Search results for "Spectral"
showing 10 items of 3116 documents
Radio emission of SN1993J: the complete picture. I. Re-analysis of all the available VLBI data
2010
We have performed a complete re-calibration and re-analysis of all the available VLBI observations of supernova SN1993J, following an homogeneous and well-defined methodology. Observations of SN1993J at 69 epochs, spanning 13 years, were performed by two teams, which used different strategies and analysis tools. The results obtained by each group are similar, but their conclusions on the supernova expansion and the shape and evolution of the emitting region differ significantly. From our analysis of the combined set of observations, we have obtained an expansion curve with unprecedented time resolution and coverage. We find that the data from both teams are compatible when analyzed with the…
Swift Observations of the High-mass X-ray Binary IGR J16283-4838 unveil a 288-day Orbital Period
2013
We report on the temporal and spectral properties of the HMXB IGR J16283-4838 in the hard X-ray band. We searched the first 88 months of Swift BAT survey data for long-term periodic modulations. We also investigated the broad band (0.2--150 keV) spectral properties of IGR J16283--4838 complementing the BAT dataset with the soft X-ray data from the available Swift-XRT pointed observations. The BAT light curve of IGR J16283-4838 revealed a periodic modulation at P_o=287.6+7-1.7 days (with a significance higher than 4 standard deviations). The profile of the light curve folded at P_o shows a sharp peak lasting ~ 12 d, over a flat plateau. The long-term light curve shows also a ~300 d interval …
A complete X-ray spectral coverage of the 2010 May-June outbursts of Circinus X-1
2012
Circinus X-1 is a neutron-star-accreting X-ray binary in a wide (P$_{\rm orb}$ = 16.6 d), eccentric orbit. After two years of relatively low X-ray luminosity, in May 2010 Circinus X-1 went into outburst, reaching 0.4 Crab flux. This outburst lasted for about two orbital cycles and was followed by another shorter and fainter outburst in June. We focus here on the broadband X-ray spectral evolution of the source as it spans about three order of magnitudes in flux. We attempt to relate luminosity, spectral shape, local absorption, and orbital phase. We use multiple Rossi-XTE/PCA (3.0--25 keV) and Swift/XRT (1.0--9.0 keV) observations and a 20 ks long Chandra/HETGS observation (1.0--9.0 keV), t…
General relativistic neutrino transport using spectral methods
2014
We present a new code, Lorene's Ghost (for Lorene's gravitational handling of spectral transport) developed to treat the problem of neutrino transport in supernovae with the use of spectral methods. First, we derive the expression for the nonrelativistic Liouville operator in doubly spherical coordinates (r, theta, phi, epsilon, Theta, Phi)$, and further its general relativistic counterpart. We use the 3 + 1 formalism with the conformally flat approximation for the spatial metric, to express the Liouville operator in the Eulerian frame. Our formulation does not use any approximations when dealing with the angular arguments (theta, phi, Theta, Phi), and is fully energy-dependent. This approa…
A population of isolated hard X-ray sources near the supernova remnant Kes 69
2012
Recent X-ray observations of the supernova remnant IC443 interacting with molecular clouds have shown the presence of a new population of hard X-ray sources related to the remnant itself, which has been interpreted in terms of fast ejecta fragment propagating inside the dense environment. Prompted by these studies, we have obtained a deep {\sl XMM-Newton} observation of the supernova remnant (SNR) Kes 69, which also shows signs of shock-cloud interaction. We report on the detection of 18 hard X-ray sources in the field of Kes 69, a significant excess of the expected galactic source population in the field, spatially correlated with CO emission from the cloud in the remnant environment. The …
BOOTES observation of GRB 080603B
2012
We report on multicolor photometry of long GRB080603B afterglow from BOOTES-1B and BOOTES-2. The optical afterglow has already been reported to present a break in the optical lightcurve at 0.12 ± 0.2 days after the trigger. We construct the lightcurve and the spectral energy distribution and discuss the nature of the afterglow.
Broadband spectral analysis of MXB 1659−298 in its soft and hard state
2018
The X-ray transient eclipsing source MXB 1659-298 went into outburst in 1999 and 2015. During these two outbursts the source was observed by XMM-Newton, nuSTAR, and Swift/XRT. Using these observations, we studied the broadband spectrum of the source to constrain the continuum components and to verify whether it had a reflection component, as is observed in other X-ray eclipsing transient sources. We combined the available spectra to study the soft and hard state of the source in the 0.45-55 keV energy range. We report a reflection component in the soft and hard state. The direct emission in the soft state can be modeled with a thermal component originating from the inner accretion disk plus…
Threshold expansion of Feynman diagrams within a configuration space technique
2000
The near threshold expansion of generalized sunset-type (water melon) diagrams with arbitrary masses is constructed by using a configuration space technique. We present analytical expressions for the expansion of the spectral density near threshold and compare it with the exact expression obtained earlier using the method of the Hankel transform. We formulate a generalized threshold expansion with partial resummation of the small mass corrections for the strongly asymmetric case where one particle in the intermediate state is much lighter than the others.
Nonlocally-induced (quasirelativistic) bound states: Harmonic confinement and the finite well
2015
Nonlocal Hamiltonian-type operators, like e.g. fractional and quasirelativistic, seem to be instrumental for a conceptual broadening of current quantum paradigms. However physically relevant properties of related quantum systems have not yet received due (and scientifically undisputable) coverage in the literature. In the present paper we address Schr\"{o}dinger-type eigenvalue problems for $H=T+V$, where a kinetic term $T=T_m$ is a quasirelativistic energy operator $T_m = \sqrt{-\hbar ^2c^2 \Delta + m^2c^4} - mc^2$ of mass $m\in (0,\infty)$ particle. A potential $V$ we assume to refer to the harmonic confinement or finite well of an arbitrary depth. We analyze spectral solutions of the per…
A Study of the Nuclear Structure at High Energy and Low Spin
1983
A novel method to study nuclear structure at low spin as a function of temperature is developed and used on 146,148Sm, 154,156Gd and 160,162Dy, by means of the (3He, α) reaction. The nuclear level density for a wide energy range is also studied. The γ-multiplicities and the first generation γ-ray spectra indicate a structure change in deformed nuclei at about 6 MeV.