5,797 research outputs found
Linking gamma-ray spectra of supernova remnants to the cosmic ray injection properties in the aftermath of supernovae
The acceleration times of the highest-energy particles which emit gamma-rays
in young and middle-age SNRs are comparable with SNR age. If the number of
particles starting acceleration was varying during early times after the
supernova explosion then this variation should be reflected in the shape of the
gamma-ray spectrum. We use the solution of the non-stationary equation for
particle acceleration in order to analyze this effect. As a test case, we apply
our method to describe gamma-rays from IC443. As a proxy of the IC443 parent
supernova we consider SN1987A. First, we infer the time dependence of injection
efficiency from evolution of the radio spectral index in SN1987A. Then, we use
the inferred injection behavior to fit the gamma-ray spectrum of IC443. We show
that the break in the proton spectrum needed to explain the gamma-ray emission
is a natural consequence of the early variation of the cosmic ray injection,
and that the very-high energy gamma-rays originate from particles which began
acceleration during the first months after the supernova explosion. We conclude
that the shape of the gamma-ray spectrum observed today in SNRs critically
depends on the time variation of the cosmic ray injection process in the
immediate post explosion phases. With the same model, we estimate also the
possibility in the future to detect gamma-rays from SN 1987A.Comment: A&A, accepte
The lattice Landau gauge gluon propagator: lattice spacing and volume dependence
The interplay between the finite volume and finite lattice spacing is
investigated using lattice QCD simulations to compute the Landau gauge gluon
propagator. Comparing several ensembles with different lattice spacings and
physical volumes, we conclude that the dominant effects, in the infrared
region, are associated with the use of a finite lattice spacing. The
simulations show that decreasing the lattice spacing, while keeping the same
physical volume, leads to an enhancement of the infrared gluon propagator. In
this sense, the data from simulations, which uses an fm, provides a lower bound for the infinite volume propagator.Comment: Final version to appear in Phys Rev
Radio polarization maps of shell-type SNRs II. Sedov models with evolution of turbulent magnetic field
Polarized radio emission has been mapped with great detail in several
Galactic supernova remnants (SNRs), but has not yet been exploited to the
extent it deserves. We have developed a method to model maps of the Stokes
parameters for shell-like SNRs during their Sedov evolution phase. At first,
3-dimensional structure of a SNR has been computed, by modeling the
distribution of the magnetohydrodynamic parameters and of the accelerated
particles. The generation and dissipation of the turbulent component of
magnetic field everywhere in SNR are also considered taking into account its
interaction with accelerated particles. Then, in order to model the emission,
we have used a generalization of the classical synchrotron theory, valid for
the case in which the magnetic field has ordered and disordered components.
Finally, 2-dimensional projected maps have been derived, for different
orientations of SNR and of interstellar magnetic field with respect to the
observer. An important effect to consider is the Faraday rotation of the
polarization planes inside the SNR interior. In this paper we present details
of the model, and describe general properties of the images.Comment: accepted in MNRA
Migrations and Unexpected Interreligious Dialogue
The author takes first steps toward theologically unpacking the growing, but often unnoticed, interreligious dialogue occurring among the world’s “popular” religions. Christian theologies of religions in the last forty years have directed considerable attention to theological dialogue with non-Christian religions. However, these have seldom methodically analyzed the universe of the so-called “popular” religions — the actual religions of the vast majority of humankind. Much less have theologians wondered about the mutual impact that these “popular” religions might have on each other at the “popular” level. Building on earlier writings on culture, popular religion, and interculturality, the author’s addresses these lacunae, arguing that an important grassroots interreligious dialogue very often follows human migrations
Isogrid design handbook
Handbook has been published which presents information needed for design of isogrid triangular integral-stiffened structures. It develops equations, methods, and graphs to handle wide variety of loadings, materials, and geometry. Handbook is divided into seven sections. Handbook may be used by marine and civil engineers and by students and designers without access to computers
Kesiapan Implementasi Otonomi Daerah di Municipio Liquica Timor-Leste
Penelitan ini bertujuan untuk mendeskripsikan dan menganalisis implementasi otonomi daerah di Municipio Liquica Timor-Leste, serta untuk mengetahui factor-faktor yang turut mempengaruhi implementasi otonomi daerah di Municipio Liquica Timor-Leste. Penelitian ini menggunakan metode kualitatif deskriptif dengan teknik triangulasi. Lokasi penelitian dilaksanakan di Municipio Liquica Timor-Leste. Lokasi ini dipilih karena merupakan salah satu Municipio yang secara demografis berbatasan langsung dengan Posto Administrativo (Kecamatan) Atabae Municipio Bobonaro. Kesiapan implementasi otonomi daerah dari sisi sumber daya yakni menyangkut sarana dan prasarana yang ada di Municipio Liquica ini sudah siap untuk menerima otonomi daerah itu sendiri. Faktor dan upaya yang menghambat pelaksanaan implementasi otonomi daerah di Municipio Liquica yaitu: (a) Masih terbatasnya pengetahuan dan kemampuan dalam menggunakan empat bahasa yang ada, di mana tidak semua aparat Municipio menguasai empat bahasa tersebut. (b) Terbatasnya anggaran pelaksanaan implementasi otonomi daerah di Municipio Liquica. (c) Masih terbatasnya tenaga operasional implementasi otonomi daerah di Municipio Liquica
Some properties of synchrotron radio and inverse-Compton gamma-ray images of supernova remnants
The synchrotron radio maps of supernova remnants (SNRs) in uniform
interstellar medium and interstellar magnetic field (ISMF) are analyzed,
allowing different `sensitivity' of injection efficiency to the shock
obliquity. The very-high energy gamma-ray maps due to inverse Compton process
are also synthesized. The properties of images in these different wavelength
bands are compared, with particular emphasis on the location of the bright
limbs in bilateral SNRs. Recent H.E.S.S. observations of SN 1006 show that the
radio and IC gamma-ray limbs coincide, and we found that this may happen if: i)
injection is isotropic but the variation of the maximum energy of electrons is
rather quick to compensate for differences in magnetic field; ii) obliquity
dependence of injection (either quasi-parallel or quasi-perpendicular) and the
electron maximum energy is strong enough to dominate magnetic field variation.
In the latter case, the obliquity dependence of the injection and the maximum
energy should not be opposite. We argue that the position of the limbs alone
and even their coincidence in radio, X-rays and gamma-rays, as it is discovered
by H.E.S.S. in SN 1006, cannot be conclusive about the dependence of the
electron injection efficiency, the compression/amplification of ISMF and the
electron maximum energy on the obliquity angle.Comment: Accepted for publication in MNRA
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