Browsing by Title
Now showing items 5453-5472 of 35445
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Constraining a general-relativistic frame-dragging model for pulsed radiation from a population of millisecond pulsars in 47 Tucanae using GLAST LAT
(IOP Publications, 2008)Although only 22 millisecond pulsars (MSPs) are currently known to exist in the globular cluster (GC) 47 Tucanae, this cluster may harbor 30-60 MSPs, or even up to ∼200. In this Letter, we model the pulsed curvature radiation ... -
Constraining modified gravity models with cosmological data
(North-West University (South Africa), 2020)In this dissertation, we looked at the cosmological constraints of some f(R)-modi ed gravity models, such as f(R) = Rn (our rst toy model), f(R) = R + Rn (our second toy model), and more realistic ones like the Starobinsky ... -
Constraining relativistic bow shock properties in rotation-powered millisecond pulsar binaries
(AAS, 2017)Multiwavelength follow-up of unidentified Fermi sources has vastly expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret ... -
Constraining the dark matter density in galaxy clusters
(PoS, 2015)We illustrate the potential of using stellar velocity dispersion profiles of brightest cluster galaxies (BCGs), in combination with X-ray and weak-lensing derived cluster mass profiles, to constrain the matter distribution ... -
Constraining the emission geometry and mass of the white Dwarf Pulsar AR Sco
(North-West University (South Africa), 2020)Marsh et al. (2016) detected radio and optical pulsations from the binary system AR Scorpii (AR Sco). This system, with an orbital period of 3.55 h, is composed of a cool, low-mass M-dwarf and a white dwarf with a spin ... -
Constraining the emission geometry and mass of the white dwarf pulsar AR Sco using the rotating vector model
(IOP Publishing, 2019)We apply the standard radio pulsar rotating vector model to the white dwarf (WD) pulsar AR Sco's optical polarization position angle swings folded at the WD's spin period as obtained by Buckley et al. Owing to the long ... -
Constraining the environment of neutrino-emitting regions in jets of FSRQs
(Sissa Medialab, 2019)Recently, the gamma-ray blazar TXS 0506+056 has been proposed as the source of neutrino events detected by IceCube in 2014-15 and 2017. This has further pushed the idea of blazar jets being among those cosmic sites where ... -
Constraining the geometry of PSR J0855-4644: a nearby pulsar wind nebula with double torus/jet morphology
(EDP Sciences, 2017)Aims. PSR J0855−4644 is a fast-spinning, energetic pulsar discovered at radio wavelengths near the south-eastern rim of the supernova remnant RX J0852.0−4622. A follow-up XMM-Newton observation revealed the X-ray counterpart ... -
Constraining viewing geometries of pulsars with single-peaked γ-ray profiles using a multiwavelength approach
(SAIP, 2011)Since the launch of the Large Area Telescope (LAT) on board the Fermi spacecraft in June 2008, the number of observed γ-ray pulsars has increased dramatically. A large number of these are also observed at radio frequencies. ... -
Constraints experienced in managing Triple Helix in South Africa
(North-West University, 2012)Rapid changes in the global economy forces Industry to continuously seek competitive advantages; the University on the other hand pursue additional funding. Both Industry and University are trying to keep up with the ... -
Constraints on an annihilation signal from a core of constant dark matter density around the Milky Way center with H.E.S.S.
(American Physical Society, 2015)An annihilation signal of dark matter is searched for from the central region of the Milky Way. Data acquired in dedicated on-off observations of the Galactic center region with H.E.S.S. are analyzed for this purpose. No ... -
Constraints on axionlike particles with H.E.S.S. from the irregularity of the PKS 2155-304 energy spectrum
(APS, 2013)Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model of particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent ... -
Constraints on particle acceleration in SS433/W50 from MAGIC and H.E.S.S. observations
(EDP Sciences, 2018)Context. The large jet kinetic power and non-thermal processes occurring in the microquasar SS 433 make this source a good candidate for a very high-energy (VHE) gamma-ray emitter. Gamma-ray fluxes above the sensitivity ... -
Constraints on photosynthesis and antioxidant metabolism in winter and summer crops induced by sulphur dioxide fumigation
(North-West University, 2012)Recently, major advances have been made in developed countries elucidating the effects of air pollutants on crop plants. In contrast, similar studies on the effects of elevated SO2 concentrations on crops in developing ... -
Constraints on the emission geometries and spin evolution of gamma-ray millisecond pulsars
(IOP Publishing, 2014)Millisecond pulsars (MSPs) are a growing class of gamma-ray emitters. Pulsed gamma-ray signals have been detected from more than 40 MSPs with the Fermi Large Area Telescope (LAT). The wider radio beams and more compact ... -
Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE γ-ray observations with H.E.S.S.
(EDP Sciences, 2019)The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV < E < 100 GeV) γ-ray band, which is continuously monitored with Fermi-LAT. During two periods of high activity ... -
Constraints on the gamma-ray emission from the cluster-scale AGN outburst in the hydra A galaxy cluster
(EDP Sciences, 2012)Context. In some galaxy clusters, powerful active galactic nuclei (AGN) have blown bubbles with cluster scale extent into the ambient medium. The main pressure support of these bubbles is not known to date, but cosmic rays ... -
Constraints on the lepton content of PWN from the local CR positron spectrum
(ICRC, 2008)Geminga is a nearby pulsar with an age of 3.42×105 yr and a spindown power of 3.2×1034 erg/s at present. B0656+14 has comparable spindown power, with an age of 1.11×105 yr and a distance of 290 pc. The winds of these ... -
Constraints on the multi-TeV particle population in the Coma galaxy cluster with HESS observations
(EDP Sciences, 2009)Aims. Galaxy clusters are key targets in the search for ultra high energy particle accelerators. The Coma cluster represents one of the best candidates for such a search owing to its high mass, proximity, and the established ...