Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMulti-frequency Study of the LMC Supernova Remnant (SNR) B0513-692 and New SNR Candidate J051327-6911
119
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present a new multi-wavelength study of supernova remnant (SNR) B0513-692 in the Large Magellanic Cloud (LMC). The remnant also has a strong, superposed, essentially unresolved, but unrelated radio source at its north-western edge, J051324-691049. This is identified as a likely compact HII region based on related optical imaging and spectroscopy. We use the Australia Telescope Compact Array (ATCA) at 4790 and 8640 MHz to determine the large scale morphology, spectral index and polarization characteristics of B0513-692 for the first time. We detect a strongly polarized region (49%) in the remnants southern edge. Interestingly we also detect a small (~40 arcsec) moderately bright, but distinct optical, circular shell in our Halpha imagery which is adjacent to the compact HII region and just within the borders of the NE edge of B0513-692. We suggest this is a separate new SNR candidate based on its apparently distinct character in terms of optical morphology in 3 imaged emission lines and indicative SNR optical spectroscopy (including enhanced optical [SII] emission relative to Halpha).
rate research
Read More
The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs) which can be investigated in detail with radio, optical and X-ray observations. SNR J0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies. We study the emission of SNR J0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant. We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNR J0453-6829. We studied the morphology of SNR J0453-6829 from radio, optical and X-ray images and investigated the energy spectra in the different parts of the remnant. Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index alpha_Core of -0.04+/-0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with alpha_Shell = -0.43+/-0.01. We detect regions with a mean polarisation of P ~ (12+/-4)% at 6 cm and (9+/-2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31+/-1) pc x (29+/-1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12000-15000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56 cm^-3, typical for LMC remnants, a large swept-up mass of 830 solar masses, and an explosion energy of 7.6 x 10^50 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material.
Context: The Supernova Remnants (SNRs) known in the Large Magellanic Cloud (LMC) show a variety of morphological structures in the different wavelength bands. This variety is the product of the conditions in the surrounding medium with which the remnant interacts and the inherent circumstances of the supernova event itself. Aims: This paper performs a multi-frequency study of the LMC SNR J0530-7007 by combining Australia Telescope Compact Array (ATCA), Molonglo Observatory Synthesis Telescope (MOST), Rontgensatellit (ROSAT) and Magellanic Clouds Emission Line Survey (MCELS) observations. Methods: We analysed radio-continuum, X-ray and optical data and present a multi-wavelength morphological study of LMC SNR J0530-7007. Results We find that this object has a shell-type morphology with a size of 215x180 (52 pc x 44 pc); a radio spectral index (alpha=-0.85+-0.13); with [Sii]/Halpha > 0.4 in the optical; and the presence of non-thermal radio and X-ray emission. Conclusions: We confirmed this object as a bona-fide shell-type SNR which is probably a result of a Type Ia supernova.
We present compelling evidence for confirmation of a Galactic supernova remnant (SNR) candidate, G332.5-5.6, based initially on identification of new, filamentary, optical emission line nebulosity seen in the arcsecond resolution images from the AAO/UKST HAlpha survey. The extant radio observations and X-ray data which we have independently re-reduced, together with new optical spectroscopy of the large-scale fragmented nebulosity, confirms the identification. Optical spectra, taken across five different, widely separated nebula regions of the remnant as seen on the HAlpha images, show average ratios of [NII]/HAlpha =2.42, [SII]/HAlpha = 2.10, and [SII] 6717/6731 = 1.23, as well as strong [OI] 6300, 6364A and [OII] 3727A emission. These ratios are firmly within those typical of SNRs. Here, we also present the radio-continuum detection of the SNR at 20/13cm from observations with the Australia Telescope Compact Array (ATCA). Radio emission is also seen at 4850 MHz, in the PMN survey (Griffith and Wright 1993) and at 843 MHz from the SUMSS survey (Bock, Large and Sadler 1999). We estimate an angular diameter of ~30 arcmin and obtain an average radio spectral index of alpha = -0.6 +- 0.1 which indicates the non-thermal nature of G332.5-5.6. Fresh analysis of existing ROSAT X-ray data in the vicinity also confirms the existence of the SNR. The distance to G332.5-5.6 has been independently estimated by Reynoso and Green (2007) as 3.4 kpc based on measurements of the HI lambda21 cm line seen in absorption against the continuum emission. Our cruder estimates via assumptions on the height of the dust layer (3.1 kpc) and using the Sigma-D relation (4 kpc) are in good agreement.
We have used the ESO NTT/EMMI and VLT/FORS1 instruments to examine the LMC supernova remnant 0540-69.3 as well as its pulsar (PSR B0540-69) and pulsar-powered nebula in the optical range.Spectroscopic observations of the remnant covering the range of 3600-7350 A centered on the pulsar produced results consistent with those of Kirshner et al. (1989), but also revealed many new emission lines. The most important are [Ne III] 3869, 3967 and Balmer lines of hydrogen. In both the central part of the remnant, as well as in nearby H II regions, the [O III] temperature is higher than about 20 000 K, but lower than previously estimated. For PSR B0540-69, previous optical data are mutually inconsistent: HST/FOS spectra indicate a significantly higher absolute flux and steeper spectral index than suggested by early time-resolved groundbased UBVRI photometry. We show that the HST and VLT spectroscopic data for the pulsar have more then about 50% nebular contamination, and that this is the reason for the previous difference. Using HST/WFPC2 archival images obtained in various bands from the red part of the optical to the NUV range we have performed an accurate photometric study of the pulsar, and find that the spectral energy distribution of the pulsar emission has a negative slope with 1.07 +/- 0.2. This is steeper than derived from previous UBVRI photometry, and also different from the almost flat spectrum of the Crab pulsar. We also estimate that the proper motion of the pulsar is 4.9 +/- 2.3 mas/yr, corresponding to a transverse velocity of 1190 +/- 560 km/s, projected along the southern jet of the pulsar nebula.
We report the discovery of an unidentified, extended source of very-high-energy (VHE) gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hours of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0.23^{circ} pm 0.03^{circ} (stat)+0.04^{circ}_{-0.02}^{circ}(sys) and its spectrum is well-characterized by a differential power law (dN/dE = N_0 times (E/TeV)^{-Gamma}) with a photon index of {Gamma} = 2.37 pm 0.14 (stat) pm 0.20 (sys) and a flux normalization of N0 = 1.5 pm 0.2 (stat) pm 0.4(sys) times 10^-12 ph TeV^{-1} cm^{-2} s^{-1}. This yields an integral flux of 5.2 pm 0.8 (stat) pm 1.4 (sys) times 10^-12 ph cm^{-2} s^{-1} above 320 GeV, corresponding to 3.7% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the supernova remnant shock.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
