* Astronomy

Title: Newly confirmed and high quality candidate Galactic SNRs uncovered from the AAO/UKST HAlpha survey
Authors: M. Stupar, Q. A. Parker, M. D. Filipovic

We report catalogue of 21 new Galactic supernova remnants (SNRs) which we have uncovered in the optical regime as filamentary emissions and extended nebulosities on images of the Anglo Australian Observatory/United Kingdom Schmidt Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane. Our follow-up spectral observations of about 60 candidate nebulosities confirmed classical optical SNR emission lies for 21 structures, especially via the presence of a very strong [SII] doublet at 6717 and 6731A relative to HAlpha Morphologically, 11 of these new remnants are in the form of a coherent, extended arc or shell of nebulosity, while the remaining objects are more irregular in form but clearly filamentary in nature, typical of optically detected SNRs. In 11 cases there was a clear if not complete match between the optical and radio structures with HAlpha filamentary structures registered inside and along the presumed radio borders. Additionally, ROSAT X-ray sources were detected inside the optical/radio borders of 11 of these new remnants and 3 may have an associated pulsar. When the multi-wavelength data is considered together it presents strong evidence to confirm identification of 21 new, mostly senile Galactic SNRs, including G288.7-6.3, G315.1+2.7 and G332.5-5.6, previously identified as possible remnants from preliminary radio observations. We also confirm existence of radio quite but optically active supernova remnants.

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Title: Study of Nonthermal Emission from SNR RX J1713.7-3946 with Suzaku
Authors: Takaaki Tanaka, Yasunobu Uchiyama, Felix A. Aharonian, Tadayuki Takahashi, Aya Bamba, Junko S. Hiraga, Jun Kataoka, Tetsuichi Kishi****a, Motohide Kokubun, Koji Mori, Kazuhiro Nakazawa, Robert Petre, Hiroyasu Tajima, Shin Watanabe

We present results obtained from a series of observations of the supernova remnant RX J1713.7-3946 by the Suzaku satellite. The observations cover about two-thirds of the remnant surface. We successfully detected hard X-rays up to ~ 40 keV from each pointing. The hard X-ray spectra are described by power-law functions with photon indices of ~ 3.0, which are larger than those in the energy region below 10 keV. Connection of the spatially-integrated XIS and HXD spectra clearly reveals a spectral cutoff in the 0.4--40 keV X-ray spectrum. This cutoff is interpreted to correspond to the maximum acceleration energy of electrons emitting synchrotron radiation. The wide-band coverage of Suzaku for the first time allows us to derive the parent electron spectrum in the cutoff region, which shows good agreement with theoretical predictions. The inferred cutoff energy in the spatially-integrated X-ray spectrum indicates that particle acceleration in the remnant is so efficient that it is almost at the theoretical limit, the so-called Bohm limit. Based on the Suzaku data, we present results of multi-wavelength studies from spectral and morphological points of view. The spectral energy distribution favours the hadronic scenario rather than the leptonic scenario. For the morphology studies, we compare the surface brightness maps from the Suzaku XIS and the H.E.S.S. telescope. We confirm the strong correlation between X-ray and TeV gamma-ray emission. In addition to the correlation, we found that in the bright western rim regions the X-ray emission is brighter than expected from the general X-ray to gamma-ray correlation.

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Title: Spitzer Observations of Supernova Remnant IC 443
Authors: A. Noriega-Crespo (Spitzer Science Center), D.C. Hines (Space Science Institute), K. Gordon (Space Telescope Institute), F.R. Marleau (Spitzer Science Center), G.H. Rieke (Steward Observatory), J. Rho (Spitzer Science Center), W.B. Latter (NASA Herschel Science Center)

We present Spitzer observations of IC 443 obtained with MIPS and IRS as part of our GTO program on the astrophysics of ejecta from evolved stars. We find that the overall morphology at mid/far IR wavelengths resembles even more closely a loop or a shell than the ground based optical and/or near IR images. The dust temperature map, based on the 70/160micron ratio, shows a range from 18 to 30 K degrees. The IRS spectra confirm the findings from previous near+mid IR spectroscopic observations of a collisionally excited gas, atomic and molecular, rich in fine structure atomic and pure H2 rotational emission lines, respectively. The spectroscopic shock indicator, [Ne II] 12.8micron, suggests shock velocities ranging from 60-90 km/s, consistent with the values derived from other indicators.

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Title: Massive-Star Forming Infrared Loop around the Crab-like Supernova Remnant G54.1+0.3: Post Main-Sequence Triggered Star Formation?
Authors: Bon-Chul Koo, Christopher F. McKee, Jae-Joon Lee, Ho-Gyu Lee, Jeong-Eun Lee, Dae-Sik Moon, Seung Soo Hong, Hidehiro Kaneda, Takashi Onaka

We report the discovery of a star-forming loop around the young, Crab-like supernova remnant (SNR) G54.1+0.3 using the AKARI infrared satellite. The loop consists of at least eleven young stellar objects (YSOs) embedded in a ring-like diffuse emission of radius ~1'. The YSOs are bright in the mid-infrared and are also visible in the Spitzer Space Telescope Galactic plane survey images. Their Spitzer colours are similar to those of class II YSOs in [3.6]-[5.8] but significantly redder in [8]-[24], i.e., 0<[3.6]-[5.8]<1.2 and 5<[8]-[24]<9. Most of them have near-infrared counterparts in the 2MASS JHKs images, and some of them have an optical counterpart too. Their JHKs colours and magnitudes indicate that the YSOs are massive (<= 10 Msun) pre-main-sequence stars at the same distance to the SNR, i.e., 8 kpc, which supports the association of the star-forming loop with the SNR. The dereddened spectral energy distributions are similar to eraly Herbig Be stars, which are early B-type pre-main-sequence stars with inner disks that have been destroyed. The confinement to a loop structure indicates that the YSOs are young, i.e., <= 2 Myr. We propose that their formation is triggered by the progenitor star of G54.1+0.3, which has a mass of <= 15 Msun. The triggering must have occurred near the end of the progenitor's life, possibly after it had evolved off the main sequence.

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