A5006526357- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Cosmology and Gravitation Theories
- Geomagnetism and Paleomagnetism Studies
- Nuclear Physics and Applications
- Magnetic confinement fusion research
- Neutrino Physics Research
- Planetary Science and Exploration
- Geophysics and Sensor Technology
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- Esophageal and GI Pathology
- earthquake and tectonic studies
- Radio Astronomy Observations and Technology
- Advanced Malware Detection Techniques
- Carbohydrate Chemistry and Synthesis
Brigham and Women's Hospital
2014-2025
Harvard University
2014-2025
Space Telescope Science Institute
2023
Canadian Institute for Theoretical Astrophysics
2012-2022
University of Toronto
1994-2021
Google (United States)
2019
University of California, Berkeley
2012-2018
Purdue University West Lafayette
2015-2017
Lawrence Berkeley National Laboratory
2014
Arturo Prat University
2011
view Abstract Citations (2209) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Formation of Very Strongly Magnetized Neutron Stars: Implications for Gamma-Ray Bursts Duncan, Robert C. ; Thompson, Christopher stars with unusually strong magnetic dipole fields B_dipole ~ 10^14 - 10^15 G, can form when conditions efficient helical dynamo action are met during the first few seconds after gravitational collapse. Such high-field neutron stars,...
A radiative model for the soft gamma repeaters and energetic 1979 March 5 burst is presented. We identify sources of these bursts with neutron stars external magnetic fields which are much stronger than those ordinary pulsars. Several independent arguments point to a star Bdipole ~ × 1014 G as source event. very strong field can (i) spin down an 8-s period in 104-yr age surrounding supernova remnant N49; (ii) provide enough energy event; (iii) undergo large-scale interchange instability...
We calculate the quiescent X-ray, neutrino, and Alfvén wave emission from a neutron star with very strong magnetic field, Bdipole ~ 1014 − 1015 G Binterior (5–10) × G. These results are compared observations of soft gamma repeaters small class anomalous X-ray pulsars that we have previously identified such objects. The rather than rotation, provides main source free energy, decaying field is capable powering particle observed these sources. New features not present in decay weaker fields...
view Abstract Citations (860) References (125) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Neutron Star Dynamos and the Origins of Pulsar Magnetism Thompson, Christopher ; Duncan, Robert C. star convection is a transient phenomenon has an extremely high magnetic Reynolds number. In this sense, neutron dynamo quintessential fast dynamo. The convective motions are only mildly turbulent on scales larger than approximately 100 cm neutrino mean free path, but...
(ABBREVIATED) We consider the structure of neutron star magnetospheres threaded by large-scale electrical currents, and effect resonant Compton scattering charge carriers (both electrons ions) on emergent X-ray spectra pulse profiles. In magnetar model for SGRs AXPs, these currents are maintained magnetic stresses acting deep inside star. construct self-similar, force-free equilibria current-carrying magnetosphere with a power-law dependence field radius, B ~ r^(-2-p), show that twist...
We present a model that reproduces the basic spectral properties of classical gamma-ray bursts with essentially no free parameters. It is an elaboration scenario for cosmological outlined by Duncan & Thompson. The starting point Poynting-flux-dominated, relativistic, MHD wind extremely high luminosity, L ~ 1050 erg s –1 compactness parameter measured at ·the base exceeds Crab pulsar, or luminous AGN, factor 1012. emanates from rapidly rotating neutron star, disc, in which poloidal field ≳...
Controlling the structure of colloidal nanocrystals (NCs) is key to generation their complex functionality. This requires an understanding NC surface at atomic level. The PbS NCs passivated with oleic acid has been studied theoretically and experimentally. We show existence OH(-) groups, which play a role in stabilizing PbS(111) facets, consistent x-ray photoelectron spectroscopy as well other spectroscopic chemical experiments. water synthesis process also revealed. Our model, along...
The soft-gamma repeater SGR 1900+14 became active again on June 1998 after a long period of quiescence; it remained at low state activity until August 1998, when emitted series extraordinarily intense outbursts. We have observed the source with RXTE twice, during onset each episode. confirm pulsations 5.16 s reported earlier (Hurley et al. 1998b, Hurley e) from 1900+14. Here we report detection secular spindown pulse an average rate 1.1*10^{-10} s/s. In view strong similarities between SGRs,...
The extraordinary 1998 August 27 giant flare places strong constraints on the physical properties of its source, SGR 1900+14. We make detailed comparisons published data with magnetar model, which identifies soft gamma repeaters as neutron stars endowed ~1015 G magnetic fields. evolved through three stages, whose radiative mechanisms we address in turn. extreme peak luminosity L > 106LEdd, hard spectrum, and rapid variability initial ~0.5 s spike emission all point to an expanding pair...
Vancomycin is an important drug for the treatment of Gram-positive bacterial infections. Resistance to vancomycin has begun appear, posing a serious public health threat. analogs containing modified carbohydrates are very active against resistant microorganisms. Results presented here show that these carbohydrate derivatives operate by different mechanism than vancomycin; moreover, peptide binding not required activity. It proposed carbohydrate-modified compounds effective bacteria because...
We develop a theoretical model that explains the formation of hot coronae around strongly magnetized neutron stars—magnetars. The starquakes magnetar shear its external magnetic field, which becomes nonpotential and threaded by an electric current. Once twisted, magnetosphere cannot untwist immediately because self-induction. self-induction field lifts particles from stellar surface, accelerates them, initiates avalanches pair creation in magnetosphere. created plasma corona maintains...
Web browser warnings should help protect people from malware, phishing, and network attacks. Adhering to keeps safer online. Recent improvements in warning design have raised adherence rates, but they could still be higher. And prior work suggests many do not understand them. Thus, two challenges remain: increasing both comprehension rates. To dig deeper into user decision making of warnings, we performed an experience sampling study web security which involved surveying over 6,000 Chrome...
An outburst of more than 80 individual bursts, similar to those seen from Soft Gamma Repeaters (SGRs), was detected the anomalous X-ray pulsar (AXP) 1E 2259+586 in 2002 June. Coincident with this burst activity were gross changes pulsed flux, persistent energy spectrum, pulse profile, and spin-down underlying source. We present Rossi X-Ray Timing Explorer Multi-Mirror Mission observations that show evolution aforementioned source parameters during following episode identify recovery...
We present two new formulations of magnetohydrodynamics (MHD), in the limit where inertia charge carriers can be neglected. The first employs Lagrangian coordinates and generalizes Newcomb's formalism to allow for a variable time slicing. It contains an extremely simple prescription generalizing action relativistic Nambu-Goto string four dimensions. is also related by duality transformation presented Achterberg. This causes perturbed unperturbed exchange roles as dynamical fields background...
We study the statistics of soft gamma repeater (SGR) bursts, using a data base 187 events detected with BATSE and 837 RXTE PCA, all from SGR 1900+14 during its 1998-1999 active phase. find that fluence or energy distribution bursts is consistent power law index 1.66, over 4 orders magnitude. This scale-free resembles Gutenberg-Richter Law for earthquakes, gives evidence self-organized criticality in SGRs. The time intervals between successive log-normal distribution. There no correlation...
We present an interpretation of the phenomenological relations between spectral peak, isotropic luminosity and duration long gamma ray bursts that have been discovered by Amati et al., Ghirlanda Firmani Liang & Zhang.In our proposed model, a jet undergoes internal dissipation which prevents its bulk Lorentz factor from exceeding 1/θ (θ being opening angle) until it escapes core progenitor star, at radius order 10 cm; may continue larger radii.The dissipated radiation will be partially...
The giant flare of 1998 August 27 from SGR 1900+14 was extraordinary in many ways: it the most intense flux gamma rays ever detected a source outside our solar system; longer than any previously burst soft repeater (SGR) Galaxy by more an order magnitude; and showed remarkable four-peaked, periodic pattern hard X-rays with same rotation period that found modulating star quiescence. event several gamma-ray experiments space, including Ulysses detector BeppoSAX Gamma-Ray Burst Monitor. These...
We study the gravitational collapse of a magnetized neutron star using novel numerical approach able to capture both dynamics and behavior surrounding plasma. In this approach, fully general relativistic magnetohydrodynamics implementation models provides appropriate boundary conditions force-free model which describes stellar exterior. validate strategy by comparing with known results for rotating monopole aligned rotator solutions then apply it nonrotating scenarios contrast what is...
Decoy Routing is a new approach to Internet censorship circumvention that was recently and independently proposed at FOCI'11, USENIX Security'11 CCS'11. routing aims hamper nation-state level by having routers, rather than end hosts, relay traffic blocked destinations. We analyze the security of these schemes against capable adversary, censoring authority willing make decisions in response decoy systems.
We consider the physical implications of rapid spin-down soft gamma repeater SGR 1900+14 reported by Woods and colleagues in 1999. During an 80 day interval between 1998 June large outburst on August 27, mean rate increased a factor 2.3, resulting positive period offset ΔP/P = 10-4. A radiation-hydrodynamical outflow associated with 27 event could impart required torque, but only if dipole magnetic field is stronger than ~1014 G lasts longer and/or more energetic observed X-ray flare....
The recently discovered soft gamma-ray emission from the anomalous X-ray pulsar 1E 1841-045 has a luminosity Lγ ~ 1036 ergs s-1. This exceeds spin-down power by 3 orders of magnitude and must be fed an alternative source energy such as ultrastrong magnetic field. A gradual release in stellar magnetosphere is expected if it twisted strong electric current induced on closed field lines. We examine two mechanisms associated with dissipation this current. (1) thin surface layer star heated...