Search results for "Vela"

Lejos de nosotros la funesta manía de pensar

2008

Looking through the photoionisation wake: Vela X−1 at φorb ≈ 0.75 with Chandra/HETG

2021

Context. The supergiant X-ray binary Vela X−1 represents one of the best astrophysical sources to investigate the wind environment of an O/B star irradiated by an accreting neutron star. Previous studies and hydrodynamic simulations of the system have revealed a clumpy environment and the presence of two wakes: an accretion wake surrounding the compact object and a photoionisation wake trailing it along the orbit. Aims. Our goal is to conduct, for the first time, high-resolution spectroscopy on Chandra/HETGS data at the orbital phase φorb ≈ 0.75, when the line of sight is crossing the photoionisation wake. We aim to conduct plasma diagnostics, inferring the structure and the geometry of the…

Physical and Chemical Inhomogeneities Inside the Vela SNR Shell: Indications of Ejecta Shrapnels

2007

We present the results of the combined analysis of three XMM-Newton EPIC observations of the northern rim of the Vela SNR. The three pointings cover an area of ~10 pc^2 (at 250 pc) behind the main shock front and we aim at studying with high resolution the spatial distribution of the physical and chemical properties of the X-ray emitting plasma on this large scale. We produce count-rate images and equivalent width maps of the Ne IX and Mg XI emission blends. We also perform a spatially resolved spectral analysis of a set of physically homogeneous regions. We reveal physical and chemical inhomogeneities in the X-ray emitting plasma. In particular, we find large variations of the O, Ne, Mg, a…

Shock-cloud interaction in the Vela SNR II. Hydrodynamic model

2006

In the framework of the study of the X-ray and optical emission in supernova remnants we focus on an isolated X-ray knot in the northern rim of the Vela SNR (Vela FilD), whose X-ray emission has been studied and discussed in Paper I. We aim at understanding the physical origin of the X-ray and optical emission in FilD, at understanding the role of the different physical processes at work, and at obtaining a key for the interpretation of future X-ray observations of SNRs. To this end we have pursued an accurate ``forward'' modeling of the interaction of the Vela SNR shock with an ISM cloud. We perform hydrodynamic simulations and we directly compare the observables synthesized from the simul…

Multi-phase interstellar clouds in the Vela SNR resolved with XMM-Newton

2005

XMM-Newton spatial/spectral resolution and high effective area allow to deepen our knowledge about the shocks in Supernova Remnants and their interaction with the interstellar medium. We present the analysis of an EPIC observation of the northern rim of the Vela SNR and we compare the X-ray and optical morphology of the emission. We derive a description of the internal structure of the shocked interstellar clouds, arguing that the transmitted shock model is compatible with our data. We also suggest that thermal conduction between clouds and inter-cloud medium is very efficient and produces the evaporation of the clouds in the interstellar medium. � 2005 COSPAR. Published by Elsevier Ltd. Al…

Shock–cloud interactions in the Vela SNR: preliminary results of an XMM-Newton observation

2004

Abstract The study of the clumpy and irregular features in the X-ray emission of middle-aged supernova remnants shells allows us to shed light on the various characteristic of the interstellar medium, like its structure and composition. We have observed with XMM-Newton a small knot in the Vela SNR, which previous ROSAT studies have indicated as one of the best examples of an interaction between the SNR shock and an isolated cloud. We present preliminary results of this study. Thanks to the combination of good spectral and spatial resolution of the EPIC camera, we have realized maps of the X-ray emission in three different bands, pinpointing the contribution from different spatial regions. W…

Suzaku Detection of Diffuse Hard X-Ray Emission outside Vela X

2011

著者人数: 12名

Shock-cloud interaction in the Vela SNR observed with XMM-Newton

2005

We analyzed an XMM-Newton EPIC observation of a bright knot, named FilD, in the northern rim of the Vela SNR, where the shock has encountered a cloud. The good combination of sensitivity, spectral, and spatial resolution allowed us to describe the internal structure of the observed ISM clouds and to obtain estimates of their temperature, density, O, Ne, and Fe abundances, and of their extension along the line of sight. We also examined the interaction of the shock with the FilD knot and estimated that the time elapsed from the shock impact is about one cloud crushing time. Our analysis allowed us to conclude that the observed X-ray emission is best explained by the propagation of transmitte…

Observability of γ-ray pulsars

1978

PULSARS seem to play a major role as γ-ray emitters. Of the 13 objects listed in the first COS B catalogue1 the two brightest, CG185-5 and CG263-2, have been identified with the Crab (PSR0531+21) and Vela (PSR0833–;45) pulsars respectively. This privileged role of pulsars as identified γ-ray sources could be simply related to observational reasons: in fact, because of the poor angular resolution intrinsic to the γ-ray telescopes, the only possibility of identification for individual sources is the time structure of the emission, and the periodical pattern of pulsars is particularly suited. On the other hand, for PSR0531+21 and PSR0833−45, the observed pulsed energy release is essentially in…

Layout and performance of RPC used in the Argo-YBJ experiment

2006

The layout of the RPCs, used in the Argo-YBJ experiment to image with a high space-time granularity the atmospheric shower, is described in this paper. The detector has been assembled to provide both digital and analog informations in order to cover a wide particle density range with a time accuracy of 1 ns. The experimental results obtained operating the chambers in streamer mode at sea level with a standard gas mixture are presented. (c) 2006 Elsevier B.V. All rights reserved.