The X-ray reflection spectrum of the radio-loud quasar 4C 74.26

The relativistic jets created by some active galactic nuclei are important agents of AGN feedback. In spite of this, our understanding of what produces these jets is still incomplete. X-ray observations, which can probe the processes operating in the central regions in immediate vicinity of the supermassive black hole, the presumed jet launching point, are potentially particularly valuable in illuminating the jet formation process. Here, we present the hard X-ray NuSTAR observations of the radio-loud quasar 4C 74.26 in a joint analysis with quasi-simultaneous, soft X-ray Swift observations. Our spectral analysis reveals a high-energy cut-off of 183$_{-35}^{+51}$ keV and confirms the presence of ionized reflection in the source. From the average spectrum we detect that the accretion disk is mildly recessed with an inner radius of $R_\mathrm{in}=4-180\,R_\mathrm{g}$. However, no significant evolution of the inner radius is seen during the three months covered by our NuSTAR campaign. This lack of variation could mean that the jet formation in this radio-loud quasar differs from what is observed in broad-line radio galaxies.Comment: Accepted for publication in Ap

Interpretation of NASA-STD-3001 Levels of Care for Exploration Medical System Development

No abstract availabl

W/SiC x-ray multilayers optimized for use above 100 keV

We have developed a new depth-graded multilayer system comprising W and SiC layers, suitable for use as hard x-ray reflective coatings operating in the energy range 100-200 keV. Grazing-incidence x-ray reflectance at E = 8 keV was used to characterize the interface widths, as well as the temporal and thermal stability in both periodic and depth-graded W/SiC structures, whereas synchrotron radiation was used to measure the hard x-ray reflectance of a depth-graded multilayer designed specifically for use in the range E ~150-170 keV. We have modeled the hard x-ray reflectance using newly derived optical constants, which we determined from reflectance versus incidence angle measurements also made using synchrotron radiation, in the range E = 120-180 keV. We describe our experimental investigation in detail, compare the new W/SiC multilayers with both W/Si and W/B4C films that have been studied previously, and discuss the significance of these results with regard to the eventual development of a hard x-ray nuclear line telescope

Development of thermally formed glass optics for astronomical hard x-ray telescopes

The next major observational advance in hard X-ray/soft gamma-ray astrophysics will come with the implementation of telescopes capable of focusing 10-200 keV radiation. Focusing allows high signal-to-noise imaging and spectroscopic observations of many sources in this band for the first time. The recent development of depth-graded multilayer coatings has made the design of telescopes for this bandpass practical, however the ability to manufacture inexpensive substrates with appropriate surface quality and figure to achieve sub-arcminute performance has remained an elusive goal. In this paper, we report on new, thermally-formed glass micro-sheet optics capable of meeting the requirements of the next-generation of astronomical hard X-ray telescopes

Aortic pulse wave velocity in children with Cushing syndrome: A window into a marker of early cardiovascular disease.

ObjectiveTo investigate early signs of cardiovascular arterial remodelling in paediatric patients with Cushing syndrome (CS) in comparison with normative values from healthy children.Study designThe metrics used to assess cardiac health were from thoracic aorta and carotid MRI. Scans were performed on 18 children with CS (mean: 12.5 ± 3.1 years, range: 6.0-16.8 years, 10 female). Pulse wave velocity (PWV), aortic distensibility (AD) and carotid intima-media thickness (cIMT), well-validated measurements of cardiac compromise, were measured from the images and compared to normative age-matched values where available.ResultsPatients with CS had significantly higher PWV compared to age-adjusted normal median control values (4.0 ± 0.7 m/s vs. 3.4 ± 0.2 m/s, respectively, P = 0.0115). PWV was positively correlated with midnight plasma cortisol (r = 0.56, P = 0.02). Internal and common cIMT were negatively correlated with ascending AD (r = -0.75, P = 0.0022, r = -0.69, P = 0.0068, respectively).ConclusionPulse wave velocity data indicate that paediatric patients with CS have early evidence of cardiovascular remodelling. The results suggest the opportunity for monitoring as these changes begin in childhood

The X-ray reflection spectrum of the radio-loud quasar 4C 74.26

The relativistic jets created by some active galactic nuclei are important agents of AGN feedback. In spite of this, our understanding of what produces these jets is still incomplete. X-ray observations, which can probe the processes operating in the central regions in immediate vicinity of the supermassive black hole, the presumed jet launching point, are potentially particularly valuable in illuminating the jet formation process. Here, we present the hard X-ray NuSTAR observations of the radio-loud quasar 4C 74.26 in a joint analysis with quasi-simultaneous, soft X-ray Swift observations. Our spectral analysis reveals a high-energy cut-off of 183$_{-35}^{+51}$ keV and confirms the presence of ionized reflection in the source. From the average spectrum we detect that the accretion disk is mildly recessed with an inner radius of $R_\mathrm{in}=4-180\,R_\mathrm{g}$. However, no significant evolution of the inner radius is seen during the three months covered by our NuSTAR campaign. This lack of variation could mean that the jet formation in this radio-loud quasar differs from what is observed in broad-line radio galaxies.Comment: Accepted for publication in Ap

Optical constants for hard x-ray multilayers over the energy range E = 35 - 180 keV

We have determined experimentally optical constants for eight thin film materials that can be used in hard X-ray multilayer coatings. Thin film samples of Ni_(.97)V_(.03), Mo, W, Pt, C, B_4C, Si and SiC were deposited by magnetron sputtering onto superpolished optical flats. Optical constants were determined from fits to reflectance-vs-incidence angle measurements made using synchrotron radiation over the energy range E=35-180 keV. We have also measured the X-ray reflectance of a prototype W/SiC multilayer coating over the energy range E=35-100 keV, and we compare the measured reflectance with a calculation using the newly derived optical constants

NuSTAR Detection Of A Cyclotron Line In The Supergiant Fast X-ray Transient IGR J17544-2619

We present NuSTAR spectral and timing studies of the Supergiant Fast X-ray Transient (SFXT) IGR J17544-2619. The spectrum is well-described by a ~1 keV blackbody and a hard continuum component, as expected from an accreting X-ray pulsar. We detect a cyclotron line at 17 keV, confirming that the compact object in IGR J17544-2619 is indeed a neutron star. This is the first measurement of the magnetic field in a SFXT. The inferred magnetic field strength, B = (1.45 +/- 0.03) * 10^12 G * (1+z) is typical of neutron stars in X-ray binaries, and rules out a magnetar nature for the compact object. We do not find any significant pulsations in the source on time scales of 1-2000 s.Comment: MNRAS Accepted. 8 pages, 4 figures, 3 table

First NuSTAR Limits on Quiet Sun Hard X-Ray Transient Events

We present the first results of a search for transient hard X-ray (HXR) emission in the quiet solar corona with the \textit{Nuclear Spectroscopic Telescope Array} (\textit{NuSTAR}) satellite. While \textit{NuSTAR} was designed as an astrophysics mission, it can observe the Sun above 2~keV with unprecedented sensitivity due to its pioneering use of focusing optics. \textit{NuSTAR} first observed quiet Sun regions on 2014 November 1, although out-of-view active regions contributed a notable amount of background in the form of single-bounce (unfocused) X-rays. We conducted a search for quiet Sun transient brightenings on time scales of 100 s and set upper limits on emission in two energy bands. We set 2.5--4~keV limits on brightenings with time scales of 100 s, expressed as the temperature T and emission measure EM of a thermal plasma. We also set 10--20~keV limits on brightenings with time scales of 30, 60, and 100 s, expressed as model-independent photon fluxes. The limits in both bands are well below previous HXR microflare detections, though not low enough to detect events of equivalent T and EM as quiet Sun brightenings seen in soft X-ray observations. We expect future observations during solar minimum to increase the \textit{NuSTAR} sensitivity by over two orders of magnitude due to higher instrument livetime and reduced solar background.Comment: 11 pages, 7 figures; accepted for publication in The Astrophysical Journa

Post-acute Brain Injury Urinary Signature: A New Resource for Molecular Diagnostics

Heterogeneity within brain injury presents a challenge to the development of informative molecular diagnostics. Recent studies show progress particularly in cerebrospinal fluid with biomarker assays targeting one or a few structural proteins. Protein-based assays in peripheral fluids, however, have been more challenging to develop in part due to restricted and intermittent barrier access. Further, a greater number of molecular variables may be required to inform on patient status given the multifactorial nature of brain injury. Presented is an alternative approach profiling peripheral fluid for a class of small metabolic by-products rendered by ongoing brain pathobiology. Urine specimens were collected for head trauma subjects upon admission to acute brain injury rehabilitation and nontraumatized matched controls. An innovative data-independent mass spectrometry approach was employed for reproducible molecular quantification across osmolarity-normalized samples. The postacute human traumatic brain injury urinary signature encompassed 2,476 discriminant variables reproducibly measured in specimens for subject classification. Multiple sub-profiles were then discerned in correlation with injury severity per Glasgow Comma Scale and behavioral and neurocognitive function per Patient Competency Rating Scale and Frontal Systems Behavioral Scale. Identified peptide constituents were enriched for outgrowth and guidance, extracellular matrix and post-synaptic density proteins, which were reflective of ongoing post-acute neuroplastic processes demonstrating pathobiological relevance. Taken together, these findings support further development of diagnostics based on brain injury urinary signatures using either combinatorial quantitative models or patternrecognition methods. Particularly, these findings espouse assay development to address unmet diagnostic and theragnostic needs in brain injury rehabilitative medicine