A5086933989- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Ionosphere and magnetosphere dynamics
- Astrophysics and Star Formation Studies
- Neutrino Physics Research
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
- Astronomy and Astrophysical Research
- Dark Matter and Cosmic Phenomena
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Stellar, planetary, and galactic studies
- Superconducting Materials and Applications
- Historical Astronomy and Related Studies
- Space Exploration and Technology
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Sensor Technology
- History and Developments in Astronomy
- Cosmology and Gravitation Theories
North Carolina State University
2015-2024
North Central State College
2013-2023
Orano (United States)
2022
AVEVA (Sweden)
2022
Piedmont International University
2019
The University of Sydney
2011
Osservatorio Astronomico di Palermo
2011
Harvard University
2011
Osservatorio Astronomico di Cagliari
2007
West Virginia University
2007
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...
Many shell supernova remnants are now known to radiate synchrotron X-rays. Several objects have also been detected in TeV gamma rays. Nonthermal X-rays and rays can be produced by extremely energetic ions electrons due decay of π 0 mesons inelastic collisions between thermal gas, or electron synchrotron, bremsstrahlung, inverse-Compton radiation. Thus observations at X-ray gamma-ray wavelengths constrain the process particle acceleration high energies shock waves remnants. This review...
Improved calculations of X-ray spectra for supernova remnants (SNRs) in the Sedov-Taylor phase are reported, which first time include reliable atomic data Fe L-shell lines. This new set Sedov models also allows a partial collisionless heating electrons at blast wave and energy transfer from ions to through Coulomb collisions. emission based on updated Hamilton-Sarazin spectral model. The calculated successfully interpreted terms three distribution functions: electron temperature ionization...
The evolution of a supernova remnant through the transition from an adiabatic Sedov-Taylor blast wave to radiative pressure-driven snowplow phase is studied using one- and two-dimensional hydrodynamic simulations. This marked by catastrophic collapse postshock gas, forming thin, dense shell behind forward shock. After transition, shock front characterized deceleration parameter, Vt/R ≈ 0.33, which considerably higher than analytic estimate for snowplow. In two dimensions, accompanied violent...
view Abstract Citations (294) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Continuum Spectra of Collimated, Ionized Stellar Winds Reynolds, S. P. The behavior well-collimated ionized flows is studied. derivation and calculation the opaque spectral index, collimation distance, mass-loss rate, radio flux for an unresolved, partially opaque, collimated thermal jet are described. Unresolved sources exhibit spectra with indices between 2 -0.1....
The diffusive shock acceleration process can accelerate particles to a maximum energy depending on the speed and age any competing loss processes particles. waves of young supernova remnants easily electrons energies in excess 1 TeV, where they produce X-rays by synchrotron process. I describe detailed calculation morphology spectrum from remnants. Remnants are assumed be spherical Sedov evolutionary phase, though results insensitive dynamics. upstream magnetic field is uniform; downstream...
view Abstract Citations (267) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evolution of pulsar-driven supernova remnants. Reynolds, S. P. ; Chevalier, R. A. Radio and X-ray observations the growing class Crab-like remnants ("plerions") suggest that a central pulsar dominates their evolution. The authors model plerion as spherical, homogeneous bubble relativistic particles magnetic field inflated by amid uniformly expanding ejecta. They...
Our 50 ks Chandra observation of the small radio supernova remnant (SNR) G1.9+0.3 shows a complete shell structure with strong bilateral symmetry, about $100''$ in diameter. The morphology is also shell-like, but only $84''$ diameter, based on observations made 1985. We attribute size difference to expansion between 1985 and our 2007. Expansion confirmed comparing images from 2008. deduce that order 100 years old -- youngest Galaxy. Based very high absorbing column density $5.5 \times...
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...
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...
Young supernova remnants (SNRs) are often assumed to be the source of cosmic rays up energies approaching slight steepening in cosmic-ray spectrum at around 1000 TeV, known as "knee." We show that observed X-ray emission 14 radio-bright shell remnants, including all five historical shells, can used put limits on Emax, energy which electron distribution must steepen from its slope radio-emitting energies. Most thermal spectra, so any synchrotron component fall below fluxes. obtain upper Emax...
Supernova remnants (SNRs) are widely believed to be the principal source of Galactic cosmic rays, produced by diffusive shock acceleration in environs remnant's expanding blast wave. Such energetic particles can produce gamma rays and lower energy photons via interactions with ambient plasma. The recently reported observation TeV from SN 1006 Collaboration Australia Nippon for a Gamma-Ray Observatory Outback (CANGAROO), combined fact that several unidentified EGRET sources have been...
view Abstract Citations (167) References (63) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS First-Order Fermi Particle Acceleration by Relativistic Shocks Ellison, Donald C. ; Jones, Frank Reynolds, Stephen P. Monte Carlo calculations of test particle spectra and acceleration times are presented from first-order for parallel shocks with arbitrary flow velocities compression ratios r up to seven, shock u1 0.98c, injection energies ranging thermal highly...
We present deep images of the SN 1006 remnant (G327.6+14.6) with ACIS instrument on Chandra X-Ray Observatory. Two regions have been observed, synchrotron-dominated northeast limb and thermally dominated northwest limb, as well a substantial portion interior shell. The brightest features in X-ray correspond closely to radio Balmer-dominated filaments northwest. spectra brighter are harder, less prominent line emission than those In addition highly elongated filaments, both show enhanced...
view Abstract Citations (157) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Electron Acceleration in Tycho's and Kepler's Supernova Remnants: Spectral Evidence of Fermi Shock Reynolds, Stephen P. ; Ellison, Donald C. First model synchrotron spectra calculated with a self-consistent nonlinear shock first order acceleration are presented compared the observed radio SNR. Excellent agreement is obtained, correct mean spectral indices about -0.64...
We present initial results of a 750 ks Chandra observation the remnant Kepler's supernova AD 1604. The strength and prominence iron emission, together with absence O-rich ejecta, demonstrate that Kepler resulted from thermonuclear supernova, even though evidence for circumstellar interaction is also strong. have analyzed spectra over 100 small regions, find they fall into three classes. (1) vast majority show Fe L emission between 0.7 1 keV Si S Kα emission; we associate these shocked...
view Abstract Citations (129) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nonthermal radiation from supernova remnants in the adiabatic stage of evolution. Reynolds, S. P. ; Chevalier, R. A. We develop a physically self-consistent model for nonthermal blast-wave (Sedov) phase evolution, assuming relativistic electrons are accelerated shock to an energy density proportional postshock pressure, and that magnetic field is either compressed...
We report results from a multi-wavelength analysis of the Galactic SNR RCW 86, proposed remnant supernova 185 A.D. new infrared observations {\it Spitzer} and WISE}, where entire shell is detected at 24 22 $\mu$m. fit flux ratios with models collisionally heated ambient dust, finding post-shock gas densities in non-radiative shocks 2.4 2.0 cm$^{-3}$ SW NW portions remnant, respectively. The Balmer-dominated around periphery shell, large amount iron X-ray emitting ejecta, lack compact support...
Some supernovae (SNe) may be powered by the interaction of SN ejecta with a large amount circumstellar matter (CSM). However, quantitative estimates CSM mass around such SNe are missing when material is optically thick. Specifically, current estimators sensitive to uncertainties regarding density profile and velocity. Here we outline method measure thick SNe. We present new visible-light X-ray observations 2010jl (PTF 10aaxf), including first detection an in hard band using NuSTAR. The total...
We introduce a deep (670 ks) X-ray survey of the SN1006 remnant from Chandra, plus H-alpha image 4m telescope at CTIO. Comparison with Chandra images 2003 gives first measurement proper motions around entire rim. find that expansion velocity varies significantly azimuth: highest ~7400 km/s (almost 2.5 times in NW) is found along SE rim, where both kinematics and spectra indicate most X-rays stem undecelerated ejecta. Asymmetries distribution ejecta are seen on variety spatial scales. Si-rich...
We present broadband (3–78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula pulsar. show that while phase-averaged spatially integrated + pulsar spectrum is a power law in this energy band, resolved finds break at ∼9 keV spectral photon index torus structure with steepening characterized by ΔΓ ∼ 0.25. also confirm previously reported pulsed spectrum, quantify it broken ∼12 0.27. maps inner 100'' remnant measure size as function seven bands. These results find rate shrinkage can...
Spitzer images of Tycho's supernova remnant in the mid-infrared reveal limb-brightened emission from entire periphery shell and faint filamentary structures interior. As with other young remnants, this is produced by dust grains, warmed to ∼100 K post-shock environment collisions energetic electrons ions. The ratio 70 24 μm fluxes a diagnostic temperature, which turn sensitive function plasma density. We find significant variations 70/24 flux around forward shock, implying order-of-magnitude...