1047 erg s‑1 at z = 1.5–3.2 with evidence for high-velocity (v ≥slant 1000 km s‑1) [O III] λ5007 outflows. X-rays allow us to directly probe circumnuclear obscuration and to measure the instantaneous accretion luminosity. We detect 10 out of 11 ERQs available in targeted and archival data. Using a combination of X-ray spectral fitting and hardness ratios, we find that all of the ERQs show signs of absorption in the X-rays with inferred column densities of N H ≈ 1023 cm‑2, including four Compton-thick candidates (N H ≥slant 1024 cm‑2). We stack the X-ray emission of the seven weakly detected sources, measuring an average column density of N H ∼ 8 × 1023 cm‑2. The absorption-corrected (intrinsic) 2–10 keV X-ray luminosity of the stack is 2.7 × 1045 erg s‑1, consistent with X-ray luminosities of type 1 quasars of the same infrared luminosity. Thus, we find that ERQs are a highly obscured, borderline Compton-thick population, and based on optical and infrared data we suggest that these objects are partially hidden by their own equatorial outflows. However, unlike some quasars with known outflows, ERQs do not appear to be intrinsically underluminous in X-rays for their bolometric luminosity. Our observations indicate that low X-rays are not necessary to enable some types of radiatively driven winds.

Evaluation of variations in absorbed dose and image noise according to patient forms in X-ray computed tomography.

PubMed

Matsubara, Kosuke; Koshida, Kichiro; Suzuki, Masayuki; Hayakawa, Mayumi; Tsujii, Hideo; Yamamoto, Tomoyuki

2005-12-20

Excessive radiation exposure in pediatric computed tomography (CT) scanning has become a serious problem, and it is difficult to select scan parameters for the scanning of small patients such as children. We investigated differences in absorbed dose and standard deviation (SD) in Hounsfield unit (HU) caused by differences in the form of the subject using a body-type phantom with removable body parts. Using four X-ray CT scanners, measurements were made with values from 50 mAs to 300 mAs, with slices of 50 mAs, using scan protocols that were assumed to perform thorough examinations. The results showed that the mAs values and absorbed doses were almost proportional, and the absorbed doses in the phantom without body parts were about 1.1-2.2-fold higher than those of the phantom with body parts at the same points. The SD values obtained indicated that the absorbed doses in the phantom with body parts were 0.3-0.6 times those of the phantom without body parts when the mAs values used were adjusted so that both SD values were the same. The absorbed doses in various patient forms can be estimated from these results, and they will become critical data for the selection of appropriate scan protocols.

High-Resolution X-Ray Spectroscopy and Modeling of the Absorbing and Emitting Outflow in NGC 3783

NASA Astrophysics Data System (ADS)

Kaspi, Shai; Brandt, W. N.; Netzer, Hagai; George, Ian M.; Chartas, George; Behar, Ehud; Sambruna, Rita M.; Garmire, Gordon P.; Nousek, John A.

2001-06-01

The high-resolution X-ray spectrum of NGC 3783 shows several dozen absorption lines and a few emission lines from the H-like and He-like ions of O, Ne, Mg, Si, and S, as well as from Fe XVII-Fe XXIII L-shell transitions. We have reanalyzed the Chandra HETGS spectrum using better flux and wavelength calibrations, along with more robust methods. Combining several lines from each element, we clearly demonstrate the existence of the absorption lines and determine that they are blueshifted relative to the systemic velocity by -610+/-130 km s-1. We find the Ne absorption lines in the High-Energy Grating spectrum to be resolved with FWHM=840+490-360 km s-1; no other lines are resolved. The emission lines are consistent with being at the systemic velocity. We have used regions in the spectrum where no lines are expected to determine the X-ray continuum, and we model the absorption and emission lines using photoionized-plasma calculations. The model consists of two absorption components, with different covering factors, which have an order-of-magnitude difference in their ionization parameters. The two components are spherically outflowing from the active galactic nucleus, and thus contribute to both the absorption and the emission via P Cygni profiles. The model also clearly requires O VII and O VIII absorption edges. The low-ionization component of our model can plausibly produce UV absorption lines with equivalent widths consistent with those observed from NGC 3783. However, we note that this result is highly sensitive to the unobservable UV to X-ray continuum, and the available UV and X-ray observations cannot firmly establish the relationship between the UV and X-ray absorbers. We find good agreement between the Chandra spectrum and simultaneous ASCA and RXTE observations. The 1 keV deficit previously found when modeling ASCA data probably arises from iron L-shell absorption lines not included in previous models. We also set an upper limit on the FWHM of the narrow Fe

New Constraints for X-ray Reprocessing Around Supermassive Black Holes: Near and Far with State-of-the-Art Multi-Mission Modeling

NASA Astrophysics Data System (ADS)

Tzanavaris, Panayiotis

Fluorescent Fe K emission from neutral matter in AGN spectracan arise in the accretion disk around the centralsupermassive black hole [SMBH] ("broad" line) and/or in distant matter ("narrow"line). If it is broad, it provides a unique windowto the strong gravity SMBH regime, including information on SMBH spin;if it is narrow, it probesthe distant reprocessor, likely a clumpy torus. We will use broadband X-ray data from four NASA X-ray missionsfor 45 nearby AGNs, and 1. Assess whether any known "broad" relativistic lines can be modeledas "narrow"instead, by means of self-consistent modeling of fluorescence,direct, and scattered continua; 2. Measure absorbing column densities both in and out of the line of sight; 3. Bootstrap measures of intrinsic bolometric AGN luminosity, with X-ray and optical data. This work will provide updated results on a) black hole spin, with implications on AGN jet power and accretion history; b) the census of highly-obscured (Compton thick) vs. Compton thin AGNs, with implications on models of the Cosmic X-ray Background; c) calibrations of Fe K line, X-ray intrinsic continuum, [OIII] and [OIV] luminosities as measures of intrinsc bolometric AGN luminosity, with implications on AGN feedback and galaxy evolution. Key in our approach is a physically based, self-consistent modeling of the narrow line, with finite column density in and out of the line of sight, and the latest relativistic modeling of the broad line.

Heating the Primordial Soup: X-raying the Circumstellar Disk of RY Lupi

NASA Astrophysics Data System (ADS)

Principe, David

2015-09-01

X-ray irradiation of circumstellar disks plays a vital role in their chemical evolution yet few high resolution X-ray observations exist characterizing both the disk-illuminating radiation field and the soft energy spectrum absorbed by the disk. We propose HETG spectroscopic observations of RY Lupi, a rare example of a nearly edge-on, actively accreting star-disk system within 150 pc. We aim to take advantage of its unique viewing geometry with the goals of (a) determining the intrinsic X-ray spectrum of the central pre-MS star so as to establish whether its X-ray emission can be attributed to accretion shocks or coronal emission, and (b) model the spectrum of X-rays absorbed by its gaseous disk. These results will serve as essential input to models of irradiated, planet-forming disks.

X Ray Mask Of Gold-Carbon Mixture Absorber On BCN Compound Substrate Fabricated By Plasma Processes

NASA Astrophysics Data System (ADS)

Aiyer, Chandrasekhar R.; Itoh, Satoshi; Yamada, Hitomi; Morita, Shinzo; Hattori, Shuzo

1988-06-01

X-ray mask fabrication based on BCN compound membrane and gold containing polymeric carbon ( Au-C ) absorber by totally dry processes is proposed. The Au-C films were depo-sited by plasma polymerization of propylene or styrene monomers and co-evaporation of gold. These films have 2 to 5 times higher etching rate than that of pure gold for 09 RIE, depending on the Au content. The stress in the films could be reduced to 1.9 E 7 N/m2 by annealing. The BCN films were deposited on silicon wafers by rf (13.56 MHz) plasma CVD with diborane, methane and nitrogen as source gases at typical deposition rate of 30 nm/min. The optical (633nm) and X ray (Pd L~) transparencies were nearly 80% for film thickness of 6 um. Patterning of Au-C was achieved by using tungsten as intermediate layer and PMMA electron beam resist. CF4 RIE was used to etch the tungsten layer which in turn acted as mask for the gold carbide 02 RIE. The process parameters and the characteristics of the Au-C and BCN films are presented.

Normal incidence X-ray mirror for chemical microanalysis

DOEpatents

Carr, Martin J.; Romig, Jr., Alton D.

1990-01-01

A non-planar, focusing mirror, to be utilized in both electron column instruments and micro-x-ray fluorescence instruments for performing chemical microanalysis on a sample, comprises a concave, generally spherical base substrate and a predetermined number of alternating layers of high atomic number material and low atomic number material contiguously formed on the base substrate. The thickness of each layer is an integral multiple of the wavelength being reflected and may vary non-uniformly according to a predetermined design. The chemical analytical instruments in which the mirror is used also include a predetermined energy source for directing energy onto the sample and a detector for receiving and detecting the x-rays emitted from the sample; the non-planar mirror is located between the sample and detector and collects the x-rays emitted from the sample at a large solid angle and focuses the collected x-rays to the sample. For electron column instruments, the wavelengths of interest lie above 1.5 nm, while for x-ray fluorescence instruments, the range of interest is below 0.2 nm. Also, x-ray fluorescence instruments include an additional non-planar focusing mirror, formed in the same manner as the previously described m The invention described herein was made in the performance of work under contract with the Department of Energy, Contract No. DE-AC04-76DP00789, and the United States Government has rights in the invention pursuant to this contract.

A COMPREHENSIVE SPECTRAL ANALYSIS OF THE X-RAY PULSAR 4U 1907+09 FROM TWO OBSERVATIONS WITH THE SUZAKU X-RAY OBSERVATORY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivers, Elizabeth; Markowitz, Alex; Suchy, Slawomir

2010-01-20

We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku Observatory. The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx19 keV. Additionally, using the narrow CCD response of Suzaku near 6 keV allows us to study in detail the Fe K bandpass and to quantify the Fe Kbeta line for this source for the first time. The source is absorbed by fully covering material along the line of sight with a column density of N{sub H} approx 2 x 10{sup 22}more » cm{sup -2}, consistent with a wind-accreting geometry, and a high Fe abundance (approx3-4 times solar). Time- and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in N{sub H} along the line of sight, perhaps indicating clumpiness in the stellar wind.« less

Spectral formation in a radiative shock: application to anomalous X-ray pulsars and soft gamma-ray repeaters

NASA Astrophysics Data System (ADS)

Kylafis, N. D.; Trümper, J. E.; Ertan, Ü.

2014-02-01

Context. In the fallback disk model for the persistent emission of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), the hard X-ray emission arises from bulk- and thermal Comptonization of bremsstrahlung photons, which are generated in the accretion column. The relatively low X-ray luminosity of these sources implies a moderate transverse optical depth to electron scattering, with photons executing a small number of shock crossings before escaping sideways. Aims: We explore the range of spectral shapes that can be obtained with this model and characterize the most important parameter dependencies. Methods: We use a Monte Carlo code to study the crisscrossing of photons in a radiative shock in an accretion column and compute the resulting spectrum. Results: As expected, high-energy power-law X-ray spectra are produced in radiative shocks with photon-number spectral index Γ ≳ 0.5. We find that the required transverse optical depth is 1 ≲ τ⊥ ≲ 7. Such spectra are observed in low-luminosity X-ray pulsars. Conclusions: We demonstrate here with a simple model that Compton upscattering in the radiative shock in the accretion column can produce hard X-ray spectra similar to those seen in the persistent and transient emission of AXPs and SGRs. In particular, one can obtain a high-energy power-law spectrum, with photon-number spectral-index Γ ~ 1 and a cutoff at 100 - 200 keV, with a transverse Thomson optical depth of ~5, which is shown to be typical in AXPs/SGRs.

Small scale H I structure and the soft X-ray background

NASA Technical Reports Server (NTRS)

Jahoda, K.; Mccammon, D.; Lockman, F. J.

1986-01-01

The observed anticorrelation between diffuse soft X-ray flux and H I column density has been explained as absorption of soft X-rays produced in a hot galactic halo, assuming that the neutral interstellar material is sufficiently clumped to reduce the soft X-ray absorption cross section by a factor of two to three. A 21 cm emission line study of H I column density variations at intermediate and high galactic latitudes to 10' spatial resolution has been done. The results confirm conclusions from preliminary work at coarser resolution, and in combination with other data appear to rule out the hypothesis that clumping of neutral interstellar matter on any angular scale significantly reduces X-ray absorption cross sections in the 0.13 - 0.28 keV energy range. It is concluded therefore that the observed anticorrelation is not primarily a consequence of absorption of soft X-rays produced in a hot galactic halo.

Discovery of an Ultraviolet Counterpart to an Ultrafast X-Ray Outflow in the Quasar PG 1211+143

NASA Astrophysics Data System (ADS)

Kriss, Gerard A.; Lee, Julia C.; Danehkar, Ashkbiz; Nowak, Michael A.; Fang, Taotao; Hardcastle, Martin J.; Neilsen, Joseph; Young, Andrew

2018-02-01

We observed the quasar PG 1211+143 using the Cosmic Origins Spectrograph on the Hubble Space Telescope in 2015 April as part of a joint campaign with the Chandra X-ray Observatory and the Jansky Very Large Array. Our ultraviolet spectra cover the wavelength range 912–2100 Å. We find a broad absorption feature (∼ 1080 {km} {{{s}}}-1) at an observed wavelength of 1240 Å. Interpreting this as H I Lyα, in the rest frame of PG 1211+143 (z = 0.0809), this corresponds to an outflow velocity of ‑16,980 {km} {{{s}}}-1 (outflow redshift {z}{out}∼ -0.0551), matching the moderate ionization X-ray absorption system detected in our Chandra observation and reported previously by Pounds et al. With a minimum H I column density of {log} {N}{{H}{{I}}}> 14.5, and no absorption in other UV resonance lines, this Lyα absorber is consistent with arising in the same ultrafast outflow as the X-ray absorbing gas. The Lyα feature is weak or absent in archival ultraviolet spectra of PG 1211+143, strongly suggesting that this absorption is transient, and intrinsic to PG 1211+143. Such a simultaneous detection in two independent wavebands for the first time gives strong confirmation of the reality of an ultrafast outflow in an active galactic nucleus.

Planetary X ray experiment

NASA Technical Reports Server (NTRS)

Anderson, K. A.

1972-01-01

Design studies for an X-ray experiment using solid state detectors and for an experiment using a proportional counter for investigating Jovian and Saturnian magnetospheres are reported. Background counting rates through the forward aperture and leakage fluxes are discussed for each design. It is concluded that the best choice of instrument appears to have following the characteristics: (1) two separate multiwire proportional counters for redundancy; (2) passive collimation to restrict the field to about 5 deg, wiregrid modulation collimation to about 0.1 deg angular resolution; (3) no active shielding system around the counter body; and (4) light passive shielding around any portion of the counter body exposed to space to absorb most of the cosmic X-ray background.

Microfabrication of High Resolution X-ray Magnetic Calorimeters

NASA Astrophysics Data System (ADS)

Hsieh, Wen-Ting; Bandler, Simon R.; Kelly, Daniel P.; Porst, Jan P.; Rotzinger, Hannes; Seidel, George M.; Stevenson, Thomas R.

2009-12-01

Metallic magnetic calorimeter (MMC) is one of the most promising x-ray detector technologies for providing the very high energy resolution needed for future astronomical x-ray imaging spectroscopy. For this purpose, we have developed micro-fabricated 5×5 arrays of MMC of which each individual pixel has excellent energy resolution as good as 3.4 eV at 6 keV x-ray. Here we report on the fabrication techniques developed to achieve good resolution and high efficiency. These include: processing of a thin insulation layer for strong magnetic coupling between the AuEr sensor film and the niobium pick-up coil; production of overhanging absorbers for enhanced efficiency of x-ray absorption; fabrication on SiN membranes to minimize the effects on energy resolution from athermal phonon loss. We have also improved the deposition of the magnetic sensor film such that the film magnetization is nearly completely that is expected from the AuEr sputter target bulk material. In addition, we have included a study of a positional sensitive design, the Hydra design, which allows thermal coupling of four absorbers to a common MMC sensor and circuit.

A deep X-ray observation of the supernova remnant G304.6+0.1 (Kes 17) using Suzaku

NASA Astrophysics Data System (ADS)

Gök, F.; Sezer, A.

2012-06-01

In this paper, we present the analysis of a deep (99.6 ks) observation of G304.6+0.1 with the X-ray Imaging Spectrometer on board the Suzaku satellite. The X-ray spectral data are well fitted with a plasma model consisting of a thermal component, in collisional ionization equilibrium, and a non-thermal component. The thermal emission is well fitted with the VMEKAL model with an electron temperature of kTe˜ 0.75 keV, a high absorbing column density of NH˜ 3.9 × 1022 cm-2 and near/lower solar abundances, which indicate that the X-ray emitting plasma of G304.6+0.1 is dominated by a swept-up ambient medium. The non-thermal component is well fitted with a power-law model with a photon index of Γ˜ 1.4. We have found a relatively high electron density ne˜ 2.3f-1/2 cm-3, an age t˜ 1.4 × 104f1/2 yr and an X-ray emitting mass Mx˜ 380f1/2 M⊙ at an adopted distance of d= 10 kpc. Using the morphological and spectral X-ray data, we confirm that the remnant is a new member of the mixed-morphology supernova remnants.

X ray spectra of cataclysmic variables

NASA Technical Reports Server (NTRS)

Patterson, Joseph; Halpern, Jules

1990-01-01

X ray spectral parameters of cataclysmic variables observed with the 'Einstein' imaging proportional counter were determined by fitting an optically thin, thermal bremsstrahlung spectrum to the raw data. Most of the sources show temperatures of order a few keV, while a few sources exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1 to 3.5 keV luminosities are generally in the range from 10(exp 30) to 10(exp 32) erg/sec. The results are consistent with the x rays originating in a disk/white dwarf boundary layer of non-magnetic systems, or in a hot, post-shock region in the accretion column of DQ Her stars, with a negligible contribution from the corona of the companion. In a few objects column densities were found that are unusually high for interstellar material. It was suggested that the absorption occurs in the system itself.

The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

NASA Astrophysics Data System (ADS)

Kollatschny, W.; Schartel, N.; Zetzl, M.; Santos-Lleó, M.; Rodríguez-Pascual, P. M.; Ballo, L.; Talavera, A.

2016-01-01

Context. The object PG 0043+039 has been identified as a broad absorption line (BAL) quasar based on its UV spectra. However, this optical luminous quasar has not been detected before in deep X-ray observations, making it the most extreme X-ray weak quasar known today. Aims: This study aims to detect PG 0043+039 in a deep X-ray exposure. The question is what causes the extreme X-ray weakness of PG 0043+039? Does PG 0043+039 show other spectral or continuum peculiarities? Methods: We took simultaneous deep X-ray spectra with XMM-Newton, far-ultraviolet (FUV) spectra with the Hubble Space Telescope (HST), and optical spectra of PG 0043+039 with the Hobby-Eberly Telescope (HET) and Southern African Large Telescope (SALT) in July, 2013. Results: We have detected PG 0043+039 in our X-ray exposure taken in 2013. We presented our first results in a separate paper (Kollatschny et al. 2015). PG 0043+039 shows an extreme αox gradient (αox = -2.37). Furthermore, we were able to verify an X-ray flux of this source in a reanalysis of the X-ray data taken in 2005. At that time, it was fainter by a factor of 3.8 ±0.9 with αox = -2.55. The X-ray spectrum is compatible with a normal quasar power-law spectrum (Γ = 1.70-0.45+0.57) with moderate intrinsic absorption (NH = 5.5-3.9+6.9 × 1021 cm-2) and reflection. The UV/optical flux of PG 0043+039 has increased by a factor of 1.8 compared to spectra taken in the years 1990-1991. The FUV spectrum is highly peculiar and dominated by broad bumps besides Lyα. There is no detectable Lyman edge associated with the BAL absorbing gas seen in the CIV line. PG 0043+039 shows a maximum in the overall continuum flux at around λ ≈ 2500 Å in contrast to most other AGN where the maximum is found at shorter wavelengths. All the above is compatible with an intrinsically X-ray weak quasar, rather than an absorbed X-ray emission. Besides strong FeII multiplets and broad Balmer and HeI lines in the optical band we only detect a narrow [O II

Temperature dependence of a superconducting tunnel junction x-ray detector

NASA Astrophysics Data System (ADS)

Hiller, Lawrence J.; Labov, Simon E.; Mears, Carl A.; Barfknecht, Andrew T.; Frank, Matthias A.; Netel, Harrie; Lindeman, Mark A.

1995-09-01

Superconducting tunnel junctions can be used as part of a high-resolution, energy-dispersive x- ray detector. The energy of the absorbed x ray is used to break superconducting electron pairs, producing on the order of 10(superscript 6) excitations, called quasiparticles. The number of quasiparticles produced is proportional to the energy of the absorbed x ray. When a bias voltage is maintained across the barrier, these quasiparticles produce a net tunneling current. Either the peak tunneling current or the total tunneled charge may be measured to determine the energy of the absorbed x ray. The tunneling rate, and therefore the signal, is enhanced by the use of a quasiparticle trap near the tunnel barrier. The trapping efficiency is improved by decreasing the energy gap, though this reduces the maximum temperature at which the device may operate. In our niobium/aluminum configuration, we can very the energy gap in the trapping layer by varying its thickness. This paper examines the performance of two devices with 50 nm aluminum traps at temperatures ranging from 100 mK to 700 mK. We found that this device has a very good energy resolution of about 12 eV FWHM at 1 keV. This energy resolution is independent of temperature for much of this temperature range.

X-RAY PROPERTIES OF THE NORTHERN GALACTIC CAP SOURCES IN THE 58 MONTH SWIFT/BAT CATALOG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasudevan, Ranjan V.; Mushotzky, Richard F.; Shimizu, Thomas T.

2013-02-15

We present a detailed X-ray spectral analysis of the non-beamed, hard X-ray selected active galactic nuclei (AGNs) in the northern Galactic cap of the 58 month Swift Burst Alert Telescope (Swift/BAT) catalog, consisting of 100 AGNs with b > 50 Degree-Sign . This sky area has excellent potential for further dedicated study due to a wide range of multi-wavelength data that are already available, and we propose it as a low-redshift analog to the 'deep field' observations of AGNs at higher redshifts (e.g., CDFN/S, COSMOS, Lockman Hole). We present distributions of luminosity, absorbing column density, and other key quantities formore » the catalog. We use a consistent approach to fit new and archival X-ray data gathered from XMM-Newton, Swift/XRT, ASCA, and Swift/BAT. We probe to deeper redshifts than the 9 month BAT catalog ((z) = 0.043 compared to (z) = 0.03 for the 9 month catalog), and uncover a broader absorbing column density distribution. The fraction of obscured (log N {sub H} {>=} 22) objects in the sample is {approx}60%, and 43%-56% of the sample exhibits 'complex' 0.4-10 keV spectra. We present the properties of iron lines, soft excesses, and ionized absorbers for the subset of objects with sufficient signal-to-noise ratio. We reinforce previous determinations of the X-ray Baldwin (Iwasawa-Taniguchi) effect for iron K{alpha} lines. We also identify two distinct populations of sources; one in which a soft excess is well-detected and another where the soft excess is undetected, suggesting that the process responsible for producing the soft excess is not at work in all AGNs. The fraction of Compton-thick sources (log N {sub H} > 24.15) in our sample is {approx}9%. We find that 'hidden/buried AGNs' (which may have a geometrically thick torus or emaciated scattering regions) constitute {approx}14% of our sample, including seven objects previously not identified as hidden. Compton reflection is found to be important in a large fraction of our sample using joint

Detection of Highly-Absorbed X-rays from Nova Mus 2018 with Swift

NASA Astrophysics Data System (ADS)

Nelson, Thomas; Kuin, Paul; Mukai, Koji; Page, Kim; Chomiuk, Laura; Kawash, Adam; Sokoloski, J. L.; Linford, Justin; Rupen, Michael P.; Mioduszewski, Amy

2018-03-01

We report the detection of X-rays from Nova Mus 2018 with the Swift XRT instrument. We have been carrying out weekly monitoring of the nova with Swift since its discovery on 2018 Jan 15 (see ATel #11220), and observations up to 2018 Feb 24 yielded X-ray non-detections.

Hard X-Ray Emission of the Luminous Infrared Galaxy NGC 6240 as Observed by Nustar

NASA Technical Reports Server (NTRS)

Puccetti, S.; Comastri, A.; Bauer, F. E.; Brandt, W. N.; Fiore, F.; Harrison, F. A.; Luo, B.; Stern, D.; Urry, C. M.; Alexander, D. M.;

Symbiotic Stars in X-rays

NASA Technical Reports Server (NTRS)

Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

2014-01-01

Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate

NASA Technical Reports Server (NTRS)

Swank, J. H.; Fabian, A. C.; Ross, R. R.

1983-01-01

Phenomenological fits to the hard X-ray spectrum of AM Herculis left unexplained the high equivalent width (0.8 + or - 0.1 keV) of Fe K alpha emission. A purely thermal origin implies a much steeper spectrum than was observed. With Monte Carlo calculations, scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base were investigated. The strength of the iron emission and the flat spectral continuum can be explained by the effects of fluorescence and absorption within the accretion column and the surface of the white dwarf on a thermal X-ray spectrum. Thomson optical depths across the column in the range 0.2 to 0.7 are acceptable. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values. Estimates of the column size differ by a factor of 40. Small spot sizes and low luminosities would be consistent with the soft component being the expected reprocessed bremsstrahlung and cyclotron radiation, although the constraint of matching the spectrum confines one to solutions with fluxes exceeding 20% the Eddington limits.

MO-FG-CAMPUS-IeP1-05: New Ionization Chamber Dosimetry of Absorbed Dose to Water in Diagnostic KV X-Ray Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Araki, F; Ohno, T

Purpose: To develop new ionization chamber dosimetry of absorbed dose to water in diagnostic kV x-ray beams, by using a beam quality conversion factor, kQ, for Co-60 to kV x-ray and an ionization conversion factor for a water-substitute plastic phantom. Methods: kQ was calculated for aluminum half value-layers (Al-HVLs) of 1.5 mm to 8 mm which were generated by kV x-ray beams of 50 to 120 kVp. Twenty-two energy spectra for ten effective energies (Eeff) were calculated by a SpecCalc program. Depth doses in water were calculated at 5 × 5 to 30 × 30 cm{sup 2} fields. Output factorsmore » were also obtained from the dose ratio for a 10 × 10 cm{sup 2} field. kQ was obtained for a PTW30013 Former ion chamber. In addition, an ionization conversion factor of the PWDT phantom to water was calculated. All calculations were performed with EGSnrc/cavity code and egs-chamber codes. Results: The x-ray beam energies for 1.5 mm to 8 mm Al-HVLs ranged in Eeff of 25.7 to 54.3 keV. kQ for 1.5 mm to 8 mm Al-HVLs were 0.831 to 0.897, at 1 and 2 cm depths for a 10 × 10 cm2 field. Similarly, output factors for 5 × 5 to 30 × 30 cm{sup 2} fields were 0.937 to 1.033 for 25.7 keV and 0.857 to 1.168 for 54.3 keV. The depth dose in a PWDT phantom decreased up to 5% compared to that in water at depth of ten percent of maximum dose for 1.5 mm Al-HVL. The ionization ratios of water/PWDT phantoms for the PTW30013 chamber were 1.012 to 1.007 for 1.5 mm to 8 mm Al-HVLs at 1 cm depth. Conclusion: It became possible to directly measure the absorbed dose to water with the ionization chamber in diagnostic kV x-ray beams, by using kQ and the PWDT phantom.« less

Broadband short term X-ray variability of the quasar PDS 456

NASA Astrophysics Data System (ADS)

Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

2016-05-01

We present a detailed analysis of a recent 500 ks net exposure Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_bol˜1047 erg s-1) quasar PDS 456 in which the X-ray flux was unusually low. The short term X-ray spectral variability has been interpreted in terms of variable absorption and/or intrinsic continuum changes. In the former scenario, the spectral variability is due to variable covering factors of two regions of partially covering absorbers. We find that these absorbers are characterised by an outflow velocity comparable to that of the highly ionised wind, i.e. ˜ 0.25 c, at the 99.9% (3.26σ) confidence level. This suggests that the partially absorbing clouds may be the denser clumpy part of the inhomogeneous wind. Following an obscuration event we obtained a direct estimate of the size of the X-ray emitting region, to be not larger than 20 R_g in PDS 456.

The development of high resolution silicon x-ray microcalorimeters

NASA Astrophysics Data System (ADS)

Porter, F. S.; Kelley, R. L.; Kilbourne, C. A.

2005-12-01

Recently we have produced x-ray microcalorimeters with resolving powers approaching 2000 at 5.9 keV using a spare XRS microcalorimeter array. We attached 400 um square, 8 um thick HgTe absorbers using a variety of attachment methods to an XRS array and ran the detector array at temperatures between 40 and 60 mK. The best results were for absorbers attached using the standard XRS absorber-pixel thermal isolation scheme utilizing SU8 polymer tubes. In this scenario we achieved a resolution of 3.2 eV FWHM at 5.9 keV. Substituting a silicon spacer for the SU8 tubes also yielded sub-4eV results. In contrast, absorbers attached directly to the thermistor produced significant position dependence and thus degraded resolution. Finally, we tested standard 640um-square XRS detectors at reduced bias power at 50mK and achieved a resolution of 3.7eV, a 50% improvement over the XRS flight instrument. Implanted silicon microcalorimeters are a mature flight-qualified technology that still has a substantial phase space for future development. We will discuss these new high resolution results, the various absorber attachment schemes, planned future improvements, and, finally, their relevance to future high resolution x-ray spectrometers including Constellation-X.

Boundary layers in cataclysmic variables: The HEAO-1 X-ray constraints

NASA Technical Reports Server (NTRS)

Jensen, K. A.

1983-01-01

The predictions of the boundary layer model for the X-ray emission from novae are summarized. A discrepancy between observations and theory in the X-ray observations is found. Constraints on the nature of the boundary layers in novae, based on the lack of detections of novae in the HEAO-1 soft X-ray survey are provided. Temperature and column densities for optically thick boundary layers in novae are estimated.

X-ray radiative transfer in protoplanetary disks. The role of dust and X-ray background fields

NASA Astrophysics Data System (ADS)

Rab, Ch.; Güdel, M.; Woitke, P.; Kamp, I.; Thi, W.-F.; Min, M.; Aresu, G.; Meijerink, R.

2018-01-01

Context. The X-ray luminosities of T Tauri stars are about two to four orders of magnitude higher than the luminosity of the contemporary Sun. As these stars are born in clusters, their disks are not only irradiated by their parent star but also by an X-ray background field produced by the cluster members. Aims: We aim to quantify the impact of X-ray background fields produced by young embedded clusters on the chemical structure of disks. Further, we want to investigate the importance of the dust for X-ray radiative transfer in disks. Methods: We present a new X-ray radiative transfer module for the radiation thermo-chemical disk code PRODIMO (PROtoplanetary DIsk MOdel), which includes X-ray scattering and absorption by both the gas and dust component. The X-ray dust opacities can be calculated for various dust compositions and dust-size distributions. For the X-ray radiative transfer we consider irradiation by the star and by X-ray background fields. To study the impact of X-rays on the chemical structure of disks we use the well established disk ionization tracers N2H+ and HCO+. Results: For evolved dust populations (e.g. grain growth), X-ray opacities are mostly dominated by the gas; only for photon energies E ≳ 5-10 keV do dust opacities become relevant. Consequently the local disk X-ray radiation field is only affected in dense regions close to the disk midplane. X-ray background fields can dominate the local X-ray disk ionization rate for disk radii r ≳ 20 au. However, the N2H+ and HCO+ column densities are only significantly affected in cases of low cosmic-ray ionization rates (≲10-19 s-1), or if the background flux is at least a factor of ten higher than the flux level of ≈10-5 erg cm-2 s-1 expected for clusters typical for the solar vicinity. Conclusions: Observable signatures of X-ray background fields in low-mass star-formation regions, like Taurus, are only expected for cluster members experiencing a strong X-ray background field (e.g. due to

High-density arrays of x-ray microcalorimeters for Constellation-X

NASA Astrophysics Data System (ADS)

Kilbourne, Caroline A.; Bandler, Simon R.; Brown, Ari D.; Chervenak, James A.; Figueroa-Feliciano, Enectali; Finkbeiner, Fred M.; Iyomoto, Naoko; Kelley, Richard L.; Porter, F. Scott; Saab, Tarek; Sadleir, John; White, Jennifer

2006-06-01

We have been developing x-ray microcalorimeters for the Constellation-X mission. Devices based on superconducting transition-edge sensors (TES) have demonstrated the potential to meet the Constellation-X requirements for spectral resolution, speed, and array scale (> 1000 pixels) in a close-packed geometry. In our part of the GSFC/NIST collaboration on this technology development, we have been concentrating on the fabrication of arrays of pixels suitable for the Constellation-X reference configuration. We have fabricated 8x8 arrays with 0.25-mm pixels arranged with 92% fill factor. The pixels are based on Mo/Au TES and Bi/Cu or Au/Bi absorbers. We have achieved a resolution of 4.0 eV FWHM at 6 keV in such devices, which meets the Constellation-X resolution requirement at 6 keV. Studies of the thermal transport in our Bi/Cu absorbers have shown that, while there is room for improvement, for 0.25-mm pixels the standard absorber design is adequate to avoid unacceptable line-broadening from position dependence caused by thermal diffusion. In order to improve reproducibility and to push closer to the 2-eV goal at 6 keV, however, we are refining the design of the TES and the interface to the absorber. Recent efforts to introduce a barrier layer between the Bi and the Mo/Au to avoid variable interface chemistry and thus improve the reproducibility of device characteristics have thus far yielded unsatisfactory results. However, we have developed a new set of absorber designs with contacts to the TES engineered to allow contact only in regions that do not serve as the active thermometer. We have further constrained the design so that a low-resistance absorber will not electrically short the TES. It is with such a design that we have achieved 4.0 eV resolution at 6 keV.

Ultrafast isomerization initiated by X-ray core ionization

NASA Astrophysics Data System (ADS)

Liekhus-Schmaltz, Chelsea E.; Tenney, Ian; Osipov, Timur; Sanchez-Gonzalez, Alvaro; Berrah, Nora; Boll, Rebecca; Bomme, Cedric; Bostedt, Christoph; Bozek, John D.; Carron, Sebastian; Coffee, Ryan; Devin, Julien; Erk, Benjamin; Ferguson, Ken R.; Field, Robert W.; Foucar, Lutz; Frasinski, Leszek J.; Glownia, James M.; Gühr, Markus; Kamalov, Andrei; Krzywinski, Jacek; Li, Heng; Marangos, Jonathan P.; Martinez, Todd J.; McFarland, Brian K.; Miyabe, Shungo; Murphy, Brendan; Natan, Adi; Rolles, Daniel; Rudenko, Artem; Siano, Marco; Simpson, Emma R.; Spector, Limor; Swiggers, Michele; Walke, Daniel; Wang, Song; Weber, Thorsten; Bucksbaum, Philip H.; Petrovic, Vladimir S.

2015-09-01

Rapid proton migration is a key process in hydrocarbon photochemistry. Charge migration and subsequent proton motion can mitigate radiation damage when heavier atoms absorb X-rays. If rapid enough, this can improve the fidelity of diffract-before-destroy measurements of biomolecular structure at X-ray-free electron lasers. Here we study X-ray-initiated isomerization of acetylene, a model for proton dynamics in hydrocarbons. Our time-resolved measurements capture the transient motion of protons following X-ray ionization of carbon K-shell electrons. We Coulomb-explode the molecule with a second precisely delayed X-ray pulse and then record all the fragment momenta. These snapshots at different delays are combined into a `molecular movie' of the evolving molecule, which shows substantial proton redistribution within the first 12 fs. We conclude that significant proton motion occurs on a timescale comparable to the Auger relaxation that refills the K-shell vacancy.

Simulating the effect of high column density absorbers on the one-dimensional Lyman α forest flux power spectrum

NASA Astrophysics Data System (ADS)

Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris

2018-03-01

We measure the effect of high column density absorbing systems of neutral hydrogen (H I) on the one-dimensional (1D) Lyman α forest flux power spectrum using cosmological hydrodynamical simulations from the Illustris project. High column density absorbers (which we define to be those with H I column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}) cause broadened absorption lines with characteristic damping wings. These damping wings bias the 1D Lyman α forest flux power spectrum by causing absorption in quasar spectra away from the location of the absorber itself. We investigate the effect of high column density absorbers on the Lyman α forest using hydrodynamical simulations for the first time. We provide templates as a function of column density and redshift, allowing the flexibility to accurately model residual contamination, i.e. if an analysis selectively clips out the largest damping wings. This flexibility will improve cosmological parameter estimation, for example, allowing more accurate measurement of the shape of the power spectrum, with implications for cosmological models containing massive neutrinos or a running of the spectral index. We provide fitting functions to reproduce these results so that they can be incorporated straightforwardly into a data analysis pipeline.

Development of Position-Sensitive Magnetic Calorimeters for X-Ray Astronomy

NASA Technical Reports Server (NTRS)

Bandler, SImon; Stevenson, Thomas; Hsieh, Wen-Ting

2011-01-01

Metallic magnetic calorimeters (MMC) are one of the most promising devices to provide very high energy resolution needed for future astronomical x-ray spectroscopy. MMC detectors can be built to large detector arrays having thousands of pixels. Position-sensitive magnetic (PoSM) microcalorimeters consist of multiple absorbers thermally coupled to one magnetic micro calorimeter. Each absorber element has a different thermal coupling to the MMC, resulting in a distribution of different pulse shapes and enabling position discrimination between the absorber elements. PoSMs therefore achieve the large focal plane area with fewer number of readout channels without compromising spatial sampling. Excellent performance of PoSMs was achieved by optimizing the designs of key parameters such as the thermal conductance among the absorbers, magnetic sensor, and heat sink, as well as the absorber heat capacities. Micro fab ri - cation techniques were developed to construct four-absorber PoSMs, in which each absorber consists of a two-layer composite of bismuth and gold. The energy resolution (FWHM full width at half maximum) was measured to be better than 5 eV at 6 keV x-rays for all four absorbers. Position determination was demonstrated with pulse-shape discrimination, as well as with pulse rise time. X-ray microcalorimeters are usually designed to thermalize as quickly as possible to avoid degradation in energy resolution from position dependence to the pulse shapes. Each pixel consists of an absorber and a temperature sensor, both decoupled from the cold bath through a weak thermal link. Each pixel requires a separate readout channel; for instance, with a SQUID (superconducting quantum interference device). For future astronomy missions where thousands to millions of resolution elements are required, having an individual SQUID readout channel for each pixel becomes difficult. One route to attaining these goals is a position-sensitive detector in which a large continuous or

Unveiling Obscured AGN with X-ray Spectral Analysis

NASA Astrophysics Data System (ADS)

LaMassa, Stephanie M.; Yaqoob, Tahir; Ptak, Andrew; Jia, Jianjun; Heckman, Timothy M.; Gandhi, Poshak; Urry, C. Megan

2014-06-01

With the recent advent of physically motivated, self-consistent X-ray models, the circumnuclear medium enshrouding AGN can now be investigated in unprecedented detail. We applied these models to 19 SDSS [OIII] 5007 Angstrom selected Type 2 AGN, where 9 are local Seyfert 2 galaxies and 10 are more luminous and distant Type 2 quasars. For the first time in a sample of AGN, we constrained both the line-of-sight and global column densities, finding that over half (11/19) are heavily obscured or Compton-thick (NH > 10^23 cm^-2). Four objects have different global from line-of-sight column densities. When correcting the observed X-ray luminosities for obscuration, the L_x/L_[OIII] ratio for these Type 2 AGN is essentially identical to the Seyfert 1 (i.e., unabsorbed AGN) value, which is consistent with both parameters cleanly probing AGN emission.

Galactic and extragalactic hydrogen in the X-ray spectra of Gamma Ray Bursts

NASA Astrophysics Data System (ADS)

Rácz, I. I.; Bagoly, Z.; Tóth, L. V.; Balázs, L. G.; Horváth, I.; Pintér, S.

2017-07-01

Two types of emission can be observed from gamma-ray bursts (GRBs): the prompt emission from the central engine which can be observed in gamma or X-ray (as a low energy tail) and the afterglow from the environment in X-ray and at shorter frequencies. We examined the Swift XRT spectra with the XSPEC software. The correct estimation of the galactic interstellar medium is very important because we observe the host emission together with the galactic hydrogen absorption. We found that the estimated intrinsic hydrogen column density and the X-ray flux depend heavily on the redshift and the galactic foreground hydrogen. We also found that the initial parameters of the iteration and the cosmological parameters did not have much effect on the fitting result.

Anatomy of the AGN in NGC 5548. IX. Photoionized emission features in the soft X-ray spectra

NASA Astrophysics Data System (ADS)

Mao, Junjie; Kaastra, J. S.; Mehdipour, M.; Gu, Liyi; Costantini, E.; Kriss, G. A.; Bianchi, S.; Branduardi-Raymont, G.; Behar, E.; Di Gesu, L.; Ponti, G.; Petrucci, P.-O.; Ebrero, J.

2018-04-01

The X-ray narrow emission line region (NELR) of the archetypal Seyfert 1 galaxy NGC 5548 has been interpreted as a single-phase photoionized plasma that is absorbed by some of the warm absorber components. This scenario requires those overlaying warm absorber components to have larger distance (to the central engine) than the X-ray NELR, which is not fully consistent with the distance estimates found in the literature. Therefore, we reanalyze the high-resolution spectra obtained in 2013-2014 with the Reflection Grating Spectrometer (RGS) aboard XMM-Newton to provide an alternative interpretation of the X-ray narrow emission features. We find that the X-ray narrow emission features in NGC 5548 can be described by a two-phase photoionized plasma with different ionization parameters (logξ = 1.3 and 0.1) and kinematics (vout = -50 and -400 km s-1), and no further absorption by the warm absorber components. The X-ray and optical NELR might be the same multi-phase photoionized plasma. Both X-ray and optical NELR have comparable distances, asymmetric line profiles, and the underlying photoionized plasma is turbulent and compact in size. The X-ray NELR is not the counterpart of the UV/X-ray absorber outside the line of sight because their distances and kinematics are not consistent. In addition, X-ray broad emission features that we find in the spectrum can be accounted for by a third photoionized emission component. The RGS spectrum obtained in 2016 is analyzed as well, where the luminosity of most prominent emission lines (the O VII forbidden line and O VIII Lyα line) are the same (at a 1σ confidence level) as in 2013-2014.

Hard X-ray emission of the luminous infrared galaxy NGC 6240 as observed by NuSTAR

NASA Astrophysics Data System (ADS)

Puccetti, S.; Comastri, A.; Bauer, F. E.; Brandt, W. N.; Fiore, F.; Harrison, F. A.; Luo, B.; Stern, D.; Urry, C. M.; Alexander, D. M.; Annuar, A.; Arévalo, P.; Baloković, M.; Boggs, S. E.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Gandhi, P.; Hailey, C. J.; Koss, M. J.; La Massa, S.; Marinucci, A.; Ricci, C.; Walton, D. J.; Zappacosta, L.; Zhang, W.

2016-01-01

We present a broadband (~0.3-70 keV) spectral and temporal analysis of NuSTAR observations of the luminous infrared galaxy NGC 6240 combined with archival Chandra, XMM-Newton, and BeppoSAX data. NGC 6240 is a galaxy in a relatively early merger state with two distinct nuclei separated by ~1.̋5. Previous Chandra observations resolved the two nuclei and showed that they are both active and obscured by Compton-thick material. Although they cannot be resolved by NuSTAR, we were able to clearly detect, for the first time, both the primary and the reflection continuum components thanks to the unprecedented quality of the NuSTAR data at energies >10 keV. The NuSTAR hard X-ray spectrum is dominated by the primary continuum piercing through an absorbing column density which is mildly optically thick to Compton scattering (τ ≃ 1.2, NH ~ 1.5 × 1024 cm-2). We detect moderately hard X-ray (>10 keV) flux variability up to 20% on short (15-20 ks) timescales. The amplitude of the variability is largest at ~30 keV and is likely to originate from the primary continuum of the southern nucleus. Nevertheless, the mean hard X-ray flux on longer timescales (years) is relatively constant. Moreover, the two nuclei remain Compton-thick, although we find evidence of variability in the material along the line of sight with column densities NH ≤ 2 × 1023 cm-2 over long (~3-15 yr) timescales. The observed X-ray emission in the NuSTAR energy range is fully consistent with the sum of the best-fit models of the spatially resolved Chandra spectra of the two nuclei.

Design of High Resolution Soft X-Ray Microcalorimeters Using Magnetic Penetration Thermometers

NASA Technical Reports Server (NTRS)

Busch. Sarah; Balvin, Manuel; Bandler, Simon; Denis, Kevin; Finkbeiner, Fred; Porst, Jan-Patrick; Sadlier, Jack; Smith, Stephen; Stevenson, Thomas

2012-01-01

We have designed high-resolution soft x-ray microcalorimeters using magnetic penetration thermometers (MPTs) in an array of pixels covering a total of 2 square centimeters to have a resolving power of 300 at energies around 300 eV. This performance is desirable for studying the soft x-ray background from the warm hot intergalactic medium. MPT devices have small sensor heat capacity and high responsivities, which makes them excellent detector technology for attempting to attain sub-eV resolution. We are investigating the feasibility of pixels with absorbers that are 625 x 625 square micrometers, up to 1 x 1 square millimeters in area and 0.35 micrometer thick and thinner. Our tests have shown that suspended gold absorbers 0.35 micrometers thick (RRR = 6.7) are feasible to fabricate. We modeled the thermal diffusion from such thin gold over the size of a 625 x 625 square micrometer absorber, and conclude that the effect of the thermalization on the resolution of a 300 eV photon is an additional approximately 0.2 eV FWHM of broadening. We discuss the thermal effects of small absorber attachment sterns on solid substrate, as well as considerations for multiplexed readout. We will present the progress we have made towards building and testing this soft x-ray detector.

Limits on soft X-ray flux from distant emission regions

NASA Technical Reports Server (NTRS)

Burrows, D. N.; Mccammon, D.; Sanders, W. T.; Kraushaar, W. L.

1984-01-01

The all-sky soft X-ray data of McCammon et al. and the new N sub H survey (Stark et al. was used to place limits on the amount of the soft X-ray diffuse background that can originate beyond the neutral gas of the galactic disk. The X-ray data for two regions of the sky near the galactic poles are shown to be uncorrelated with 21 cm column densities. Most of the observed x-ray flux must therefore originate on the near side of the most distant neutral gas. The results from these regions are consistent with X-ray emission from a locally isotropic, unabsorbed source, but require large variations in the emission of the local region over large angular scales.

Automated Absorber Attachment for X-ray Microcalorimeter Arrays

NASA Technical Reports Server (NTRS)

Moseley, S.; Allen, Christine; Kilbourne, Caroline; Miller, Timothy M.; Costen, Nick; Schulte, Eric; Moseley, Samuel J.

2007-01-01

Our goal is to develop a method for the automated attachment of large numbers of absorber tiles to large format detector arrays. This development includes the fabrication of high quality, closely spaced HgTe absorber tiles that are properly positioned for pick-and-place by our FC150 flip chip bonder. The FC150 also transfers the appropriate minute amount of epoxy to the detectors for permanent attachment of the absorbers. The success of this development will replace an arduous, risky and highly manual task with a reliable, high-precision automated process.

Advanced refractory-metal and process technology for the fabrication of x-ray masks

NASA Astrophysics Data System (ADS)

Brooks, Cameron J.; Racette, Kenneth C.; Lercel, Michael J.; Powers, Lynn A.; Benoit, Douglas E.

1999-06-01

This paper provides an in-depth report of the advanced materials and process technology being developed for x-ray mask manufacturing at IBM. Masks using diamond membranes as replacement for silicon carbide are currently being fabricated. Alternate tantalum-based absorbers, such as tantalum boron, which offer improved etch resolution and critical dimension control, as well as higher x-ray absorption, are also being investigated. In addition to the absorber studies, the development of conductive chromium- based hard-mask films to replace the current silicon oxynitride layer is being explored. The progress of this advanced-materials work, which includes significant enhancements to x-ray mask image-placement performance, will be outlined.

Soft X-ray astronomy proportional counter electronics

NASA Technical Reports Server (NTRS)

Gardner, W. R.

1971-01-01

The X-ray multiwire proportional counter is designed to measure cosmic X-ray fluxes at sounding rocket altitudes in the energy range of 0.1 to 10 keV. Four instruments will be launched in a Black Brant 4 rocket employing different combinations of detector windows and gas. The detector is constructed with two layers of twelve cells. A columnator is mounted on the face of one layer whose cells are wired together alternately to form two main detector sections. The electronics and gas regulation systems are mounted on the face of the second layer whose cells are wired together to form one anticoincidence detector section. Normally X-rays will have short ionization paths in only one of the main detector cells at a time and won't enter the anticoincidence detector cells. To distinguish between X-rays and charged particles, the instrument includes a coincidence discriminator, an anticoincidence discriminator, and a pulse rise time discriminator.

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics

PubMed Central

Picón, A.; Lehmann, C. S.; Bostedt, C.; Rudenko, A.; Marinelli, A.; Osipov, T.; Rolles, D.; Berrah, N.; Bomme, C.; Bucher, M.; Doumy, G.; Erk, B.; Ferguson, K. R.; Gorkhover, T.; Ho, P. J.; Kanter, E. P.; Krässig, B.; Krzywinski, J.; Lutman, A. A.; March, A. M.; Moonshiram, D.; Ray, D.; Young, L.; Pratt, S. T.; Southworth, S. H.

2016-01-01

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site. PMID:27212390

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics

DOE PAGES

Picón, A.; Lehmann, C. S.; Bostedt, C.; ...

2016-05-23

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Specifically, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. In this paper, we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ionsmore » during the fragmentation of XeF 2 molecules following X-ray absorption at the Xe site.« less

Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics.

PubMed

Picón, A; Lehmann, C S; Bostedt, C; Rudenko, A; Marinelli, A; Osipov, T; Rolles, D; Berrah, N; Bomme, C; Bucher, M; Doumy, G; Erk, B; Ferguson, K R; Gorkhover, T; Ho, P J; Kanter, E P; Krässig, B; Krzywinski, J; Lutman, A A; March, A M; Moonshiram, D; Ray, D; Young, L; Pratt, S T; Southworth, S H

2016-05-23

New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site.

Boundary layers in cataclysmic variables - The HEAO 1 X-ray constraints

NASA Technical Reports Server (NTRS)

Jensen, K. A.

1984-01-01

The predictions of the boundary layer model for the X-ray emission from novae are summarized. A discrepancy between observations and theory in the X-ray observations is found. Constraints on the nature of the boundary layers in novae, based on the lack of detections of novae in the HEAO-1 soft X-ray survey are provided. Temperature and column densities for optically thick boundary layers in novae are estimated. Previously announced in STAR as N84-13046

Soft x ray properties of the Geminga pulsar

NASA Technical Reports Server (NTRS)

Halpern, J. P.; Ruderman, M.

1993-01-01

The ROSAT soft x ray spectrum and pulse profile of the Geminga pulsar are analyzed and interpreted in terms of thermal emission from the surface of the neutron star. The x ray spectrum appears to consist of two blackbody components with T(sub 1) = (5.2 +/- 1.0) x 10 (exp 5) K and T(sub 2) approximately 3 x 10(exp 6) K, respectively. The inferred ratio of surface areas, A(sub 2)/A(sub 1), is approximately 3 x 10(exp -5). Both components are highly modulated at the pulsar rotation period, but the harder x ray pulse is narrower, and leads the main (soft) x ray pulse by about 105 deg of phase. The soft x ray component is interpreted as photospheric cooling of much of the neutron star's surface area, while the small, hot region could be part of the much smaller polar cap heated by energetic particles flowing inward from the magnetospheric accelerator which is responsible for the production of Geminga's gamma rays. Geminga's gamma ray emission is consistent with outer-magnetosphere accelerator models for highly inclined dipoles. These predict the beaming of energetic gamma rays close enough to the star to give copious e(+/-) production in the stellar magnetic field and a large circumstellar pair density from pair inflow toward the surface. These pairs may quench radio emission, and also reflect most of the hard polar cap x rays back to the stellar surface by cyclotron resonance scattering. They are then reemitted from that much larger area at the lower temperature T(sub 1). The single-peaked nature of the x ray pulse and its energy-dependent phase suggest an off-center dipole geometry for the surface magnetic field. Under the assumption that the soft x ray emission comes from the full surface of a neutron star of radius R = 10 km, a distance estimate of (150-400) pc is derived. This range is consistent with the fit interstellar column density of (1.5 +/- 0.5) x 10(exp 20) cm(exp -2). Distances less than 150 pc are probably ruled out both by the lower limit on the column

Bayesian Abel Inversion in Quantitative X-Ray Radiography

DOE PAGES

Howard, Marylesa; Fowler, Michael; Luttman, Aaron; ...

2016-05-19

A common image formation process in high-energy X-ray radiography is to have a pulsed power source that emits X-rays through a scene, a scintillator that absorbs X-rays and uoresces in the visible spectrum in response to the absorbed photons, and a CCD camera that images the visible light emitted from the scintillator. The intensity image is related to areal density, and, for an object that is radially symmetric about a central axis, the Abel transform then gives the object's volumetric density. Two of the primary drawbacks to classical variational methods for Abel inversion are their sensitivity to the type andmore » scale of regularization chosen and the lack of natural methods for quantifying the uncertainties associated with the reconstructions. In this work we cast the Abel inversion problem within a statistical framework in order to compute volumetric object densities from X-ray radiographs and to quantify uncertainties in the reconstruction. A hierarchical Bayesian model is developed with a likelihood based on a Gaussian noise model and with priors placed on the unknown density pro le, the data precision matrix, and two scale parameters. This allows the data to drive the localization of features in the reconstruction and results in a joint posterior distribution for the unknown density pro le, the prior parameters, and the spatial structure of the precision matrix. Results of the density reconstructions and pointwise uncertainty estimates are presented for both synthetic signals and real data from a U.S. Department of Energy X-ray imaging facility.« less

X-ray spectroscopy of the z = 6.4 quasar SDSS J1148+5251

NASA Astrophysics Data System (ADS)

Gallerani, S.; Zappacosta, L.; Orofino, M. C.; Piconcelli, E.; Vignali, C.; Ferrara, A.; Maiolino, R.; Fiore, F.; Gilli, R.; Pallottini, A.; Neri, R.; Feruglio, C.

2017-05-01

We present the 78 ks Chandra observations of the z = 6.4 quasar SDSS J1148+5251. The source is clearly detected in the energy range 0.3-7 keV with 42 counts (with a significance ≳9σ). The X-ray spectrum is best fitted by a power law with photon index Γ = 1.9 absorbed by a gas column density of N_H=2.0^{+2.0}_{-1.5}× {10}^{23} cm^{-2}. We measure an intrinsic luminosity at 2-10 and 10-40 keV equal to ˜ 1.5 × 1045 erg s- 1, comparable with luminous local and intermediate-redshift quasar properties. Moreover, the X-ray to optical power-law slope value (αOX = -1.76 ± 0.14) of J1148 is consistent with the one found in quasars with similar rest-frame 2500 Å luminosity (L2500 ˜ 1032 erg s- 1 Å- 1). Then we use Chandra data to test a physically motivated model that computes the intrinsic X-ray flux emitted by a quasar starting from the properties of the powering black hole and assuming that X-ray emission is attenuated by intervening, metal-rich (Z ≥ Z⊙) molecular clouds (MC) distributed on ˜kpc scales in the host galaxy. Our analysis favours a black hole mass MBH ˜ 3 × 109 M⊙ and a molecular hydrogen mass M_H_2˜ 2× {10}^{10} {M_{\\odot }}, in good agreement with estimates obtained from previous studies. We finally discuss strengths and limits of our analysis.

Stellar wind measurements for Colliding Wind Binaries using X-ray observations

NASA Astrophysics Data System (ADS)

Sugawara, Yasuharu; Maeda, Yoshitomo; Tsuboi, Yohko

2017-11-01

We report the results of the stellar wind measurement for two colliding wind binaries. The X-ray spectrum is the best measurement tool for the hot postshock gas. By monitoring the changing of the the X-ray luminosity and column density along with the orbital phases, we derive the mass-loss rates of these stars.

Optoelectronic Picosecond Detection of Synchrotron X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durbin, Stephen M.

2017-08-04

The goal of this research program was to develop a detector that would measure x-ray time profiles with picosecond resolution. This was specifically aimed for use at x-ray synchrotrons, where x-ray pulse profiles have Gaussian time spreads of 50-100 ps (FWHM), so the successful development of such a detector with picosecond resolution would permit x-ray synchrotron studies to break through the pulse width barrier. That is, synchrotron time-resolved studies are currently limited to pump-probe studies that cannot reveal dynamics faster than ~50 ps, whereas the proposed detector would push this into the physically important 1 ps domain. The results ofmore » this research effort, described in detail below, are twofold: 1) the original plan to rely on converting electronic signals from a semiconductor sensor into an optical signal proved to be insufficient for generating signals with the necessary time resolution and sensitivity to be widely applicable; and 2) an all-optical method was discovered whereby the x-rays are directly absorbed in an optoelectronic material, lithium tantalate, which can then be probed by laser pulses with the desired picosecond sensitivity for detection of synchrotron x-rays. This research program has also produced new fundamental understanding of the interaction of x-rays and optical lasers in materials that has now created a viable path for true picosecond detection of synchrotron x-rays.« less

Treatment of foods with high-energy X rays

NASA Astrophysics Data System (ADS)

Cleland, M. R.; Meissner, J.; Herer, A. S.; Beers, E. W.

2001-07-01

The treatment of foods with ionizing energy in the form of gamma rays, accelerated electrons, and X rays can produce beneficial effects, such as inhibiting the sprouting in potatoes, onions, and garlic, controlling insects in fruits, vegetables, and grains, inhibiting the growth of fungi, pasteurizing fresh meat, poultry, and seafood, and sterilizing spices and food additives. After many years of research, these processes have been approved by regulatory authorities in many countries and commercial applications have been increasing. High-energy X rays are especially useful for treating large packages of food. The most attractive features are product penetration, absorbed dose uniformity, high utilization efficiency and short processing time. The ability to energize the X-ray source only when needed enhances the safety and convenience of this technique. The availability of high-energy, high-power electron accelerators, which can be used as X-ray generators, makes it feasible to process large quantities of food economically. Several industrial accelerator facilities already have X-ray conversion equipment and several more will soon be built with product conveying systems designed to take advantage of the unique characteristics of high-energy X rays. These concepts will be reviewed briefly in this paper.

The clumpy absorber in the high-mass X-ray binary Vela X-1

DOE PAGES

Grinberg, V.; Hell, N.; El Mellah, I.; ...

2017-12-15

Bright and eclipsing, the high-mass X-ray binary Vela X-1 offers a unique opportunity to study accretion onto a neutron star from clumpy winds of O/B stars and to disentangle the complex accretion geometry of these systems. In Chandra-HETGS spectroscopy at orbital phase ~0.25, when our line of sight towards the source does not pass through the large-scale accretion structure such as the accretion wake, we observe changes in overall spectral shape on timescales of a few kiloseconds. This spectral variability is, at least in part, caused by changes in overall absorption and we show that such strongly variable absorption cannotmore » be caused by unperturbed clumpy winds of O/B stars. We detect line features from high and low ionization species of silicon, magnesium, and neon whose strengths and presence depend on the overall level of absorption. Finally, these features imply a co-existence of cool and hot gas phases in the system, which we interpret as a highly variable, structured accretion flow close to the compact object such as has been recently seen in simulations of wind accretion in high-mass X-ray binaries.« less

The clumpy absorber in the high-mass X-ray binary Vela X-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grinberg, V.; Hell, N.; El Mellah, I.

Bright and eclipsing, the high-mass X-ray binary Vela X-1 offers a unique opportunity to study accretion onto a neutron star from clumpy winds of O/B stars and to disentangle the complex accretion geometry of these systems. In Chandra-HETGS spectroscopy at orbital phase ~0.25, when our line of sight towards the source does not pass through the large-scale accretion structure such as the accretion wake, we observe changes in overall spectral shape on timescales of a few kiloseconds. This spectral variability is, at least in part, caused by changes in overall absorption and we show that such strongly variable absorption cannotmore » be caused by unperturbed clumpy winds of O/B stars. We detect line features from high and low ionization species of silicon, magnesium, and neon whose strengths and presence depend on the overall level of absorption. Finally, these features imply a co-existence of cool and hot gas phases in the system, which we interpret as a highly variable, structured accretion flow close to the compact object such as has been recently seen in simulations of wind accretion in high-mass X-ray binaries.« less

High-z X-ray Obscured Quasars in Galaxies with Extreme Mid-IR/Optical Colors

NASA Astrophysics Data System (ADS)

Piconcelli, E.; Lanzuisi, G.; Fiore, F.; Feruglio, C.; Vignali, C.; Salvato, M.; Grappioni, C.

2009-05-01

Extreme Optical/Mid-IR color cuts have been used to uncover a population of dust-enshrouded, mid-IR luminous galaxies at high redshifts. Several lines of evidence point towards the presence of an heavily absorbed, possibly Compton-thick quasar at the heart of these systems. Nonetheless, the X-ray spectral properties of these intriguing sources still remain largely unexplored. Here we present an X-ray spectroscopic study of a large sample of 44 extreme dust-obscured galaxies (EDOGs) with F24 μm/FR>2000 and F24 μm>1.3 mJy selected from a 6 deg2 region in the SWIRE fields. The application of our selection criteria to a wide area survey has been capable of unveiling a population of X-ray luminous, absorbed z>1 quasars which is mostly missed in the traditional optical/X-ray surveys performed so far. Advances in the understanding of the X-ray properties of these recently-discovered sources by Simbol-X observations will be also discussed.

Bismuth Passivation Technique for High-Resolution X-Ray Detectors

NASA Technical Reports Server (NTRS)

Chervenak, James; Hess, Larry

2013-01-01

The Athena-plus team requires X-ray sensors with energy resolution of better than one part in 3,000 at 6 keV X-rays. While bismuth is an excellent material for high X-ray stopping power and low heat capacity (for large signal when an X-ray is stopped by the absorber), oxidation of the bismuth surface can lead to electron traps and other effects that degrade the energy resolution. Bismuth oxide reduction and nitride passivation techniques analogous to those used in indium passivation are being applied in a new technique. The technique will enable improved energy resolution and resistance to aging in bismuth-absorber-coupled X-ray sensors. Elemental bismuth is lithographically integrated into X-ray detector circuits. It encounters several steps where the Bi oxidizes. The technology discussed here will remove oxide from the surface of the Bi and replace it with nitridized surface. Removal of the native oxide and passivating to prevent the growth of the oxide will improve detector performance and insulate the detector against future degradation from oxide growth. Placing the Bi coated sensor in a vacuum system, a reduction chemistry in a plasma (nitrogen/hydrogen (N2/H2) + argon) is used to remove the oxide and promote nitridization of the cleaned Bi surface. Once passivated, the Bi will perform as a better X-ray thermalizer since energy will not be trapped in the bismuth oxides on the surface. A simple additional step, which can be added at various stages of the current fabrication process, can then be applied to encapsulate the Bi film. After plasma passivation, the Bi can be capped with a non-diffusive layer of metal or dielectric. A non-superconducting layer is required such as tungsten or tungsten nitride (WNx).

Distributed transition-edge sensors for linearized position response in a phonon-mediated X-ray imaging spectrometer

NASA Astrophysics Data System (ADS)

Cabrera, Blas; Brink, Paul L.; Leman, Steven W.; Castle, Joseph P.; Tomada, Astrid; Young, Betty A.; Martínez-Galarce, Dennis S.; Stern, Robert A.; Deiker, Steve; Irwin, Kent D.

2004-03-01

For future solar X-ray satellite missions, we are developing a phonon-mediated macro-pixel composed of a Ge crystal absorber with four superconducting transition-edge sensors (TES) distributed on the backside. The X-rays are absorbed on the opposite side and the energy is converted into phonons, which are absorbed into the four TES sensors. By connecting together parallel elements into four channels, fractional total energy absorbed between two of the sensors provides x-position information and the other two provide y-position information. We determine the optimal distribution for the TES sub-elements to obtain linear position information while minimizing the degradation of energy resolution.

Ionized Absorbers in Active Galactic Nuclei and Very Steap Soft X-Ray Quasars

NASA Technical Reports Server (NTRS)

Fiore, Fabrizio; White, Nicholas (Technical Monitor)

2000-01-01

Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow Balmer lines, strong Fe II emission, large and fast X-ray variability, and a rather steep 2-10 keV spectrum. These intriguing objects have been suggested to be the analogues of Galactic black hole candidates in the high, soft state. We present here results from ASCA observations for two of these quasars: NAB 0205 + 024 and PG 1244 + 026. Both objects show similar variations (factor of approximately 2 in 10 ks), despite a factor of approximately 10 difference in the 0.5-10 keV luminosity (7.3 x 10(exp 43) erg/s for PG 1244 + 026 and 6.4 x 10(exp 44) erg/s for NAB 0205 + 024, assuming isotropic emission, H(sub 0) = 50.0 and q(sub 0) = 0.0). The X-ray continuum of the two quasars flattens by 0.5-1 going from the 0.1-2 keV band towards higher energies, strengthening recent results on another half-dozen steep soft X-ray active galactic nuclei. PG 1244 + 026 shows a significant feature in the '1-keV' region, which can be described either as a broad emission line centered at 0.95 keV (quasar frame) or as edge or line absorption at 1.17 (1.22) keV. The line emission could be a result of reflection from a highly ionized accretion disc, in line with the view that steep soft X-ray quasars are emitting close to the Eddington luminosity. Photoelectric edge absorption or resonant line absorption could be produced by gas outflowing at a large velocity (0.3-0.6 c).

Resolving the Crab Nebula with Direct Hard X-Ray Imaging

NASA Technical Reports Server (NTRS)

Swartz, Douglas A.; Ramsey, Brian D.; Tennant, Allyn F.; Dietz, Kurtis L.; Apple, Jeff A.; Gaskin, Jessica A.; Weisskopf, Martin

2008-01-01

We report the first direct hard (25--60 keV) X-ray imaging observation of the Crab Nebula that resolves structure to approximately 0.25 pc. The observation was performed over a 1.4 hour period during a balloon flight from Ft. Sumner, NM, on 2007 May 27. The source was detected in the energy band above the atmospheric cutoff at approx.25 keV and below the mirror graze angle cutoff at approx.60 keV. The image shows elongation about 25 degrees E of N in the direction along the plane of the torus (and perpendicular to the jet axis) with a slight surface-brightness enhancement NE of the pulsar. The spectrum within a 1.7 arcminute radius region centered on the Crab pulsar can be fitted with a Gamma=2 power law absorbed by an atmospheric column consistent with the balloon altitude at the time of observation.

High-density arrays of x-ray microcalorimeters for Constellation-X

NASA Astrophysics Data System (ADS)

Kilbourne, C. A.; Bandler, S. R.; Chervenak, J. A.; Figueroa-Feliciano, E.; Finkbeiner, F. M.; Iyomoto, N.; Kelley, R. L.; Porter, F. S.; Saab, T.; Sadleir, J.

2005-12-01

We have been developing x-ray microcalorimeters for the Constellation-X mission. Devices based on superconducting transition edge sensors (TES) have demonstrated the potential to meet the Constellation-X requirements for spectral resolution, speed, and array scale (> 1000 pixels) in a close-packed geometry. In our part of the GSFC/NIST collaboration on this technology development, we have been concentrating on the fabrication of arrays of pixels suitable for the Constellation-X reference configuration. We have fabricated 8x8 arrays with 0.25-mm pixels arranged with 92% fill factor. The pixels are based on Mo/Au TES and Bi/Cu absorbers. We have achieved a resolution of 4.9 eV FWHM at 6 keV in such devices. Studies of the thermal transport in our Bi/Cu absorbers have shown that, while there is room for improvement, for 0.25 mm pixels our existing absorber design is adequate to avoid line-broadening from position dependence caused by thermal diffusion. In order to push closer to the 4-eV requirement and 2-eV goal at 6 keV, we are refining the design of the TES and the interface to the absorber. For the 32x32 arrays ultimately needed for Constellation-X, signal lead routing and heatsinking will drive the design. We have had early successes with experiments in electroplating electrical vias and thermal busses into micro-machined features in silicon substrates. The next steps will be fabricating arrays that have all of the essential features of the required flight design, testing, and then engineering a prototype array for optimum performance.

NuSTAR OBSERVATIONS OF THE COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND ULTRALUMINOUS X-RAY SOURCE CANDIDATE IN NGC 5643

DOE Office of Scientific and Technical Information (OSTI.GOV)

Annuar, A.; Gandhi, P.; Alexander, D. M.

2015-12-10

We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (∼0.5–100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X–1, have left significantmore » uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X–1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of N{sub H} ≳ 5 × 10{sup 24} cm{sup −2}. The range of 2–10 keV absorption-corrected luminosity inferred from the best-fitting models is L{sub 2–10,int} = (0.8–1.7) × 10{sup 42} erg s{sup −1}, consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X–1 and show that it exhibits evidence of a spectral cutoff at energy E ∼ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3–8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X–1.« less

Energy discriminating x-ray camera utilizing a cadmium telluride detector

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Purkhet, Abderyim; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Wantanabe, Manabu; Nagao, Jiro; Nomiya, Seiichiro; Hitomi, Keitaro; Tanaka, Etsuro; Kawai, Toshiaki; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2009-07-01

An energy-discriminating x-ray camera is useful for performing monochromatic radiography using polychromatic x rays. This x-ray camera was developed to carry out K-edge radiography using iodine-based contrast media. In this camera, objects are exposed by a cone beam from a cerium x-ray generator, and penetrating x-ray photons are detected by a cadmium telluride detector with an amplifier unit. The optimal x-ray photon energy and the energy width are selected out using a multichannel analyzer, and the photon number is counted by a counter card. Radiography was performed by the detector scanning using an x-y stage driven by a two-stage controller, and radiograms obtained by energy discriminating are shown on a personal computer monitor. In radiography, the tube voltage and current were 60 kV and 36 μA, respectively, and the x-ray intensity was 4.7 μGy/s. Cerium K-series characteristic x rays are absorbed effectively by iodine-based contrast media, and iodine K-edge radiography was performed using x rays with energies just beyond iodine K-edge energy 33.2 keV.

Diagnostic x-ray dosimetry using Monte Carlo simulation.

PubMed

Ioppolo, J L; Price, R I; Tuchyna, T; Buckley, C E

2002-05-21

An Electron Gamma Shower version 4 (EGS4) based user code was developed to simulate the absorbed dose in humans during routine diagnostic radiological procedures. Measurements of absorbed dose using thermoluminescent dosimeters (TLDs) were compared directly with EGS4 simulations of absorbed dose in homogeneous, heterogeneous and anthropomorphic phantoms. Realistic voxel-based models characterizing the geometry of the phantoms were used as input to the EGS4 code. The voxel geometry of the anthropomorphic Rando phantom was derived from a CT scan of Rando. The 100 kVp diagnostic energy x-ray spectra of the apparatus used to irradiate the phantoms were measured, and provided as input to the EGS4 code. The TLDs were placed at evenly spaced points symmetrically about the central beam axis, which was perpendicular to the cathode-anode x-ray axis at a number of depths. The TLD measurements in the homogeneous and heterogenous phantoms were on average within 7% of the values calculated by EGS4. Estimates of effective dose with errors less than 10% required fewer numbers of photon histories (1 x 10(7)) than required for the calculation of dose profiles (1 x 10(9)). The EGS4 code was able to satisfactorily predict and thereby provide an instrument for reducing patient and staff effective dose imparted during radiological investigations.

A new transient pulsar in the Small Magellanic Cloud with an unusual x-ray spectrum

NASA Technical Reports Server (NTRS)

Hughes, John P.

1994-01-01

This article reports the discovery of a luminous (3.5 x 10(exp 37) ergs/sec over the 0.2 to 2 keV band) transient X-ray pulsar in the Small Magellanic Cloud (SMC) with an extremely soft component to its X-ray spectrum. This is the first time that a spectrum of this type has been seen in this class of X-ray source. The pulse period is 2.7632 s, and the pulse modulation appears to vary with energy from nearly unpulsed in the low-energy band of the ROSAT Position Sensitive Proportional Counter (PSPC) (0.07 to 0.4 keV) to about 50% in the high-energy band (1.0 to 2.4 keV). The object, RX J0059.2-7138, also shows flickering variability in its X-ray emission on timescales of 50 to 100s. The pulse-phase-averaged PSPC X-ray spectrum can be well described by a two-component source model seen through an absorbing column density of approximately 10(exp 21) atoms cm(exp -2). One spectral component is a power law with photon index 2.4. The other component is significantly softer and can be described by either a steeply falling power law or a blackbody with a temperature KT(sub BB) approximately 35 eV. Ths component is transient, but evidently upulsed, and, for the blackbody model fits, requires a large bolometric luminosity: near, or even several times greater than, the Eddington luminosity for a 1.4 solar mass object. When these characteristics of its soft emission are considered, RX J0059.2-7138 appears quite similar to other X-ray sources in the magellanic Clouds, such as CAL 83, CAL 87, and RX J0527.8-6954, which show only extreme ultrasoft (EUS) X-ray spectra. The discovery of RX J0059.2-7138, a probably high-mass X-ray binary, clearly indicates that EUS spectra may arise from accretion-powered neutron-star X-ray sources. This result lends support to the idea that some of the 'pure' EUS sources may be shrouded low-mass X-ray binaries rather than accreting white dwarfs.

The Complex Soft X-ray Spectral Structure of MCG-6-30-15 and Mrk 766

NASA Astrophysics Data System (ADS)

Kahn, S. M.; Sako, M.; Behar, E.; Paerels, F.; Kinkhabwala, A.; Branduardi-Raymont, G.; Page, M. J.; Kaastra, J. S.; Brinkman, A. C.; den Herder, J. S.; Liedahl, D. A.

The interpretation of the soft X-ray spectra of the Seyfert 1 galaxies, MCG-6-30-15 and Mrk 766, has remained controversial since high resolution data were first obtained with the grating instruments on Chandra and XMM-Newton, roughly one year ago. In an initial paper, Branduardi-Raymont et al. (2001), we argued that the RGS spectra of these two sources are inconsistent with simple warm absorber models, as has been invoked for Seyfert 1s in the past, but instead suggest the additional presence of relativistically broadened disk line features associated with the Lyα transitions of carbon, nitrogen, and oxygen. This conclusion was subsequently questioned by Lee et al. (2001), who contended that the Chandra HETG spectrum of MCG-6-30-15 is indeed well-described by the conventional warm absorber model, if one allows for the presence of dust in the warm absorbing medium. Here we reexamine the original RGS spectra in light of the Lee et al. (2001) criticisms. We first show that the explicit model presented by Lee et al. (2001) for MCG-6-30-15 is incompatible with the RGS data on this source, even if we allow both the continuum parameters and all of the absorbing column densities to be free parameters. That model over-predicts the ion{O}{VII} absorption line equivalent widths, and yields significant systematic residuals to the fits, especially at longer wavelengths, beyond the band covered by the HETG. We next show that the column densities of the oxygen ions (ion{O}{IV} through ion{O}{VIII}) are very well-constrained by the absorption line structure in the RGS data, and that, contrary to the assertion by Lee et al. (2001), the derived values are much too low to provide any significant contribution (either from line or continuum absorption) to the observed discrete jump in the spectra near 17.5 Å. Further, we show that the RGS spectra are also incompatible with the dust model presented by Lee et al. (2001). Specifically, the derived upper limit on the neutral oxygen

Cyclotron Line and Wind studies of Galactic High Mass X-ray Binaries

NASA Astrophysics Data System (ADS)

Suchy, Slawomir

301--2 throughout its pulse phase to develop a simple dipole model of the relationship between the magnetic moment vector and the spin axis of the neutron star. In Cen X-3 I use a similar model to demonstrate that the magnetic field most likely includes higher orders than just the simple dipole. The use of a wind model in high mass X-ray binaries can give information about the type of accretion, disk or wind, and the structure of the wind by measuring the amount of the material in the line of sight versus orbital phase. In Cen X-3, I used a simple spherical wind model throughout the two binary orbits and found that the observed absorption column densities are not consistent with pure wind accretion, and that either an accretion wake or a disk are needed to be consistent with the data. Similar results were observed in GX 301--2, where the neutron star may have passed through an accretion stream, increasing the observed amount of absorbed material.

X-ray attenuation properties of stainless steel (u)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lily L; Berry, Phillip C

2009-01-01

Stainless steel vessels are used to enclose solid materials for studying x-ray radiolysis that involves gas release from the materials. Commercially available stainless steel components are easily adapted to form a static or a dynamic condition to monitor the gas evolved from the solid materials during and after the x-ray irradiation. Experimental data published on the x-ray attenuation properties of stainless steel, however, are very scarce, especially over a wide range of x-ray energies. The objective of this work was to obtain experimental data that will be used to determine how a poly-energetic x-ray beam is attenuated by the stainlessmore » steel container wall. The data will also be used in conjunction with MCNP (Monte Carlos Nuclear Particle) modeling to develop an accurate method for determining energy absorbed in known solid samples contained in stainless steel vessels. In this study, experiments to measure the attenuation properties of stainless steel were performed for a range of bremsstrahlung x-ray beams with a maximum energy ranging from 150 keV to 10 MeV. Bremsstrahlung x-ray beams of these energies are commonly used in radiography of engineering and weapon components. The weapon surveillance community has a great interest in understanding how the x-rays in radiography affect short-term and long-term properties of weapon materials.« less

Phonon-mediated superconducting transition-edge sensor X-ray detectors for use in astronomy

NASA Astrophysics Data System (ADS)

Leman, Steven W.; Martinez-Galarce, Dennis S.; Brink, Paul L.; Cabrera, Blas; Castle, Joseph P.; Morse, Kathleen; Stern, Robert A.; Tomada, Astrid

2004-09-01

Superconducting Transition-Edge Sensors (TESs) are generating a great deal of interest in the areas of x-ray astrophysics and space science, particularly to develop them as large-array, imaging x-ray spectrometers. We are developing a novel concept that is based on position-sensitive macro-pixels placing TESs on the backside of a silicon or germanium absorber. Each x-ray absorbed will be position (X/δX and Y/δY ~ 100) and energy (E/δE ~ 1000) resolved via four distributed TES readouts. In the future, combining such macropixels with advances in multiplexing could lead to 30 by 30 arrays of close-packed macro-pixels equivalent to imaging instruments of 10 megapixels or more. We report on our progress to date and discuss its application to a plausible solar satellite mission and plans for future development.

X-ray obscured AGN in the GOODS-N

NASA Astrophysics Data System (ADS)

Georgantopoulos, I.; Akylas, A.; Rovilos, E.; Xilouris, M.

2010-07-01

We explore the X-ray properties of the Dust Obscured Galaxies (DOGs) i.e. sources with f24μ/fR>1000. This population has been proposed to contain a significan fraction of Compton-thick sources at high redshift. In particular we study the X-ray spectra of the 14 DOGS detected in the CDFN 2Ms exposure. Their stacked spectrum is fla with Γ = 1+/-0.1 very similar to the stacked spectrum of the undetected DOGs (Γ = 0.8+/-0.2). However, many of our X-ray detected DOGs present only moderate absorption with column densities 1022

SUZAKU VIEW OF X-RAY SPECTRAL VARIABILITY OF THE RADIO GALAXY CENTAURUS A: PARTIAL COVERING ABSORBER, REFLECTOR, AND POSSIBLE JET COMPONENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukazawa, Yasushi; Hiragi, Kazuyoshi; Yamazaki, Syoko

2011-12-20

We observed a nearby radio galaxy, Centaurus A (Cen A), three times with Suzaku in 2009 and measured the wide-band X-ray spectral variability more accurately than previous measurements. The Cen A was in an active phase in 2009, and the flux became higher by a factor of 1.5-2.0 and the spectrum became harder than that in 2005. The Fe-K line intensity increased by 20%-30% from 2005 to 2009. The correlation of the count rate between the XIS 3-8 keV and PIN 15-40 keV band showed a complex behavior with a deviation from a linear relation. The wide-band X-ray continuum inmore » 2-200 keV can be fitted with an absorbed power-law model plus a reflection component, or a power law with a partial covering Compton-thick absorption. The difference spectra between high and low flux periods in each observation were reproduced by a power law with a partial covering Compton-thick absorption. Such a Compton-thick partial covering absorber was observed for the first time in Cen A. The power-law photon index of the difference spectra in 2009 is almost the same as that of the time-averaged spectra in 2005, but steeper by {approx}0.2 than that of the time-averaged spectra in 2009. This suggests an additional hard power-law component with a photon index of <1.6 in 2009. This hard component could be a lower part of the inverse-Compton-scattered component from the jet, whose gamma-ray emission has recently been detected with the Fermi Large Area Telescope.« less

Vitreous carbon mask substrate for X-ray lithography

DOEpatents

Aigeldinger, Georg [Livermore, CA; Skala, Dawn M [Fremont, CA; Griffiths, Stewart K [Livermore, CA; Talin, Albert Alec [Livermore, CA; Losey, Matthew W [Livermore, CA; Yang, Chu-Yeu Peter [Dublin, CA

2009-10-27

The present invention is directed to the use of vitreous carbon as a substrate material for providing masks for X-ray lithography. The new substrate also enables a small thickness of the mask absorber used to pattern the resist, and this enables improved mask accuracy. An alternative embodiment comprised the use of vitreous carbon as a LIGA substrate wherein the VC wafer blank is etched in a reactive ion plasma after which an X-ray resist is bonded. This surface treatment provides a surface enabling good adhesion of the X-ray photoresist and subsequent nucleation and adhesion of the electrodeposited metal for LIGA mold-making while the VC substrate practically eliminates secondary radiation effects that lead to delamination of the X-ray resist form the substrate, the loss of isolated resist features, and the formation of a resist layer adjacent to the substrate that is insoluble in the developer.

Segmented-spectrum detection mechanism for medical x-ray in CdTe

NASA Astrophysics Data System (ADS)

Shi, Zaifeng; Meng, Qingzhen; Cao, Qingjie; Yao, Suying

2016-01-01

This paper presents a segmented X-ray spectrum detection method based on a layered X-ray detector in Cadmium Telluride (CdTe) substrate. We describe the three-dimensional structure of proposed detector pixel and investigate the matched spectrum-resolving method. Polychromatic X-ray beam enter the CdTe substrate edge on and will be absorbed completely in different thickness varying with photon energy. Discrete potential wells are formed under external controlling voltage to collect the photo-electrons generated in different layers, and segmented X-ray spectrum can be deduced from the quantity of photo-electrons. In this work, we verify the feasibility of the segmented-spectrum detection mechanism by simulating the absorption of monochromatic X-ray in a CdTe substrate. Experiments in simulation show that the number of photo-electrons grow exponentially with the increase of incident thickness, and photons with different energy will be absorbed in various thickness. The charges generated in different layers are collected into adjacent potential wells, and collection efficiency is estimated to be about 87% for different incident intensity under the 40000V/cm electric field. Errors caused by charge sharing between neighboring layers are also analyzed, and it can be considered negligible by setting appropriate size of electrodes.

Enhancement of soft X-ray lasing action with thin blade radiators

DOEpatents

Suckewer, Szymon; Skinner, Charles H.; Voorhees, David R.

1988-01-01

An enhancement of approximately 100 of stimulated emission over spontaneous emission of the CVI 182 Angstrom line was obtained in a recombining magnetically confined plasma column. The plasma was formed by focusing a CO.sub.2 laser beam on a carbon disc. A magnetic solenoid produced a strong magnetic field which confined the plasma to the shape of a column. A single thin carbon blade extended parallel to the plasma column and served to make the column axially more uniform and also acted as a heat sink. Axial and transverse measurements of the soft X-ray lasing action were made from locations off-set from the central axis of the plasma column. Multiple carbon blades located at equal intervals around the plasma column were also found to produce acceptable results. According to another embodiment 10 a thin coating of aluminum or magnesium was placed on the carbon disc and blade. The Z of the coating should preferably be at least 5 greater than the Z of the target. Measurements of the soft X-rays generated at 182 Angstroms showed a significant increase in intensity enhancement.

Time-resolved hard x-ray spectrometer

NASA Astrophysics Data System (ADS)

Moy, Kenneth; Cuneo, Michael; McKenna, Ian; Keenan, Thomas; Sanford, Thomas; Mock, Ray

2006-08-01

Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and axial (polar) views. UNSPEC 1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment.

A STUDY OF THE X-RAYED OUTFLOW OF APM 08279+5255 THROUGH PHOTOIONIZATION CODES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saez, Cristian; Chartas, George, E-mail: saez@astro.psu.edu, E-mail: chartasg@cofc.edu

2011-08-20

We present new results from our study of the X-rayed outflow of the z = 3.91 gravitationally lensed broad absorption line quasar APM 08279+5255. These results are based on spectral fits to all the long exposure observations of APM 08279+5255 using a new quasar-outflow model. This model is based on CLOUDY{sup 3} CLOUDY is a photoionization code designed to simulate conditions in interstellar matter under a broad range of conditions. We have used version 08.00 of the code last described by Ferland et al. (1998). The atomic database used by CLOUDY is described in Ferguson et al. (2001) and http://www.pa.uky.edu/{approx}verner/atom.html.more » simulations of a near-relativistic quasar outflow. The main conclusions from our multi-epoch spectral re-analysis of Chandra, XMM-Newton, and Suzaku observations of APM 08279+5255 are the following. (1) In every observation, we confirm the presence of two strong features, one at rest-frame energies between 1-4 keV and the other between 7-18 keV. (2) We confirm that the low-energy absorption (1-4 keV rest frame) arises from a low-ionization absorber with log(N{sub H}/cm{sup -2}) {approx} 23 and the high-energy absorption (7-18 keV rest frame) arises from highly ionized (3 {approx}< log {xi} {approx}< 4, where {xi} is the ionization parameter) iron in a near-relativistic outflowing wind. Assuming this interpretation, we find that the velocities on the outflow could get up to {approx}0.7c. (3) We confirm a correlation between the maximum outflow velocity and the photon index and find possible trends between the maximum outflow velocity and the X-ray luminosity, and between the total column density and the photon index. We performed calculations of the force multipliers of material illuminated by absorbed power laws and a Mathews-Ferland spectral energy distribution (SED). We found that variations of the X-ray and UV parts of the SEDs and the presence of a moderate absorbing shield will produce important changes in the strength of

X-ray study of a sample of FR0 radio galaxies: unveiling the nature of the central engine

NASA Astrophysics Data System (ADS)

Torresi, E.; Grandi, P.; Capetti, A.; Baldi, R. D.; Giovannini, G.

2018-06-01

Fanaroff-Riley type 0 radio galaxies (FR0s) are compact radio sources that represent the bulk of the radio-loud active galactic nuclei (AGN) population, but they are still poorly understood. Pilot studies on these sources have been already performed at radio and optical wavelengths: here we present the first X-ray study of a sample of 19 FR0 radio galaxies selected from the Sloan Digital Sky Survey/NRAO VLA Sky Survey/Faint Images of the Radio Sky at Twenty-cm sample of Best & Heckman, with redshift ≤0.15, radio size ≤10 kpc, and optically classified as low-excitation galaxies. The X-ray spectra are modelled with a power-law component absorbed by Galactic column density with, in some cases, a contribution from thermal extended gas. The X-ray photons are likely produced by the jet as attested by the observed correlation between X-ray (2-10 keV) and radio (5 GHz) luminosities, similar to Fanaroff-Riley type I radio galaxies (FRIs). The estimated Eddington-scaled luminosities indicate a low accretion rate. Overall, we find that the X-ray properties of FR0s are indistinguishable from those of FRIs, thus adding another similarity between AGN associated with compact and extended radio sources. A comparison between FR0s and low-luminosity BL Lacs rules out important beaming effects in the X-ray emission of the compact radio galaxies. FR0s have different X-ray properties with respect to young radio sources (e.g. gigahertz-peaked spectrum/compact steep spectrum sources), generally characterized by higher X-ray luminosities and more complex spectra. In conclusion, the paucity of extended radio emission in FR0s is probably related to the intrinsic properties of their jets that prevent the formation of extended structures, and/or to intermittent activity of their engines.

Ginga observations of dipping low mass X ray binaries

NASA Technical Reports Server (NTRS)

Smale, Alan P.; Mukai, Koji; Williams, O. Rees; Jones, Mark H.; Parmar, Arvind N.; Corbet, Robin H. D.

1989-01-01

Ginga observations of several low mass X ray binaries displaying pronounced dips of variable depth and duration in their X ray light curves are analyzed. The periodic occultation of the central X ray source by azimuthal accretion disk structure is considered. A series of spectra selected by intensity from the dip data from XB1916-053, are presented. The effects of a rapidly changing column density upon the spectral fitting results are modeled. EXO0748-676 was observed in March 1989 for three days. The source was found to be in a bright state with a 1 to 20 keV flux of 8.8 x 10 (exp -10) erg/sqcms. The data include two eclipses, observed with high time resolution.

High-energy, high-resolution x-ray imaging for metallic cultural heritages

NASA Astrophysics Data System (ADS)

Hoshino, Masato; Uesugi, Kentaro; Shikaku, Ryuji; Yagi, Naoto

2017-10-01

An x-ray micro-imaging technique to visualize high-resolution structure of cultural heritages made of iron or copper has been developed. It utilizes high-energy x-rays from a bending magnet at the SPring-8 synchrotron radiation facility. A white x-ray beam was attenuated by 0.5 mm tungsten and 2.0 mm lead absorbers resulting in the peak energy of 200 keV. The tungsten absorber eliminated the photon energy peak below the absorption edge of lead. A sample was rotated over 180 degrees in 500 s and projection images were continuously collected with an exposure time of 500 ms by an sCMOS camera equipped with a scintillator. Tomographic reconstruction of an ancient sword containing of both copper and iron was successfully obtained at a voxel size of 14.8 μm. Beam hardening was found to cause 2.5 % differences in density in a reconstructed image of a homogeneous stainless-steel rod. Ring artefacts were reduced by continuously moving the absorbers. This work demonstrates feasibility of high-energy, high-resolution imaging at a synchrotron beamline which may be generally useful for inspecting metallic objects.

X-Ray Absorption Toward the Einstein Ring Source PKS 1830-211

NASA Technical Reports Server (NTRS)

Mathur, Smita; Nair, Sunita

1997-01-01

PKS 1830-211 is an unusually radio-loud gravitationally lensed quasar. In the radio spectrum, the system appears as two compact, dominant features surrounded by relatively extended radio emission that forms an Einstein ring. As the line of sight to it passes close to our Galactic center, PKS 1830-211 has not been detected in wave bands other than the radio and X-ray so far. Here we present X-ray data of PKS 1830-211 observed with ROSAT Position Sensitive Proportional Counter. The X-ray spectrum shows that absorption in excess of the Galactic contribution is highly likely, which at the redshift of the lensing galaxy (z(sub t)=0.886) corresponds to N(sub H)=3.5((sup 0.6)(sub -0.5))x10(exp 22) atoms sq cm. The effective optical extinction is large, A(sub V)(observed) is greater than or approximately 5.8. When corrected for this additional extinction, the two-point optical to X-ray slope alpha(sub ox) of PKS 1830-211 lies just within the observed range of quasars. It is argued here that both compact images must be covered by the X-ray absorber(s) that we infer to be the lensing galaxy (galaxies). The dust-to-gas ratio along the line of sight within the lensing galaxy is likely to be somewhat larger than for our Galaxy.

Optically stimulated luminescence in x-ray irradiated xSnO-(25-x)SrO-75B2O3 glass

NASA Astrophysics Data System (ADS)

Nanto, H.; Nakagawa, R.; Takei, Y.; Hirasawa, K.; Miyamoto, Y.; Masai, H.; Kurobori, T.; Yanagida, T.; Fujimoto, Y.

2015-06-01

An intense optically stimulated luminescence (OSL) was observed, for the first time, in x-ray irradiated xSnO-(25-x)SrO-75B2O3 glass. It was found that the peak wavelength of OSL emission spectrum and its stimulation spectrum is about 400 nm and 600 nm, respectively. The OSL intensity is depended on the SnO contents (x=0.05-1.5) and the most intense OSL was observed in 1.0 mol% SnO doped glass. It was found that the OSL intensity is increased with increasing x-ray absorbed dose. Fairly good fading characteristics were observed in the x-ray irradiated glass, showing that this glass is useful as a candidate for OSL sensor materials for ionizing radiation monitoring.

The diversity of soft X-ray spectra in quasars

NASA Technical Reports Server (NTRS)

Elvis, M.; Wilkes, B. J.; Tananbaum, H.

1985-01-01

Soft X-ray spectra for three quasars obtained with the Einstein Imaging Proportional Counter covering the 0.1-4.0 keV band are reported. Power-law fits to these spectra have best-fit energy indices of 1.2 +0.6 or -0.2, for the quasar NAB 0205 + 024, 0.6 +0.3 or -0.2 for the quasar B2 1028 + 313, and 2.2 + or -0.4 for the quasar PG 1211 + 143. None of the quasars shows any evidence for a column density of cold matter in excess of the galactic values. The derived spectra demonstrate that there is no single universal power law slope for quasar X-ray spectra. The implications of these results for the X-ray background, X-ray continuum emission mechanisms, and the production of the optical/UV emission lines are briefly discussed.

X-ray detection of the symbiotic star AG Draconis

NASA Technical Reports Server (NTRS)

Anderson, C. M.; Cassinelli, J. P.; Sanders, W. T.

1981-01-01

The detection of the yellow symbiotic star AG Draconis is reported. The star was detected by an imaging proportional counter at a count rate of 0.27 counts/s. The object is an intense source of very soft X-rays, and the X-ray luminosity is estimated to be equal to approximately 10 to the 32nd ergs/s, with a temperature of less than 2,000,000 K. If an interstellar column density of 3 x 10 to the 20th/sq cm is assumed, the emission measure is deduced to be greater than 3 x 10 to the 55th/ cu cm from the X-ray data, and less than 3 x 10 to the 59th/cu cm from the optical data. The observation is discussed in the context of various models of the symbiotic stars.

X-Ray Calorimeter Arrays for Astrophysics

NASA Technical Reports Server (NTRS)

Kilbourne, Caroline A.

2009-01-01

High-resolution x-ray spectroscopy is a powerful tool for studying the evolving universe. The grating spectrometers on the XMM and Chandra satellites started a new era in x-ray astronomy, but there remains a need for instrumentation that can provide higher spectral resolution with high throughput in the Fe-K band (around 6 keV) and can enable imaging spectroscopy of extended sources, such as supernova remnants and galaxy clusters. The instrumentation needed is a broad-band imaging spectrometer - basically an x-ray camera that can distinguish tens of thousands of x-ray colors. The potential benefits to astrophysics of using a low-temperature calorimeter to determine the energy of an incident x-ray photon via measurement of a small change in temperature was first articulated by S. H. Moseley over two decades ago. In the time since, technological progress has been steady, though full realization in an orbiting x-ray telescope is still awaited. A low-temperature calorimeter can be characterized by the type of thermometer it uses, and three types presently dominate the field. The first two types are temperature-sensitive resistors - semiconductors in the metal-insulator transition and superconductors operated in the superconducting-normal transition. The third type uses a paramagnetic thermometer. These types can be considered the three generations of x-ray calorimeters; by now each has demonstrated a resolving power of 2000 at 6 keV, but only a semiconductor calorimeter system has been developed to spaceflight readiness. The Soft X-ray Spectrometer on Astro-H, expected to launch in 2013, will use an array of silicon thermistors with I-IgTe x-ray absorbers that will operate at 50 mK. Both the semiconductor and superconductor calorimeters have been implemented in small arrays, kilo-pixel arrays of the superconducting calorimeters are just now being produced, and it is anticipated that much larger arrays will require the non-dissipative advantage of magnetic thermometers.

Air kerma calibration factors and chamber correction values for PTW soft x-ray, NACP and Roos ionization chambers at very low x-ray energies.

PubMed

Ipe, N E; Rosser, K E; Moretti, C J; Manning, J W; Palmer, M J

2001-08-01

This paper evaluates the characteristics of ionization chambers for the measurement of absorbed dose to water using very low-energy x-rays. The values of the chamber correction factor, k(ch), used in the IPEMB 1996 code of practice for the UK secondary standard ionization chambers (PTW type M23342 and PTW type M23344), the Roos (PTW type 34001) and NACP electron chambers are derived. The responses in air of the small and large soft x-ray chambers (PTW type M23342 and PTW type M23344) and the NACP and Roos electron ionization chambers were compared. Besides the soft x-ray chambers, the NACP and Roos chambers can be used for very low-energy x-ray dosimetry provided that they are used in the restricted energy range for which their response does not change by more than 5%. The chamber correction factor was found by comparing the absorbed dose to water determined using the dosimetry protocol recommended for low-energy x-rays with that for very low-energy x-rays. The overlap energy range was extended using data from Grosswendt and Knight. Chamber correction factors given in this paper are chamber dependent, varying from 1.037 to 1.066 for a PTW type M23344 chamber, which is very different from a value of unity given in the IPEMB code. However, the values of k(ch) determined in this paper agree with those given in the DIN standard within experimental uncertainty. The authors recommend that the very low-energy section of the IPEMB code is amended to include the most up-to-date values of k(ch).

Hybrid modelling of a high-power X-ray attenuator plasma.

PubMed

Martín Ortega, Álvaro; Lacoste, Ana; Minea, Tiberiu

2018-05-01

X-ray gas attenuators act as stress-free high-pass filters for synchrotron and free-electron laser beamlines to reduce the heat load in downstream optical elements without affecting other properties of the X-ray beam. The absorption of the X-ray beam triggers a cascade of processes that ionize and heat up the gas locally, changing its density and therefore the X-ray absorption. Aiming to understand and predict the behaviour of the gas attenuator in terms of efficiency versus gas pressure, a hybrid model has been developed, combining three approaches: an analytical description of the X-ray absorption; Monte Carlo for the electron thermalization; and a fluid treatment for the electron diffusion, recombination and excited-states relaxation. The model was applied to an argon-filled attenuator prototype built and tested at the European Synchrotron Radiation Facility, at a pressure of 200 mbar and assuming stationary conditions. The results of the model showed that the electron population thermalizes within a few nanoseconds after the X-ray pulse arrival and it occurs just around the X-ray beam path, recombining in the bulk of the gas rather than diffusing to the attenuator walls. The gas temperature along the beam path reached 850 K for 770 W of incident power and 182 W m -1 of absorbed power. Around 70% of the absorbed power is released as visible and UV radiation rather than as heat to the gas. Comparison of the power absorption with the experiment showed an overall agreement both with the plasma radial profile and power absorption trend, the latter within an error smaller than 20%. This model can be used for the design and operation of synchrotron gas attenuators and as a base for a time-dependent model for free-electron laser attenuators.

Liquid explosions induced by X-ray laser pulses

DOE PAGES

Stan, Claudiu A.; Milathianaki, Despina; Laksmono, Hartawan; ...

2016-05-23

Explosions are spectacular and intriguing phenomena that expose the dynamics of matter under extreme conditions. We investigated, using time-resolved imaging, explosions induced by ultraintense X-ray laser pulses in water drops and jets. Our observations revealed an explosive vaporization followed by high-velocity interacting flows of liquid and vapour, and by the generation of shock trains in the liquid jets. These flows are different from those previously observed in laser ablation, owing to a simpler spatial pattern of X-ray absorption. We show that the explosion dynamics in our experiments is consistent with a redistribution of absorbed energy, mediated by a pressure ormore » shock wave in the liquid, and we model the effects of explosions, including their adverse impact on X-ray laser experiments. As a result, X-ray laser explosions have predictable dynamics that may prove useful for controlling the state of pure liquids over broad energy scales and timescales, and for triggering pressure-sensitive molecular dynamics in solutions.« less

Monitoring X-Ray Emission from X-Ray Bursters

NASA Technical Reports Server (NTRS)

Halpern, Jules P.; Kaaret, Philip

1999-01-01

The scientific goal of this project was to monitor a selected sample of x-ray bursters using data from the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer together with data from the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory to study the long-term temporal evolution of these sources in the x-ray and hard x-ray bands. The project was closely related to "Long-Term Hard X-Ray Monitoring of X-Ray Bursters", NASA project NAG5-3891, and and "Hard x-ray emission of x-ray bursters", NASA project NAG5-4633, and shares publications in common with both of these. The project involved preparation of software for use in monitoring and then the actual monitoring itself. These efforts have lead to results directly from the ASM data and also from Target of Opportunity Observations (TOO) made with the Rossi X-Ray Timing Explorer based on detection of transient hard x-ray outbursts with the ASM and BATSE.

The XMM deep survey in the CDF-S. X. X-ray variability of bright sources

NASA Astrophysics Data System (ADS)

Falocco, S.; Paolillo, M.; Comastri, A.; Carrera, F. J.; Ranalli, P.; Iwasawa, K.; Georgantopoulos, I.; Vignali, C.; Gilli, R.

2017-12-01

Aims: We aim to study the variability properties of bright hard X-ray selected active galactic nuclei (AGN) in the redshift range between 0.3 and 1.6 detected in the Chandra Deep Field South (XMM-CDFS) by a long ( 3 Ms) XMM observation. Methods: Taking advantage of the good count statistics in the XMM CDFS, we search for flux and spectral variability using the hardness ratio (HR) techniques. We also investigate the spectral variability of different spectral components (photon index of the power law, column density of the local absorber, and reflection intensity). The spectra were merged in six epochs (defined as adjacent observations) and in high and low flux states to understand whether the flux transitions are accompanied by spectral changes. Results: The flux variability is significant in all the sources investigated. The HRs in general are not as variable as the fluxes, in line with previous results on deep fields. Only one source displays a variable HR, anti-correlated with the flux (source 337). The spectral analysis in the available epochs confirms the steeper when brighter trend consistent with Comptonisation models only in this source at 99% confidence level. Finding this trend in one out of seven unabsorbed sources is consistent, within the statistical limits, with the 15% of unabsorbed AGN in previous deep surveys. No significant variability in the column densities, nor in the Compton reflection component, has been detected across the epochs considered. The high and low states display in general different normalisations but consistent spectral properties. Conclusions: X-ray flux fluctuations are ubiquitous in AGN, though in some cases the data quality does not allow for their detection. In general, the significant flux variations are not associated with spectral variability: photon index and column densities are not significantly variable in nine out of the ten AGN over long timescales (from three to six and a half years). Photon index variability is

X-ray Transients in M31

NASA Astrophysics Data System (ADS)

Kong, A. K. H.; Garcia, M. R.; Primini, F. A.; Murray, S. S.; McClintock, J. E.

2002-06-01

A bright X-ray transient was detected by Chandra on 2002 June 2 with a series of 5 HRC-I snapshots. The new source CXOU J004154.6+405648 (R.A.=00h41m54s.64, Dec.=+40d56m48s.0, +/- 1", J2000) is discovered at a luminosity (0.3-10 keV) of 1.5 x 1038 erg/s (assuming an absorbed power-law model with photon index = 2 and NH = 1021 cm-2 at a distance of 780 kpc).

X-ray dense cellular inclusions in the cells of the green alga Chlamydomonas reinhardtii as seen by soft-x-ray microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stead, A.D.; Ford, T.W.; Page, A.M.

1997-04-01

Soft x-rays, having a greater ability to penetrate biological material than electrons, have the potential for producing images of intact, living cells. In addition, by using the so-called {open_quotes}water window{close_quotes} area of the soft x-ray spectrum, a degree of natural contrast is introduced into the image due to differential absorption of the wavelengths by compounds with a high carbon content compared to those with a greater oxygen content. The variation in carbon concentration throughout a cell therefore generates an image which is dependent upon the carbon density within the specimen. Using soft x-ray contact microscopy the authors have previously examinedmore » the green alga Chlamydomonas reinhardtii, and the most prominent feature of the cells are the numerous x-ray absorbing spheres, But they were not seen by conventional transmission electron microscopy. Similar structures have also been reported by the Goettingen group using their cryo transmission x-ray microscope at BESSY. Despite the fact that these spheres appear to occupy up to 20% or more of the cell volume when seen by x-ray microscopy, they are not visible by transmission electron microscopy. Given the difficulties and criticisms associated with soft x-ray contact microscopy, the present study was aimed at confirming the existence of these cellular inclusions and learning more of their possible chemical composition.« less

X-ray Obscured AGN in the GOODS-N

NASA Astrophysics Data System (ADS)

Georgantopoulos, I.; Akylas, A.; Rovilos, E.; Xilouris, E.

2010-07-01

We explore the X-ray properties of the Dust Obscured Galaxies (DOGs) i.e. sources with f24μ / fR > 1000. This population has been proposed to contain a significant fraction of Compton-thick sources at high redshift. In particular we study the X-ray spectra of the 14 DOGS detected in the CDFN 2Ms exposure. Their stacked spectrum is flat with Γ=1±0.1 very similar to the stacked spectrum of the undetected DOGs (Γ=0.8±0.2). However, most of our X-ray detected DOGs present only moderate absorption with column densities 1022 < NH < 1024 cm-2. Only three sources (20%) present very flat spectra and are probably associated with reflection dominated Compton-thick sources. Our finding is rather at odds with papers which claim that the vast majority of DOGs are associated with Compton-thick sources. In any case, such sources at high redshift (z > 2) present limited interest for the X-ray background: the population synthesis models predict a contribution, for the z > 2 Compton-thick AGN, to the X-ray background flux at 30 keV, of less than 1 percent.

Diesel NO{sub x} reduction by plasma-regenerated absorbent beds

DOEpatents

Wallman, P.H.; Vogtlin, G.E.

1998-02-10

Reduction of NO{sub x} from diesel engine exhaust by use of plasma-regenerated absorbent beds is described. This involves a process for the reduction of NO{sub x} and particulates from diesel engines by first absorbing NO{sub x} onto a solid absorbent bed that simultaneously acts as a physical trap for the particulate matter, and second regenerating said solid absorbent by pulsed plasma decomposition of absorbed NO{sub x} followed by air oxidation of trapped particulate matter. The absorbent bed may utilize all metal oxides, but the capacity and the kinetics of absorption and desorption vary between different materials, and thus the composition of the absorbent bed is preferably a material which enables the combination of NO{sub x} absorption capability with catalytic activity for oxidation of hydrocarbons. Thus, naturally occurring or synthetically prepared materials may be utilized, particularly those having NO{sub x} absorption properties up to temperatures around 400 C which is in the area of diesel engine exhaust temperatures. 1 fig.

Nustar Reveals an Intrinsically X-ray Weak Broad Absorption Line Quasar in the Ultraluminous Infrared Galaxy Markarian 231

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Brandt. W. N.; Harrison, F. A.; Luo, B.; Alexander, D. M.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W.;

Microwave Kinetic Inductance Detectors: Large Format X-ray Spectral Imagers for the Next Generation of X-ray Telescopes

NASA Astrophysics Data System (ADS)

Eckart, Megan E.; Mazin, B. A.; Bumble, B.; Golwala, S. R.; Zmuidzinas, J.; Day, P. K.; Harrison, F. A.

2006-09-01

Microwave Kinetic Inductance Detectors (MKIDs) have the potential to provide megapixel imagers with few eV spectral resolution for future X-ray missions such as Gen-X. MKIDs offer the advantage over many other cryogenic detector technologies that they can be easily multiplexed, so that arrays with many thousand pixels are readily achievable. In addition, the readout electronics can be operated at room temperature, a significant advantage for space applications. MKIDs exploit the dependence of surface impedance of a superconductorwith the quasiparticle density. Quasiparticles are created by absorption of X-rays, with number proportional to the X-ray energy. The impedance change may be sensitively measured using a thin-film resonant circuit. The practical application of MKIDs for photon detection requires a method of efficiently coupling the photon energy to the MKID. To apply the MKID scheme to X-ray detection we pattern tantalum strips with aluminum MKIDs attached at each end. An incident X-ray is absorbed in the Ta and creates millions of quasiparticle excitations, which diffuse to each end of the strip, finally entering the Al resonators where they are trapped and sensed. Simultaneous monitoring of the signal at both ends of the strip allow position and energy determination for each photon. We have demonstrated working strip detectors in the laboratory, and will present our measurements of the quasiparticle diffusion constant and the quasiparticle lifetime in tantalum, the aluminum quasiparticle lifetime, and the energy resolution of the detector. We will also discuss ideas for future detector designs and suggest ultimate performance goals for X-ray astronomy applications.

X-Ray Emission from the Millisecond Pulsar J1012+5307

NASA Technical Reports Server (NTRS)

Halpern, Jules P.; Wang, F. Y.-H.; Oliversen, Ronald (Technical Monitor)

2001-01-01

The recently discovered 5.3 ms pulsar J1012+5307 at a distance of 520 pc is in an area of the sky which is particularly deficient in absorbing gas. The column density along the line of sight is less than 7.5 x 10(exp 19)/sq cm, which facilitates soft X-ray observations. Halpern reported a possible ROSAT PSPC detection of the pulsar in a serendipitous, off-axis observation. We have now confirmed the X-ray emission of PSR J1012+5307 in a 23 ksec observation with the ROSAT HRI. A point source is detected within 3 sec. of the radio position. Its count rate of 1.6 +/- 0.3 x 10(exp -3)/s corresponds to an unabsorbed 0.1 - 2.4 keV flux of 6.4 x 10(exp -14) ergs/sq cm s, similar to that reported previously. This counts-to-flux conversion is valid for N(sub H) = 5 x 10(exp 19)/sq cm, and either a power-law spectrum of photon index 2.5 or a blackbody of kT = 0.1 keV. The implied X-ray luminosity of 2.0 x 10(exp 30) ergs/ s is 5 x 10(exp -4) of the pulsar's spin-down power E, and similar to that of the nearest millisecond pulsar J0437-4715, which is nearly a twin of J1012+5307 in P and E. We subjected the 37 photons (and 13 background counts) within the source region to a pulsar search, but no evidence for pulsation was found. The pulsar apparently emits over a large fraction of its rotation cycle, and the absence of sharp modulation can be taken as evidence for surface thermal emission, as favored for PSR J0437-4715, rather than magnetospheric X-ray emission which is apparent in the sharp pulses of the much more energetic millisecond pulsar B1821-24. A further test of of the interpretation will be made with a longer ROSAT observation, which will increase the number of photons collected by a factor of 5, and permit a more sensitive examination of the light curve for modulation due to emission from heated polar caps. If found, such modulation will be further evidence that surface reheating by the impact of particles accelerated along open field lines operates in these approx

The Einstein objective grating spectrometer survey of galactic binary X-ray sources

NASA Technical Reports Server (NTRS)

Vrtilek, S. D.; Mcclintock, J. E.; Seward, F. D.; Kahn, S. M.; Wargelin, B. J.

1991-01-01

The results of observations of 22 bright Galactic X-ray point sources are presented, and the most reliable measurements to date of X-ray column densities to these sources are derived. The results are consistent with the idea that some of the objects have a component of column density intrinsic to the source in addition to an interstellar component. The K-edge absorption due to oxygen is clearly detected in 10 of the sources and the Fe L and Ne K edges are detected in a few. The spectra probably reflect emission originating in a collisionally excited region combined with emission from a photoionized region excited directly by the central source.

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutton, Kristin A.; Black, Paul J.; Mercer, Kermit R.

2013-12-01

Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage, to confirm a multi-track radiation-damage process and to develop a model of that process. Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV–visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5–0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. Themore » observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure.« less

NuSTAR Hard X-Ray Survey of the Galactic Center Region I: Hard X-Ray Morphology and Spectroscopy of the Diffuse Emission

NASA Astrophysics Data System (ADS)

Mori, Kaya; Hailey, Charles J.; Krivonos, Roman; Hong, Jaesub; Ponti, Gabriele; Bauer, Franz; Perez, Kerstin; Nynka, Melania; Zhang, Shuo; Tomsick, John A.; Alexander, David M.; Baganoff, Frederick K.; Barret, Didier; Barrière, Nicolas; Boggs, Steven E.; Canipe, Alicia M.; Christensen, Finn E.; Craig, William W.; Forster, Karl; Giommi, Paolo; Grefenstette, Brian W.; Grindlay, Jonathan E.; Harrison, Fiona A.; Hornstrup, Allan; Kitaguchi, Takao; Koglin, Jason E.; Luu, Vy; Madsen, Kristen K.; Mao, Peter H.; Miyasaka, Hiromasa; Perri, Matteo; Pivovaroff, Michael J.; Puccetti, Simonetta; Rana, Vikram; Stern, Daniel; Westergaard, Niels J.; Zhang, William W.; Zoglauer, Andreas

2015-12-01

We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Γ ˜ 1.3-2.3 up to ˜50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe Kα fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (˜1023 cm-2), primary X-ray spectra (power-laws with Γ ˜ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to LX ≳ 1038 erg s-1. Above ˜20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95-0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses MWD ˜ 0.9 M⊙. Spectral energy distribution analysis suggests that G359.95-0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745-290, strongly favoring a leptonic origin of the GC TeV emission.

Lithium metal for x-ray filters and refractive optics

NASA Astrophysics Data System (ADS)

Pereira, N. R.; Dufresne, Eric; Dierker, Steve

2001-04-01

Lithium is the most x-ray transparent solid element. Lithium is very stable in dry air with a dew point below -50 C or so, but as the humidity increases lithium starts to react with the air's nitrogen and oxygen. Under usual laboratory conditions a shiny piece of lithium metal becomes a white powder within the hour, preventing lithium's widespread use in x-ray work. Use of lithium as a window for pulsed x-rays demands that lithium withstands corrosion in open air for at least 15 minutes. Protection by a one micron layer of parylene turns out to be enough. Although parylene absorbs soft x-rays 12 times more than lithium, the parylene layer can remain in place for the window application. Lithium is also ideal for refractive x-ray lenses. We are evaluating the performance of such lenses with 10 keV photons from the MHATT-CAT beam line at the Advanced Photon Source. These measurements are in progress: the paper will show the results from these measurements as available.

An X-ray spectral study of colliding wind binaries

NASA Astrophysics Data System (ADS)

Sugawara, Yasuharu; Maeda, Yoshitomo; Tsuboi, Yohko

2012-03-01

We present results of spectral studies of two Wolf-Rayet colliding wind binaries (WR 140 and WR 30a), using the data obtained by the Suzaku and XMM-Newton satellites. WR 140 is one of the best known examples of a Wolf-Rayet star. We executed the Suzaku X-ray observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. We detected hard X-ray excess in the HXD band (> 10 keV) for the first time from a W-R binary. The emission measure of the dominant, high temperature component is not inversely proportional to the distance between the two stars. WR 30a is the rare WO-type W-R binary. We executed XMM-Newton observations and detected X-ray emission for the first time. The broad-band spectrum was well-fitted with double-absorption model. The hard X-ray emission was heavily absorbed. This can be interpreted that the hard X-ray emitting plasma exist near WO star.

Development of Position-sensitive Transition-edge Sensor X-ray Detectors

NASA Technical Reports Server (NTRS)

Smith, S. J.; Bandler, S. R.; Brekosky, R. P.; Brown, A.-D.; Chervenak, J. A.; Eckard, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. s.;

3XMM J181923.7-170616: An X-Ray Binary with a 408 s Pulsar

NASA Astrophysics Data System (ADS)

Qiu, Hao; Zhou, Ping; Yu, Wenfei; Li, Xiangdong; Xu, Xiaojie

2017-09-01

We carry out a dedicated study of 3XMM J181923.7-170616 with an approximate pulsation period of 400 s using the XMM-Newton and Swift observations spanning across nine years. We have refined the period of the source to 407.904(7) s (at epoch MJD 57142) and constrained the 1σ upper limit on the period derivative \\dot{P}≤slant 1.1× {10}-8 {{s}} {{{s}}}-1. The source radiates hard, persistent X-ray emission during the observation epochs, which is best described by an absorbed power-law model (Γ ˜ 0.2-0.8) plus faint Fe lines at 6.4 and 6.7 keV. The X-ray flux revealed a variation within a factor of 2, along with a spectral hardening as the flux increased. The pulse shape is sinusoid-like and the spectral properties of different phases do not present significant variation. The absorption {N}{{H}} (˜ 1.3× {10}22 {{cm}}-2) is similar to the total Galactic hydrogen column density along the direction, indicating that it is a distant source. A search for the counterpart in optical and near-infrared surveys reveals a low-mass K-type giant, while the existence of a Galactic OB supergiant is excluded. A symbiotic X-ray binary (SyXB) is the favored nature of 3XMM J181923.7-170616 and can essentially explain the low luminosity of 2.78× {10}34{d}102 {erg} {{{s}}}-1, slow pulsation, hard X-ray spectrum, and possible K3 III companion. An alternative explanation of the source is a persistent Be X-ray binary (BeXB) with a companion star no earlier than B3-type.

A Non-thermal Pulsed X-Ray Emission of AR Scorpii

NASA Astrophysics Data System (ADS)

Takata, J.; Hu, C.-P.; Lin, L. C. C.; Tam, P. H. T.; Pal, P. S.; Hui, C. Y.; Kong, A. K. H.; Cheng, K. S.

2018-02-01

We report the analysis result of UV/X-ray emission from AR Scorpii, which is an intermediate polar (IP) composed of a magnetic white dwarf and an M-type star, with the XMM-Newton data. The X-ray/UV emission clearly shows a large variation over the orbit, and their intensity maximum (or minimum) is located at the superior conjunction (or inferior conjunction) of the M star orbit. The hardness ratio of the X-ray emission shows a small variation over the orbital phase and shows no indication of the absorption by an accretion column. These properties are naturally explained by the emission from the M star surface rather than that from the accretion column on the white dwarf’s (WD) star, which is similar to usual IPs. Additionally, the observed X-ray emission also modulates with the WD’s spin with a pulse fraction of ∼14%. The peak position is aligned in the optical/UV/X-ray band. This supports the hypothesis that the electrons in AR Scorpii are accelerated to a relativistic speed and emit non-thermal photons via the synchrotron radiation. In the X-ray bands, evidence of the power-law spectrum is found in the pulsed component, although the observed emission is dominated by the optically thin thermal plasma emissions with several different temperatures. It is considered that the magnetic dissipation/reconnection process on the M star surface heats up the plasma to a temperature of several keV and also accelerates the electrons to the relativistic speed. The relativistic electrons are trapped in the WD’s closed magnetic field lines by the magnetic mirror effect. In this model, the observed pulsed component is explained by the emissions from the first magnetic mirror point.

Observation of Reverse Saturable Absorption of an X-ray Laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, B. I.; Cho, M. S.; Kim, M.

A nonlinear absorber in which the excited state absorption is larger than the ground state can undergo a process called reverse saturable absorption. It is a well-known phenomenon in laser physics in the optical regime, but is more difficult to generate in the x-ray regime, where fast nonradiative core electron transitions typically dominate the population kinetics during light matter interactions. Here, we report the first observation of decreasing x-ray transmission in a solid target pumped by intense x-ray free electron laser pulses. The measurement has been made below the K-absorption edge of aluminum, and the x-ray intensity ranges are 10more » 16 –10 17 W=cm 2. It has been confirmed by collisional radiative population kinetic calculations, underscoring the fast spectral modulation of the x-ray pulses and charge states relevant to the absorption and transmission of x-ray photons. The processes shown through detailed simulations are consistent with reverse saturable absorption, which would be the first observation of this phenomena in the x-ray regime. These light matter interactions provide a unique opportunity to investigate optical transport properties in the extreme state of matters, as well as affording the potential to regulate ultrafast x-ray freeelectron laser pulses.« less

Observation of Reverse Saturable Absorption of an X-ray Laser

DOE PAGES

Cho, B. I.; Cho, M. S.; Kim, M.; ...

2017-08-16

A nonlinear absorber in which the excited state absorption is larger than the ground state can undergo a process called reverse saturable absorption. It is a well-known phenomenon in laser physics in the optical regime, but is more difficult to generate in the x-ray regime, where fast nonradiative core electron transitions typically dominate the population kinetics during light matter interactions. Here, we report the first observation of decreasing x-ray transmission in a solid target pumped by intense x-ray free electron laser pulses. The measurement has been made below the K-absorption edge of aluminum, and the x-ray intensity ranges are 10more » 16 –10 17 W=cm 2. It has been confirmed by collisional radiative population kinetic calculations, underscoring the fast spectral modulation of the x-ray pulses and charge states relevant to the absorption and transmission of x-ray photons. The processes shown through detailed simulations are consistent with reverse saturable absorption, which would be the first observation of this phenomena in the x-ray regime. These light matter interactions provide a unique opportunity to investigate optical transport properties in the extreme state of matters, as well as affording the potential to regulate ultrafast x-ray freeelectron laser pulses.« less

High Precision Grids for Neutron, Hard X-Ray, and Gamma-Ray Imaging Systems

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2002-01-01

Fourier telescopes permit observations over a very broad band of energy. They generally include synthetic spatial filtering structures, known as multilayer grids or grid pairs consisting of alternate layers of absorbing and transparent materials depending on whether neutrons or photons are being imaged. For hard x-rays and gamma rays high (absorbing) and low (transparent) atomic number elements, termed high-Z and low-Z materials may be used. Fabrication of these multilayer grid structures is not without its difficulties. Herein the alternate layers of the higher material and the lower material are inserted in a polyhedron, transparent to photons of interest, through an open face of the polyhedron. The inserted layers are then uniformly compressed to form a multilayer grid.

The soft X-ray diffuse background

NASA Technical Reports Server (NTRS)

Mccammon, D.; Burrows, D. N.; Sanders, W. T.; Kraushaar, W. L.

1982-01-01

Maps of the diffuse X-ray background intensity covering essentially the entire sky with approx. 7 deg spatial resolution are presented for seven energy bands. The data were obtained on a series of ten sounding rocket flights conducted over a seven-year period. The different nature of the spatial distributions in different bands implies at least three distinct origins for the diffuse X-rays, none of which is well-understood. At energies or approx. 2000 eV, an isotropic and presumably extraglalactic 500 and 1000 eV, an origin which is at least partially galactic seems called for. At energies 284 eV, the observed intensity is anticorrelated with neutral hydrogen column density, but we find it unlikely that this anticorrelation is simply due to absorption of an extragalactic or halo source.

X1908+075: An X-Ray Binary with a 4.4 Day Period

NASA Astrophysics Data System (ADS)

Wen, Linqing; Remillard, Ronald A.; Bradt, Hale V.

2000-04-01

X1908+075 is an optically unidentified and highly absorbed X-ray source that appeared in early surveys such as Uhuru, OSO 7, Ariel 5, HEAO-1, and the EXOSAT Galactic Plane Survey. These surveys measured a source intensity in the range 2-12 mcrab at 2-10 keV, and the position was localized to ~0.5d. We use the Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor (ASM) to confirm our expectation that a particular Einstein/IPC detection (1E 1908.4+0730) provides the correct position for X1908+075. The analysis of the coded mask shadows from the ASM for the position of 1E 1908.4+0730 yields a persistent intensity ~8 mcrab (1.5-12 keV) over a 3 yr interval beginning in 1996 February. Furthermore, we detect a period of 4.400+/-0.001 days with a false-alarm probability less than 10-7. The folded light curve is roughly sinusoidal, with an amplitude that is 26% of the mean flux. The X-ray period may be attributed to the scattering and absorption of X-rays through a stellar wind combined with the orbital motion in a binary system. We suggest that X1908+075 is an X-ray binary with a high-mass companion star.

HS 1603+3820 and its Warm Absorber

NASA Astrophysics Data System (ADS)

Nikołajuk, M.; Różańska, A.; Czerny, B.; Dobrzycki, A.

2009-07-01

We use photoionization codes CLOUDY and TITAN to obtain physical conditions in the absorbing medium close to the nucleus of a distant quasar (z = 2.54) HS 1603+3820. We found that the total column density of this Warm Absorber is 2 x 1022 cm-2. Due to the softness of the quasars spectrum the modelling allowed us also to determine uniquely the volume hydrogen density of this warm gas (n = 1010 cm-3) which combined with the other quasar parameters leads to a distance determination to the Warm Absorber from the central source which is ~ 1.5 x 1016 cm.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Liyi; Makishima, Kazuo; Yagi, Masafumi

We report the detection of an X-ray absorption feature near the galaxy M86 in the Virgo cluster. The absorber has a column density of 2-3 × 10{sup 20} cm{sup –2}, and its position coincides with the peak of an intracluster H I cloud which was removed from the galaxy NGC 4388 presumably by ram pressure. These results indicate that the H I cloud is located in front of M86 along the line-of-sight, and suggest that the stripping was primarily created by an interaction between NGC 4388 and the hot plasmas of the Virgo cluster, not the M86 halo. By calculatingmore » an X-ray temperature map, we further detected an X-ray counterpart of the H I cloud up to ≈3' south of M86. It has a temperature of 0.89 keV and a mass of ∼4.5 × 10{sup 8} M {sub ☉}, exceeding the estimated H I gas mass. The high hot-to-cold gas ratio in the cloud indicates a significant evaporation of the H I gas, probably by thermal conduction from the hotter cluster plasma with a sub-Spitzer rate.« less

High Spectral Resolution, High Cadence, Imaging X-Ray Microcalorimeters for Solar Physics

NASA Technical Reports Server (NTRS)

Bandler, Simon R.; Bailey, Catherine N.; Bookbinder, Jay A.; DeLuca, Edward E.; Chervenak, Jay A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Daniel P.; Kelley, Richard L.; Kilbourne, Caroline A.;

The Two-Phase, Two-Velocity Ionized Absorber in the Seyfert 1 Galaxy NGC 5548

NASA Astrophysics Data System (ADS)

Andrade-Velázquez, Mercedes; Krongold, Yair; Elvis, Martin; Nicastro, Fabrizio; Brickhouse, Nancy; Binette, Luc; Mathur, Smita; Jiménez-Bailón, Elena

2010-03-01

different outflow velocity systems have been modeled independently in the X-ray band for this source. The kinematic components and column densities found from the X-rays are in agreement with the main kinematic components found in the UV absorber. This supports the idea that the UV and X-ray absorbing gas is part of the same phenomenon. NGC 5548 can now be seen to fit in a pattern established for other WAs: two or three discrete phases in pressure equilibrium. There are no remaining cases of a well-studied WA in which a model consisting of a multi-phase medium is not viable.

Absorbed dose-to-water protocol applied to synchrotron-generated x-rays at very high dose rates

NASA Astrophysics Data System (ADS)

Fournier, P.; Crosbie, J. C.; Cornelius, I.; Berkvens, P.; Donzelli, M.; Clavel, A. H.; Rosenfeld, A. B.; Petasecca, M.; Lerch, M. L. F.; Bräuer-Krisch, E.

2016-07-01

Microbeam radiation therapy (MRT) is a new radiation treatment modality in the pre-clinical stage of development at the ID17 Biomedical Beamline of the European synchrotron radiation facility (ESRF) in Grenoble, France. MRT exploits the dose volume effect that is made possible through the spatial fractionation of the high dose rate synchrotron-generated x-ray beam into an array of microbeams. As an important step towards the development of a dosimetry protocol for MRT, we have applied the International Atomic Energy Agency’s TRS 398 absorbed dose-to-water protocol to the synchrotron x-ray beam in the case of the broad beam irradiation geometry (i.e. prior to spatial fractionation into microbeams). The very high dose rates observed here mean the ion recombination correction factor, k s , is the most challenging to quantify of all the necessary corrections to apply for ionization chamber based absolute dosimetry. In the course of this study, we have developed a new method, the so called ‘current ramping’ method, to determine k s for the specific irradiation and filtering conditions typically utilized throughout the development of MRT. Using the new approach we deduced an ion recombination correction factor of 1.047 for the maximum ESRF storage ring current (200 mA) under typical beam spectral filtering conditions in MRT. MRT trials are currently underway with veterinary patients at the ESRF that require additional filtering, and we have estimated a correction factor of 1.025 for these filtration conditions for the same ESRF storage ring current. The protocol described herein provides reference dosimetry data for the associated Treatment Planning System utilized in the current veterinary trials and anticipated future human clinical trials.

Ionization nebulae surrounding supersoft X-ray sources

NASA Technical Reports Server (NTRS)

Rappaport, S.; Chiang, E.; Kallman, T.; Malina, R.

1994-01-01

In this work we carry out a theoretical investigation of a new type of astrophysical gaseous nebula, viz., ionized regions surrounding supersoft X-ray sources. Supersoft X-ray sources, many of which have characteristic luminosities of approximately 10(exp 37)-(10(exp 38) ergs/s and effective temperatures of approximately 4 x 10(exp 5) K, were first discovered with the Einstein Observatory. These sources have now been shown to constitute a distinct class of X-ray source and are being found in substantial numbers with ROSAT. We predict that these sources should be surrounded by regions of ionized hydrogen and helium with properties that are distinct from other astrophysical gaseous nebulae. We present caluations of the ionization and temperature structure of these ionization nebulae, as well as the expected optical line fluxes. The ionization profiles for both hydrogen and helium exhibit substantially more gradual transitions from the ionized to the unionized state than is the case for conventional H II regions. The calculated optical line intensitites are presented as absolute fluxes from sources in the Large Magellanic Cloud and as fractions of the central source luminosity. We find, in particular, that (O III) lambda 5008 and He II lambda 4686 are especially prominent in these ionization nebulae as compared to other astrophysical nebulae. We propose that searches for supersoft X-rays via their characteristic optical lines may reveal sources in regions where the soft X-rays are nearly completely absorbed by the interstellar medium.

X-Ray Psoralen Activated Cancer Therapy (X-PACT)

PubMed Central

Oldham, Mark; Yoon, Paul; Fathi, Zak; Beyer, Wayne F.; Adamson, Justus; Liu, Leihua; Alcorta, David; Xia, Wenle; Osada, Takuya; Liu, Congxiao; Yang, Xiao Y.; Dodd, Rebecca D.; Herndon, James E.; Meng, Boyu; Kirsch, David G.; Lyerly, H. Kim; Dewhirst, Mark W.; Fecci, Peter; Walder, Harold; Spector, Neil L.

2016-01-01

This work investigates X-PACT (X-ray Psoralen Activated Cancer Therapy): a new approach for the treatment of solid cancer. X-PACT utilizes psoralen, a potent anti-cancer therapeutic with current application to proliferative disease and extracorporeal photopheresis (ECP) of cutaneous T Cell Lymphoma. An immunogenic role for light-activated psoralen has been reported, contributing to long-term clinical responses. Psoralen therapies have to-date been limited to superficial or extracorporeal scenarios due to the requirement for psoralen activation by UVA light, which has limited penetration in tissue. X-PACT solves this challenge by activating psoralen with UV light emitted from novel non-tethered phosphors (co-incubated with psoralen) that absorb x-rays and re-radiate (phosphoresce) at UV wavelengths. The efficacy of X-PACT was evaluated in both in-vitro and in-vivo settings. In-vitro studies utilized breast (4T1), glioma (CT2A) and sarcoma (KP-B) cell lines. Cells were exposed to X-PACT treatments where the concentrations of drug (psoralen and phosphor) and radiation parameters (energy, dose, and dose rate) were varied. Efficacy was evaluated primarily using flow cell cytometry in combination with complimentary assays, and the in-vivo mouse study. In an in-vitro study, we show that X-PACT induces significant tumor cell apoptosis and cytotoxicity, unlike psoralen or phosphor alone (p<0.0001). We also show that apoptosis increases as doses of phosphor, psoralen, or radiation increase. Finally, in an in-vivo pilot study of BALBc mice with syngeneic 4T1 tumors, we show that the rate of tumor growth is slower with X-PACT than with saline or AMT + X-ray (p<0.0001). Overall these studies demonstrate a potential therapeutic effect for X-PACT, and provide a foundation and rationale for future studies. In summary, X-PACT represents a novel treatment approach in which well-tolerated low doses of x-ray radiation are delivered to a specific tumor site to generate UVA light which

X-ray Variations at the Orbital Period from Cygnus X-1 IN the High/Soft State

NASA Astrophysics Data System (ADS)

Boroson, Bram; Vrtilek, Saeqa Dil

2010-02-01

Orbital variability has been found in the X-ray hardness of the black hole candidate Cygnus X-1 during the soft/high X-ray state using light curves provided by the Rossi X-ray Timing Explorer's All-Sky Monitor. We are able to set broad limits on how the mass-loss rate and X-ray luminosity vary between the hard and soft states. The folded light curve shows diminished flux in the soft X-ray band at phi = 0 (defined as the time of the superior conjunction of the X-ray source). Models of the orbital variability provide slightly superior fits when the absorbing gas is concentrated in neutral clumps and better explain the strong variability in hardness. In combination with the previously established hard/low state dips, our observations give a lower limit to the mass-loss rate in the soft state (\\dot{M}<2× 10^{-6} M_{⊙} yr-1) than the limit in the hard state (\\dot{M}<4× 10^{-6} M_{⊙} yr-1). Without a change in the wind structure between X-ray states, the greater mass-loss rate during the low/hard state would be inconsistent with the increased flaring seen during the high-soft state.

The hard x-ray imager onboard IXO

NASA Astrophysics Data System (ADS)

Nakazawa, Kazuhiro; Takahashi, Tadayuki; Limousin, Olivier; Kokubun, Motohide; Watanabe, Shin; Laurent, Philippe; Arnaud, Monique; Tajima, Hiroyasu

2010-07-01

The Hard X-ray Imager (HXI) is one of the instruments onboard International X-ray Observatory (IXO), to be launched into orbit in 2020s. It covers the energy band of 10-40 keV, providing imaging-spectroscopy with a field of view of 8 x 8 arcmin2. The HXI is attached beneath the Wide Field Imager (WFI) covering 0.1-15 keV. Combined with the super-mirror coating on the mirror assembly, this configuration provides observation of X-ray source in wide energy band (0.1-40.0 keV) simultaneously, which is especially important for varying sources. The HXI sensor part consists of the semiconductor imaging spectrometer, using Si in the medium energy detector and CdTe in the high energy detector as its material, and an active shield covering its back to reduce background in orbit. The HXI technology is based on those of the Japanese-lead new generation X-ray observatory ASTRO-H, and partly from those developed for Simbol-X. Therefore, the technological development is in good progress. In the IXO mission, HXI will provide a major assets to identify the nature of the object by penetrating into thick absorbing materials and determined the inherent spectral shape in the energy band well above the structure around Fe-K lines and edges.

The Peculiar X-ray Transient IGR 16358-4726

NASA Technical Reports Server (NTRS)

Patel, S. K.; Kouveliotou, C.; Tennant, A. F.; Woods, P. M.; King, A.; Ubertini, P.; Winkler, C.; Courvoisier, T.; VanDerKlis, M.; Wachter, S.

2003-01-01

The new transient IGR 16358-4726 was discovered on 2003 March 19 with INTEGRAL. We detected the source serendipitously during our 2003 March 24 observation of SGR 1627 - 4lwith the Chandra X-ray observatory at the 1.7 x 10(exp -l0) ergs/s sq cm flux level ( 2-10 keV) with a very high absorption column (N_H = 3.3 x 10(exp 23)/sq cm and a hard power law spectrum of index 0.5(1). We discovered a very strong flux modulation with a period of 5880(50) s and peak-to-peak pulse fraction of 70(6)% (2-10 keV), clearly visible in the X-ray data. The nature of IGR 16358-4726 remains unresolved. The only neutron star systems known with similar spin periods are low luminosity persistent wind-fed pulsars; if this is a spin period, this transient is a new kind of object. If this is an orbital period, then the system could be a compact Low Mass X-ray Binary (LMXB).

Gold nanoparticle contrast agents in advanced X-ray imaging technologies.

PubMed

Ahn, Sungsook; Jung, Sung Yong; Lee, Sang Joon

2013-05-17

Recently, there has been significant progress in the field of soft- and hard-X-ray imaging for a wide range of applications, both technically and scientifically, via developments in sources, optics and imaging methodologies. While one community is pursuing extensive applications of available X-ray tools, others are investigating improvements in techniques, including new optics, higher spatial resolutions and brighter compact sources. For increased image quality and more exquisite investigation on characteristic biological phenomena, contrast agents have been employed extensively in imaging technologies. Heavy metal nanoparticles are excellent absorbers of X-rays and can offer excellent improvements in medical diagnosis and X-ray imaging. In this context, the role of gold (Au) is important for advanced X-ray imaging applications. Au has a long-history in a wide range of medical applications and exhibits characteristic interactions with X-rays. Therefore, Au can offer a particular advantage as a tracer and a contrast enhancer in X-ray imaging technologies by sensing the variation in X-ray attenuation in a given sample volume. This review summarizes basic understanding on X-ray imaging from device set-up to technologies. Then this review covers recent studies in the development of X-ray imaging techniques utilizing gold nanoparticles (AuNPs) and their relevant applications, including two- and three-dimensional biological imaging, dynamical processes in a living system, single cell-based imaging and quantitative analysis of circulatory systems and so on. In addition to conventional medical applications, various novel research areas have been developed and are expected to be further developed through AuNP-based X-ray imaging technologies.

Soft X-ray maps of the Large Magellanic Cloud (LMC)

NASA Technical Reports Server (NTRS)

Singh, K. P.; Nousek, J. A.; Burrows, D. N.; Garmire, G. P.

1985-01-01

Soft X-ray maps of the Large Magellanic Cloud (LMC) were obtained from scanning-observations with the HEAO-1 low energy detectors. Comparison of the 1/4 keV X-ray observations with the neutral hydrogen column densities in the LMC obtained from a 21 cm line survey, shows no evidence for absorption effects in the 1/4 keV X-ray flux from the LMC due to the neutral matter in the LMC. Instead, faint X-ray emission is detected from the LMC. The extent of this emission is smaller than the size of the halo or the disk of the LMC. Assuming this 1/4 keV emission to be diffuse, it is identified with a supergiant shell of optical nebulosity known as Shapley III, and the bar of the LMC. The X-ray luminosities of the regions are estimated to be 9 times 10 to the 38th power ergs/sec and 1.8 times 10 to the 39th power ergs/sec for the Shapley III region and the bar of the LMC respectively. Shapley III could be an X-ray superbubble.

[Contrast of Z-Pinch X-Ray Yield Measure Technique].

PubMed

Li, Mo; Wang, Liang-ping; Sheng, Liang; Lu, Yi

2015-03-01

Resistive bolometer and scintillant detection system are two mainly Z-pinch X-ray yield measure techniques which are based on different diagnostic principles. Contrasting the results from two methods can help with increasing precision of X-ray yield measurement. Experiments with different load material and shape were carried out on the "QiangGuang-I" facility. For Al wire arrays, X-ray yields measured by the two techniques were largely consistent. However, for insulating coating W wire arrays, X-ray yields taken from bolometer changed with load parameters while data from scintillant detection system hardly changed. Simulation and analysis draw conclusions as follows: (1) Scintillant detection system is much more sensitive to X-ray photons with low energy and its spectral response is wider than the resistive bolometer. Thus, results from the former method are always larger than the latter. (2) The responses of the two systems are both flat to Al plasma radiation. Thus, their results are consistent for Al wire array loads. (3) Radiation form planar W wire arrays is mainly composed of sub-keV soft X-ray. X-ray yields measured by the bolometer is supposed to be accurate because of the nickel foil can absorb almost all the soft X-ray. (4) By contrast, using planar W wire arrays, data from scintillant detection system hardly change with load parameters. A possible explanation is that while the distance between wires increases, plasma temperature at stagnation reduces and spectra moves toward the soft X-ray region. Scintillator is much more sensitive to the soft X-ray below 200 eV. Thus, although the total X-ray yield reduces with large diameter load, signal from the scintillant detection system is almost the same. (5) Both Techniques affected by electron beams produced by the loads.

Does the X-ray outflow quasar PDS 456 have a UV outflow at 0.3c?

NASA Astrophysics Data System (ADS)

Hamann, Fred; Chartas, George; Reeves, James; Nardini, Emanuele

2018-05-01

The quasar PDS 456 (at redshift ˜0.184) has a prototype ultra-fast outflow (UFO) measured in X-rays. This outflow is highly ionized with relativistic speeds, large total column densities log NH(cm-2) > 23, and large kinetic energies that could be important for feedback to the host galaxy. A UV spectrum of PDS 456 obtained with the Hubble Space Telescope in 2000 contains one well-measured broad absorption line (BAL) at ˜1346 Å (observed) that might be Ly α at v ≈ 0.06c or N V λ1240 at v ≈ 0.08c. However, we use photoionization models and comparisons to other outflow quasars to show that these BAL identifications are problematic because other lines that should accompany them are not detected. We argue that the UV BAL is probably C IV at v ≈ 0.30c. This would be the fastest UV outflow ever reported, but its speed is similar to the X-ray outflow and its appearance overall is similar to relativistic UV BALs observed in other quasars. The C IV BAL identification is also supported indirectly by the tentative detection of another broad C IV line at v ≈ 0.19c. The high speeds suggest that the UV outflow originates with the X-ray UFO crudely 20-30 rg from the central black hole. We speculate that the C IV BAL might form in dense clumps embedded in the X-ray UFO, requiring density enhancements of only ≳0.4 dex compared to clumpy structures already inferred for the soft X-ray absorber in PDS 456. The C IV BAL might therefore be the first detection of low-ionization clumps proposed previously to boost the opacities in UFOs for radiative driving.

NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mori, Kaya; Hailey, Charles J.; Perez, Kerstin

2015-12-01

We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456–2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Γ ∼ 1.3–2.3 up to ∼50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4more » keV Fe Kα fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (∼10{sup 23} cm{sup −2}), primary X-ray spectra (power-laws with Γ ∼ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to L{sub X} ≳ 10{sup 38} erg s{sup −1}. Above ∼20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95–0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses M{sub WD} ∼ 0.9 M{sub ⊙}. Spectral energy distribution analysis suggests that G359.95–0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745–290, strongly favoring a leptonic origin of the GC TeV emission.« less

X-ray motion analysis of the vertebral column during the startle response in striped bass, Morone saxatilis.

PubMed

Nowroozi, B N; Brainerd, E L

2013-08-01

Whole-body stiffness has a substantial impact on propulsive wave speed during axial undulatory locomotion in fishes. The connective tissues of the vertebral column may contribute to body stiffness, but without mechanical and kinematic analysis it is unclear whether the in vivo range of motion of intervertebral joints (IVJs) is great enough to stress IVJ tissues, thus generating stiffness. The present study used 2D videoradiography and 3D X-ray reconstruction of moving morphology (XROMM) to quantify vertebral kinematics during the startle response in striped bass (Morone saxatilis). X-ray video revealed two distinct patterns of bending: pattern I begins in the abdominal region and then proceeds to maximum IVJ angles in the caudal region, whereas pattern II begins in the cervical region and proceeds to maximum IVJ angles in the abdominal and then the caudal joints. In pattern II bends, the cervical joints exhibit a greater in vivo range of motion than previously reported in other species. XROMM analysis of caudal IVJs suggests primarily lateral bending: mean axial and dorsoventral rotations were less than 2 deg and inconsistent across 51 sequences analyzed from five individuals, whereas mean maximum lateral bending angles were 10.4±3.57 deg. These angles, combined with previous investigations of mechanical properties, reveal that the maximum angles all occur within the neutral zone of bending, indicating that little stress is experienced about the joint. This suggests that the IVJs of striped bass are quite compliant and likely do not contribute significantly to whole-body stiffness or elastic recoil during swimming in vivo.

On the radiation beaming of bright X-ray pulsars and constraints on neutron star mass-radius relation

NASA Astrophysics Data System (ADS)

Mushtukov, Alexander A.; Verhagen, Patrick A.; Tsygankov, Sergey S.; van der Klis, Michiel; Lutovinov, Alexander A.; Larchenkova, Tatiana I.

2018-03-01

The luminosity of accreting magnetized neutron stars can largely exceed the Eddington value due to appearance of accretion columns. The height of the columns can be comparable to the neutron star radius. The columns produce the X-rays detected by the observer directly and illuminate the stellar surface, which reprocesses the X-rays and causes additional component of the observed flux. The geometry of the column and the illuminated part of the surface determine the radiation beaming. Curved space-time affects the angular flux distribution. We construct a simple model of the beam patterns formed by direct and reflected flux from the column. We take into account the possibility of appearance of accretion columns, whose height is comparable to the neutron star radius. We argue that depending on the compactness of the star, the flux from the column can be either strongly amplified due to gravitational lensing, or significantly reduced due to column eclipse by the star. The eclipses of high accretion columns result in specific features in pulse profiles. Their detection can put constraints on the neutron star radius. We speculate that column eclipses are observed in X-ray pulsar V 0332+53, leading us to the conclusion of large neutron star radius in this system (˜15 km if M ˜ 1.4 M⊙). We point out that the beam pattern can be strongly affected by scattering in the accretion channel at high luminosity, which has to be taken into account in the models reproducing the pulse profiles.

X-Ray Spectra of Quasars from the ROSAT Public Archive

NASA Technical Reports Server (NTRS)

Elvis, Martin S.; West, Donald (Technical Monitor)

2000-01-01

This has been a most productive proposal. We have: (1) Found many new X-ray absorbed quasars at z>2; (2) Determined that all of these are radio-loud, favoring an intrinsic origin for the absorption; (3) Found that the one radio-quiet exception lay close to a nearby galaxy, so initiating the X-ray study of the ISM of normal galaxies via X-ray spectroscopy; (4) Discovered a class of 'red quasars', probably the tip of a large obscured population; and (5) Discovered a class of 'blank field X-ray sources'. These are a heterogeneous collection but probably include several peculiar types of active galactic nuclei (AGN). Follow-up of the 'blanks' is being undertaken under a separate ADP program. Chandra and XMM-Newton observing time for these objects has been approved. This program has produced six refereed papers and six published conference proceedings.

Radio and X-Ray Observations of SN 2006jd: Another Strongly Interacting Type IIn Supernova

NASA Technical Reports Server (NTRS)

Chandra, Poonam; Chevalier, Roger A.; Chugai, Nikolai; Fransson, Claes; Irwin, Christopher M.; Soderberg, Alicia M.; Chakraborti, Sayan; Immler, Stefan

2012-01-01

We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope and Expanded Very Large Array at X-ray wavelengths with Chandra, XMM-Newton and Swift-XRT. We assume that the radio and X-ray emitting particles are produced by shock interaction with a dense circumstellar medium. The radio emission shows an initial rise that can be attributed to free-free absorption by cool gas mixed into the nonthermal emitting region external free-free absorption is disfavored because of the shape of the rising light curves and the low gas column density inferred along the line of sight to the emission region. The X-ray luminosity implies a preshock circumstellar density approximately 10(exp 6) per cubic meter at a radius r approximately 2 x 10(exp 16) centimeter, but the column density inferred from the photoabsorption of X-rays along the line of sight suggests a significantly lower density. The implication may be an asymmetry in the interaction. The X-ray spectrum shows Fe line emission at 6.9 keV that is stronger than is expected for the conditions in the X-ray emitting gas. We suggest that cool gas mixed into the hot gas plays a role in the line emission. Our radio and X-ray data both suggest the density profile is flatter than r2 because of the slow evolution of the unabsorbed emission.

Designing the X-Ray Microcalorimeter Spectrometer for Optimal Science Return

NASA Technical Reports Server (NTRS)

Ptak, Andrew; Bandler, Simon R.; Bookbinder, Jay; Kelley, Richard L.; Petre, Robert; Smith, Randall K.; Smith, Stephen

2013-01-01

Recent advances in X-ray microcalorimeters enable a wide range of possible focal plane designs for the X-ray Microcalorimeter Spectrometer (XMS) instrument on the future Advanced X-ray Spectroscopic Imaging Observatory (AXSIO) or X-ray Astrophysics Probe (XAP). Small pixel designs (75 microns) oversample a 5-10" PSF by a factor of 3-6 for a 10 m focal length, enabling observations at both high count rates and high energy resolution. Pixel designs utilizing multiple absorbers attached to single transition-edge sensors can extend the focal plane to cover a significantly larger field of view, albeit at a cost in maximum count rate and energy resolution. Optimizing the science return for a given cost and/or complexity is therefore a non-trivial calculation that includes consideration of issues such as the mission science drivers, likely targets, mirror size, and observing efficiency. We present a range of possible designs taking these factors into account and their impacts on the science return of future large effective-area X-ray spectroscopic missions.

Scintillating Quantum Dots for Imaging X-Rays (SQDIX) for Aircraft Inspection

NASA Technical Reports Server (NTRS)

Burke, E. R.; DeHaven, S. L.; Williams, P. A.

2015-01-01

Scintillation is the process currently employed by conventional X-ray detectors to create X-ray images. Scintillating quantum dots (StQDs) or nano-crystals are novel, nanometer-scale materials that upon excitation by X-rays, re-emit the absorbed energy as visible light. StQDs theoretically have higher output efficiency than conventional scintillating materials and are more environmentally friendly. This paper will present the characterization of several critical elements in the use of StQDs that have been performed along a path to the use of this technology in wide spread X-ray imaging. Initial work on the scintillating quantum dots for imaging X-rays (SQDIX) system has shown great promise to create state-of-the-art sensors using StQDs as a sensor material. In addition, this work also demonstrates a high degree of promise using StQDs in microstructured fiber optics. Using the microstructured fiber as a light guide could greatly increase the capture efficiency of a StQDs based imaging sensor.

Characteristics of X-Ray Emission from the PFRC-2 Capacitively Coupled Plasma

NASA Astrophysics Data System (ADS)

Oliver, Richard; Pearcy, Jacob; Jandovitz, Peter; Swanson, Charles; Matteucci, Jackson; Cohen, Samuel; PFRC Team

2015-11-01

It is uncertain what causes keV X-rays emitted from the central-cell region of a cool (bulk Te ~ 4 eV), tenuous (ne ~1010 cm-3), 5 cm diameter, weakly ionized hydrogen plasma column generated in a tandem high-mirror-ratio mirror machine (PFRC-2 device) by a low-power, external, capacitively-coupled RF (27 MHz) antenna. We explored whether the energetic electrons responsible for the X-rays exist only in the central cell (ER) or also in the asymmetric mirror regions at opposite ends of the machine, as well as how the spectra compare if they do exist in both regions. To address this, we have designed, built, calibrated, installed and operated an X-ray detector system to view the PFRC-2 region near the RF antenna in one end cell (MC). We observe somewhat different X-ray spectra emanating from the two regions. The system comprises two Amptek XR-100CR detectors with moveable slits that scan across the plasma column. Further control of radial resolution (to 0.4 cm) is afforded by changing the detector-to-slit distance. Calibrations were performed with an 55Fe source. These data are being used to understand the source of the fast electrons that create the X-rays in the MC and in the ER. This work is supported by the US DOE Contract No. DE-AC02-09CH11466 and the Princeton Environmental Institute.

Multi-epoch analysis of the X-ray spectrum of the active galactic nucleus in NGC 5506

NASA Astrophysics Data System (ADS)

Sun, Shangyu; Guainazzi, Matteo; Ni, Qingling; Wang, Jingchun; Qian, Chenyang; Shi, Fangzheng; Wang, Yu; Bambi, Cosimo

2018-05-01

We present a multi-epoch X-ray spectroscopy analysis of the nearby narrow-line Seyfert I galaxy NGC 5506. For the first time, spectra taken by Chandra, XMM-Newton, Suzaku, and NuSTAR - covering the 2000-2014 time span - are analyzed simultaneously, using state-of-the-art models to describe reprocessing of the primary continuum by optical thick matter in the AGN environment. The main goal of our study is determining the spin of the supermassive black hole (SMBH). The nuclear X-ray spectrum is photoelectrically absorbed by matter with column density ≃ 3 × 1022 cm-2. A soft excess is present at energies lower than the photoelectric cut-off. Both photo-ionized and collisionally ionized components are required to fit it. This component is constant over the time-scales probed by our data. The spectrum at energies higher than 2 keV is variable. We propose that its evolution could be driven by flux-dependent changes in the geometry of the innermost regions of the accretion disk. The black hole spin in NGC ,5506 is constrained to be 0.93± _{ 0.04 }^{0.04} at 90% confidence level for one interesting parameter.

THE NuSTAR X-RAY SPECTRUM OF HERCULES X-1: A RADIATION-DOMINATED RADIATIVE SHOCK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolff, Michael T.; Wood, Kent S.; Becker, Peter A.

2016-11-10

We report on new spectral modeling of the accreting X-ray pulsar Hercules X-1. Our radiation-dominated radiative shock model is an implementation of the analytic work of Becker and Wolff on Comptonized accretion flows onto magnetic neutron stars. We obtain a good fit to the spin-phase-averaged 4–78 keV X-ray spectrum observed by the Nuclear Spectroscopic Telescope Array during a main-on phase of the Her X-1 35 day accretion disk precession period. This model allows us to estimate the accretion rate, the Comptonizing temperature of the radiating plasma, the radius of the magnetic polar cap, and the average scattering opacity parameters inmore » the accretion column. This is in contrast to previous phenomenological models that characterized the shape of the X-ray spectrum, but could not determine the physical parameters of the accretion flow. We describe the spectral fitting details and discuss the interpretation of the accretion flow physical parameters.« less

Improving Signal-to-Noise Ratio in Scanning Transmission Electron Microscopy Energy-Dispersive X-Ray (STEM-EDX) Spectrum Images Using Single-Atomic-Column Cross-Correlation Averaging.

PubMed

Jeong, Jong Seok; Mkhoyan, K Andre

2016-06-01

Acquiring an atomic-resolution compositional map of crystalline specimens has become routine practice, thus opening possibilities for extracting subatomic information from such maps. A key challenge for achieving subatomic precision is the improvement of signal-to-noise ratio (SNR) of compositional maps. Here, we report a simple and reliable solution for achieving high-SNR energy-dispersive X-ray (EDX) spectroscopy spectrum images for individual atomic columns. The method is based on standard cross-correlation aided by averaging of single-column EDX maps with modifications in the reference image. It produces EDX maps with minimal specimen drift, beam drift, and scan distortions. Step-by-step procedures to determine a self-consistent reference map with a discussion on the reliability, stability, and limitations of the method are presented here.

X-ray Emission from the Millisecond Pulsar J1012+5307

NASA Astrophysics Data System (ADS)

Halpern, J. P.; Wang, F. Y.-H.

1997-12-01

The recently discovered 5.3 ms pulsar J1012+5307 at a distance of 520 pc is in an area of the sky which is particularly deficient in absorbing gas. The column density along the line of sight is less than 7.5 x 10(19) cm(-2) , which facilitates soft X-ray observations. Halpern (1996, ApJ, 459, L9) reported a possible ROSAT PSPC detection of the pulsar in a serendipitous, off-axis observation. We have now confirmed the X-ray emission of PSR J1012+5307 in a 23 ksec observation with the ROSAT HRI. A point source is detected within 3('') of the radio position. Its count rate of 1.6 +/- 0.3 x 10(-3) s(-1) corresponds to an unbsorbed 0.1--2.4 keV flux of 6.4 x 10(-14) ergs cm(-2) s(-1) , similar to that reported previously. This counts-to-flux conversion is valid for N_H = 5 x 10(19) cm(-2) , and either a power-law spectrum of photon index 2.5 or a blackbody of kT = 0.1 keV. The implied X-ray luminosity of 2.0 x 10(30) ergs s(-1) is 5 x 10(-4) of the pulsar's spin-down power dot E, and similar to that of the nearest millisecond pulsar J0437--4715, which is nearly a twin of J1012+5307 in P and dot E. We subjected the 37 photons (and 13 background counts) within the source region to a pulsar search, but no evidence for pulsation was found. The pulsar apparently emits over a large fraction of its rotation cycle, and the absence of sharp modulation can be taken as evidence for surface thermal emission, as is favored for PSR J0437--4715 (Zavlin & Pavlov 1997, A&A, in press), rather than magnetospheric X-ray emission which is apparent in the sharp pulses of the much more energetic millisecond pulsar B1821--24 (Saito et al. 1997, ApJ, 477, L37). A further test of this interpretation will be made with a longer ROSAT observation, which will increase the number of photons collected by a factor of 5, and permit a more sensitive examination of the light curve for modulation due to emission from heated polar caps. If found, such modulation will be further evidence that surface

On Lunar Exospheric Column Densities and Solar Wind Access Beyond the Terminator from ROSAT Soft X-Ray Observations of Solar Wind Charge Exchange

NASA Technical Reports Server (NTRS)

Collier, Michael R.; Snowden, S. L.; Sarantos, M.; Benna, M.; Carter, J. A.; Cravens, T. E.; Farrell, W. M.; Fatemi, S.; Hills, H. Kent; Hodges, R. R.;

PATIENT RADIATION DOSE FROM CHEST X-RAY EXAMINATIONS IN THE WEST BANK-PALESTINE.

PubMed

Lahham, Adnan; Issa, Ahlam; ALMasri, Hussein

2018-02-01

Radiation doses to patients resulting from chest X-ray examinations were evaluated in four medical centers in the West Bank and East Jerusalem-Palestine. Absorbed organ and effective doses were calculated for a total of 428 adult male and female patients by using commercially available Monte Carlo based softwares; CALDOSE-X5 and PCXMC-2.0, and hermaphrodite mathematical adult phantoms. Patients were selected randomly from medical records in the time period from November 2014 to February 2015. A database of surveyed patients and exposure factors has been established and includes: patient's height, weight, age, gender, X-ray tube voltage, electric current (mAs), examination projection (anterior posterior (AP), posterior anterior (PA), lateral), X-ray tube filtration thickness in each X-ray equipment, anode angle, focus to skin distance and X-ray beam size. The average absorbed doses in the whole body from different projections were: 0.06, 0.07 and 0.11 mGy from AP, PA and lateral projections, respectively. The average effective dose for all surveyed patients was 0.14 mSv for all chest X-ray examinations and projections in the four investigated medical centers. The effect of projection geometry was also investigated. The average effective doses for AP, PA and lateral projections were 0.14, 0.07 and 0.22 mSv, respectively. The collective effective dose estimated for the exposed population was ~60 man-mSv. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science

PubMed Central

Mayo, Sheridan C.; Stevenson, Andrew W.; Wilkins, Stephen W.

2012-01-01

X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies. PMID:28817018

In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science.

PubMed

Mayo, Sheridan C; Stevenson, Andrew W; Wilkins, Stephen W

2012-05-24

X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies.

The 2014 X-Ray Minimum of Eta Carinae as Seen by Swift

NASA Technical Reports Server (NTRS)

Corcoran, M. F.; Liburd, J.; Morris, D.; Russell, C. M. P.; Hamaguchi, K.; Gull, T. R.; Madura, T. I.; Teodoro, M.; Moffat, A. F. J.; Richardson, N. D.

2017-01-01

We report on Swift X-ray Telescope observations of Eta Carinae ( Car), an extremely massive, long-period, highly eccentric binary obtained during the 2014.6 X-ray minimumperiastron passage. These observations show that Car may have been particularly bright in X-rays going into the X-ray minimum state, while the duration of the 2014 X-ray minimum was intermediate between the extended minima seen in 1998.0 and 2003.5 by Rossi X-Ray Timing Explorer (RXTE), and the shorter minimum in 2009.0. The hardness ratios derived from the Swift observations showed a relatively smooth increase to a peak value occurring 40.5 days after the start of the X-ray minimum, though these observations cannot reliably measure the X-ray hardness during the deepest part of the X-ray minimum when contamination by the central constant emission component is significant. By comparing the timings of the RXTE and Swift observations near the X-ray minima, we derive an updated X-ray period of P X equals 2023.7 +/- 0.7 days, in good agreement with periods derived from observations at other wavelengths, and we compare the X-ray changes with variations in the He ii lambda 4686 emission. The middle of the Deep Minimum interval, as defined by the Swift column density variations, is in good agreement with the time of periastron passage derived from the He ii 4686 line variations.

The 2014 X-Ray Minimum of η Carinae as Seen by Swift

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corcoran, M. F.; Hamaguchi, K.; Liburd, J.

We report on Swift X-ray Telescope observations of Eta Carinae ( η Car), an extremely massive, long-period, highly eccentric binary obtained during the 2014.6 X-ray minimum/periastron passage. These observations show that η Car may have been particularly bright in X-rays going into the X-ray minimum state, while the duration of the 2014 X-ray minimum was intermediate between the extended minima seen in 1998.0 and 2003.5 by Rossi X-Ray Timing Explorer ( RXTE ), and the shorter minimum in 2009.0. The hardness ratios derived from the Swift observations showed a relatively smooth increase to a peak value occurring 40.5 days aftermore » the start of the X-ray minimum, though these observations cannot reliably measure the X-ray hardness during the deepest part of the X-ray minimum when contamination by the “central constant emission” component is significant. By comparing the timings of the RXTE and Swift observations near the X-ray minima, we derive an updated X-ray period of P {sub X} = 2023.7 ± 0.7 days, in good agreement with periods derived from observations at other wavelengths, and we compare the X-ray changes with variations in the He ii 4686 emission. The middle of the “Deep Minimum” interval, as defined by the Swift column density variations, is in good agreement with the time of periastron passage derived from the He ii λ 4686 line variations.« less

The X-ray spectrum and time variability of narrow emission line galaxies

NASA Technical Reports Server (NTRS)

Mushotzky, R.

1981-01-01

X-ray spectral and temporal observations are reported for six narrow emission line galaxies (NELGs), all of which are fitted by power-law X-ray spectra of energy slope 0.8 and have column densities in the line of sight greater than 1 x 10 to the 22nd atoms/sq cm. Three of the objects, NGC 526a, NGC 2110 and MCG-5-23-16 are variable in their X-ray flux, and the latter two, along with NGC 5506 and NGC 7582, showed detectable variability in at least one observation. The measured X-ray properties of these NELGs, which also included NGC 2992, strongly resemble those of previously-measured type 1 Seyferts of the same X-ray luminosity and lead to the conclusion of great similarity between the NELGs and low-luminosity type 1 Seyferts. The implications of these observations for the optical line-emitting region structure of these galaxies are discussed.

X-ray observations of EX Hydrae with the Einstein Solid State Spectrometer

NASA Technical Reports Server (NTRS)

Singh, Jyoti; Swank, Jean

1993-01-01

Einstein SSS X-ray observations of the eclipsing intermediate polar EX Hya are presented. The SSS data have a better resolution at energies extending below 2 keV than do the EXOSAT data. These data reveal the presence of a soft component with a temperature of about 0.74 keV. The phase-resolved data can be fitted to a model of two-temperature thermal plasma with a single absorber, with the result that only the normalization varies with phase. This suggests that part of the soft component might become occulted at minimum. If we assume that the reduction in the flux occurs due to the photoelectric absorption, we find that a high-density material covering only about 40 percent of the emission can fit the data equally well. The EXOSAT and Ginga data of this source favor the accretion curtain model rather than the occultation model. We modify the accretion curtain model by assuming that the modulation is caused by an absorber which partially covers the accreting column at the minimum of the 67-min pulse. An emission line at 1.72 keV is present in the data. The equivalent width of this line varies in phase with the continuum. We associate this line with Si fluorescence.

Serendipitous Detections of XTE J1906+09 with the Rossi X-Ray Timing Explorer

NASA Technical Reports Server (NTRS)

Wilson, Colleen A.; Finger, Mark H.; Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa

2002-01-01

The 89 s X-ray pulsar XTE J1906+09 was discovered during Rossi X-Ray Timing Explorer (RXTE) observations of SGR 1900+14 in 1996. Because of monitoring campaigns of SGR 1900+14, XTE J1906+09 was also monitored regularly in 1996 September, 1998 May-June, 1998 August-1999 July, and 2000 March-2001 January. A search for pulsations resulted in detections of only the two previously reported outbursts in 1996 September and 1998 August-September. Pulsed flux upper limits for the rest of the observations show that XTE J1906+09 is a transient X-ray pulsar and likely has a Be star companion. The RXTE all-sky monitor did not reveal XTE J1906+09. Pulse-timing analysis of the second outburst discovered a sinusoidal signature in the pulse frequencies that is likely produced by an orbital periastron passage. Fits to pulse phases using an orbital model and quadratic phase model have chi(exp 2) minima at orbital periods of 26-30 days for fixed mass functions of 5, 10, 15, and 20 solar masses. The pulse shape showed energy- and intensity-dependent variations. Pulse-phase spectroscopy quantified the energy-dependent variations. The phase-averaged spectrum used the pulse minimum spectrum as the background spectrum to eliminate effects from SGR 1900+14 and the Galactic ridge and was well fitted by an absorbed power law with a high-energy cutoff with column density N(sub H) = 6 +/- 1 x 10(exp 22)/sq cm, a photon index of 1.01 +/- 0.08, cutoff energy E(sub cut) = 11 +/- 1 keV, and e-folding energy E(sub fold) = 19 +/- 4 keV. Estimated 2-10 keV peak fluxes, corrected for contributions from the Galactic ridge and SGR 1900+14, are 6 x l0(exp -12) and 1.1 x 10(exp -10) ergs/sq cm/s for the 1996 and 1998 outbursts, respectively. XTE J1906+09 may be part of an unusual class of Be/X-ray binaries that do not lie on the general spin period versus orbital period correlation with the majority of Be/X-ray binaries.

Tracking reaction dynamics in solution by pump-probe X-ray absorption spectroscopy and X-ray liquidography (solution scattering).

PubMed

Kim, Jeongho; Kim, Kyung Hwan; Oang, Key Young; Lee, Jae Hyuk; Hong, Kiryong; Cho, Hana; Huse, Nils; Schoenlein, Robert W; Kim, Tae Kyu; Ihee, Hyotcherl

2016-03-07

Characterization of transient molecular structures formed during chemical and biological processes is essential for understanding their mechanisms and functions. Over the last decade, time-resolved X-ray liquidography (TRXL) and time-resolved X-ray absorption spectroscopy (TRXAS) have emerged as powerful techniques for molecular and electronic structural analysis of photoinduced reactions in the solution phase. Both techniques make use of a pump-probe scheme that consists of (1) an optical pump pulse to initiate a photoinduced process and (2) an X-ray probe pulse to monitor changes in the molecular structure as a function of time delay between pump and probe pulses. TRXL is sensitive to changes in the global molecular structure and therefore can be used to elucidate structural changes of reacting solute molecules as well as the collective response of solvent molecules. On the other hand, TRXAS can be used to probe changes in both local geometrical and electronic structures of specific X-ray-absorbing atoms due to the element-specific nature of core-level transitions. These techniques are complementary to each other and a combination of the two methods will enhance the capability of accurately obtaining structural changes induced by photoexcitation. Here we review the principles of TRXL and TRXAS and present recent application examples of the two methods for studying chemical and biological processes in solution. Furthermore, we briefly discuss the prospect of using X-ray free electron lasers for the two techniques, which will allow us to keep track of structural dynamics on femtosecond time scales in various solution-phase molecular reactions.

Ultraviolet and X-ray Variability of the Seyfert 1.5 Galaxy Markarian 817

NASA Astrophysics Data System (ADS)

Winter, Lisa M.; Danforth, Charles; Vasudevan, Ranjan; Brandt, W. N.; Scott, Jennifer; Froning, Cynthia; Keeney, Brian; Shull, J. Michael; Penton, Steve; Mushotzky, Richard; Schneider, Donald P.; Arav, Nahum

2011-02-01

We present an investigation of the ultraviolet and X-ray spectra of the Seyfert 1.5 galaxy Markarian 817. The ultraviolet analysis includes two recent observations taken with the Cosmic Origins Spectrograph (COS) in 2009 August and December, as well as archival spectra from the International Ultraviolet Explorer and the Hubble Space Telescope. Twelve Lyα absorption features are detected in the 1997 Goddard High Resolution Spectrograph (GHRS) and 2009 COS spectra—of these, four are associated with high-velocity clouds in the interstellar medium, four are at low significance, and the remaining four are intrinsic features, which vary between the GHRS and COS observations. The strongest intrinsic absorber in the 1997 spectrum has a systemic velocity of ~-4250 km s-1. The corresponding feature in the COS data is five times weaker than the GHRS absorber. The three additional weak (equivalent width from 13 to 54 mÅ) intrinsic Lyα absorbers are at systemic velocities of -4100 km s-1, -3550 km s-1, and -2600 km s-1. However, intrinsic absorption troughs from highly ionized C IV and N V are not detected in the COS observations. No ionized absorption signatures are detected in the ~14 ks XMM-Newton EPIC spectra. The factor of five change in the intrinsic Lyα absorber is most likely due to bulk motions in the absorber, since there is no drastic change in the UV luminosity of the source from the GHRS to the COS observations. In a study of the variability of Mrk 817, we find that the X-ray luminosity varies by a factor of ~40 over 20 years, while the UV continuum/emission lines vary by at most a factor of ~2.3 over 30 years. The variability of the X-ray luminosity is strongly correlated with the X-ray power-law index, but no correlation is found with the simultaneous optical/UV photometry.

Fabrication of X-ray Microcalorimeter Focal Planes Composed of Two Distinct Pixel Types

NASA Technical Reports Server (NTRS)

Wassell, Edward J.; Adams, Joseph S.; Bandler, Simon R.; Betancour-Martinez, Gabriele L; Chiao, Meng P.; Chang, Meng Ping; Chervenak, James A.; Datesman, Aaron M.; Eckart, Megan E.; Ewin, Audrey J.;

Diagnostic x-ray dosimetry using Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Ioppolo, J. L.; Price, R. I.; Tuchyna, T.; Buckley, C. E.

2002-05-01

An Electron Gamma Shower version 4 (EGS4) based user code was developed to simulate the absorbed dose in humans during routine diagnostic radiological procedures. Measurements of absorbed dose using thermoluminescent dosimeters (TLDs) were compared directly with EGS4 simulations of absorbed dose in homogeneous, heterogeneous and anthropomorphic phantoms. Realistic voxel-based models characterizing the geometry of the phantoms were used as input to the EGS4 code. The voxel geometry of the anthropomorphic Rando phantom was derived from a CT scan of Rando. The 100 kVp diagnostic energy x-ray spectra of the apparatus used to irradiate the phantoms were measured, and provided as input to the EGS4 code. The TLDs were placed at evenly spaced points symmetrically about the central beam axis, which was perpendicular to the cathode-anode x-ray axis at a number of depths. The TLD measurements in the homogeneous and heterogenous phantoms were on average within 7% of the values calculated by EGS4. Estimates of effective dose with errors less than 10% required fewer numbers of photon histories (1 × 107) than required for the calculation of dose profiles (1 × 109). The EGS4 code was able to satisfactorily predict and thereby provide an instrument for reducing patient and staff effective dose imparted during radiological investigations.

Close-packed Arrays of Transition-edge X-ray Microcalorimeters with High Spectral Resolution at 5.9 keV

NASA Technical Reports Server (NTRS)

Iyomoto, N.; Bandler, S. R.; Brekosky, R. P.; Brown, A.-D.; Chervenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.;

Symbiotic Stars in X-rays. II. Faint Sources Detected with XMM-Newton and Chandra

NASA Technical Reports Server (NTRS)

Nunez, N. E.; Luna, G. J. M.; Pillitteri, I.; Mukai, K.

2014-01-01

We report the detection from four symbiotic stars that were not known to be X-ray sources. These four object show a ß-type X-ray spectrum, that is, their spectra can be modeled with an absorbed optically thin thermal emission with temperatures of a few million degrees. Photometric series obtained with the Optical Monitor on board XMM-Newton from V2416 Sgr and NSV 25735 support the proposed scenario where the X-ray emission is produced in a shock-heated region inside the symbiotic nebulae.

Soft X-ray production by photon scattering in pulsating binary neutron star sources

NASA Technical Reports Server (NTRS)

Bussard, R. W.; Meszaros, P.; Alexander, S.

1985-01-01

A new mechanism is proposed as a source of soft (less than 1 keV) radiation in binary pulsating X-ray sources, in the form of photon scattering which leaves the electron in an excited Landau level. In a plasma with parameters typical of such sources, the low-energy X-ray emissivity of this mechanism far exceeds that of bremsstrahlung. This copious source of soft photons is quite adequate to provide the seed photons needed to explain the power-law hard X-ray spectrum by inverse Comptonization on the hot electrons at the base of the accretion column.

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

NASA Astrophysics Data System (ADS)

Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Filkins, T.; Steidle, Jeffrey A.; Steidle, Jessica A.; Traynor, N.; Freeman, C.

2015-12-01

The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1-100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5-9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.

The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protonsmore » with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. Furthermore, the impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.« less

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinderknecht, H. G., E-mail: rinderknecht1@llnl.gov; Rojas-Herrera, J.; Zylstra, A. B.

The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protonsmore » with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.« less

Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

DOE PAGES

Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.; ...

2015-12-23

The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protonsmore » with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. Furthermore, the impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.« less

High Resolution X-Ray Absorption Spectroscopy: Distribution of Matter in and around Galaxies

NASA Astrophysics Data System (ADS)

Schulz, Norbert; MIT/CAT Team

2015-10-01

The chemical evolution of the Universe embraces aspects that reachdeep into modern astrophysics and cosmology. We want to know how present and past matter is affected by various levels and types of nucleo-synthesis and stellar evolution. Three major categories were be identified: 1. The study of pre-mordial star formation including periods of super-massive black hole formation, 2. The embedded evolution of the intergalactic medium IGM, 3. The status and evolution of stars and the interstellar medium ISM in galaxies. Today a fourth category relates to our understanding of dark matter in relationwith these three categories. The X-ray band is particularly sensitive to K- and L-shell absorption and scattering from high abundant elements like C, N, O, Ne, Mg, Si, S,Ar, Ca, Fe, and Ni. Like the Lyman alpha forest in the optical band, absorbers in the IGM produce an X-ray line forest along the line of sight in the X-rayspectrum of a background quasar. Similary bright X-ray sources within galaxies and the Milky Way produce a continuum, which is being absorbed by elements invarious phases of the ISM. High resolution X-ray absorption surveys are possible with technologies ready for flight within decade. == high efficiency X-ray optics with optical performance 3== high resolution X-ray gratings with R 3000 for E 1.5 keV== X-ray micro-calorimeters with R 2000 for E 1.5 keV. The vision for the next decade needs to lead to means and strategies which allows us to perform such absorption surveys as effectively as surveys are now or in very near future quite common in astronomy pursued in other wave length bands such as optical, IR, and sub-mm.

The X-ray Spectra of Accreting Pulsars: Studies of Three Sources Using Empirical and Phenomenological Models

NASA Astrophysics Data System (ADS)

Hemphill, Paul Britton

Accreting X-ray pulsars are a class of astrophysical objects consisting of a neutron star in a binary system with a stellar companion. Matter expelled by the companion star is captured by the neutron star's gravity; as this matter falls towards the neutron star's surface, is compressed and heated, giving off X-rays. As the matter falls the last few miles above the neutron star surface, a number of physical processes compete for dominance, resulting in a highly complex environment governed by the interplay of magnetic, hydrodynamical, and radiative processes. The resulting spectrum often shows broad absorption-like features called cyclotron lines, which provide the only direct measurement of the magnetic field of a neutron star and act as probes of the properties of the accretion column, and their behavior with respect to changes in the accretion rate onto the neutron star has been of interest in recent years. My work in this dissertation brings together nearly 20 years of data from three X-ray satellites to study the X-ray emission from accreting pulsars, with a focus on the hard X-ray continuum and cyclotron lines. I present results for the accreting pulsars 4U 1538-522 and 4U 1907+09, examining the behavior of their cyclotron lines with respect to their luminosity, finding evidence for a positive correlation between the line energy and luminosity in 4U 1907+09. A combined analysis of most of the available X-ray data for the accreting pulsar 4U 1538-522 shows no such correlation in this source, either positive or negative. However, I do present evidence that the cyclotron line energy in 4U 1538-522 has shifted upwards by ˜ 5% in recent years compared to measurements from 10-20 years ago. I additionally carry out an extensive analysis of the environment around 4U 1538-522 using the soft X-ray detectors aboard the satellite Suzaku. I finally present a set of new results from the transient X-ray pulsar V 0332+53, which I fit with a new physics-based model for the

A compact and modular x- and gamma-ray detector with a CsI scintillator and double-readout Silicon Drift Detectors

NASA Astrophysics Data System (ADS)

Campana, R.; Fuschino, F.; Labanti, C.; Marisaldi, M.; Amati, L.; Fiorini, M.; Uslenghi, M.; Baldazzi, G.; Bellutti, P.; Evangelista, Y.; Elmi, I.; Feroci, M.; Ficorella, F.; Frontera, F.; Picciotto, A.; Piemonte, C.; Rachevski, A.; Rashevskaya, I.; Rignanese, L. P.; Vacchi, A.; Zampa, G.; Zampa, N.; Zorzi, N.

2016-07-01

A future compact and modular X and gamma-ray spectrometer (XGS) has been designed and a series of proto- types have been developed and tested. The experiment envisages the use of CsI scintillator bars read out at both ends by single-cell 25 mm2 Silicon Drift Detectors. Digital algorithms are used to discriminate between events absorbed in the Silicon layer (lower energy X rays) and events absorbed in the scintillator crystal (higher energy X rays and -rays). The prototype characterization is shown and the modular design for future experiments with possible astrophysical applications (e.g. for the THESEUS mission proposed for the ESA M5 call) are discussed.

Levels of 2-dodecylcyclobutanone in ground beef patties irradiated by low-energy X-ray and gamma rays.

PubMed

Hijaz, Faraj M; Smith, J Scott

2010-01-01

Food irradiation improves food safety and maintains food quality by controlling microorganisms and extending shelf life. However, acceptance and commercial adoption of food irradiation is still low. Consumer groups such as Public Citizen and the Food and Water Watch have opposed irradiation because of the formation of 2-alkylcyclobutanones (2-ACBs) in irradiated, lipid-containing foods. The objectives of this study were to measure and to compare the level of 2-dodecylcyclobutanone (2-DCB) in ground beef irradiated by low-energy X-rays and gamma rays. Beef patties were irradiated by low-energy X-rays and gamma rays (Cs-137) at 3 targeted absorbed doses of 1.5, 3.0, and 5.0 kGy. The samples were extracted with n-hexane using a Soxhlet apparatus, and the 2-DCB concentration was determined with gas chromatography-mass spectrometry. The 2-DCB concentration increased linearly (P < 0.05) with irradiation dose for gamma-ray and low-energy X-ray irradiated patties. There was no significant difference in 2-DCB concentration between gamma-ray and low-energy X-ray irradiated patties (P > 0.05) at all targeted doses. © 2010 Institute of Food Technologists®

Searching for outflows in ultraluminous X-ray sources through high-resolution X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Kosec, P.; Pinto, C.; Fabian, A. C.; Walton, D. J.

2018-02-01

Ultraluminous X-ray sources (ULXs) are non-nuclear point sources exceeding the Eddington luminosity of a 10 M⊙ black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or neutron stars accreting well above the Eddington limit. Theoretical models of super-Eddington accretion predict existence of powerful outflows of moderately ionized gas at mildly relativistic velocities. So far, these winds have been found in three systems: NGC 1313 X-1, NGC 5408 X-1 and NGC 55 ULX. In this work, we create a sample of all ULXs with usable archival high-resolution X-ray data, with 10 sources in total, in which we aim to find more signatures of outflows. We perform Gaussian line scans to find any narrow spectral signatures, and physical wind model scans where possible. We tentatively identify an outflow in NGC 5204 X-1, blueshifted to 0.34c, which produces emission features with a total significance of at least 3σ. Next we compare ULXs with similar hardness ratios. Holmberg IX X-1 shows absorption features that could be associated with a photoionized outflowing absorber, similar to that seen in NGC 1313 X-1. The spectrum of Holmberg II X-1 possesses features similar to NGC 5408 X-1 and NGC 6946 X-1 shows O VIII rest-frame emission. All other sources from the sample also show tentative evidence of spectral features in their high-resolution spectra. Further observations with the XMM-Newton and Chandra gratings will place stronger constraints. Future missions like XARM and Athena will be able to detect them at larger distances and increase our sample.

Supergiant X-Ray Binaries Observed by Suzaku

NASA Technical Reports Server (NTRS)

Bodaghee, A.; Tomsick, J. A.; Rodriquez, J.; Chaty, S.; Pottschmidt, K.; Walter, R.; Romano, P.

2011-01-01

Suzaku observations are presented for the high-mass X-ray binaries IGR 116207-5129 and IGR 117391-3021. For IGR 116207-5129, we provide the first X-ray broadband (0.5-60 keV) spectrum from which we confirm a large intrinsic column density (N(sub H) = 1.6 x 10(exp 23)/sq cm), and we constrain the cutoff energy for the first time (E(sub cut) = 19 keV). A prolonged (> 30 ks) attenuation of the X-ray flux was observed which we tentatively attribute to an eclipse of the probable neutron star by its massive companion, in a binary system with an orbital period between 4 and 9 days, and inclination angles> 50 degrees. For IGRJ17391-3021, we witnessed a transition from quiescence to a low-activity phase punctuated by weak flares whose peak luminosities in the 0.5-10keV band are only a factor of 5 times that of the pre-flare emission. These micro flares are accompanied by an increase in NH which suggests the accretion of obscuring clumps of wind. We now recognize that these low-activity epochs constitute the most common emission phase for this system, and perhaps in other supergiant fast X-ray transients (SFXTs) as well. We close with an overview of our upcoming program in which Suzaku will provide the first ever observation of an SFXT (IGRJ16479-4514) during a binary orbit enabling us to probe the accretion wind at every phase.

Macrophage and tumor cell responses to repetitive pulsed X-ray radiation

NASA Astrophysics Data System (ADS)

Buldakov, M. A.; Tretyakova, M. S.; Ryabov, V. B.; Klimov, I. A.; Kutenkov, O. P.; Kzhyshkowska, J.; Bol'shakov, M. A.; Rostov, V. V.; Cherdyntseva, N. V.

2017-05-01

To study a response of tumor cells and macrophages to the repetitive pulsed low-dose X-ray radiation. Methods. Tumor growth and lung metastasis of mice with an injected Lewis lung carcinoma were analysed, using C57Bl6. Monocytes were isolated from a human blood, using CD14+ magnetic beads. IL6, IL1-betta, and TNF-alpha were determined by ELISA. For macrophage phenotyping, a confocal microscopy was applied. “Sinus-150” was used for the generation of pulsed X-ray radiation (the absorbed dose was below 0.1 Gy, the pulse repetition frequency was 10 pulse/sec). The irradiation of mice by 0.1 Gy pulsed X-rays significantly inhibited the growth of primary tumor and reduced the number of metastatic colonies in the lung. Furthermore, the changes in macrophage phenotype and cytokine secretion were observed after repetitive pulsed X-ray radiation. Conclusion. Macrophages and tumor cells had a different response to a low-dose pulsed X-ray radiation. An activation of the immune system through changes of a macrophage phenotype can result in a significant antitumor effect of the low-dose repetitive pulsed X-ray radiation.

Columnar recombination for X-ray generated electron-holes in amorphous selenium and its significance in a-Se x-ray detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bubon, O.; Thunder Bay Regional Research Institute, Thunder Bay, Ontario, P7A 7T1; Jandieri, K.

Although amorphous selenium (a-Se) has a long and successful history of application in optical and X-ray imaging, some of its fundamental properties are still puzzling. In particularly, the mechanism of carrier recombination following x-ray excitation and electric field and temperature dependences of the electron-hole pair creation energy (W{sub ehp}) remain unclear. Using the combination of X-ray photocurrent and pulse height spectroscopy measurements, we measure W{sub ehp} in a wide range of temperatures (218–320 K) and electric fields (10–100 V/µm) and show that the conventional columnar recombination model which assumes Langevin recombination within a column (a primary electron track) fails to explain experimentalmore » results in a wide range of electric fields and temperatures. The reason for the failure of the conventional model is revealed in this work, and the theory of the columnar recombination is modified to include the saturation of the recombination rate at high electric field in order to account for the experimental results in the entire range of fields and temperatures.« less

Prediction and Measurement of X-Ray Spectral and Intensity Distributions from Low Energy Electron Impact Sources

NASA Technical Reports Server (NTRS)

Edwards, David L.

1999-01-01

In-vacuum electron beam welding is a technology that NASA considered as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. The radiation exposure to astronauts performing the in-vacuum electron beam welding must be characterized and minimized to insure safe operating conditions. This investigation characterized the x-ray environment due to operation of an in-vacuum electron beam welding tool. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests consisted of Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) and exposed to x-ray radiation generated by operation of an in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 KeV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by electron impact with metal. These x-ray spectra were used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the in-vacuum electron beam welding tool. The calculated absorbed dose

Overview of the Chandra X-Ray Observatory Facility

NASA Technical Reports Server (NTRS)

Weisskopf, M. C.; Six, N. Frank (Technical Monitor)

2002-01-01

The Chandra X-Ray Observatory (originally called the Advanced X-Ray Astrophysics Facility - AXAF) is the X-Ray component of NASA's "Great Observatory" Program. Chandra is a NASA facility that provides scientific data to the international astronomical community in response to scientific proposals for its use. The Observatory is the product of the efforts of many organizations in the United States and Europe. The Great Observatories also include the Hubble Space Telescope for space-based observations of astronomical objects primarily in the visible portion of the electromagnetic spectrum, the now defunct Compton Gamma- Ray Observatory that was designed to observe gamma-ray emission from astronomical objects, and the soon-to-be-launched Space Infrared Telescope Facility (SIRTF). The Chandra X-Ray Observatory (hereafter CXO) is sensitive to X-rays in the energy range from below 0.1 to above 10.0 keV corresponding to wavelengths from 12 to 0.12 nanometers. The relationship among the various parts of the electromagnetic spectrum, sorted by characteristic temperature and the corresponding wavelength, is illustrated. The German physicist Wilhelm Roentgen discovered what he thought was a new form of radiation in 1895. He called it X-radiation to summarize its properties. The radiation had the ability to pass through many materials that easily absorb visible light and to free electrons from atoms. We now know that X-rays are nothing more than light (electromagnetic radiation) but at high energies. Light has been given many names: radio waves, microwaves, infrared, visible, ultraviolet, X-ray and gamma radiation are all different forms. Radio waves are composed of low energy particles of light (photons). Optical photons - the only photons perceived by the human eye - are a million times more energetic than the typical radio photon, whereas the energies of X-ray photons range from hundreds to thousands of times higher than that of optical photons. Very low temperature systems

Hematite from Natural Iron Stones as Microwave Absorbing Material on X-Band Frequency Ranges

NASA Astrophysics Data System (ADS)

Zainuri, Mochamad

2017-05-01

This study has been investigated the effect of hematite as microwave absorbing materials (RAM) on X-Band frequency ranges. Hematite was succesfully processed by coprecipitation method and calcined at 500 °C for 5 hour. It was synthesized from natural iron stones from Tanah Laut, South Kalimantan, Indonesia. The products were characterized by X-ray diffraxtion (XRD), conductivity measurement, Vibrating Sample Magnetometer (VSM), and Vector Network Analyzer (VNA). The result was shown that hematite has conductivity value on (2.5-3).10-7 S/cm and be included as dielectric materials. The hysterisis curve was shown that hematite was a super paramagnetic materials. The product was mixed on paint with procentage 10% of total weight and coated on steel grade AH36 with spray methods. Then, the maximum of reflection loss on x - band’s frequency range (8,2-12,4) GHz was -7 dB on frequency of 10.5 GHz. It mean that almost 50% electromagnetic energy was absorbed by hematite.

The NuSTAR Extragalactic Survey: Average Broadband X-Ray Spectral Properties of the NuSTAR-detected AGNs

NASA Astrophysics Data System (ADS)

Del Moro, A.; Alexander, D. M.; Aird, J. A.; Bauer, F. E.; Civano, F.; Mullaney, J. R.; Ballantyne, D. R.; Brandt, W. N.; Comastri, A.; Gandhi, P.; Harrison, F. A.; Lansbury, G. B.; Lanz, L.; Luo, B.; Marchesi, S.; Puccetti, S.; Ricci, C.; Saez, C.; Stern, D.; Treister, E.; Zappacosta, L.

2017-11-01

We present a study of the average X-ray spectral properties of the sources detected by the NuSTAR extragalactic survey, comprising observations of the Extended Chandra Deep Field South (E-CDFS), Extended Groth Strip (EGS), and the Cosmic Evolution Survey (COSMOS). The sample includes 182 NuSTAR sources (64 detected at 8-24 keV), with 3-24 keV fluxes ranging between {f}3{--24{keV}}≈ {10}-14 and 6 × 10-13 erg cm-2 s-1 ({f}8{--24{keV}}≈ 3× {10}-14{--}3× {10}-13 erg cm-2 s-1) and redshifts in the range of z=0.04{--}3.21. We produce composite spectra from the Chandra + NuSTAR data (E≈ 2{--}40 {keV}, rest frame) for all the sources with redshift identifications (95%) and investigate the intrinsic, average spectra of the sources, divided into broad-line (BL) and narrow-line (NL) active galactic nuclei (AGNs), and also in different bins of X-ray column density and luminosity. The average power-law photon index for the whole sample is {{Γ }}={1.65}-0.03+0.03, flatter than the {{Γ }}≈ 1.8 typically found for AGNs. While the spectral slope of BL and X-ray unabsorbed AGNs is consistent with the typical values ({{Γ }}={1.79}-0.01+0.01), a significant flattening is seen in NL AGNs and heavily absorbed sources ({{Γ }}={1.60}-0.05+0.08 and {{Γ }}={1.38}-0.12+0.12, respectively), likely due to the effect of absorption and to the contribution from the Compton reflection component to the high-energy flux (E> 10 keV). We find that the typical reflection fraction in our spectra is R≈ 0.5 (for {{Γ }}=1.8), with a tentative indication of an increase of the reflection strength with X-ray column density. While there is no significant evidence for a dependence of the photon index on X-ray luminosity in our sample, we find that R decreases with luminosity, with relatively high levels of reflection (R≈ 1.2) for {L}10{--40{keV}}< {10}44 erg s-1 and R≈ 0.3 for {L}10{--40{keV}}> {10}44 erg s-1 AGNs, assuming a fixed spectral slope of {{Γ }}=1.8.

Fabrication of X-ray Microcalorimeter Focal Planes Composed of Two Distinct Pixel Types.

PubMed

Wassell, E J; Adams, J S; Bandler, S R; Betancourt-Martinez, G L; Chiao, M P; Chang, M P; Chervenak, J A; Datesman, A M; Eckart, M E; Ewin, A J; Finkbeiner, F M; Ha, J Y; Kelley, R; Kilbourne, C A; Miniussi, A R; Sakai, K; Porter, F; Sadleir, J E; Smith, S J; Wakeham, N A; Yoon, W

2017-06-01

We are developing superconducting transition-edge sensor (TES) microcalorimeter focal planes for versatility in meeting specifications of X-ray imaging spectrometers including high count-rate, high energy resolution, and large field-of-view. In particular, a focal plane composed of two sub-arrays: one of fine-pitch, high count-rate devices and the other of slower, larger pixels with similar energy resolution, offers promise for the next generation of astrophysics instruments, such as the X-ray Integral Field Unit (X-IFU) instrument on the European Space Agency's Athena mission. We have based the sub-arrays of our current design on successful pixel designs that have been demonstrated separately. Pixels with an all gold X-ray absorber on 50 and 75 micron scales where the Mo/Au TES sits atop a thick metal heatsinking layer have shown high resolution and can accommodate high count-rates. The demonstrated larger pixels use a silicon nitride membrane for thermal isolation, thinner Au and an added bismuth layer in a 250 micron square absorber. To tune the parameters of each sub-array requires merging the fabrication processes of the two detector types. We present the fabrication process for dual production of different X-ray absorbers on the same substrate, thick Au on the small pixels and thinner Au with a Bi capping layer on the larger pixels to tune their heat capacities. The process requires multiple electroplating and etching steps, but the absorbers are defined in a single ion milling step. We demonstrate methods for integrating heatsinking of the two types of pixel into the same focal plane consistent with the requirements for each sub-array, including the limiting of thermal crosstalk. We also discuss fabrication process modifications for tuning the intrinsic transition temperature (T c ) of the bilayers for the different device types through variation of the bilayer thicknesses. The latest results on these "hybrid" arrays will be presented.

Fabrication of X-ray Microcalorimeter Focal Planes Composed of Two Distinct Pixel Types

PubMed Central

Wassell, E. J.; Adams, J. S.; Bandler, S. R.; Betancourt-Martinez, G. L.; Chiao, M. P.; Chang, M. P.; Chervenak, J. A.; Datesman, A. M.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Ha, J. Y.; Kelley, R.; Kilbourne, C. A.; Miniussi, A. R.; Sakai, K.; Porter, F.; Sadleir, J. E.; Smith, S. J.; Wakeham, N. A.; Yoon, W.

2017-01-01

We are developing superconducting transition-edge sensor (TES) microcalorimeter focal planes for versatility in meeting specifications of X-ray imaging spectrometers including high count-rate, high energy resolution, and large field-of-view. In particular, a focal plane composed of two sub-arrays: one of fine-pitch, high count-rate devices and the other of slower, larger pixels with similar energy resolution, offers promise for the next generation of astrophysics instruments, such as the X-ray Integral Field Unit (X-IFU) instrument on the European Space Agency’s Athena mission. We have based the sub-arrays of our current design on successful pixel designs that have been demonstrated separately. Pixels with an all gold X-ray absorber on 50 and 75 micron scales where the Mo/Au TES sits atop a thick metal heatsinking layer have shown high resolution and can accommodate high count-rates. The demonstrated larger pixels use a silicon nitride membrane for thermal isolation, thinner Au and an added bismuth layer in a 250 micron square absorber. To tune the parameters of each sub-array requires merging the fabrication processes of the two detector types. We present the fabrication process for dual production of different X-ray absorbers on the same substrate, thick Au on the small pixels and thinner Au with a Bi capping layer on the larger pixels to tune their heat capacities. The process requires multiple electroplating and etching steps, but the absorbers are defined in a single ion milling step. We demonstrate methods for integrating heatsinking of the two types of pixel into the same focal plane consistent with the requirements for each sub-array, including the limiting of thermal crosstalk. We also discuss fabrication process modifications for tuning the intrinsic transition temperature (Tc) of the bilayers for the different device types through variation of the bilayer thicknesses. The latest results on these “hybrid” arrays will be presented. PMID:28804229

A study of coronal X-ray emission from short-period Algol binaries

NASA Technical Reports Server (NTRS)

Singh, K. P.; Drake, S. A.; White, N. E.

1995-01-01

A study of X-ray emission from five short-period Algol-type binaries based on observations with Advanced Satellite for Cosmology and Astrophysics (ASCA) and ROSAT is presented. We have observed RZ Cas with both satellites, and beta Per, U Cep, delta Lib, and TW Dra with ROSAT. Significant intensity variations are seen in the X-ray emission from RZ Cas, U Cep, TW Dra, and delta Lib. These variations seem unrelated to the eclipsing behavior of these systems and are probably due to either rotational modulation of compact active regions on the surfaces of the chromospherically active secondary components or to flaring activity in the systems. The spectra of all but one of the systems require the presence of at least two discrete plasma components with different temperatures (0.6 - 0.7 keV, and approximately 2 keV) and the abundances of the medium-Z elements 20% - 50% of the solar photospheric values. The high resolving power and signal-to-noise ratio of the ASCA spectra allow us to individually constrain the coronal abundances of O, Ne, Mg, Si, S, and Fe in RZ Cas. We demonstrate that, if we use the elemental abundances and temperatures obtained from the analysis of their ASCA spectra as (fixed) inputs, to fit the ROSAT PSPC spectra well requires the presence of a third component (kT approximately 0.2 - 0.3 keV) in RZ Cas and beta Per. A continuous emission measure model of the power-law type (EM(T) variesas (T/T(sub max)(sup alpha)) generally gives a poor fit to the ASCA and ROSAT data on most sources. Circumstellar or circumbinary absorbing matter seems to be present in some of these systems, as indicated by the variable total column density needed to fit their X-ray spectra.

SN 2005ip: A Luminous Type IIn Supernova Emerging from a Dense Circumstellar Medium as Revealed by X-Ray Observations

NASA Astrophysics Data System (ADS)

Katsuda, Satoru; Maeda, Keiichi; Nozawa, Takaya; Pooley, David; Immler, Stefan

2014-01-01

We report on the X-ray spectral evolution of the nearby Type IIn supernova (SN) 2005ip based on Chandra and Swift observations covering ~1-6 yr after explosion. X-ray spectra in all epochs are well fitted by a thermal emission model with kT >~ 7 keV. The somewhat high temperature suggests that the X-ray emission mainly arises from the circumstellar medium (CSM) heated by the forward shock. We find that the spectra taken two to three years after the explosion are heavily absorbed (N H ~ 5 × 1022 cm-2), but the absorption gradually decreases to the level of the Galactic absorption (N H ~ 4 × 1020 cm-2) at the final epoch. This indicates that the SN went off in a dense CSM and that the forward shock has overtaken it. The intrinsic X-ray luminosity stays constant until the final epoch, when it drops by a factor of ~2. The intrinsic 0.2-10 keV luminosity during the plateau phase is measured to be ~1.5 × 1041 erg s-1, ranking SN 2005ip as one of the brightest X-ray SNe. Based on the column density, we derive a lower limit of a mass-loss rate to be \\dot{M}˜ 1.5× 10-2 (Vw /100 km s-1) M ⊙ yr-1, which roughly agrees with that inferred from the X-ray luminosity, \\dot{M}˜ 2× 10-2 (Vw /100 km s-1) M ⊙ yr-1, where Vw is the circumstellar wind speed. Such a high mass-loss rate suggests that the progenitor star had eruptive mass ejections similar to a luminous blue variable star. The total mass ejected in the eruptive period is estimated to be ~15 M ⊙, indicating that the progenitor mass is >~ 25 M ⊙.

Determination of absorbed dose to water from a miniature kilovoltage x-ray source using a parallel-plate ionization chamber

NASA Astrophysics Data System (ADS)

Watson, Peter G. F.; Popovic, Marija; Seuntjens, Jan

2018-01-01

Electronic brachytherapy sources are widely accepted as alternatives to radionuclide-based systems. Yet, formal dosimetry standards for these devices to independently complement the dose protocol provided by the manufacturer are lacking. This article presents a formalism for calculating and independently verifying the absorbed dose to water from a kV x-ray source (The INTRABEAM System) measured in a water phantom with an ionization chamber calibrated in terms of air-kerma. This formalism uses a Monte Carlo (MC) calculated chamber conversion factor, CQ , to convert air-kerma in a reference beam to absorbed dose to water in the measurement beam. In this work CQ was determined for a PTW 34013 parallel-plate ionization chamber. Our results show that CQ was sensitive to the chamber plate separation tolerance, with differences of up to 15%. CQ was also found to have a depth dependence which varied with chamber plate separation (0 to 10% variation for the smallest and largest cavity height, over 3 to 30 mm depth). However for all chamber dimensions investigated, CQ was found to be significantly larger than the manufacturer reported value, suggesting that the manufacturer recommended method of dose calculation could be underestimating the dose to water.

The X-Ray and Mid-infrared Luminosities in Luminous Type 1 Quasars

NASA Astrophysics Data System (ADS)

Chen, Chien-Ting J.; Hickox, Ryan C.; Goulding, Andrew D.; Stern, Daniel; Assef, Roberto; Kochanek, Christopher S.; Brown, Michael J. I.; Harrison, Chris M.; Hainline, Kevin N.; Alberts, Stacey; Alexander, David M.; Brodwin, Mark; Del Moro, Agnese; Forman, William R.; Gorjian, Varoujan; Jones, Christine; Murray, Stephen S.; Pope, Alexandra; Rovilos, Emmanouel

2017-03-01

Several recent studies have reported different intrinsic correlations between the active galactic nucleus (AGN) mid-IR luminosity ({L}MIR}) and the rest-frame 2–10 keV luminosity (L X) for luminous quasars. To understand the origin of the difference in the observed {L}{{X}}{--}{L}MIR} relations, we study a sample of 3247 spectroscopically confirmed type 1 AGNs collected from Boötes, XMM-COSMOS, XMM-XXL-North, and the Sloan Digital Sky Survey quasars in the Swift/XRT footprint spanning over four orders of magnitude in luminosity. We carefully examine how different observational constraints impact the observed {L}{{X}}{--}{L}MIR} relations, including the inclusion of X-ray-nondetected objects, possible X-ray absorption in type 1 AGNs, X-ray flux limits, and star formation contamination. We find that the primary factor driving the different {L}{{X}}{--}{L}MIR} relations reported in the literature is the X-ray flux limits for different studies. When taking these effects into account, we find that the X-ray luminosity and mid-IR luminosity (measured at rest-frame 6 μ {{m}}, or {L}6μ {{m}}) of our sample of type 1 AGNs follow a bilinear relation in the log–log plane: {log}{L}{{X}}=(0.84+/- 0.03)× {log}{L}6μ {{m}}/{10}45 erg s‑1 + (44.60 ± 0.01) for {L}6μ {{m}}< {10}44.79 erg s‑1, and {log}{L}{{X}}=(0.40+/- 0.03)× {log}{L}6μ {{m}}/{10}45 erg s‑1 + (44.51 ± 0.01) for {L}6μ {{m}} ≥slant {10}44.79 erg s‑1. This suggests that the luminous type 1 quasars have a shallower {L}{{X}}{--}{L}6μ {{m}} correlation than the approximately linear relations found in local Seyfert galaxies. This result is consistent with previous studies reporting a luminosity-dependent {L}{{X}}{--}{L}MIR} relation and implies that assuming a linear {L}{{X}}{--}{L}6μ {{m}} relation to infer the neutral gas column density for X-ray absorption might overestimate the column densities in luminous quasars.

NuSTAR Hard X-Ray Observation of the Gamma-Ray Binary Candidate HESS J1832-093

NASA Astrophysics Data System (ADS)

Mori, Kaya; Gotthelf, E. V.; Hailey, Charles J.; Hord, Ben J.; de Oña Wilhelmi, Emma; Rahoui, Farid; Tomsick, John A.; Zhang, Shuo; Hong, Jaesub; Garvin, Amani M.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Harrison, Fiona A.; Stern, Daniel; Zhang, William W.

2017-10-01

We present a hard X-ray observation of the TeV gamma-ray binary candidate HESS J1832-093, which is coincident with the supernova remnant G22.7-0.2, using the Nuclear Spectroscopic Telescope Array. Non-thermal X-ray emission from XMMU J183245-0921539, the X-ray source associated with HESS J1832-093, is detected up to ˜30 keV and is well-described by an absorbed power-law model with a best-fit photon index {{Γ }}=1.5+/- 0.1. A re-analysis of archival Chandra and XMM-Newton data finds that the long-term X-ray flux increase of XMMU J183245-0921539 is {50}-20+40 % (90% C.L.), much less than previously reported. A search for a pulsar spin period or binary orbit modulation yields no significant signal to a pulse fraction limit of {f}p< 19 % in the range 4 ms < P< 40 ks. No red noise is detected in the FFT power spectrum to suggest active accretion from a binary system. While further evidence is required, we argue that the X-ray and gamma-ray properties of XMMU J183245-0921539 are most consistent with a non-accreting binary generating synchrotron X-rays from particle acceleration in the shock formed as a result of the pulsar and stellar wind collision. We also report on three nearby hard X-ray sources, one of which may be associated with diffuse emission from a fast-moving supernova fragment interacting with a dense molecular cloud.

High-Resolution X-Ray Spectra of the Symbiotic Star SS73 17

NASA Technical Reports Server (NTRS)

Eze, R. N. C.; Luna, G. J. M.; Smith, R. K.

2010-01-01

SS73 17 was an innocuous Mira-type symbiotic star until the International Gamma-Ray Astrophysics Laboratory and Swift discovered its bright hard X-ray emission, adding it to the small class of "hard X-ray emitting symbiotics." Suzaku observations in 2006 then showed it emits three bright iron lines as well, with little to no emission in the 0.3-2.0 keV bandpass. We present here follow-up observations with the Chandra High Energy Transmission Grating and Suzaku that confirm the earlier detection of strong emission lines of Fe K(alpha) fluorescence, Fe XXV and Fe XXVI but also show significantly more soft X-ray emission. The high-resolution spectrum also shows emission lines of other highly ionized ions as Si xiv and possibly S XVI. In addition, a re-analysis of the 2006 Suzaku data using the latest calibration shows that the hard (15-50 keV) X-ray emission is brighter than previously thought and remains constant in both the 2006 and 2008 data. The G ratio calculated from the Fe xxv lines shows that these lines are thermal, not photoionized, in origin.With the exception of the hard X-ray emission, the spectra from both epochs can be fit using thermal radiation assuming a differential emission measure based on a cooling-flow model combined with a full and partial absorber. We show that acceptable fits can be obtained for all the data in the 1-10 keV band varying only the partial absorber. Based on the temperature and accretion rate, the thermal emission appears to be arising from the boundary layer between the accreting white dwarf and the accretion disk.

An X-Ray Spectral Model for Clumpy Tori in Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Liu, Yuan; Li, Xiaobo

2014-05-01

We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN) using Geant4, which includes the physical processes of the photoelectric effect, Compton scattering, Rayleigh scattering, γ conversion, fluorescence line, and Auger process. Since the electrons in the torus are expected to be bounded instead of free, the deviation of the scattering cross section from the Klein-Nishina cross section has also been included, which changes the X-ray spectra by up to 25% below 10 keV. We have investigated the effect of the clumpiness parameters on the reflection spectra and the strength of the fluorescent line Fe Kα. The volume filling factor of the clouds in the clumpy torus only slightly influences the reflection spectra, however, the total column density and the number of clouds along the line of sight significantly change the shapes and amplitudes of the reflection spectra. The effect of column density is similar to the case of a smooth torus, while a small number of clouds along the line of sight will smooth out the anisotropy of the reflection spectra and the fluorescent line Fe Kα. The smoothing effect is mild in the low column density case (N H = 1023 cm-2), whereas it is much more evident in the high column density case (N H = 1025 cm-2). Our model provides a quantitative tool for the spectral analysis of the clumpy torus. We suggest that the joint fits of the broad band spectral energy distributions of AGNs (from X-ray to infrared) should better constrain the structure of the torus.

Applying a physical continuum model to describe the broadband X-ray spectra of accreting pulsars at high luminosity

NASA Astrophysics Data System (ADS)

Pottschmidt, Katja; Hemphill, Paul B.; Wolff, Michael T.; Cheatham, Diana M.; Iwakiri, Wataru; Gottlieb, Amy M.; Falkner, Sebastian; Ballhausen, Ralf; Fuerst, Felix; Kuehnel, Matthias; Ferrigno, Carlo; Becker, Peter A.; Wood, Kent S.; Wilms, Joern

2018-01-01

A new window for better understanding the accretion onto strongly magnetized neutron stars in X-ray binaries is opening. In these systems the accreted material follows the magnetic field lines as it approaches the neutron star, forming accretion columns above the magnetic poles. The plasma falls toward the neutron star surface at near-relativistic speeds, losing energy by emitting X-rays. The X-ray spectral continua are commonly described using phenomenological models, i.e., power laws with different types of curved cut-offs at higher energies. Here we consider high luminosity pulsars. In these systems the mass transfer rate is high enough that the accreting plasma is thought to be decelerated in a radiation-dominated radiative shock in the accretion columns. While the theory of the emission from such shocks had already been developed by 2007, a model for direct comparison with X-ray continuum spectra in xspec or isis has only recently become available. Characteristic parameters of this model are the accretion column radius and the plasma temperature, among others. Here we analyze the broadband X-ray spectra of the accreting pulsars Centaurus X-3 and 4U 1626-67 obtained with NuSTAR. We present results from traditional empirical modeling as well as successfully apply the radiation-dominated radiative shock model. We also take the opportunity to compare to similar recent analyses of both sources using these and other observations.

Deep Chandra Survey of the Small Magellanic Cloud. II. Timing Analysis of X-Ray Pulsars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, JaeSub; Antoniou, Vallia; Zezas, Andreas

We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg{sup 2} region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb–Scargle and epoch-folding techniques, we detected periodic modulations from 20 pulsars and a new candidate pulsar. The survey also covered 11 other pulsars with no clear sign of periodic modulation. The 0.5–8 keV X-ray luminosity ( L {sub X} ) of the pulsars ranges from 10{sup 34} to 10{sup 37} ergmore » s{sup −1} at 60 kpc. All of the Chandra sources with L {sub X} ≳ 4 × 10{sup 35} erg s{sup −1} exhibit X-ray pulsations. The X-ray spectra of the SMC pulsars (and high-mass X-ray binaries) are in general harder than those of the SMC field population. All but SXP 8.02 can be fitted by an absorbed power-law model with a photon index of Γ ≲ 1.5. The X-ray spectrum of the known magnetar SXP 8.02 is better fitted with a two-temperature blackbody model. Newly measured pulsation periods of SXP 51.0, SXP 214, and SXP 701, are significantly different from the previous XMM-Newton and RXTE measurements. This survey provides a rich data set for energy-dependent pulse profile modeling. Six pulsars show an almost eclipse-like dip in the pulse profile. Phase-resolved spectral analysis reveals diverse spectral variations during pulsation cycles: e.g., for an absorbed power-law model, some exhibit an (anti)-correlation between absorption and X-ray flux, while others show more intrinsic spectral variation (i.e., changes in photon indices).« less

Revising the Local Bubble Model due to Solar Wind Charge Exchange X-ray Emission

NASA Astrophysics Data System (ADS)

Shelton, Robin L.

The hot Local Bubble surrounding the solar neighborhood has been primarily studied through observations of its soft X-ray emission. The measurements were obtained by attributing all of the observed local soft X-rays to the bubble. However, mounting evidence shows that the heliosphere also produces diffuse X-rays. The source is solar wind ions that have received an electron from another atom. The presence of this alternate explanation for locally produced diffuse X-rays calls into question the existence and character of the Local Bubble. This article addresses these questions. It reviews the literature on solar wind charge exchange (SWCX) X-ray production, finding that SWCX accounts for roughly half of the observed local 1/4 keV X-rays found at low latitudes. This article also makes predictions for the heliospheric O VI column density and intensity, finding them to be smaller than the observational error bars. Evidence for the continued belief that the Local Bubble contains hot gas includes the remaining local 1/4 keV intensity, the observed local O VI column density, and the need to fill the local region with some sort of plasma. If the true Local Bubble is half as bright as previously thought, then its electron density and thermal pressure are 1/sqrt{2} as great as previously thought, and its energy requirements and emission measure are 1/2 as great as previously thought. These adjustments can be accommodated easily, and, in fact, bring the Local Bubble's pressure more in line with that of the adjacent material. Suggestions for future work are made.

Revising the Local Bubble Model due to Solar Wind Charge Exchange X-ray Emission

NASA Astrophysics Data System (ADS)

Shelton, Robin L.

2009-03-01

The hot Local Bubble surrounding the solar neighborhood has been primarily studied through observations of its soft X-ray emission. The measurements were obtained by attributing all of the observed local soft X-rays to the bubble. However, mounting evidence shows that the heliosphere also produces diffuse X-rays. The source is solar wind ions that have received an electron from another atom. The presence of this alternate explanation for locally produced diffuse X-rays calls into question the existence and character of the Local Bubble. This article addresses these questions. It reviews the literature on solar wind charge exchange (SWCX) X-ray production, finding that SWCX accounts for roughly half of the observed local 1/4 keV X-rays found at low latitudes. This article also makes predictions for the heliospheric O VI column density and intensity, finding them to be smaller than the observational error bars. Evidence for the continued belief that the Local Bubble contains hot gas includes the remaining local 1/4 keV intensity, the observed local O VI column density, and the need to fill the local region with some sort of plasma. If the true Local Bubble is half as bright as previously thought, then its electron density and thermal pressure are 1/sqrt{2} as great as previously thought, and its energy requirements and emission measure are 1/2 as great as previously thought. These adjustments can be accommodated easily, and, in fact, bring the Local Bubble’s pressure more in line with that of the adjacent material. Suggestions for future work are made.

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies.

PubMed

Sutton, Kristin A; Black, Paul J; Mercer, Kermit R; Garman, Elspeth F; Owen, Robin L; Snell, Edward H; Bernhard, William A

2013-12-01

Electron paramagnetic resonance (EPR) and online UV-visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV-visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5-0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. The observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure.

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

PubMed Central

Sutton, Kristin A.; Black, Paul J.; Mercer, Kermit R.; Garman, Elspeth F.; Owen, Robin L.; Snell, Edward H.; Bernhard, William A.

2013-01-01

Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV–visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5–0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. The observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure. PMID:24311579

Measuring the Impact of AGN Outflows via Intensive UV and X-ray Monitoring Campaigns

NASA Astrophysics Data System (ADS)

Kriss, Gerard

2015-08-01

Observations of AGN outflows have progressed from the era of single-object surveys to intensive monitoring campaigns spanning weeks to months. The combination of multiple observations, improved temporal coverage, multi-wavelength monitoring in both the X-ray and UV bands, and the baseline of prior historical observations has enabled determinations of the locations, mass flux, and kinetic luminosities of the outflowing absorbing gas in several AGN, notably Mrk 509, NGC 5548, Mrk 335, and NGC 985. Another intensive campaign is planned for 2015-2016 on NGC 7469. In all cases, the mass flux and kinetic energy is dominated by the higher-ionization X-ray absorbing gas. But the higher-resolution UV observations give a kinematically resolved picture of the overall outflow. In most cases, the outflowing gas is located at parsec to kpc scales, with insufficient kinetic luminosity to have an evolutionary impact on the host galaxy. Typically, the kinetic luminosity is less than a percent of the Eddington luminosity. In some cases, transient, broad UV absorption troughs have appeared (e.g., Mrk 335 and NGC 5548), with variability timescales suggesting locations near the broad-line region of the AGN. Yet these higher-velocity outflows also have low-impact kinetic luminosities. In the best-studied case of NGC 5548, the strength of the broad UV absorption lines varies with the degree of soft X-ray obscuration first revealed by XMM-Newton spectra. The lower-ionization, narrow associated absorption lines in the UV spectrum of NGC 5548 that appeared concurrently with the soft X-ray obscuration vary in response to the changing UV flux on a daily basis. The intensive monitoring allows us to fit time-dependent photoionization models to the UV-absorbing gas, allowing precise determinations of the locations, mass flux, and kinetic luminosities of the absorbers.

Development Status of Adjustable X-ray Optics with 0.5 Arcsec Imaging for the X-ray Surveyor Mission Concept

NASA Astrophysics Data System (ADS)

Reid, Paul B.; Allured, Ryan; ben-Ami, Sagi; Cotroneo, Vincenzo; Schwartz, Daniel A.; Tananbaum, Harvey; Vikhlinin, Alexey; Trolier-McKinstry, Susan; Wallace, Margeaux L.; Jackson, Tom

2016-04-01

The X-ray Surveyor mission concept is designed as a successor to the Chandra X-ray Observatory. As currently envisioned, it will have as much as 30-50 times the collecting area of Chandra with the same 0.5 arcsec imaging resolution. This combination of telescope area and imaging resolution, along with a detector suite for imaging and dispersive and non-dispersive imaging spectroscopy, will enable a wide range of astrophysical observations. These observations will include studies of the growth of large scale structure, early black holes and the growth of SMBHs, and high resolution spectroscopy with arcsec resolution, among many others. We describe the development of adjustable grazing incidence X-ray optics, a potential technology for the high resolution, thin, lightweight mirrors. We discuss recent advancements including the demonstration of deterministic figure correction via the use of the adjusters, the successful demonstration of integrating control electronics directly on the actuator cells to enable row-column addressing, and discuss the feasibility of on-orbit piezoelectric performance and figure monitoring via integrated semiconductor strain gauges. We also present the telescope point design and progress in determining the telescope thermal sensitivities and achieving alignment and mounting requirements.

Developments in Time-Division Multiplexing of X-ray Transition-Edge Sensors

NASA Astrophysics Data System (ADS)

Doriese, W. B.; Morgan, K. M.; Bennett, D. A.; Denison, E. V.; Fitzgerald, C. P.; Fowler, J. W.; Gard, J. D.; Hays-Wehle, J. P.; Hilton, G. C.; Irwin, K. D.; Joe, Y. I.; Mates, J. A. B.; O'Neil, G. C.; Reintsema, C. D.; Robbins, N. O.; Schmidt, D. R.; Swetz, D. S.; Tatsuno, H.; Vale, L. R.; Ullom, J. N.

2016-07-01

Time-division multiplexing (TDM) is a mature scheme for the readout of arrays of transition-edge sensors (TESs). TDM is based on superconducting-quantum-interference-device (SQUID) current amplifiers. Multiple spectrometers based on gamma-ray and X-ray microcalorimeters have been operated with TDM readout, each at the scale of 200 sensors per spectrometer, as have several astronomical cameras with thousands of sub-mm or microwave bolometers. Here we present the details of two different versions of our TDM system designed to read out X-ray TESs. The first has been field-deployed in two 160-sensor (8 columns × 20 rows) spectrometers and four 240-sensor (8 columns × 30 rows) spectrometers. It has a three-SQUID-stage architecture, switches rows every 320 ns, and has total readout noise of 0.41 μ Φ 0 / surd Hz. The second, which is presently under development, has a two-SQUID-stage architecture, switches rows every 160 ns, and has total readout noise of 0.19 μ Φ 0 / surd Hz. Both quoted noise values are non-multiplexed and referred to the first-stage SQUID. In a demonstration of this new architecture, a multiplexed 1-column × 32-row array of NIST TESs achieved average energy resolution of 2.55± 0.01 eV at 6 keV.

Heating the Primordial Soup: X-raying the Circumstellar Disk of T Cha

NASA Astrophysics Data System (ADS)

Principe, David

2012-09-01

T Cha is the only known example of a nearly edge-on actively accreting young star-disk system within 100 pc, and is likely orbited by a very low-mass companion or massive planet that has cleared an inner hole in its disk. We propose to obtain a 150 ks observation of T Cha with Chandra's HETGS with twin goals of (a) determining the intrinsic X-ray spectrum of T Cha so as to establish whether its X-ray emission can be attributed to accretion shocks or coronal emission, and (b) model the spectrum of X-rays absorbed by its gaseous disk. These results will serve as essential input to models of irradiated, planet-forming disks.

MONTE CARLO STUDY OF THE CARDIAC ABSORBED DOSE DURING X-RAY EXAMINATION OF AN ADULT PATIENT.

PubMed

Kadri, O; Manai, K; Alfuraih, A

2016-12-01

The computational voxel phantom 'High-Definition Reference Korean-Man (HDRK-Man)' was implemented into the Monte Carlo transport toolkit Geant4. The voxel model, adjusted to the Reference Korean Man, is 171 cm in height and 68 kg in weight and composed of ∼30 million voxels whose size is 1.981 × 1.981 × 2.0854 mm 3 The Geant4 code is then utilised to compute the dose conversion coefficients (DCCs) expressed in absorbed dose per air kerma free in air for >30 tissues and organs, including almost all organs required in the new recommendation of the ICRP 103, due to a broad parallel beam of monoenergetic photons impinging in antero-postero direction with energy ranging from 10 to 150 keV. The computed DCCs of different organs are found to be in good agreement with data published using other simulation codes. Also, the influence of patient size on DCC values was investigated for a representative body size of the adult Korean patient population. The study was performed using five different sizes covering the range of 0.8-1.2 magnification order of the original HDRK-Man. It focussed on the computation of DCC for the human heart. Moreover, the provided DCCs were used to present an analytical parameterisation for the calculation of the cardiac absorbed dose for any arbitrary X-ray spectrum and for those patient sizes. Thus, the present work can be considered as an enhancement of the continuous studies performed by medical physicist as part of quality control tests and radiation protection dosimetry. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

X-Ray Investigation of the Diffuse Emission around Plausible γ-Ray Emitting Pulsar Wind Nebulae in Kookaburra Region

NASA Astrophysics Data System (ADS)

Kishishita, Tetsuichi; Bamba, Aya; Uchiyama, Yasunobu; Tanaka, Yasuyuki; Takahashi, Tadayuki

2012-05-01

We report on the results from Suzaku X-ray observations of the radio complex region called Kookaburra, which includes two adjacent TeV γ-ray sources HESS J1418-609 and HESS J1420-607. The Suzaku observation revealed X-ray diffuse emission around a middle-aged pulsar PSR J1420-6048 and a plausible pulsar wind nebula (PWN) Rabbit with elongated sizes of σX = 1farcm66 and σX = 1farcm49, respectively. The peaks of the diffuse X-ray emission are located within the γ-ray excess maps obtained by H.E.S.S. and the offsets from the γ-ray peaks are 2farcm8 for PSR J1420-6048 and 4farcm5 for Rabbit. The X-ray spectra of the two sources were well reproduced by absorbed power-law models with Γ = 1.7-2.3. The spectral shapes tend to become softer according to the distance from the X-ray peaks. Assuming the one-zone electron emission model as the first-order approximation, the ambient magnetic field strengths of HESS J1420-607 and HESS J1418-609 can be estimated as 3 μG and 2.5 μG, respectively. The X-ray spectral and spatial properties strongly support that both TeV sources are PWNe, in which electrons and positrons accelerated at termination shocks of the pulsar winds are losing their energies via the synchrotron radiation and inverse Compton scattering as they are transported outward.

X-ray fluorescence camera for imaging of iodine media in vivo.

PubMed

Matsukiyo, Hiroshi; Watanabe, Manabu; Sato, Eiichi; Osawa, Akihiro; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; Aizawa, Katsuo; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ehara, Shigeru; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2009-01-01

X-ray fluorescence (XRF) analysis is useful for measuring density distributions of contrast media in vivo. An XRF camera was developed for carrying out mapping for iodine-based contrast media used in medical angiography. Objects are exposed by an X-ray beam from a cerium target. Cerium K-series X-rays are absorbed effectively by iodine media in objects, and iodine fluorescence is produced from the objects. Next, iodine Kalpha fluorescence is selected out by use of a 58-microm-thick stannum filter and is detected by a cadmium telluride (CdTe) detector. The Kalpha rays are discriminated out by a multichannel analyzer, and the number of photons is counted by a counter card. The objects are moved and scanned by an x-y stage in conjunction with a two-stage controller, and X-ray images obtained by iodine mapping are shown on a personal computer monitor. The scan pitch of the x and y axes was 2.5 mm, and the photon counting time per mapping point was 2.0 s. We carried out iodine mapping of non-living animals (phantoms), and iodine Kalpha fluorescence was produced from weakly remaining iodine elements in a rabbit skin cancer.

Engineering solar cells based on correlative X-ray microscopy

DOE PAGES

Stuckelberger, Michael; West, Bradley; Nietzold, Tara; ...

2017-05-01

In situ and operando measurement techniques combined with nanoscale resolution have proven invaluable in multiple fields of study. We argue that evaluating device performance as well as material behavior by correlative X-ray microscopy with <100 nm resolution can radically change the approach for optimizing absorbers, interfaces and full devices in solar cell research. Here, we thoroughly discuss the measurement technique of X-ray beam induced current and point out fundamental differences between measurements of wafer-based silicon and thin-film solar cells. Based on reports of the last years, we showcase the potential that X-ray microscopy measurements have in combination with in situmore » and operando approaches throughout the solar cell lifecycle: from the growth of individual layers to the performance under operating conditions and degradation mechanisms. Enabled by new developments in synchrotron beamlines, the combination of high spatial resolution with high brilliance and a safe working distance allows for the insertion of measurement equipment that can pave the way for a new class of experiments. When applied to photovoltaics research, we highlight today’s opportunities and challenges in the field of nanoscale X-ray microscopy, and give an outlook on future developments.« less

Scintillating Quantum Dots for Imaging X-rays (SQDIX) for Aircraft Inspection

NASA Technical Reports Server (NTRS)

Burke, Eric (Principal Investigator); Williams, Phillip (Principal Investigator); Dehaven, Stan

2015-01-01

Scintillation is the process currently employed by conventional x-ray detectors to create x-ray images. Scintillating quantum dots or nano-crystals (StQDs) are a novel, nanometer-scale material that upon excitation by x-rays, re-emit the absorbed energy as visible light. StQDs theoretically have higher output efficiency than conventional scintillating materials and are more environmental friendly. This paper will present the characterization of several critical elements in the use of StQDs that have been performed along a path to the use of this technology in wide spread x-ray imaging. Initial work on the SQDIX system has shown great promise to create state-of-the-art sensors using StQDs as a sensor material. In addition, this work also demonstrates a high degree of promise using StQDs in microstructured fiber optics. Using the microstructured fiber as a light guide could greatly increase the capture efficiency a StQDs based imaging sensor.

Aging effect on Zn retention on a calcareous soil: column experiments and synchrotron X-ray micro-spectroscopic investigation.

PubMed

Sayen, Stéphanie; Guillon, Emmanuel

2014-07-15

In this study, a combination of column experiments and micro-analytical techniques exploiting synchrotron generated X-rays was used to assess the effect of aging time on Zn retention and mobility in the specific case of calcareous soils (high pH value, ≈ 8). The samples were subjected to aging for 2, 6, 17, and 63 days. Freshly added Zn mainly existed as an exchangeable form, and this metal fraction decreased over time due to Zn redistribution to stronger binding sites. Thus, after aging for 63 days, 45% of Zn is remobilized from exchangeable sites to stronger binding sites. μ-XRF maps were used to find correlations among elements in the sample, and μ-XANES spectra were recorded to precise Zn speciation. These analyses evidenced an increasing partitioning of Zn from organic matter to iron oxy(hydr)oxides over time. The occurrence of hydrozincite is evidenced in all samples. Copyright © 2014 Elsevier B.V. All rights reserved.

X-ray beamsplitter

DOEpatents

Ceglio, Natale M.; Stearns, Daniel S.; Hawryluk, Andrew M.; Barbee, Jr., Troy W.

1989-01-01

An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5-50 pairs of alternate Mo/Si layers with a period of 20-250 A. The support membrane is 10-200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window.

X-ray phase contrast imaging at MAMI

NASA Astrophysics Data System (ADS)

El-Ghazaly, M.; Backe, H.; Lauth, W.; Kube, G.; Kunz, P.; Sharafutdinov, A.; Weber, T.

2006-05-01

Experiments have been performed to explore the potential of the low emittance 855MeV electron beam of the Mainz Microtron MAMI for imaging with coherent X-rays. Transition radiation from a micro-focused electron beam traversing a foil stack served as X-ray source with good transverse coherence. Refraction contrast radiographs of low absorbing materials, in particular polymer strings with diameters between 30 and 450μm, were taken with a polychromatic transition radiation X-ray source with a spectral distribution in the energy range between 8 and about 40keV. The electron beam spot size had standard deviation σh = (8.6±0.1)μm in the horizontal and σv = (7.5±0.1)μm in the vertical direction. X-ray films were used as detectors. The source-to-detector distance amounted to 11.4m. The objects were placed in a distance of up to 6m from the X-ray film. Holograms of strings were taken with a beam spot size σv = (0.50±0.05)μm in vertical direction, and a monochromatic X-ray beam of 6keV energy. A good longitudinal coherence has been obtained by the (111) reflection of a flat silicon single crystal in Bragg geometry. It has been demonstrated that a direct exposure CCD chip with a pixel size of 13×13μm^2 provides a highly efficient on-line detector. Contrast images can easily be generated with a complete elimination of all parasitic background. The on-line capability allows a minimization of the beam spot size by observing the smallest visible interference fringe spacings or the number of visible fringes. It has been demonstrated that X-ray films are also very useful detectors. The main advantage in comparison with the direct exposure CCD chip is the resolution. For the Structurix D3 (Agfa) X-ray film the standard deviation of the resolution was measured to be σf = (1.2±0.4)μm, which is about a factor of 6 better than for the direct exposure CCD chip. With the small effective X-ray spot size in vertical direction of σv = (1.2±0.3)μm and a geometrical

Search for Hard X-Ray Emission from the Soft X-Ray Transient Aquila X-1

NASA Astrophysics Data System (ADS)

Harmon, B. A.; Zhang, S. N.; Paciesas, W. S.; Tavani, M.; Kaaret, P.; Ford, E.

1994-12-01

We are investigating the possibility of hard x-ray emission from the recurrent soft x-ray transient and x-ray burst source Aquila X-1 (Aql X-1). Outbursts of this source are relatively frequent with a spacing of ~ 4-10 months (Kitamoto, S. et al. 1993, ApJ, 403, 315). The recent detections of hard tails (\\(>\\)20 keV) in low luminosity x-ray bursters (Barret, D. & Vedrenne, G. 1994, ApJ Supp. S. 92, 505) suggest that neutron star transient systems such as Aql X-1 can produce hard x-ray emission which is detectable by BATSE. We are correlating reported optical and soft x-ray observations since 1991 of Aql X-1 with BATSE observations in order to search for hard x-ray emission episodes, and to study their temporal and spectral evolution. We will present preliminary results of this search in the 20-1000 keV band using the Earth occultation technique applied to the large area detectors. If this work is successful, we hope to alert the astronomical community for the next Aql X-1 outburst expected in 1995. Simultaneous x-ray/hard x-ray and optical observations of Aql X-1 during outburst would be of great importance for the modeling of soft x-ray transients and related systems.

Ionized Absorbers in AGN

NASA Technical Reports Server (NTRS)

Mathur, S.

1999-01-01

As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

Heavy X-ray obscuration in the most luminous galaxies discovered by WISE

NASA Astrophysics Data System (ADS)

Vito, F.; Brandt, W. N.; Stern, D.; Assef, R. J.; Chen, C.-T. J.; Brightman, M.; Comastri, A.; Eisenhardt, P.; Garmire, G. P.; Hickox, R.; Lansbury, G.; Tsai, C.-W.; Walton, D. J.; Wu, J. W.

2018-03-01

Hot dust-obscured galaxies (DOGs) are hyperluminous (L8-1000 μm > 1013 L⊙) infrared galaxies with extremely high (up to hundreds of K) dust temperatures. The sources powering both their extremely high luminosities and dust temperatures are thought to be deeply buried and rapidly accreting supermassive black holes (SMBHs). Hot DOGs could therefore represent a key evolutionary phase in which the SMBH growth peaks. X-ray observations can be used to study their obscuration levels and luminosities. In this work, we present the X-ray properties of the 20 most luminous (Lbol ≳ 1014 L⊙) known hot DOGs at z = 2-4.6. Five of them are covered by long-exposure (10-70 ks) Chandra and XMM-Newton observations, with three being X-ray detected, and we study their individual properties. One of these sources (W0116-0505) is a Compton-thick candidate, with column density NH = (1.0-1.5) × 1024 cm-2 derived from X-ray spectral fitting. The remaining 15 hot DOGs have been targeted by a Chandra snapshot (3.1 ks) survey. None of these 15 are individually detected; therefore, we applied a stacking analysis to investigate their average emission. From hardness ratio analysis, we constrained the average obscuring column density and intrinsic luminosity to be log NH (cm-2) > 23.5 and LX ≳ 1044 erg s-1, which are consistent with results for individually detected sources. We also investigated the LX-L6 μm and LX-Lbol relations, finding hints that hot DOGs are typically X-ray weaker than expected, although larger samples of luminous obscured quasi-stellar objects are needed to derive solid conclusions.

The Discovery of an Evolving Dust Scattered X-ray Halo Around GRB 031203

NASA Technical Reports Server (NTRS)

Vaughan, S.; Willingale, R.; OBrien, P. T.; Osborne, J. P.; Reeves, J. N.; Levan, A. J.; Watson, M. G.; Tedds, J. A.; Watson, D.; Santos-Lleo, M.

2003-01-01

We report the first detection of a time-dependent, dust-scattered X-ray halo around a gamma-ray burst. GRB3 031203 was observed by XMM-Newton starting six hours after the burst. The halo appeared as concentric ring-like structures centered on the GRB location. The radii of these structures increased with time as t(sup 1/2), consistent with small-angle X-ray scattering caused by a large column of dust along the line of sight to a cosmologically distant GRB. The rings are due to dust concentrated in two distinct slabs in the Galaxy located at distances of 880 and 1390 pc, consistent with known Galactic features. The halo brightness implies an initial soft X-ray pulse consistent with the observed GRB.

Experimental Results and Modeling of Low-Heat-Capacity TES Microcalorimeters for Soft-X-ray Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckart, Megan E.; NASA Postdoctoral Program Fellow; Adams, Joseph S.

2009-12-16

Transition-edge-sensor (TES) X-ray microcalorimeters have mostly been targeted at mid-band energies from 0.05-10 keV and high energies to above 100 keV. However, many other optimizations are possible. Here we present results from devices optimized for soft X-ray applications. For spectroscopy below 1 keV, the X-ray stopping power and heat capacity (C) of the TES itself are high enough that we can omit a separate absorber. The resulting devices have low C and the best-achievable energy resolution should be under 1 eV. We are interested in pursuing such devices primarily for astrophysical applications and laboratory astrophysics at LLNL's Electron-Beam Ion Trap.more » To this end, we have studied arrays in which 'bare' TESs are interspersed with broad-band pixels that have absorbers. By extending the absorbers to cover the area where the leads contact the low-energy pixels, we have eliminated a significant source of non-Gaussian detector response. The bare devices are in a different regime from our typical devices in that C is ten times lower and the conductance to the bath is four times lower. We have explored this regime through simultaneous fitting of noise and impedance data. These data cannot be fit by the simple model we employ to describe our typical broad-band devices. In this contribution we present X-ray spectra and the results from modeling.« less

X-ray beamsplitter

DOEpatents

Ceglio, N.M.; Stearns, D.G.; Hawryluk, A.M.; Barbee, T.W. Jr.

1987-08-07

An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5--50 pairs of alternate Mo/Si layers with a period of 20--250 A. The support membrane is 10--200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window. 6 figs.

Fabrication of Transition Edge Sensor Microcalorimeters for X-Ray Focal Planes

NASA Technical Reports Server (NTRS)

Chervenak, James A.; Adams, Joseph S.; Audley, Heather; Bandler, Simon R.; Betancourt-Martinez, Gabriele; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline; Lee, Sang Jun;

An X-Ray Survey for Polar CAP Qpos in AM Herculis Systems

NASA Astrophysics Data System (ADS)

Wood, Kent

Five AM Herculis binary systems show an optical QPO that is known to be associated with magentically channeled polar cap accretion. Hard X-ray QPOs are predicted by the time-depndent hydrodynamic models. We propose to search selected AM Her systems for polar cap X-ray QPOs using the XTE PCA. Because of its large collecting area, the PCA is the only instrument that can do this job. No other accreting objects provide comparable high-quality observational diagnostics on the accretion flow. The detailed understanding of flow geometry, shock heating, ion-electron energy exchange, accretion column structure, and emission and radiative transfer mechanisms that go to make up the picture of AM Her accretion needs to be tested against X-ray timing information.

X-ray Observations of Binary and Single Wolf-Rayet Stars with XMM-Newton and Chandra

NASA Technical Reports Server (NTRS)

Skinner, Stephen; Gudel, Manuel; Schmutz, Werner; Zhekov, Svetozar

2006-01-01

We present an overview of recent X-ray observations of Wolf-Rayet (WR) stars with XMM-Newton and Chandra. These observations are aimed at determining the differences in X-ray properties between massive WR + OB binary systems and putatively single WR stars. A new XMM spectrum of the nearby WN8 + OB binary WR 147 shows hard absorbed X-ray emission (including the Fe Ka line complex), characteristic of colliding wind shock sources. In contrast, sensitive observations of four of the closest known single WC (carbon-rich) WR stars have yielded only nondetections. These results tentatively suggest that single WC stars are X-ray quiet. The presence of a companion may thus be an essential factor in elevating the X-ray emission of WC + OB stars to detectable levels.

X-ray microscopy with high-resolution zone plates: recent developments

NASA Astrophysics Data System (ADS)

Schneider, Gerd; Wilhein, Thomas; Niemann, Bastian; Guttman, P.; Schliebe, T.; Lehr, J.; Aschoff, H.; Thieme, Juergen; Rudolph, Dietbert M.; Schmahl, Guenther A.

1995-09-01

In order to expand the applications of x-ray microscopy, developments in the fields of zone plate technology, specimen preparation and imaging techniques have been made. A new cross- linked polymer chain electron beam resist allows us to record zone plate pattern down to 19 nm outermost zone width. High resolution zone plates in germanium with outermost zone widths down to 19 nm have been developed. In addition, phase zone plates in nickel down to 30 nm zone width have been made by electroplating. In order to enhance the image contrast for weak absorbing objects, the phase contrast method for x-ray microscopy was developed and implemented on the Gottingen x-ray microscope at BESSY. The effects of x ray absorption on the structure of biological specimen limits the maximum applicable radiation dose and therefore the achievable signal to noise ratio for an artifact-free x-ray image. To improve the stability especially of biological specimen, a cryogenic object chamber has been developed and tested. It turns out that at the operating temperature T less than or equal to 130 K unfixed biological specimen can be exposed to a radiation dose of 109 - 1010 Gy without any observable structural changes. A multiple-angle viewing stage allows us to take stereoscopic images with the x-ray microscope, giving a 3D-impression of the object. As an example for the applications of x-ray microscopy in biology, erythrocytes infected by malaria parasite have been examined. Studies of the aggregation of hematite by sodium sulfate gives an example for the application of x-ray microscopy in the field of colloid research.

X-Ray Polarization from High Mass X-Ray Binaries

NASA Technical Reports Server (NTRS)

Kallman, T.; Dorodnitsyn, A.; Blondin, J.

2015-01-01

X-ray astronomy allows study of objects which may be associated with compact objects, i.e. neutron stars or black holes, and also may contain strong magnetic fields. Such objects are categorically non-spherical, and likely non-circular when projected on the sky. Polarization allows study of such geometric effects, and X-ray polarimetry is likely to become feasible for a significant number of sources in the future. A class of potential targets for future X-ray polarization observations is the high mass X-ray binaries (HMXBs), which consist of a compact object in orbit with an early type star. In this paper we show that X-ray polarization from HMXBs has a distinct signature which depends on the source inclination and orbital phase. The presence of the X-ray source displaced from the star creates linear polarization even if the primary wind is spherically symmetric whenever the system is viewed away from conjunction. Direct X-rays dilute this polarization whenever the X-ray source is not eclipsed; at mid-eclipse the net polarization is expected to be small or zero if the wind is circularly symmetric around the line of centers. Resonance line scattering increases the scattering fraction, often by large factors, over the energy band spanned by resonance lines. Real winds are not expected to be spherically symmetric, or circularly symmetric around the line of centers, owing to the combined effects of the compact object gravity and ionization on the wind hydrodynamics. A sample calculation shows that this creates polarization fractions ranging up to tens of percent at mid-eclipse.

Development of a low-cost x-ray mask for high-aspect-ratio MEM smart structures

NASA Astrophysics Data System (ADS)

Ajmera, Pratul K.; Stadler, Stefan; Abdollahi, Neda

1998-07-01

A cost-effective process with short fabrication time for making x-ray masks for research and development purposes is described here for fabricating high-aspect ratio microelectromechanical structures using synchrotron based x- ray lithography. Microscope cover glass slides as membrane material is described. Slides with an initial thickness of 175 micrometers are etched to a thickness in the range of 10 - 25 micrometers using a diluted HF and buffered hydrofluoric acid solutions. The thinned slides are glued on supportive mask frames and sputtered with a chromium/silver sandwich layer which acts as a plating base layer for the deposition of the gold absorber. The judicial choice of glue and mask frame material are significant parameters in a successful fabrication process. Gold absorber structures are electroplated on the membrane. Calculations are done for contrast and dose ratio obtained in the photoresist after synchrotron radiation as a function of the mask design parameters. Exposure experiments are performed to prove the applicability of the fabricated x-ray mask.

TWO DISTINCT-ABSORPTION X-RAY COMPONENTS FROM TYPE IIn SUPERNOVAE: EVIDENCE FOR ASPHERICITY IN THE CIRCUMSTELLAR MEDIUM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsuda, Satoru; Tsuboi, Yohko; Maeda, Keiichi

2016-12-01

We present multi-epoch X-ray spectral observations of three Type IIn supernovae (SNe), SN 2005kd, SN 2006jd, and SN 2010jl, acquired with Chandra , XMM-Newton , Suzaku , and Swift . Previous extensive X-ray studies of SN 2010jl have revealed that X-ray spectra are dominated by thermal emission, which likely arises from a hot plasma heated by a forward shock propagating into a massive circumstellar medium (CSM). Interestingly, an additional soft X-ray component was required to reproduce the spectra at a period of ∼1–2 years after the SN explosion. Although this component is likely associated with the SN, its origin remained an open question. Wemore » find a similar, additional soft X-ray component from the other two SNe IIn as well. Given this finding, we present a new interpretation for the origin of this component; it is thermal emission from a forward shock essentially identical to the hard X-ray component, but directly reaches us from a void of the dense CSM. Namely, the hard and soft components are responsible for the heavily and moderately absorbed components, respectively. The co-existence of the two components with distinct absorptions as well as the delayed emergence of the moderately absorbed X-ray component could be evidence for asphericity of the CSM. We show that the X-ray spectral evolution can be qualitatively explained by considering a torus-like geometry for the dense CSM. Based on our X-ray spectral analyses, we estimate the radius of the torus-like CSM to be on the order of ∼5 × 10{sup 16} cm.« less

Be/X-ray Binary Science for Future X-ray Timing Missions

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.

2011-01-01

For future missions, the Be/X-ray binary community needs to clearly define our science priorities for the future to advocate for their inclusion in future missions. In this talk, I will describe current designs for two potential future missions and Be X-ray binary science enabled by these designs. The Large Observatory For X-ray Timing (LOFT) is an X-ray timing mission selected in February 2011 for the assessment phase from the 2010 ESA M3 call for proposals. The Advanced X-ray Timing ARray (AXTAR) is a NASA explorer concept X-ray timing mission. This talk is intended to initiate discussions of our science priorities for the future.

ASCA Observation of an "X-Ray Shadow" in the Galactic Plane

NASA Technical Reports Server (NTRS)

Park, Sangwook; Ebisawa, Ken

2001-01-01

The diffuse X-ray background (DXB) emission near the Galactic plane (l,b approximately 25.6 degrees, 0.78 degrees) has been observed with ASCA (Advanced Satellite for Cosmology and Astrophysics). The observed region is toward a Galactic molecular cloud which was recently reported to cast a deep X-ray shadow in the 0.5 - 2.0 keV band DXB. The selection of this particular region is intended to provide a constraint on the spatial distribution of the DXB emission along the line of sight: i.e., the molecular cloud is optically thick at <2 keV and so the bulk of the observed soft X-rays must originate in the foreground of the cloud, which is at approximately 3 kpc from the Sun. In the 0.8 - 9.0 keV band, the observed spectrum is primarily from multiple components of thermal plasmas. We here report a detection of soft X-ray (0.5 - 2 keV) emission from an approximately 10(exp 7) K thermal plasma. Comparisons with the ROSAT (Roentgen Satellite) data suggest that this soft X-ray emission is absorbed by N(sub H) = 1 - 3 x 10(exp 21) cm(exp -2), which implies a path-length through the soft X-ray emitting regions of approximately less than 1 kpc from the Sun.

Abdomen X-Ray (Radiography)

MedlinePlus

... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a ... of an abdominal x-ray? What is abdominal x-ray? An x-ray (radiograph) is a noninvasive ...

Diffracting aperture based differential phase contrast for scanning X-ray microscopy.

PubMed

Kaulich, Burkhard; Polack, Francois; Neuhaeusler, Ulrich; Susini, Jean; di Fabrizio, Enzo; Wilhein, Thomas

2002-10-07

It is demonstrated that in a zone plate based scanning X-ray microscope, used to image low absorbing, heterogeneous matter at a mesoscopic scale, differential phase contrast (DPC) can be implemented without adding any additional optical component to the normal scheme of the microscope. The DPC mode is simply generated by an appropriate positioning and alignment of microscope apertures. Diffraction from the apertures produces a wave front with a non-uniform intensity. The signal recorded by a pinhole photo diode located in the intensity gradient is highly sensitive to phase changes introduced by the specimen to be recorded. The feasibility of this novel DPC technique was proven with the scanning X-ray microscope at the ID21 beamline of the European Synchrotron Radiation facility (ESRF) operated at 6 keV photon energy. We observe a differential phase contrast, similar to Nomarski's differential interference contrast for the light microscope, which results in a tremendous increase in image contrast of up to 20 % when imaging low absorbing specimen.

Comparison of bactericidal efficiency of 7.5 MeV X-rays, gamma-rays, and 10 MeV e-beams

NASA Astrophysics Data System (ADS)

Song, Beom-Seok; Lee, Yunjong; Moon, Byeong-Geum; Go, Seon-Min; Park, Jong-Heum; Kim, Jae-Kyung; Jung, Koo; Kim, Dong-Ho; Ryu, Sang-Ryeol

2016-08-01

This study was performed to verify the feasibility of 7.5 MeV X-rays for food pasteurization through a comparison of the bactericidal efficiency with those of other sources for selected bacterial pathogens. No significant differences were observed between the overall bactericidal efficiency for beef-inoculated pathogens based on the uncertainty of the absorbed dose and variations in bacterial counts. This result supported that all three irradiation sources were effective for inactivation of food-borne bacteria and that 7.5 MeV X-rays may be used for food pasteurization.

Hydrodynamic study of plasma amplifiers for soft-x-ray lasers: a transition in hydrodynamic behavior for plasma columns with widths ranging from 20 μm to 2 mm.

PubMed

Oliva, Eduardo; Zeitoun, Philippe; Velarde, Pedro; Fajardo, Marta; Cassou, Kevin; Ros, David; Sebban, Stephan; Portillo, David; le Pape, Sebastien

2010-11-01

Plasma-based seeded soft-x-ray lasers have the potential to generate high energy and highly coherent short pulse beams. Due to their high density, plasmas created by the interaction of an intense laser with a solid target should store the highest amount of energy density among all plasma amplifiers. Our previous numerical work with a two-dimensional (2D) adaptive mesh refinement hydrodynamic code demonstrated that careful tailoring of plasma shapes leads to a dramatic enhancement of both soft-x-ray laser output energy and pumping efficiency. Benchmarking of our 2D hydrodynamic code in previous experiments demonstrated a high level of confidence, allowing us to perform a full study with the aim of the way for 10-100 μJ seeded soft-x-ray lasers. In this paper, we describe in detail the mechanisms that drive the hydrodynamics of plasma columns. We observed transitions between narrow plasmas, where very strong bidimensional flow prevents them from storing energy, to large plasmas that store a high amount of energy. Millimeter-sized plasmas are outstanding amplifiers, but they have the limitation of transverse lasing. In this paper, we provide a preliminary solution to this problem.

A search for X-ray polarization in cosmic X-ray sources. [binary X-ray sources and supernovae remnants

NASA Technical Reports Server (NTRS)

Hughes, J. P.; Long, K. S.; Novick, R.

1983-01-01

Fifteen strong X-ray sources were observed by the X-ray polarimeters on board the OSO-8 satellite from 1975 to 1978. The final results of this search for X-ray polarization in cosmic sources are presented in the form of upper limits for the ten sources which are discussed elsewhere. These limits in all cases are consistent with a thermal origin for the X-ray emission.

X-Ray Emission from the Soft X-Ray Transient Aquila X-1

NASA Technical Reports Server (NTRS)

Tavani, Marco

1998-01-01

Aquila X-1 is the most prolific of soft X-ray transients. It is believed to contain a rapidly spinning neutron star sporadically accreting near the Eddington limit from a low-mass companion star. The interest in studying the repeated X-ray outbursts from Aquila X-1 is twofold: (1) studying the relation between optical, soft and hard X-ray emission during the outburst onset, development and decay; (2) relating the spectral component to thermal and non-thermal processes occurring near the magnetosphere and in the boundary layer of a time-variable accretion disk. Our investigation is based on the BATSE monitoring of Aquila X-1 performed by our group. We observed Aquila X-1 in 1997 and re-analyzed archival information obtained in April 1994 during a period of extraordinary outbursting activity of the source in the hard X-ray range. Our results allow, for the first time for this important source, to obtain simultaneous spectral information from 2 keV to 200 keV. A black body (T = 0.8 keV) plus a broken power-law spectrum describe accurately the 1994 spectrum. Substantial hard X-ray emission is evident in the data, confirming that the accretion phase during sub-Eddington limit episodes is capable of producing energetic hard emission near 5 x 10(exp 35) ergs(exp -1). A preliminary paper summarizes our results, and a more comprehensive account is being written. We performed a theoretical analysis of possible emission mechanisms, and confirmed that a non-thermal emission mechanism triggered in a highly sheared magnetosphere at the accretion disk inner boundary can explain the hard X-ray emission. An anticorrelation between soft and hard X-ray emission is indeed prominently observed as predicted by this model.

Much NICER Monitoring of the X-ray Spectrum of Eta Carinae

NASA Astrophysics Data System (ADS)

Corcoran, Michael Francis; Hamaguchi, Kenji; Drake, Stephen; Pasham, Dheeraj; Gendreau, Keith C.; Arzoumanian, Zaven

2018-01-01

Eta Carinae is the most massive and luminous stellar system within 3 kpc. It is a known binary system with an orbital period of 5.52 years in which bright, thermal, X-ray emission is produced by a strong shock driven by the collisions of the wind of the visible primary star with the thin, fast wind of an otherwise unseen companion. Variations of the X-ray spectrum are produced by intrinsic changes in the density of the hot shocked gas and by intervening changes in wind absorption as the two stars revolve in a long-period, highly eccentric orbit. Previous X-ray monitoring studies since 1996 have detailed these variations, but have been either restricted to the E>3 keV band or have been affected by optical loading which limited measurement of X-ray absorption changes which can be used to determine the overlying density profile of the primary's wind around the orbit. The Neutron Star Interior Composition Explorer (NICER) is an excellent general-purpose observatory for X-ray astronomy, and in particular, its soft response and large effective area facilitate monitoring of X-ray spectral variations for bright sources like Eta Car without any bias due to photon pileup. We present the first observations of the X-ray spectrum of Eta Car obtained by NICER, and discuss limits on changes in column density, emission measure and temperature we derive from the NICER spectra.

A soft X-ray flare in the Seyfert I galaxy Markarian 335

NASA Technical Reports Server (NTRS)

Lee, M. G.; Balick, Bruce; Halpern, J. P.; Heckman, T. M.

1988-01-01

Strong, erratic, and primarily soft X-ray flux variations observed in Mrk 335 with the Einstein high-resolution imager (HRI) and monitor proportional counter (MPC) are reported. The variability time scales lie from about 6000 s to the period of observation, 60,000 s. The variability consisted of a decrease followed by an increase at X-ray energies below 2-3 keV. The variability is most pronounced at the softest energies. The X-ray spectrum was harder before the flare than afterward, even after the flare had ended. Averaged over the time of the observations, the MPC data are well-fitted by a power-law spectrum with a spectral index of 1.25 + or - 0.19 with no evidence of absorption by foreground neutral hydrogen at energies above 1.2 keV. If the observed value of the Galactic H I column density is assumed, then the HRI observations require the existence of an additional soft and variable X-ray component.

"X-Ray Transients in Star-Forming Regions" and "Hard X-Ray Emission from X-Ray Bursters"

NASA Technical Reports Server (NTRS)

Halpern, Jules P.; Kaaret, Philip

1999-01-01

This grant funded work on the analysis of data obtained with the Burst and Transient Experiment (BATSE) on the Compton Gamma-Ray Observatory. The goal of the work was to search for hard x-ray transients in star forming regions using the all-sky hard x-ray monitoring capability of BATSE. Our initial work lead to the discovery of a hard x-ray transient, GRO J1849-03. Follow-up observations of this source made with the Wide Field Camera on BeppoSAX showed that the source should be identified with the previously known x-ray pulsar GS 1843-02 which itself is identified with the x-ray source X1845-024 originally discovered with the SAS-3 satellite. Our identification of the source and measurement of the outburst recurrence time, lead to the identification of the source as a Be/X-ray binary with a spin period of 94.8 s and an orbital period of 241 days. The funding was used primarily for partial salary and travel support for John Tomsick, then a graduate student at Columbia University. John Tomsick, now Dr. Tomsick, received his Ph.D. from Columbia University in July 1999, based partially on results obtained under this investigation. He is now a postdoctoral research scientist at the University of California, San Diego.

Cancer diagnosis using a conventional x-ray fluorescence camera with a cadmium-telluride detector

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Enomoto, Toshiyuki; Hagiwara, Osahiko; Abudurexiti, Abulajiang; Sato, Koetsu; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2011-10-01

X-ray fluorescence (XRF) analysis is useful for mapping various atoms in objects. Bremsstrahlung X-rays are selected using a 3.0 mm-thick aluminum filter, and these rays are absorbed by indium, cerium and gadolinium atoms in objects. Then XRF is produced from the objects, and photons are detected by a cadmium-telluride detector. The Kα photons are discriminated using a multichannel analyzer, and the number of photons is counted by a counter card. The objects are moved and scanned by an x-y stage in conjunction with a two-stage controller, and X-ray images obtained by atomic mapping are shown on a personal computer monitor. The scan steps of the x and y axes were both 2.5 mm, and the photon-counting time per mapping point was 0.5 s. We carried out atomic mapping using the X-ray camera, and Kα photons from cerium and gadolinium atoms were produced from cancerous regions in nude mice.

Magnetoelectric confinement and stabilization of Z pinch in a soft-x-ray Ar(+8) laser.

PubMed

Szasz, J; Kiss, M; Santa, I; Szatmari, S; Kukhlevsky, S V

2013-05-03

Magnetoelectric confinement and stabilization of the plasma column in a soft-x-ray Ar(+8) laser, which is excited by a capillary Z pinch, via the combined magnetic and electric fields of the gliding surface discharge is experimentally demonstrated. Unlike soft-x-ray lasers excited by the conventional capillary Z pinches, the magnetoelectric confinement and stabilization of plasma do provide the laser operation without using any external preionization circuit.

Lumbosacral spine x-ray

MedlinePlus

X-ray - lumbosacral spine; X-ray - lower spine ... The test is done in a hospital x-ray department or your health care provider's office by an x-ray technician. You will be asked to lie on the x-ray ...

X-ray ptychography

NASA Astrophysics Data System (ADS)

Pfeiffer, Franz

2018-01-01

X-ray ptychographic microscopy combines the advantages of raster scanning X-ray microscopy with the more recently developed techniques of coherent diffraction imaging. It is limited neither by the fabricational challenges associated with X-ray optics nor by the requirements of isolated specimen preparation, and offers in principle wavelength-limited resolution, as well as stable access and solution to the phase problem. In this Review, we discuss the basic principles of X-ray ptychography and summarize the main milestones in the evolution of X-ray ptychographic microscopy and tomography over the past ten years, since its first demonstration with X-rays. We also highlight the potential for applications in the life and materials sciences, and discuss the latest advanced concepts and probable future developments.

A large format membrane-based x-ray mask for microfluidic chip fabrication

NASA Astrophysics Data System (ADS)

Wang, Lin; Zhang, Min; Desta, Yohannes; Melzak, J.; Wu, C. H.; Peng, Zhengchun

2006-02-01

X-ray lithography is a very good option for the fabrication of micro-devices especially when high aspect ratio patterns are required. Membrane-based x-ray masks are commonly used for high-resolution x-ray lithography. A thin layer of silicon nitride (Si3N4) or silicon carbide (SiC) film (1-2 µm) is normally used as the membrane material for x-ray mask fabrication (Wells G M, Reilly M, Nachman R, Cerrina F, El-Khakani M A and Chaker M 1993 Mater. Res. Soc. Conf. Proc. 306 81-9 Shoki T, Nagasawa H, Kosuga H, Yamaguchi Y, Annaka N, Amemiya I and Nagarekawa O 1993 SPIE Proc. 1924 450-6). The freestanding membrane window of an x-ray mask, which defines the exposing area of the x-ray mask, can be obtained by etching a pre-defined area on a silicon wafer from the backside (Wang L, Desta Y, Fettig R K, Goettert J, Hein H, Jakobs P and Chulz J 2004 J. Micromech. Microeng. 14 722-6). Usually, the window size of an x-ray mask is around 20 × 20 mm because of the low tensile stress of the membrane (10-100 MPa), and the larger window dimension of an x-ray mask may cause the deformation of membranes and lower the mask quality. However, x-ray masks with larger windows are preferred for micro-device fabrication in order to increase the productivity. We analyzed the factors which influence the flatness of large format x-ray masks and fabricated x-ray masks with a window size of 55 × 55 mm and 46 × 65 mm on 1 µm thick membranes by increasing the tensile stress of the membranes (>300 MPa) and optimizing the stress of the absorber layer. The large format x-ray mask was successfully applied for the fabrication of microfluidic chips.

Positron production by x rays emitted by betatron motion in a plasma wiggler.

PubMed

Johnson, D K; Auerbach, D; Blumenfeld, I; Barnes, C D; Clayton, C E; Decker, F J; Deng, S; Emma, P; Hogan, M J; Huang, C; Ischebeck, R; Iverson, R; Joshi, C; Katsouleas, T C; Kirby, N; Krejcik, P; Lu, W; Marsh, K A; Mori, W B; Muggli, P; O'Connell, C L; Oz, E; Siemann, R H; Walz, D; Zhou, M

2006-10-27

Positrons in the energy range of 3-30 MeV, produced by x rays emitted by betatron motion in a plasma wiggler of 28.5 GeV electrons from the SLAC accelerator, have been measured. The extremely high-strength plasma wiggler is an ion column induced by the electron beam as it propagates through and ionizes dense lithium vapor. X rays in the range of 1-50 MeV in a forward cone angle of 0.1 mrad collide with a 1.7 mm thick tungsten target to produce electron-positron pairs. The positron spectra are found to be strongly influenced by the plasma density and length as well as the electron bunch length. By characterizing the beam propagation in the ion column these influences are quantified and result in excellent agreement between the measured and calculated positron spectra.

X-ray observations of the colliding wind binary WR 25

NASA Astrophysics Data System (ADS)

Arora, Bharti; Pandey, Jeewan Chandra

2018-04-01

Using the archival data obtained from Chandra and Suzaku spanning over '8 years, we present an analysis of a WN6h+O4f Wolf-Rayet binary, WR 25. The X-ray light curves folded over a period of '208 d in the 0.3 - 10.0 keV energy band showed phase-locked variability where the count rates were found to be maximum near the periastron passage. The X-ray spectra of WR 25 were well explained by a two-temperature plasma model with temperatures of 0.64 ± 0.01 and 2.96 ± 0.05 keV and are consistent with previous results. The orbital phase dependent local hydrogen column density was found to be maximum just after the periastron passage, when the WN type star is in front of the O star. The hard (2.0 - 10.0 keV) X-ray luminosity was linearly dependent on the inverse of binary separation which confirms that WR 25 is a colliding wind binary.

A DEEP X-RAY VIEW OF THE BARE AGN ARK 120. I. REVEALING THE SOFT X-RAY LINE EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reeves, J. N.; Braito, V.; Porquet, D.

2016-09-10

The Seyfert 1 galaxy Ark 120 is a prototype example of the so-called class of bare nucleus active galactic nuclei (AGNs), whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep (>400 ks exposure), high-resolution X-ray spectroscopy of Ark 120 is presented from XMM-Newton observations that were carried out in 2014 March, together with simultaneous Chandra /High Energy Transmission Grating exposures. The high-resolution spectra confirmed the lack of intrinsic absorbing gas associated with Ark 120, with the only X-ray absorption present originating from the interstellar medium (ISM) of our ownmore » Galaxy, with a possible slight enhancement of the oxygen abundance required with respect to the expected ISM values in the solar neighborhood. However, the presence of several soft X-ray emission lines are revealed for the first time in the XMM-Newton RGS spectrum, associated with the AGN and arising from the He- and H-like ions of N, O, Ne, and Mg. The He-like line profiles of N, O, and Ne appear velocity broadened, with typical FWHMs of ∼5000 km s{sup −1}, whereas the H-like profiles are unresolved. From the clean measurement of the He-like triplets, we deduce that the broad lines arise from a gas of density n {sub e} ∼ 10{sup 11} cm{sup −3}, while the photoionization calculations infer that the emitting gas covers at least 10% of 4 π steradian. Thus the broad soft X-ray profiles appear coincident with an X-ray component of the optical–UV broad-line region on sub-parsec scales, whereas the narrow profiles originate on larger parsec scales, perhaps coincident with the AGN narrow-line region. The observations show that Ark 120 is not intrinsically bare and substantial X-ray-emitting gas exists out of our direct line of sight toward this AGN.« less

Method and apparatus for analog signal conditioner for high speed, digital x-ray spectrometer

DOEpatents

Warburton, William K.; Hubbard, Bradley

1999-01-01

A signal processing system which accepts input from an x-ray detector-preamplifier and produces a signal of reduced dynamic range for subsequent analog-to-digital conversion. The system conditions the input signal to reduce the number of bits required in the analog-to-digital converter by removing that part of the input signal which varies only slowly in time and retaining the amplitude of the pulses which carry information about the x-rays absorbed by the detector. The parameters controlling the signal conditioner's operation can be readily supplied in digital form, allowing it to be integrated into a feedback loop as part of a larger digital x-ray spectroscopy system.

Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?

NASA Technical Reports Server (NTRS)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-01-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi- Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with Gamma = 1.41‚+/- 0.65 and a luminosity of 7.97 x 10(exp 33) erg/s (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of approx. 8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of approx. 4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always "on."

UNDERSTANDING X-RAY STARS:. The Discovery of Binary X-ray Sources

NASA Astrophysics Data System (ADS)

Schreier, E. J.; Tananbaum, H.

2000-09-01

The discovery of binary X-ray sources with UHURU introduced many new concepts to astronomy. It provided the canonical model which explained X-ray emission from a large class of galactic X-ray sources: it confirmed the existence of collapsed objects as the source of intense X-ray emission; showed that such collapsed objects existed in binary systems, with mass accretion as the energy source for the X-ray emission; and provided compelling evidence for the existence of black holes. This model also provided the basis for explaining the power source of AGNs and QSOs. The process of discovery and interpretation also established X-ray astronomy as an essential sub-discipline of astronomy, beginning its incorporation into the mainstream of astronomy.

Thoracic spine x-ray

MedlinePlus

Vertebral radiography; X-ray - spine; Thoracic x-ray; Spine x-ray; Thoracic spine films; Back films ... The test is done in a hospital radiology department or in the health care provider's office. You will lie on the x-ray table in different positions. If the x-ray ...

X-ray binaries

NASA Technical Reports Server (NTRS)

1976-01-01

Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

Unusual Black Hole Binary LMC X-3: A Transient High-mass X-Ray Binary That Is Almost Always On?

NASA Astrophysics Data System (ADS)

Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A.

2017-11-01

We have analyzed a rich, multimission, multiwavelength data set from the black hole X-ray binary (BHXB) LMC X-3, covering a new anomalous low state (ALS), during which the source flux falls to an unprecedentedly low and barely detectable level, and a more normal low state. Simultaneous X-ray and UV/optical monitoring data from Swift are combined with pointed observations from the Rossi X-ray Timing Explorer (RXTE) and X-ray Multi-Mirror Mission (XMM-Newton) and light curves from the Monitor of All-Sky X-ray Image (MAXI) instrument to compare the source characteristics during the ALS with those seen during the normal low state. An XMM-Newton spectrum obtained during the ALS can be modeled using an absorbed power law with {{Γ }}=1.41+/- 0.65 and a luminosity of 7.97× {10}33 erg s-1 (0.6-5 keV). The Swift X-ray and UV light curves indicate an X-ray lag of ˜8 days as LMC X-3 abruptly exits the ALS, suggesting that changes in the mass accretion rate from the donor drive the X-ray lag. The normal low state displays an asymmetric profile in which the exit occurs more quickly than the entry, with minimum X-ray flux a factor of ˜4300 brighter than during the ALS. The UV brightness of LMC X-3 in the ALS is also fainter and less variable than during normal low states. The existence of repeated ALSs in LMC X-3, as well as a comparison with other BHXBs, implies that it is very close to the transient/persistent X-ray source dividing line. We conclude that LMC X-3 is a transient source that is almost always “on.”

From ultraluminous X-ray sources to ultraluminous supersoft sources: NGC 55 ULX, the missing link

NASA Astrophysics Data System (ADS)

Pinto, C.; Alston, W.; Soria, R.; Middleton, M. J.; Walton, D. J.; Sutton, A. D.; Fabian, A. C.; Earnshaw, H.; Urquhart, R.; Kara, E.; Roberts, T. P.

2017-07-01

In recent work with high-resolution reflection grating spectrometers (RGS) aboard XMM-Newton, Pinto et al. have discovered that two bright and archetypal ultraluminous X-ray sources (ULXs) have strong relativistic winds in agreement with theoretical predictions of high accretion rates. It has been proposed that such winds can become optically thick enough to block and reprocess the disc X-ray photons almost entirely, making the source appear as a soft thermal emitter or ultraluminous supersoft X-ray source (ULS). To test this hypothesis, we have studied a ULX where the wind is strong enough to cause significant absorption of the hard X-ray continuum: NGC 55 ULX. The RGS spectrum of NGC 55 ULX shows a wealth of emission and absorption lines blueshifted by significant fractions of the light speed (0.01-0.20)c indicating the presence of a powerful wind. The wind has a complex dynamical structure with the ionization state increasing with the outflow velocity, which may indicate launching from different regions of the accretion disc. The comparison with other ULXs such as NGC 1313 X-1 and NGC 5408 X-1 suggests that NGC 55 ULX is being observed at higher inclination. The wind partly absorbs the source flux above 1 keV, generating a spectral drop similar to that observed in ULSs. The softening of the spectrum at lower (˜ Eddington) luminosities and the detection of a soft lag agree with the scenario of wind clumps crossing the line of sight, partly absorbing and reprocessing the hard X-rays from the innermost region.

X-ray observations of dust obscured galaxies in the Chandra deep field south

NASA Astrophysics Data System (ADS)

Corral, A.; Georgantopoulos, I.; Comastri, A.; Ranalli, P.; Akylas, A.; Salvato, M.; Lanzuisi, G.; Vignali, C.; Koutoulidis, L.

2016-08-01

We present the properties of X-ray detected dust obscured galaxies (DOGs) in the Chandra deep field south. In recent years, it has been proposed that a significant percentage of the elusive Compton-thick (CT) active galactic nuclei (AGN) could be hidden among DOGs. This type of galaxy is characterized by a very high infrared (IR) to optical flux ratio (f24 μm/fR > 1000), which in the case of CT AGN could be due to the suppression of AGN emission by absorption and its subsequent re-emission in the IR. The most reliable way of confirming the CT nature of an AGN is by X-ray spectroscopy. In a previous work, we presented the properties of X-ray detected DOGs by making use of the deepest X-ray observations available at that time, the 2Ms observations of the Chandra deep fields, the Chandra deep field north (CDF-N), and the Chandra deep field south (CDF-S). In that work, we only found a moderate percentage (<50%) of CT AGN among the DOGs sample. However, we pointed out that the limited photon statistics for most of the sources in the sample did not allow us to strongly constrain this number. In this paper, we further explore the properties of the sample of DOGs in the CDF-S presented in that work by using not only a deeper 6Ms Chandra survey of the CDF-S, but also by combining these data with the 3Ms XMM-Newton survey of the CDF-S. We also take advantage of the great coverage of the CDF-S region from the UV to the far-IR to fit the spectral energy distributions (SEDs) of our sources. Out of the 14 AGN composing our sample, 9 are highly absorbed (NH > 1023 cm-2), whereas 2 look unabsorbed, and the other 3 are only moderately absorbed. Among the highly absorbed AGN, we find that only three could be considered CT AGN. In only one of these three cases, we detect a strong Fe Kα emission line; the source is already classified as a CT AGN with Chandra data in a previous work. Here we confirm its CT nature by combining Chandra and XMM-Newton data. For the other two CT

UCSD OSO-7 observations of the hard X-ray spectrum and variability of Centaurus A

NASA Technical Reports Server (NTRS)

Mushotzky, R. F.; Baity, W. A.; Wheaton, W. A.; Peterson, L. E.

1976-01-01

Results are reported for four X-ray scans of the region containing Cen A. It is found that the X-ray source had a hard number spectrum (spectral index of -1.2) during these observations and that the intensity in the range from 10 to 100 keV apparently increased by 230% with no detectable change in spectral shape between two observations 210 days apart. Either a Compton-synchrotron mechanism or thermal bremsstrahlung at any temperature greater than 200 keV is suggested as the source of the X-rays. It is noted that the present observations, together with a similar detection of another galaxy, may establish a distinct class of extragalactic X-ray objects with flat and highly absorbed spectra.

Reanalysis of X-ray emission from M87. 2: The multiphase medium

NASA Technical Reports Server (NTRS)

Tsai, John C.

1994-01-01

In a previous paper, we showed that a single-phase model for the gas around M87 simultaneously explained most available X-ray data. Total enclosed masses derived from the model, however, fell well below the determinations from optical measurements. In this paper, we consider possible solutions to the inconsistency, including two multiphase medium models for the gas and the consequences of systematic errors of the Einstein Focal Point Crystal Spectrometer (FPCS). First, we find that when constraints from optical mass determinations are not considered, the best-fit model to the X-ray data is always the single-phase model. Multiphase models or consideration of FPCS systematic errors are required only when optical mass constraints are included. We find that the cooling time model of White & Sarazin adequately explains the available X-ray data and predicts total masses which agree with optical measurements. An ad hoc power-law multiphase does not. This shows both that the existence of mass dropping out of the ambient phase is consistent with the data and that the cooling-time model gives a reasonable parameterization of the dropout rate. Our derived mass accretion rate is similar to previous determinations. The implications of this result for cluster mass determinations in general are discussed. We then consider 'self absorbing' models where we assume that material dropping out of the ambient medium goes completely into X-ray absorbing gas. The resulting internal absorption is small compared to Galactic absorption at most radii. The models are therefore indistinguishable from models with only Galactic absorption. We finally show that it is alternatively possible to simultaneously fit optical mass measurements and X-ray data with a single-phase model if some of the observed FPCS line fluxes are too high by the maximum systematic error. This possiblity can be checked with new data from satellites such as ASCA.

Skull x-ray

MedlinePlus

X-ray - head; X-ray - skull; Skull radiography; Head x-ray ... Chernecky CC, Berger BJ. Radiography of skull, chest, and cervical spine - diagnostic. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures . 6th ed. ...

Origin of the X-ray Spectral Variation and Seemingly Broad Iron Line Strucuture in the Seyfert Galaxies

NASA Astrophysics Data System (ADS)

Ebisawa, Ken; Naoki, Iso

2012-07-01

X-ray intensities and spectra of the Seyfert galaxies are known to be variable. Some of the sources have characteristic seemingly broad iron line structure, and their spectral variations are small in the iron line energy band. MCG-6-30-15 is such an archetypal source, and Miyakawa (2011) proposed a "Variable Partial Covering (VPC)" model to explain its continuum spectral variation, seemingly broad iron line structure, and small spectral variation in the iron energy band simultaneously, only due to variation of a single parameter. That single parameter is the "partial covering fraction" to describe the geometrical fraction of the X-ray emitting area covered by the ionized absorbers in the line of sight. The intrinsic X-ray luminosity is hardly variable in this model. We have applied the VPC model to the 27 Seyfert galaxies observed with Suzaku, and found that spectral variations of the 22 sources are successfully explained by this model only varying the partial covering fraction. Intrinsic X-ray luminosities of Seyfert galaxies are not variable, as opposed to what they apparently seem, and gravitationally red-shifted iron line is not necessary. Those ionized absorbing clouds are most likely to be Broad Line Region (BLR) clouds, and we will be able to constrain the BLR structure from X-ray observations.

Full-field transmission x-ray imaging with confocal polycapillary x-ray optics

PubMed Central

Sun, Tianxi; MacDonald, C. A.

2013-01-01

A transmission x-ray imaging setup based on a confocal combination of a polycapillary focusing x-ray optic followed by a polycapillary collimating x-ray optic was designed and demonstrated to have good resolution, better than the unmagnified pixel size and unlimited by the x-ray tube spot size. This imaging setup has potential application in x-ray imaging for small samples, for example, for histology specimens. PMID:23460760

Performance and Characterization of Magnetic Penetration Thermometer Devices for X-Ray Spectroscopy

NASA Technical Reports Server (NTRS)

Porst, J. -P.; Adams, J. S.; Bandler, S. R.; Balvin, M.; Busch, S. E.; Denis, K. L.; Kelly, D.; Nagler, P.; Sadleir, J. E.; Seidel, G. M.;

X-ray generator

DOEpatents

Dawson, John M.

1976-01-01

Apparatus and method for producing coherent secondary x-rays that are controlled as to direction by illuminating a mixture of high z and low z gases with an intense burst of primary x-rays. The primary x-rays are produced with a laser activated plasma, and these x-rays strip off the electrons of the high z atoms in the lasing medium, while the low z atoms retain their electrons. The neutral atoms transfer electrons to highly excited states of the highly striped high z ions giving an inverted population which produces the desired coherent x-rays. In one embodiment, a laser, light beam provides a laser spark that produces the intense burst of coherent x-rays that illuminates the mixture of high z and low z gases, whereby the high z atoms are stripped while the low z ones are not, giving the desired mixture of highly ionized and neutral atoms. To this end, the laser spark is produced by injecting a laser light beam, or a plurality of beams, into a first gas in a cylindrical container having an adjacent second gas layer co-axial therewith, the laser producing a plasma and the intense primary x-rays in the first gas, and the second gas containing the high and low atomic number elements for receiving the primary x-rays, whereupon the secondary x-rays are produced therein by stripping desired ions in a neutral gas and transfer of electrons to highly excited states of the stripped ions from the unionized atoms. Means for magnetically confining and stabilizing the plasma are disclosed for controlling the direction of the x-rays.

Probing the Spatial Distribution of the Interstellar Dust Medium by High Angular Resolution X-ray Halos of Point Sources

NASA Astrophysics Data System (ADS)

Xiang, Jingen

X-rays are absorbed and scattered by dust grains when they travel through the interstellar medium. The scattering within small angles results in an X-ray ``halo''. The halo properties are significantly affected by the energy of radiation, the optical depth of the scattering, the grain size distributions and compositions, and the spatial distribution of dust along the line of sight (LOS). Therefore analyzing the X-ray halo properties is an important tool to study the size distribution and spatial distribution of interstellar grains, which plays a central role in the astrophysical study of the interstellar medium, such as the thermodynamics and chemistry of the gas and the dynamics of star formation. With excellent angular resolution, good energy resolution and broad energy band, the Chandra ACIS is so far the best instrument for studying the X-ray halos. But the direct images of bright sources obtained with ACIS usually suffer from severe pileup which prevents us from obtaining the halos in small angles. We first improve the method proposed by Yao et al to resolve the X-ray dust scattering halos of point sources from the zeroth order data in CC-mode or the first order data in TE mode with Chandra HETG/ACIS. Using this method we re-analyze the Cygnus X-1 data observed with Chandra. Then we studied the X-ray dust scattering halos around 17 bright X-ray point sources using Chandra data. All sources were observed with the HETG/ACIS in CC-mode or TE-mode. Using the interstellar grain models of WD01 model and MRN model to fit the halo profiles, we get the hydrogen column densities and the spatial distributions of the scattering dust grains along the line of sights (LOS) to these sources. We find there is a good linear correlation not only between the scattering hydrogen column density from WD01 model and the one from MRN model, but also between N_{H} derived from spectral fits and the one derived from the grain models WD01 and MRN (except for GX 301-2 and Vela X-1): N

MHD Wind Models in X-Ray Binaries and AGN

NASA Astrophysics Data System (ADS)

Behar, Ehud; Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Contopoulos, Ioannis

2017-08-01

Self-similar magnetohydrodynamic (MHD) wind models that can explain both the kinematics and the ionization structure of outflows from accretion sources will be presented.The X-ray absorption-line properties of these outflows are diverse, their velocity ranging from 0.001c to 0.1c, and their ionization ranging from neutral to fully ionized.We will show how the velocity structure and density profile of the wind can be tightly constrained, by finding the scaling of the magnetic flux with the distance from the center that best matches observations, and with no other priors.It will be demonstrated that the same basic MHD wind structure that successfully accounts for the X-ray absorber properties of outflows from supermassive black holes, also reproduces the high-resolution X-ray spectrum of the accreting stellar-mass black hole GRO J1655-40 for a series of ions between ~1A and ~12A.These results support both the magnetic nature of these winds, as well as the universal nature of magnetic outflows across all black hole sizes.

Hard X-ray tests of the unified model for an ultraviolet-detected sample of Seyfert 2 galaxies

NASA Technical Reports Server (NTRS)

Mulchaey, John S.; Myshotzky, Richard F.; Weaver, Kimberly A.

1992-01-01

An ultraviolet-detected sample of Seyfert 2 galaxies shows heavy photoelectric absorption in the hard X-ray band. The presence of UV emission combined with hard X-ray absorption argues strongly for a special geometry which must have the general properties of the Antonucci and Miller unified model. The observations of this sample are consistent with the picture in which the hard X-ray photons are viewed directly through the obscuring matter (molecular torus?) and the optical, UV, and soft X-ray continuum are seen in scattered light. The large range in X-ray column densities implies that there must be a large variation in intrinsic thicknesses of molecular tori, an assumption not found in the simplest of unified models. Furthermore, constraints based on the cosmic X-ray background suggest that some of the underlying assumptions of the unified model are wrong.

Comparison between X-rays spectra and their effective energies in small animal CT tomographic imaging and dosimetry.

PubMed

Hamdi, Mahdjoub; Mimi, Malika; Bentourkia, M'hamed

2017-03-01

Small animal CT imaging and dosimetry usually rely on X-ray radiation produced by X-ray tubes. These X-rays typically cover a large energy range. In this study, we compared poly-energetic X-ray spectra against estimated equivalent (effective) mono-energetic beams with the same number of simulated photons for small animal CT imaging and dosimetry applications. Two poly-energetic X-ray spectra were generated from a tungsten anode at 50 and 120 kVp. The corresponding effective mono-energetic beams were established as 36 keV for the 50 kVp spectrum and 49.5 keV for the 120 kVp spectrum. To assess imaging applications, we investigated the spatial resolution by a tungsten wire, and the contrast-to-noise ratio in a reference phantom and in a realistic mouse phantom. For dosimetry investigation, we calculated the absorbed dose in a segmented digital mouse atlas in the skin, fat, heart and bone tissues. Differences of 2.1 and 2.6% in spatial resolution were respectively obtained between the 50 and 120 kVp poly-energetic spectra and their respective 36 and 49.5 keV mono-energetic beams. The differences in contrast-to-noise ratio between the poly-energetic 50 kVp spectrum and its corresponding mono-energetic 36 keV beam for air, fat, brain and bone were respectively -2.9, -0.2, 11.2 and -4.8%, and similarly between the 120 kVp and its effective energy 49.5 keV: -11.3, -20.2, -4.2 and -13.5%. Concerning the absorbed dose, for the lower X-ray beam energies, 50 kVp against 36 keV, the poly-energetic radiation doses were higher than the mono-energetic doses. Instead, for the higher X-ray beam energies, 120 kVp and 49.5 keV, the absorbed dose to the bones and lungs were higher for the mono-energetic 49.5 keV. The intensity and energy of the X-ray beam spectrum have an impact on both imaging and dosimetry in small animal studies. Simulations with mono-energetic beams should take into account these differences in order to study biological effects or to be compared to

Evaluation of the medical exposure doses regarding dental examinations with different X-ray instruments

NASA Astrophysics Data System (ADS)

Liu, Yi-Chi; Chuang, Keh-Shih; Yu, Cheng-Ching; Chao, Jiunn-Hsing; Hsu, Fang-Yuh

2015-11-01

Modern dental X-ray examination that consists of traditional form, panorama, and cone-beamed 3D technologies is one of the most frequent diagnostic applications nowadays. This study used the Rando Phantom and thermoluminescence dosimeters (TLD) to measure the absorbed doses of radiosensitive organs recommended by International Commission on Radiological Protection (ICRP), and whole body effective doses which were delivered due to dental X-ray examination performed with different types of X-ray instrument. Besides, enamel samples which performed reading with Electronic Paramagnetic Resonance (EPR) procedure were also used to estimate the tooth doses. EPR is a dose reconstruction method of measuring free radicals induced by radiation exposure to the calcified tissue (mainly in the tooth enamel or bone) to evaluate the accepted high dose. The tooth doses estimated by TLD and EPR methods were compared. Relationships between the tooth doses and effective doses by dental X-ray examinations with different types of X-ray equipment were investigated in this work.

X-ray lithography masking

NASA Technical Reports Server (NTRS)

Smith, Henry I. (Inventor); Lim, Michael (Inventor); Carter, James (Inventor); Schattenburg, Mark (Inventor)

1998-01-01

X-ray masking apparatus includes a frame having a supporting rim surrounding an x-ray transparent region, a thin membrane of hard inorganic x-ray transparent material attached at its periphery to the supporting rim covering the x-ray transparent region and a layer of x-ray opaque material on the thin membrane inside the x-ray transparent region arranged in a pattern to selectively transmit x-ray energy entering the x-ray transparent region through the membrane to a predetermined image plane separated from the layer by the thin membrane. A method of making the masking apparatus includes depositing back and front layers of hard inorganic x-ray transparent material on front and back surfaces of a substrate, depositing back and front layers of reinforcing material on the back and front layers, respectively, of the hard inorganic x-ray transparent material, removing the material including at least a portion of the substrate and the back layers of an inside region adjacent to the front layer of hard inorganic x-ray transparent material, removing a portion of the front layer of reinforcing material opposite the inside region to expose the surface of the front layer of hard inorganic x-ray transparent material separated from the inside region by the latter front layer, and depositing a layer of x-ray opaque material on the surface of the latter front layer adjacent to the inside region.

An Axisymmetric Hydrodynamical Model for the Torus Wind in AGN. 2; X-ray Excited Funnel Flow

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.; Proga, D.

2008-01-01

We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorption line spectra.

Sinus x-ray

MedlinePlus

Paranasal sinus radiography; X-ray - sinuses ... sinus x-ray is taken in a hospital radiology department. Or the x-ray may be taken ... Brown J, Rout J. ENT, neck, and dental radiology. In: Adam A, Dixon AK, Gillard JH, Schaefer- ...

X-Ray Data Booklet

Science.gov Websites

X-RAY DATA BOOKLET Center for X-ray Optics and Advanced Light Source Lawrence Berkeley National Laboratory Introduction X-Ray Properties of Elements Electron Binding Energies X-Ray Energy Emission Energies Table of X-Ray Properties Synchrotron Radiation Characteristics of Synchrotron Radiation History of X

Recent X-ray Variability of Eta Car Approaching The X-ray Eclipse

NASA Technical Reports Server (NTRS)

Corcoran, M.; Swank, J. H.; Ishibashi, K.; Gull, T.; Humphreys, R.; Damineli, A.; Walborn, N.; Hillier, D. J.; Davidson, K.; White, S. M.

2002-01-01

We discuss recent X-ray spectral variability of the supermassive star Eta Car in the interval since the last X-ray eclipse in 1998. We concentrate on the interval just prior to the next X-ray eclipse which is expected to occur in June 2003. We compare the X-ray behavior during the 2001-2003 cycle with the previous cycle (1996-1998) and note similarities and differences in the temporal X-ray behavior. We also compare a recent X-ray observation of Eta Car obtained with the Chandra high energy transmission grating in October 2002 with an earlier observation from Nov 2002, and interpret these results in terms of the proposed colliding wind binary model for the star. In addition we discuss planned observations for the upcoming X-ray eclipse.

Intercalation of anionic organic ultraviolet ray absorbers into layered zinc hydroxide nitrate.

PubMed

Cursino, Ana Cristina Trindade; Gardolinski, José Eduardo Ferreira da Costa; Wypych, Fernando

2010-07-01

Layered zinc hydroxide nitrate (ZHN) was synthesized and nitrate ions were topotactically exchanged with three different anionic species of commercial organic ultraviolet (UV) ray absorbers: 2-mercaptobenzoic acid, 2-aminobenzoic acid, and 4-aminobenzoic acid. The exchange reactions were confirmed by X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV-Vis) spectroscopy, and thermal analysis (thermogravimetry, TGA, and differential thermal analysis, DTA). In all the anionic exchanged products, evidence of grafting of the organic species onto the inorganic matrix was obtained. In general, after intercalation/grafting, the UV absorption ability was improved in relation to the use of the parent organic material, showing that layered hydroxide salts (LHS) can be good alternative matrixes for the immobilization of organic species with UV-blocking properties in cosmetic products. Copyright 2010 Elsevier Inc. All rights reserved.

Large area soft x-ray collimator to facilitate x-ray optics testing

NASA Technical Reports Server (NTRS)

Espy, Samuel L.

1994-01-01

The first objective of this program is to design a nested conical foil x-ray optic which will collimate x-rays diverging from a point source. The collimator could then be employed in a small, inexpensive x-ray test stand which would be used to test various x-ray optics and detector systems. The second objective is to demonstrate the fabrication of the x-ray reflectors for this optic using lacquer-smoothing and zero-stress electroforming techniques.

Probing the structure of the gas in the Milky Way through X-ray high-resolution spectroscopy

NASA Astrophysics Data System (ADS)

Gatuzz, Efraín; Churazov, Eugene

2018-02-01

We have developed a new X-ray absorption model, called IONeq, which computes the optical depth τ(E) simultaneously for ions of all abundant elements, assuming ionization equilibrium and taking into account turbulent broadening. We use this model to analyse the interstellar medium (ISM) absorption features in the Milky Way for a sample of 18 Galactic (LMXBs) and 42 extragalactic sources (mainly Blazars). The absorbing ISM was modelled as a combination of three components/phases - neutral (T ≲ 1 × 104 K), warm (T ˜ 5 × 104 K) and hot (T ˜ 2 × 106 K). We found that the spatial distribution of both, neutral and warm components, are difficult to describe using smooth profiles due to non-uniform distribution of the column densities over the sky. For the hot phase we used a combination of a flattened disc and a halo, finding comparable column densities for both spatial components, of the order of ˜6-7 × 1018 cm-2, although this conclusion depends on the adopted parametrization. If the halo component has sub-solar abundance Z, then the column density has to be scaled up by a factor of Z_{⊙}/Z. The vertically integrated column densities of the disc components suggest the following mass fractions for these three ISM phases in the Galactic disc: neutral ˜ 89 per cent, warm ˜ 8 per cent and hot ˜ 3 per cent components, respectively. The constraints on the radial distribution of the halo component of the hot component are weak.

Development of x-ray laminography under an x-ray microscopic condition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoshino, Masato; Uesugi, Kentaro; Takeuchi, Akihisa

2011-07-15

An x-ray laminography system under an x-ray microscopic condition was developed to obtain a three-dimensional structure of laterally-extended planar objects which were difficult to observe by x-ray tomography. An x-ray laminography technique was introduced to an x-ray transmission microscope with zone plate optics. Three prototype sample holders were evaluated for x-ray imaging laminography. Layered copper grid sheets were imaged as a laminated sample. Diatomite powder on a silicon nitride membrane was measured to confirm the applicability of this method to non-planar micro-specimens placed on the membrane. The three-dimensional information of diatom shells on the membrane was obtained at a spatialmore » resolution of sub-micron. Images of biological cells on the membrane were also obtained by using a Zernike phase contrast technique.« less