We present the results of new high resolution ATCA observations of SNR
J0519-6926. We found that this SNR exhibits a typical "horseshoe" appearance
with alpha = -0.55 +- 0.08 and D=28+-1 pc. No polarization (or magnetic fields)
are detected to a level of 1%. This is probably due to a relatively poor
sampling of the uv plane caused be observing in "snap-shot" mode.Comment: 6 pages 4 figures, to be published in Serbian Astronomical Journa

Crawford, E. J.

Filipović, M. D.

Payne, J. L.

Serbian Astronomical Journal

English

arXiv

E.J. Crawford

M.D. Filipovic

J.L. Payne

Crossref

Radio continuum study of the large Magellanic cloud: SNR J0519-6926

We present the results of new high resolution ATCA observations of SNR J0519-6926. We found that this SNR exhibits a typical 'horseshoe' appearance with α=-0.55±0.08 and D=28±1 pc. No polarization (or magnetic fields) were detected to a level of 1%. This is probably due to a relatively poor sampling of the UV plane caused be observing in 'snap-shot' mode

Crawford E.J.

Filipović M.D.

Payne J.L.

Directory of Open Access Journals

SUMMARY: We present the results of new high resolution ATCA observations of SNR J0519–6926. We found that this SNR exhibits a typical ”horseshoe ” ap-pearance with α=–0.55±0.08 and D=28±1 pc. No polarization (or magnetic fields) were detected to a level of 1%. This is probably due to a relatively poor sampling of the uv plane caused be observing in ”snap-shot ” mode. Key words. ISM: supernova remnants – Magellanic Clouds – ISM: individual ob-jects: SNR J0519-692

E. J. Crawford

M. D. Filipović

J. L. Payne

CiteSeerX

RADIO CONTINUUM STUDY OF THE LARGE MAGELLANIC CLOUD – SNR J0519–6926

We present the results of new high resolution ATCA observations of SNR J0519-6926. We found that this SNR exhibits a typical "horseshoe" appearance with α=0.55Â±0.08 and D=28Â±1 pc. No polarization (or magnetic fields) were detected to a level of 1%. This is probably due to a relatively poor sampling of the UV plane caused be observing in "snap-shot" mode

Crawford, Evan J. (R14178)

Filipovic, Miroslav (R7673)

Payne, Jeffrey L.

Western Sydney ResearchDirect

Radio continuum study of the Large Magellanic Cloud - SNR J0519-6926

We present the results of new high resolution ATCA observations of SNR J0519-6926. We found that this SNR exhibits a typical "horseshoe" appearance with α=-0.55±0.08 and D=28±1 pc. No polarization (or magnetic fields) were detected to a level of 1%. This is probably due to a relatively poor sampling of the uv plane caused be observing in "snap-shot" mode

Crawford, E.J.

Filipovic, M.D.

Payne, J.L.

ResearchOnline@JCU

Radio contiuum study of the large magellanic cloud: SNR J0519-6926

We present the results of new high resolution ATCA observations of SNR J0519-6926. We found that this SNR exhibits a typical "horseshoe" appearance with $alpha$=--0.55$pm$0.08 and D=28$pm1$~pc. No polarization (or magnetic fields) were detected to a level of 1\%. This is probably due to a relatively poor sampling of the $uv$ plane caused be observing in "snap-shot" mode

Serb. Astron. J. } 176 (2008), 59 - 63 UDC 524.354{77 : 524.722.3DOI: 10.2298/SAJ0876059C Preliminary reportRADIO CONTINUUM STUDY OF THE LARGEMAGELLANIC CLOUD { SNR J0519{6926E. J. Crawford1, M. D. Filipovi¶ c1 and J. L. Payne21School of Computing and Mathematics, University of Western SydneyLocked Bag 1797, Penrith South DC, NSW 1797, AustraliaE{mail: m.¯lipovic@uws.edu.au2Centre for Astronomy, James Cook UniversityTownsville, QLD 4811, Australia(Received: February 27, 2008; Accepted: March 8, 2008)SUMMARY: We present the results of new high resolution ATCA observationsof SNR J0519{6926. We found that this SNR exhibits a typical "horseshoe" ap-pearance with ®={0.55§0.08 and D=28§1 pc. No polarization (or magnetic ¯elds)were detected to a level of 1%. This is probably due to a relatively poor samplingof the uv plane caused be observing in "snap-shot" mode.Key words. ISM: supernova remnants { Magellanic Clouds { ISM: individual ob-jects: SNR J0519-69261. INTRODUCTIONThe study of radio supernova remnants(SNRs) in nearby galaxies is of major interest in or-der to understand the radio output of more distantgalaxies and to understand the processes that occuron local interstellar scales within our own Galaxy.Unfortunately, the distances to many Galactic rem-nants are uncertain by a factor of 2, leading to afactor of 4 uncertainty in luminosity and of 5.5 inthe calculated energy release of the initiating super-nova (SN). At a distance of »50 kpc (Hilditch etal. 2005), the Large Magellanic Cloud (LMC) is oneof the prime targets for the astrophysical research ofgalactic objects, including SNRs. This because theseremnants are located at a known distance, yet closeenough to allow their detailed analysis.SNRs re°ect a major process in the elementalenrichment of the interstellar medium (ISM). Mul-tiple supernova explosions close together generatesuper-bubbles typically hundreds of parsecs in ex-tent. Both are among the prime drivers controllingthe morphology and the evolution of the ISM. Theirproperties are therefore crucial for the full under-standing of the galactic matter cycle.Radio observations are commonly used to dis-cover and characterize SNRs, as the non-thermalemission typical of SNR's is easily detectable at cen-timeter radio wavelengths. Veri¯cation may be basedon a combination of radio spectral index, morphol-ogy, co-identi¯cations in other domains (such as op-tical and/or X-ray), °ux density and location withinthe galaxy under study. There are over 40 con¯rmedSNRs in the LMC and other 35-40 candidates (Payneet al. 2008).SNR J0519{6926 was initially classi¯ed as anSNR based on the Einstein X-Ray survey by Longet al. (1981) (named LHG 27) and Wang et al.(1991) (named W 19). Mathewson et al. (1983)catalogued SNR J0519{6926 as B0520-69.4 based ontheir optical observations, reporting an estimated59E. J. CRAWFORD, M. D. FILIPOVI¶ C and J. L. PAYNEsize of 13800 £ 10400. Filipovi¶ c et al. (1998) addedfurther con¯rmation, with a set of radio continuumobservations (with the Parkes telescope) on a widefrequency range. Blair et al. (2006) report detec-tion at far ultraviolet (FUV) wavelengths. Haberland Pietsch (1999) (named SNR as HP 915) andWilliams et al. (1999) discuss the X-Ray propertiesof SNR J0519{6926 based on ROSAT observations.Quite recently, Payne et al. (2008) presented opticalspectroscopy of a wide range of LMC SNRs includingSNR J0519{6926. They found an enhanced [Sii]/H®ratio of 0.8 typical for SNRs.2. OBSERVATIONSWe observed SNR J0519{6926 with the Aus-tralia Telescope Compact Array (ATCA) on the 6thof April 1997, with array con¯guration 375-m, atwavelengths of 6 and 3 cm (º=4790 and 8640 MHz).The observations were carried out in the so called"snap-shot" mode, totaling »1 hour of integrationover a 12 hour period. Source 1934-638 was used forprimary calibration and source 0530-727 was usedfor secondary calibration. The miriad (Sault andKilleen 2006) and karma (Gooch 2006) softwarepackages were used for reduction and analysis. Moreinformation about observing procedure and anothersource (LMC SNR B0513-69) observed during thissession can be found in Boji· ci¶ c et al. (2007).Images were prepared, cleaned and decon-volved using miriad tasks. Baselines formed withthe 6th ATCA antenna were excluded, as the other¯ve antennas were arranged in a compact con¯gura-tion. The 6 cm image (Fig. 1) has a resolution of 3200and the r.m.s noise is estimated to be 0.4 mJy/beam.Similarly, the 3 cm image (Fig. 2) has a resolu-tion of 2000 and the r.m.s noise is estimated to be0.4 mJy/beam. A 3 cm image was also created witha resolution of 3200 to complement the 6 cm image,and this was used in the preparation of Figs. 1 and 3.3. RESULTS AND DISCUSSIONThe remnant has a classical horseshoemorphology centered at RA(J2000)=5h19m45.3s,DEC(J2000)={69±26000.600 with a nearly circular di-ameter of 14000§500 (28§1 pc). This is reasonablyconsistent with the optical size reported by Mathew-son et al. (1983), and in agreement with the X-raysize 15600 £ 13200 reported by Williams et al. (1999).Flux density measurements were made at 6and 3 cm, resulting in values of 71.3 mJy and43.5 mJy respectively (Table 1). We made our ownmeasurement of °ux density at 1400 MHz using themosaic image described in Hughes et al. (2007). Aspectral index (de¯ned as S / º®) was plotted usingthe °ux densities in Table 1 (Fig. 4) and estimatedto be ®={ 0.55§0.08, which is typical for SNRs (Fil-ipovi¶ c et al. 1998). We note that there are two points(843 and 2300 MHz) which lie slightly o® the line ofbest ¯t. The estimate of °ux density for these pointsare very uncertain, and the error bars are probablytoo conservative. This is due to missing short spac-ings e®ects at 843 MHz. At 2300 MHz a large r.m.snoise coupled with a large Parkes beam size accountsfor the errors. We also calculated a two point spec-tral index between 6 and 3 cm and found ®={0.84.This is somewhat steeper than the overall ®={0.55but also expected as for most SNRs the °ux densityis fading with increasing frequency.From our spectral index map (Fig. 3) we cansee that spectral index is changing rapidly at theSNR front shock with the usual ®¼{0.8, due to thenon-thermal nature of emission in the shocked re-gions. Further on, inside the SNR shell, ® tends to be°atter (¡0:4·®·0) as the emission has larger ther-mal component. We note that there are two "holes"in the spectral index map (Fig. 3) were thermal emis-sion (®¸0) from this SNR tends to dominate. Com-parison of our radio-continuum images with ROSATHRI X-ray images of Williams et al. (1999, Fig. 1l)shows an anti-correlation between radio and X-rayemission.Linear polarization images for each frequencywere created using Q and U parameters. Whilewe detect no reliable polarization at 8640 MHz, the4790 MHz image reveals some very low level linearpolarization. Without reliable polarization measure-ments at the second frequency we could not deter-mine if any Faraday rotation was present.The mean fractional polarization at 4790 MHzwas calculated using °ux density and polarization:P =qS2Q + S2USI¢ 100% (1)where SQ;SU and SI are integrated intensities for Q,U and I Stokes parameters. Our estimated value isP » = 1%.4. CONCULUSIONWe conducted the highest resolution observa-tions to date of SNR J0519{6926. From these obser-vations we found a diameter of 14000 §500, a spectralindex ®={0.55§0.08 and no linear polarization to alevel of » 1%.60RADIO CONTINUUM STUDY OF THE LMC { SNR J0519{6926Table 1. Integrated Flux.SI (408 MHz) SI (843 MHz) SI (1400 MHz) SI (2300 MHz) SI (4790 MHz) SI (8640 MHz)SNR J0519{6926 280 mJy 141 mJy 135 mJy 124 mJy 71.3 mJy 43.5 mJyReference Clarke Mills This Filipovi¶ c This Thiset al. 1976 et al. 1984 Work et al. 1996 Work WorkFig. 1. ATCA observations of SNR J0519{6926 at 6 cm (4790 MHz) overlaid with 3 cm (8640 MHz)complementary resolution contours. The contours are from 1.2 to 4 mJy/beam in 0.4 mJy/beam steps. Theblue circle in the lower left corner represents the beam of 32 00. The sidebar quanti¯es the pixel map and itsunits are mJy/beam.Fig. 2. ATCA 3cm observations of SNR J0519{6926. The blue circle in the lower left corner representsthe 3 cm (8640 MHz) beam of 20 00. The sidebar quanti¯es the pixel map and its units are mJy/beam.61E. J. CRAWFORD, M. D. FILIPOVI¶ C and J. L. PAYNEFig. 3. Spectral index map of SNR J0519{6926 overlaid with 3 cm (8640 MHz) contours. The contoursare from 1.2 to 4 mJy/beam in 0.4 mJy/beam steps. The blue circle in the lower left corner represents thebeam of 32 00. The sidebar quanti¯es the pixel map, representing the spectral index.Fig. 4. Radio Spectrum of SNR J0519{6926.62RADIO CONTINUUM STUDY OF THE LMC { SNR J0519{6926Acknowledgements { We used the karma softwarepackage developed by the ATNF. The Australia Tele-scope Compact Array is part of the Australia Tele-scope which is funded by the Commonwealth of Aus-tralia for operation as a National Facility managedby CSIRO.REFERENCESBlair, W. P., Ghavamian, P., Sankrit, R., Danforth,C. W.: 2006, Astron. Astrophys. Suppl. Se-ries, 165, 480.Boji· ci¶ c, I. S., Filipovi¶ c, M. D., Parker, Q. A., Payne,J. L., Jones, P. A., Reid, W., Kawamura, A.,Fukui, Y. 2007, Mon. Not. R. Astron. Soc.,378, 1237.Clarke, J. N., Little, A. G., Mills, B. Y.: 1976, Aust.J. Phys. Astrophys. Suppl., 40, 1.Filipovi¶ c, M. D., White, G. L., Haynes, R. F., Jones,P. A., Meinert, D., Wielebinski, R., Klein, U.:1996, Astron. Astrophys. Suppl. Series, 120,77.Filipovi¶ c, M. D., Haynes, R. F., White, G. L., Jones,P. A.: 1998, Astron. Astrophys. Suppl. Se-ries, 130, 421.Gooch, R.: 2006, Karma Users Manual, ATNF.Haberl, F., Pietsch, W.: 1999, Astron. Astrophys.Suppl. Series, 139, 277.Hilditch, R. W., Howarth, I. D., Harries, T. J.: 2005,Mon. Not. R. Astron. Soc., 357, 304.Hughes, A., Staveley-Smith, L., Kim, S., Wolleben,M., Filipovi¶ c, M.: 2007, Mon. Not. R. As-tron. Soc., 382, 543.Long, K. S., Helfand, D. J., Grabelski, D. A.: 1981,Astrophys. J., 248, 925.Mathewson, D. S., Ford, V. L., Dopita, M. A., Tuohy,I. R., Long, K. S., Helfand, D. J.: 1983, As-tron. Astrophys. Suppl. Series, 51, 345.Mills, B. Y., Turtle, A. J., Little, A. G., Durdin,J. M.: 1984, Aust. J. Phys., 37, 321.Payne, J. L., White, G. L., Filipovi¶ c, M. D.: 2008,Mon. Not. R. Astron. Soc., 383, 1175.Sault, R., Killeen, N.: 2006, Miriad Users Guide,ATNF.Wang, Q., Hamilton, T., Helfand, D. J., Wu X.:1991, Astrophys. J., 374, 475.Williams, R. M., Chu, Y.-H., Dickel, J. R., Petre,R., Smith, R. C., Tavarez, M.: 1999, Astron.Astrophys. Suppl. Series, 123, 467.ZRAQE E U RADIO KONTINUUMU OSTATAKA SUPERNOVIHU VELIKOM MAGELANOVOM OBLAKU { SNR J0519{6926E. J. Crawford1, M. D Filipovi¶ c1 and J. L. Payne21School of Computing and Mathematics, University of Western SydneyLocked Bag 1797, Penrith South DC, NSW 1797, AustraliaE{mail: m.¯lipovic@uws.edu.au2Centre for Astronomy, James Cook UniversityTownsville, QLD 4811, AustraliaUDK 524.354{77 : 524.722.3Prethodno saopxteeU ovoj studiji predstav	amo noveATCA radio-kontinuum rezultate posma-traa visoke rezulucije ostatka supernove(OSN) u Velikom Magelanovom Oblaku {SNR J0519{6926. Naxli smo da ovaj OSNima tipiqnu morfologiju (potkovica) za ovuvrstu objekata sa radio spektralnim indeksom® = ¡0:55§0.08 i dijametrom D= 28§1 parseka.Nismo detektovali polarizaciju (ni magnetnopo	e) do nivoa od 1%. Razlog za nepostojaepolarizacije u rezultatima naxih posmatra-a treba traiti u primeenoj tehnici tzv."snap-xot" moda koji je pokrio samo mai deouv po	a.63

Radio Continuum Study of the Large Magellanic Cloud - SNR J0519-6926

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