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تسجيل مستخدم جديدA Morphological Study of the Supernova Remnant RX J0852.0-4622 (Vela Jr.)
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We conduct a multi-wavelength morphological study of the Galactic supernova remnant RXJ0852.0-4622 (also known as Vela Jr., Vela Z and G266.2-1.2). RX J0852.0-4622 is coincident with the edge of the larger Vela supernova remnant causing confusion in the attribution of some filamentary structures to either RX J0852.0-4622 or its larger sibling. We find that the RX J0852.0-4622 radio continuum emission can be characterised by a 2-dimensional shell with a radius of 0.90+/-0.01deg (or 11.8+/-0.6pc at an assumed distance of 750pc) centred at (l,b)=(133.08+/-0.01 deg,-46.34+/-0.01deg) (or RA=8h52m19.2s, Dec=-46deg2024.0, J2000), consistent with X-ray and gamma-ray emission. Although [OIII] emission features are generally associated with the Vela SNR, one particular [OIII] emission feature, which we denote as the Vela Claw, morphologically matches a molecular clump that is thought to have been stripped by the stellar progenitor of the RX J0852.0-4622 SNR. We argue that the Vela Claw feature is possibly associated with RX J0852.0-4622. Towards the north-western edge of RX J0852.0-4622, we find a flattening of the radio spectral index towards another molecular clump also thought to be associated with RX J0852.0-4622. It is currently unclear whether this feature and the Vela Claw result from interactions between the RX J0852.0-4622 shock and the ISM.
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Supernova remnant (SNR) RX J0852.0-4622 is one of the youngest and is most likely the closest among known galactic supernova remnants (SNRs). It was detected in X-rays, the 44Ti gamma-line, and radio. We obtain and analyze medium-resolution spectra o
f 14 stars in the direction towards the SNR RX J0852.0-4622 in an attempt to detect broad absorption lines of unshocked ejecta against background stars. Spectral synthesis is performed for all the stars in the wavelength range of 3740-4020AA to extract the broad absorption lines of Ca II related to the SNR RX J0852.0-4622. We do not detect any broad absorption line and place a 3-sigma upper limit on the relative depths of <0.04 for the broad Ca II absorption produced by the SNR. We detect narrow low and high velocity absorption components of Ca II. High velocity |V(LSR)|=100-140 km/s components are attributed to radiative shocks in clouds engulfed by the old Vela SNR. The upper limit to the absorption line strength combined with the width and flux of the 44Ti gamma-ray line 1.16 MeV lead us to conclude that SNR RX J0852.0-4622 was probably produced by an energetic SN Ic explosion.
The shell-type supernova remnant RX J0852.0-4622 was detected in 2004 and re-observed between December 2004 and May 2005 with the High Energy Stereoscopic System (H.E.S.S.), an array of four Imaging Cherenkov Telescopes located in Namibia and dedicat
ed to the observations of gamma-rays above 100 GeV. The angular resolution of <0.1 degree and the large field of view of H.E.S.S. (5 degrees diameter) are well adapted to studying the morphology of the object in very high energy gamma-rays, which exhibits a remarkably thin shell very similar to the features observed in the radio range and in X-rays. The spectral analysis of the source from 300 GeV to 20 TeV will be presented. Finally, the possible origins of the very high energy gamma-ray emission (Inverse Compton scattering by electrons or the decay of neutral pions produced by proton interactions) will be discussed, on the basis of morphological and spectral features obtained at different wavelengths.
We searched for evidence of line emission around 4keV from the northwestern rim of the supernova remnant RX J0852.0-4622 using Suzaku XIS data. Several papers have reported the detection of an emission line around 4.1keV from this region of the sky.
This line would arise from K-band fluorescence by Sc, the immediate decay product of 44Ti. We performed spectral analysis for the entire portion of the NW rim of the remnant within the XIS field of view, as well as various regions corresponding to regions of published claims of line emission. We found no line emission around 4.1keV anywhere, and are able to set a restrictive upper limit to the X-ray flux: 1.1x10^-6 s^-1 cm^-2 for the entire field. For every region, our flux upper limit falls below that of the previously claimed detection. Therefore, we conclude that, to date, no definite X-ray line feature from Sc-K emission has been detected in the NW rim of RX J0852.0-4622. Our negative-detection supports the recent claim that RX J0852-4622 is neither young (1700--4000 yr) nor nearby(~750 pc).
Aims. We study gamma-ray emission from the shell-type supernova remnant (SNR) RX J0852.0$-$4622 to better characterize its spectral properties and its distribution over the SNR. Methods. The analysis of an extended High Energy Spectroscopic System
(H.E.S.S.) data set at very high energies (E > 100 GeV) permits detailed studies, as well as spatially resolved spectroscopy, of the morphology and spectrum of the whole RX J0852.0$-$4622 region. The H.E.S.S. data are combined with archival data from other wavebands and interpreted in the framework of leptonic and hadronic models. The joint Fermi-LAT-H.E.S.S. spectrum allows the direct determination of the spectral characteristics of the parent particle population in leptonic and hadronic scenarios using only GeV-TeV data. Results. An updated analysis of the H.E.S.S. data shows that the spectrum of the entire SNR connects smoothly to the high-energy spectrum measured by Fermi-LAT. The increased data set makes it possible to demonstrate that the H.E.S.S. spectrum deviates significantly from a power law and is well described by both a curved power law and a power law with an exponential cutoff at an energy of $E_mathrm{cut} = (6.7 pm 1.2_mathrm{stat} pm 1.2_mathrm{syst})$ TeV. The joint Fermi-LAT-H.E.S.S. spectrum allows the unambiguous identification of the spectral shape as a power law with an exponential cutoff. No significant evidence is found for a variation of the spectral parameters across the SNR, suggesting similar conditions of particle acceleration across the remnant. A simple modeling using one particle population to model the SNR emission demonstrates that both leptonic and hadronic emission scenarios remain plausible. It is also shown that at least a part of the shell emission is likely due to the presence of a pulsar wind nebula around PSR J0855$-$4644.
We present a new analysis of the interstellar protons toward the TeV $gamma$-ray SNR RX J0852.0$-$4622 (G266.2$-$1.2, Vela Jr.). We used the NANTEN2 $^{12}$CO($J$ = 1-0) and ATCA & Parkes HI datasets in order to derive the molecular and atomic gas as
sociated with the TeV $gamma$-ray shell of the SNR. We find that atomic gas over a velocity range from $V_mathrm{LSR}$ = $-4$ km s$^{-1}$ to 50 km s$^{-1}$ or 60 km s$^{-1}$ is associated with the entire SNR, while molecular gas is associated with a limited portion of the SNR. The large velocity dispersion of the HI is ascribed to the expanding motion of a few HI shells overlapping toward the SNR but is not due to the Galactic rotation. The total masses of the associated HI and molecular gases are estimated to be $sim2.5 times 10^4 $ $M_{odot}$ and $sim10^3$ $M_{odot}$, respectively. A comparison with the H.E.S.S. TeV $gamma$-rays indicates that the interstellar protons have an average density around 100 cm$^{-3}$ and shows a good spatial correspondence with the TeV $gamma$-rays. The total cosmic ray proton energy is estimated to be $sim10^{48}$ erg for the hadronic $gamma$-ray production, which may still be an underestimate by a factor of a few due to a small filling factor of the SNR volume by the interstellar protons. This result presents a third case, after RX J1713.7$-$3946 and HESS J1731$-$347, of the good spatial correspondence between the TeV $gamma$-rays and the interstellar protons, lending further support for a hadronic component in the $gamma$-rays from young TeV $gamma$-ray SNRs.
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