The Relation Between the Surface Brightness and the Diameter for Galactic Supernova Remnants

In this work, we have constructed a relation between the surface brightness ($\Sigma$) and diameter (D) of Galactic C- and S-type supernova remnants (SNRs). In order to calibrate the $\Sigma$-D dependence, we have carefully examined some intrinsic (e.g. explosion energy) and extrinsic (e.g. density of the ambient medium) properties of the remnants and, taking into account also the distance values given in the literature, we have adopted distances for some of the SNRs which have relatively more reliable distance values. These calibrator SNRs are all C- and S-type SNRs, i.e. F-type SNRs (and S-type SNR Cas A which has an exceptionally high surface brightness) are excluded. The Sigma-D relation has 2 slopes with a turning point at D=36.5 pc: $\Sigma$(at 1 GHz)=8.4$^{+19.5}_{-6.3}$$\times10^{-12}$ D$^{{-5.99}^{+0.38}_{-0.33}}$ Wm$^{-2}$Hz$^{-1}$ster$^{-1}$ (for $\Sigma$$\le3.7\times10^{-21}$ Wm$^{-2}$Hz$^{-1}$ster$^{-1}$ and D$\ge$36.5 pc) and $\Sigma$(at 1 GHz)=2.7$^{+2.1}_{-1.4}$$\times$ 10$^{-17}$ D$^{{-2.47}^{+0.20}_{-0.16}}$ Wm$^{-2}$Hz$^{-1}$ster$^{-1}$ (for $\Sigma$$>3.7\times10^{-21}$ Wm$^{-2}$Hz$^{-1}$ster$^{-1}$ and D$<$36.5 pc). We discussed the theoretical basis for the $\Sigma$-D dependence and particularly the reasons for the change in slope of the relation were stated. Added to this, we have shown the dependence between the radio luminosity and the diameter which seems to have a slope close to zero up to about D=36.5 pc. We have also adopted distance and diameter values for all of the observed Galactic SNRs by examining all the available distance values presented in the literature together with the distances found from our $\Sigma$-D relation.Comment: 45 pages, 2 figures, accepted for publication in Astronomical and Astrophysical Transaction

Progressive systemic sclerosis in the elderly.

There is evidence to suggest that the incidence of progressive systemic sclerosis in the elderly is more common than in younger age groups. As in younger patients, late onset cases may have minimal skin changes and this can cause difficulty in diagnosis. The case histories of 2 patients are presented to illustrate these points

Recent science from Australian large-scale millimetre mapping projects: proceedings from a Swinburne university workshop

Since the recent upgrades to the Australia Telescope National Facility (ATNF) Mopra telescope back-end and receiver system, it has risen from an under-subscribed facility to a sought-after instrument with heavy international competition to gain time. Furthermore, the introduction of the on-the-fly mapping capability in 2004 has made this technique one of Mopra’s most popular observing modes. In addition, the recent upgrade of the NANTEN millimetre-wavelength telescope to the sub-millimetre NANTEN2 instrument, has provided a complementary, higher-frequency facility to Mopra. A two-day workshop was held at Swinburne University in June 2008 to disseminate the current state of ongoing large-scale mapping projects and associated spin-offs that the telescopes’ upgrades have facilitated, and to decide upon future research directions. Here, we provide a summary of the result-oriented talks as a record of the state of Australian-access single-dish millimetre science in 2008

R&D studies for very high energy gamma-ray astrophysics at energies greater than 10 TeV

In spite of more than 100 discoveries of TeV gamma-ray sources by the current imaging atmospheric Cherenkov telescope (IACT) arrays, Galactic cosmic ray accelerators up to the knee energies (∼ PeV) still remain unclear. PeV Explorer (or PeX) is a future project of a relatively small IACT array, optimized to detect gamma rays of energies greater than 10 TeV and aiming to explore Galactic accelerators up to PeV energies. We present the status of our hardware R & D studies for this project and some extension plans.T. Yoshikoshi, R. W. Clay, B. R. Dawson, Y. Matsubara, M. Mori, T. Naito, K. Nishijima, M. Ohishi, G. P. Rowell, T. Toyam

Connecting the ISM to TeV PWNe and PWN candidates

We investigate the interstellar medium towards seven TeV gamma-ray sources thought to be pulsar wind nebulae using Mopra molecular line observations at 7 mm [CS(1–0), SiO(1–0, v = 0)], Nanten CO(1–0) data and the Southern Galactic Plane Survey/GASS Hi survey. We have discovered several dense molecular clouds co-located to these TeV gamma-ray sources, which allows us to search for cosmic rays coming from progenitor SNRs or, potentially, from pulsar wind nebulae. We notably found SiO(1–0, v = 0) emission towards HESS J1809–193, highlighting possible interaction between the adjacent supernova remnant SNR G011.0–0.0 and the molecular cloud at d ∼ 3.7 kpc. Using morphological features, and comparative studies of our column densities with those obtained from X-ray measurements, we claim a distance d ∼ 8.6 − 9.7kpc for SNR G292.2–00.5, d ∼ 3.5 − 5.6 kpc for PSR J1418–6058 and d ∼ 1.5 kpc for the new SNR candidate found towards HESS J1303–631. From our mass and density estimates of selected molecular clouds, we discuss signatures of hadronic/leptonic components from pulsar wind nebulae and their progenitor SNRs. Interestingly, the molecular gas, which overlaps HESS J1026–582 at d ∼ 5 kpc, may support a hadronic origin. We find however that this scenario requires an undetected cosmic-ray accelerator to be located at d < 10 pc from the molecular cloud. For HESS J1809–193, the cosmic rays which have escaped SNR G011.0–0.0 could contribute to the TeV gamma-ray emission. Finally, from the hypothesis that at most 20% the pulsar spin down power could be converted into CRs, we find that among the studied pulsar wind nebulae, only those from PSR J1809–1917 could potentially contribute to the TeV emission.F.J. Voisin, G.P. Rowell, M.G. Burton, Y. Fukui, H. Sano, F. Aharonian, N. Maxted, C. Braiding, R. Blackwell, and J. La

Searching for an interstellar medium association for HESS J1534-571

The Galactic supernova remnant HESSJ1534−571 (also known as G323.7 − 1.0) has a shell-like morphology in TeV gamma-ray emission and is a key object in the study of cosmic ray origin. Little is known about its distance and local environment. We examine Mopra 12CO/13CO(1–0) data, Australian Telescope Compact Array HI⁠, and Parkes HI data towards HESSJ1534−571⁠. We trace molecular clouds in at least five velocity ranges, including clumpy interstellar medium structures near a dip in HI emission at a kinematic velocity consistent with the Scutum–Crux arm at ∼3.5 kpc. This feature may be a cavity blown-out by the progenitor star, a scenario that suggests HESSJ1534−571 resulted from a core-collapse event. By employing parametrizations fitted to a sample of supernova remnants of known distance, we find that the radio continuum brightness of HESSJ1534−571 is consistent with the ∼3.5 kpc kinematic distance of the Scutum–Crux arm HI dip. Modelling of the supernova evolution suggests a ∼8–24 kyr age for HESSJ1534−571 at this distance.Nigel I. Maxted, C. Braiding, G. F. Wong, G. P. Rowell ... Gavin P. Rowell ... Fabien Voisin ... et al

New radio continuum study of the Large Magellanic Cloud Supernova Remnant N49

International audienceWe present new Australia Telescope Compact Array (ATCA) radio observations toward N49, one of the brightest extragalactic Supernova remnants (SNRs) located in the Large Magellanic Cloud. Our new and archival ATCA radio observations were analysed along with $Chandra$ X-ray data. These observations show a prominent `bullet' shaped feature beyond the southwestern boundary of the SNR. Both X-ray morphology and radio polarisation analysis support a physical connection of this feature to the SNR. The 'bullet' feature's apparent velocity is estimated at $\sim$1300 km s$^{-1}$, based on its distance ($\sim$10 pc) from the remnant's geometric centre and estimated age ($\sim$7600 yrs). we estimated the radio spectral index, $\alpha= -0.55 \pm 0.03$ which is typical of middle-age SNRs. Polarisation maps created for N49 show low to moderate levels of mean fractional polarisation estimated at 7$\pm$1% and 10$\pm$1% for 5.5 and 9 GHz, respectively. These values are noticeably larger than found in previous studies. Moreover, the mean value for the Faraday rotation of SNR N49 from combining CABB data is 212$\pm$65 rad m$^{-2}$ and the maximum value of RM is 591$\pm$103 rad m$^{-2}$