N. J. Westergaard
A5010524716- Astrophysical Phenomena and Observations
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Advanced X-ray Imaging Techniques
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear Physics and Applications
- Calibration and Measurement Techniques
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Dark Matter and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Advanced X-ray and CT Imaging
- Geophysics and Gravity Measurements
- Atomic and Subatomic Physics Research
- X-ray Diffraction in Crystallography
- Advanced Semiconductor Detectors and Materials
- Astrophysics and Star Formation Studies
- Particle Accelerators and Free-Electron Lasers
- Adaptive optics and wavefront sensing
- Radiation Detection and Scintillator Technologies
- Astro and Planetary Science
Technical University of Denmark
2011-2023
Metropolitan University College
2022
DTU Space
2012-2018
University of Copenhagen
2017
Danish Meteorological Institute
1985-2004
Space Research Institute
2004
Center for Astrophysics Harvard & Smithsonian
1998
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates band from 3 to 79 keV, extending sensitivity of far beyond ∼10 keV cutoff achieved by all previous satellites. inherently low background associated with concentrating light enables probe hard sky a more than 100-fold improvement over collimated or coded mask instruments that have operated this bandpass. Using its unprecedented...
The JEM–X monitor provides X-ray spectra and imaging with arcminute angular resolution in the 3 to 35 keV band. good low energy response of plays an important role identification gamma ray sources analysis scientific interpretation combined data. is a coded aperture instrument consisting two identical, coaligned telescopes. Each detectors has sensitive area 500 cm2, views sky through its own mask. masks are inverted respect each other 3' across effective field view about 10° diameter.
We present the calibration of Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray satellite. used Crab as primary effective area calibrator and constructed a piece-wise linear spline function to modify vignetting response. The achieved residuals for all off-axis angles energies, compared assumed spectrum, are typically better than ±2% up 40 keV 5%–10% above due limited counting statistics. An empirical adjustment theoretical two-dimensional point-spread (PSF) was found using several strong...
The search for diffuse non-thermal inverse Compton (IC) emission from galaxy clusters at hard X-ray energies has been undertaken with many instruments, most detections being either of low significance or controversial. Background and contamination uncertainties present in the data non-focusing observatories result lower sensitivity to IC a greater chance false detection. We 266ks NuSTAR observations Bullet cluster, detected 3-30 keV. NuSTAR's unprecedented focusing capability largely...
The INTEGRAL Science Data Centre (ISDC) provides the data and means to analyse them scientific community. ISDC runs a gamma ray burst alert system that position of bursts on sky within seconds It operates quick-look analysis few hours detects new unexpected sources as well it monitors instruments. processes through standard results which are provided observers together with their data.
We report the results of a multi-band observing campaign on famous blazar 3C 279 conducted during phase increased activity from 2013 December to 2014 April, including first observations it with NuSTAR. The $\gamma$-ray emission source measured by Fermi-LAT showed multiple distinct flares reaching highest flux level in this object since beginning Fermi mission, $F(E > 100\,{\rm MeV})$ $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and doubling time scale as short 2 hours. spectrum one was very hard,...
Aims. We study the spectrum of cosmic X-ray background (CXB) in energy range ~5-100 keV.
Stellar metals shine toward our eyes only Taking a different look at familiar star may still yield surprises. Boggs et al. trained the x-ray vision of NuSTAR observatory on well-studied supernova 1987A. Core-collapse explosions such as SN 1987A produce titanium isotope, 44 Ti, whose radioactive decay yields hard emission lines. All associated with 44Ti appears to be from material moving us, none away. This implies that explosion was not symmetric. These findings help explain mechanics and...
We present coordinated multiwavelength observations of the bright, nearby BL Lac object Mrk 421 taken in 2013 January-March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations instruments, providing data from radio to very-high-energy (VHE) gamma-ray bands. NuSTAR yielded previously unattainable sensitivity 3-79 keV range, revealing that spectrum softens when source is dimmer until X-ray spectral shape saturates into a steep power law with photon index...
The distribution of elements produced in the inner-most layers a supernova explosion is key diagnostic for studying collapse massive stars. Here we present results 2.4 Ms \textit{NuSTAR} observing campaign aimed at remnant Cassiopeia A (Cas A). We perform spatially-resolved spectroscopic analyses $^{44}$Ti ejecta which use to determine Doppler shift and thus three-dimensional (3D) velocities ejecta. find an initial mass 1.54 $\pm$ 0.21 $\times 10^{-4}$ M$_{\odot}$ has day average momentum...
ABSTRACT We present the 3–8 keV and 8–24 number counts of active galactic nuclei (AGNs) identified in Nuclear Spectroscopic Telescope Array ( NuSTAR ) extragalactic surveys. has now resolved 33%–39% X-ray background band, directly identifying AGNs with obscuring columns up to <?CDATA $\sim {10}^{25}\,{\mathrm{cm}}^{-2}$?> . In softer band are general agreement those measured by XMM-Newton Chandra over flux range $5\times {10}^{-15}\,\lesssim $?> S (3–8 keV)/...
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission was launched on 2012 June 13 and is the first focusing high-energy X-ray telescope in orbit operating above ~10 keV. NuSTAR flies two co-aligned Wolter-I conical approximation optics, coated with Pt/C W/Si multilayers, combined a focal length of 10.14 meters this enables operation from 3-79 optics focus onto plane arrays, each consisting 4 CdZnTe pixel detectors, for field view 12.5 arcminutes. inherently low background associated...
We present the first sub-arcminute images of Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves hard X-ray source IGR J17456–2901 into non-thermal filaments, molecular clouds, point sources, and a previously unknown central component emission (CHXE). detects four extending detection their power-law spectra Γ ∼ 1.3–2.3 up to ∼50 keV. A morphological spectral study filaments suggests that origin may be heterogeneous, where previous studies suggested common in young pulsar wind...
We report the first hard X-ray observations with NuSTAR of BL Lac type blazar PKS 2155-304, augmented soft data from XMM-Newton and gamma-ray Fermi Large Area Telescope, obtained in April 2013 when source was a very low flux state. A joint XMM spectrum, covering energy range 0.5 - 60 keV, is best described by model consisting log-parabola component curvature beta = 0.3(+0.2,-0.1) (local) photon index 3.04 +/- 0.15 at 2 power-law tail 2.2 0.4. The can be smoothly joined to quasi-simultaneous...
We present the first survey results of hard X-ray point sources in Galactic Center (GC) region by NuSTAR. have discovered 70 (3-79 keV) a 0.6 deg^2 around Sgr A* with total exposure 1.7 Ms, and 7 B2 field 300 ks. identify clear Chandra counterparts for 58 NuSTAR assign candidate remaining 19. The reaches luminosities ~4 x ~8 10^32 erg s^-1 at GC (8 kpc) 3-10 10-40 keV bands, respectively. source list includes three persistent luminous binaries likely run-away pulsar called Cannonball. New...
The NuSTAR mission will be the first to carry a hard X-ray(5-80 keV) focusing telescope orbit. optics are based on use of multilayer coated thin slumped glass. Two different material combinations were used for flight optics, namely W/Si and Pt/C. In this paper we describe entire coating effort including final design that was two optics. We also present data performance verification coatings both Si witness samples as well individual mirrors.
We report on the analysis of 100 ks INTEGRAL observations Galactic microquasar GRS 1915+105. focus Revolution number 48 when source was found to exhibit a new type variability as preliminarily reported in Hannikainen et al. (2003). The pattern, which we name $ξ$, is characterized by pulsing behaviour, consisting main pulse and shorter, softer, smaller amplitude precursor pulse, timescale 5 minutes JEM-X 3-35 keV lightcurve. also present simultaneous RXTE data. From study individual RXTE/PCA...
A high energy telescope design is presented which combines grazing incidence geometry with Bragg reflection in a graded d-spacing multilayer coating to obtain significant sensitivity up --6O keV. The concept utilizes total and first order structure way that higher energies are reflected from the deepest layers stack. specific this paper based on Ni/C Mo/C structures dspacings ranging 25A 100 A. X-ray reflectivity data obtained Cu Kc1 (8. 05 keV) of kind.
view Abstract Citations (60) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray spectrum of Capella and its relation to coronal structure ultraviolet emission. Mewe, R. ; Gronenschild, E. H. B. M. Westergaard, N. J. Heise, Seward, F. D. Chlebowski, T. Kuin, P. Brinkman, A. C. Dijkstra, Schnopper, W. The binary system has been observed on 1979 March 15 1980 15-17, with the objective grating spectrometer board Einstein Observatory. measured...
Scans of the Galactic plane performed at regular intervals constitute a key element guaranteed time observations INTEGRAL observing programme. These scans are done for two reasons: frequent monitoring in order to detect transient sources, and resolved mapping continuum diffuse line emission. This paper describes first results obtained from executed so far during early phase (Dec. 2002–May 2003) nominal mission.
We present results of the point spread function (PSF) calibration hard X-ray optics Nuclear Spectroscopic Telescope Array (NuSTAR). Immediately post-launch, NuSTAR has observed bright sources such as Cyg X-1, Vela and Her X-1 for PSF calibration. use source observations taken at several off-axis angles together with a ray-trace model to characterize in-orbit angular response, find that alone does not fit event distributions applying empirical corrections improves significantly. describe...
The science analysis of the data from JEM–X on INTEGRAL is performed through a number levels including corrections, good time selection, imaging and source finding, spectrum light-curve extraction. These consist individual executables running complete controlled by script where parameters for detailed settings are introduced. end products FITS files with format compatible standard packages such as XSPEC.