Radio continuum and H I observations of the supernova remnant G296.8-00.3 (original) (raw)

Radio continuum and HI observations of supernova remnant G296.8-00.3

1997

We argue that the adjacent pulsar J1157-6224 is at a similar distance as the SNR, but that a physical association is highly unlikely. The pulsar is the only detectable source in the field in circular polarization, suggesting a method for finding pulsars during aperture synthesis.

A Multifrequency Radio Study of Supernova Remnant G292.0+1.8 and Its Pulsar Wind Nebula

The Astrophysical Journal, 2003

We present a detailed radio study of the young supernova remnant (SNR) G292.0+1.8 and its associated pulsar PSR J1124-5916, using the Australia Telescope Compact Array at observing wavelengths of 20, 13 and 6 cm. We find that the radio morphology of the source consists of three main components: a polarized flat-spectrum central core coincident with the pulsar J1124-5916, a surrounding circular steep-spectrum plateau with sharp outer edges and, superimposed on the plateau, a series of radial filaments with spectra significantly flatter than their surroundings. H I absorption argues for a lower limit on the distance to the system of 6 kpc. The core clearly corresponds to radio emission from a pulsar wind nebula powered by PSR J1124-5916, while we conclude that the plateau represents the surrounding SNR shell. The plateau's sharp outer rim delineates the SNR's forward shock, while the thickness of the plateau region demonstrates that the forward and reverse shocks are well-separated. Assuming a distance of 6 kpc and an age for the source of 2500 yr, we infer an expansion velocity for the SNR of ∼ 1200 km s −1 , an ambient density ∼ 0.9 cm −3 , an ejected mass ∼ 5.9 M ⊙ and a supernova explosion energy ∼ 1.1 × 10 51 erg. We interpret the flat-spectrum radial filaments superimposed on the steeperspectrum plateau as Rayleigh-Taylor unstable regions between the forward and reverse shocks of the SNR. The flat radio spectrum seen for these features results from efficient second-order Fermi acceleration in strongly amplified magnetic fields. Overall, SNR G292.0+1.8 shows an unusual set of properties not seen in any other SNR. This source may reflect a unique stage in evolution, only seen for systems at an age of ∼ 2500 yr, and only for which there is both a bright SNR shell and an energetic associated pulsar.

A Radio Supernova Remnant Associated with the Young Pulsar J1119−6127

The Astrophysical Journal, 2001

We report on Australia Telescope Compact Array observations in the direction of the young high magneticfield pulsar J1119-6127. In the resulting images we identify a non-thermal radio shell of diameter 15 ′ , which we classify as a previously uncatalogued young supernova remnant, G292.2-0.5. This supernova remnant is positionally coincident with PSR J1119-6127, and we conclude that the two objects are physically associated. No radio emission is detected from any pulsar wind nebula (PWN) associated with the pulsar; our observed upper limits are consistent with the expectation that high magnetic-field pulsars produce radio nebulae which fade rapidly. This system suggests a possible explanation for the lack of an associated radio pulsar and/or PWN in many supernova remnants.

Radio-continuum emission from the young galactic supernova remnant G1.9+0.3

Serbian Astronomical Journal, 2014

We present an analysis of a new Australia Telescope Compact Array (ATCA) radio-continuum observation of supernova remnant (SNR) G1.9+0.3, which at an age of ~181?25 years is the youngest known in the Galaxy. We analysed all available radio-continuum observations at 6-cm from the ATCA and Very Large Array. Using this data we estimate an expansion rate for G1.9+0.3 of 0.563%?0.078% per year between 1984 and 2009. We note that in the 1980's G1.9+0.3 expanded somewhat slower (0.484% per year) than more recently (0.641% per year). We estimate that the average spectral index between 20-cm and 6-cm, across the entire SNR is ?={0.72?0.26 which is typical for younger SNRs. At 6-cm, we detect an average of 6% fractionally polarised radio emission with a peak of 17%?3%. The polarised emission follows the contours of the strongest of X-ray emission. Using the new equipartition formula we estimate a magnetic field strength of B?273?G, which to date, is one of the highest magnetic field stren...

High resolution radio study of the pulsar wind nebula within the supernova remnant G0.9+0.1

Astronomy and Astrophysics, 2008

Aims. We have conducted a study in radio wavelengths and in X-rays of the pulsar wind nebula (PWN) in the supernova remnant (SNR) G0.9+0.1 with the goal of investigating in detail its morphology and to accurately determine its characteristic parameters. Method. To carry out this research we have observed the PWN at λ 3.6 and 6 cm using the Australia Telescope Compact Array (ATCA) and combined these data with existing multiconfiguration VLA data and single dish observations in order to recover information at all spatial scales. We have also reprocessed VLA archival data at λ 20 cm. From all these observational data we have produced high-fidelity images at the three radio frequencies with angular resolution better than 3 ′′ . The radio data were compared to X-ray data obtained with Chandra and in two different observing runs with XMM-Newton. Results. The new observations revealed that the morphology and symmetry suggested by Chandra observations (torus and jet-like features) are basically preserved in the radio range in spite of the rich structure observed in the radio emission of this PWN, including several arcs, bright knots, extensions and filaments. The reprocessed X-ray images show for the first time that the X-ray plasma fills almost the same volume as the radio PWN.

A multiwavelength study of the radio source G296.7−0.9: confirmation as a Galactic supernova remnant

Monthly Notices of the Royal Astronomical Society, 2012

We present a multi-wavelength study of the radio source G296.7-0.9. This source has a bilateral radio morphology, a radio spectral index of −0.5 ± 0.1, sparse patches of linear polarisation, and thermal X-rays with a bright arc near the radio boundary. Considering these characteristics, we conclude that G296.7-0.9 is a supernova remnant (SNR). The age and morphology of the SNR in the context of its environment suggest that the source is co-located with an H ii region, and that portions of the shock front have broken out into a lower density medium. We see no evidence for a neutron star or pulsar wind nebula associated with SNR G296.7-0.9.

Multifrequency radio observations of SNR J0536-6735 (N 59B) with associated pulsar

Serbian Astronomical Journal, 2012

We present a study of new Australian Telescope Compact Array (ATCA) observations of supernova remnant, SNR J0536-6735. This remnant appears to follow a shell morphology with a diameter of D=36×29 pc (with 1 pc uncertainty in each direction). There is an embedded H ii region on the northern limb of the remnant which made various analysis and measurements (such as flux density, spectral index and polarisation) difficult. The radio-continuum emission followed the same structure as the optical emission, allowing for extent and flux density estimates at 20 cm. We estimate a surface brightness for the SNR at 1 GHz of 2.55×10 −21 Wm −2 Hz −1 sr −1 . Also, we detect a distinctive radio-continuum point source which confirms the previous suggestion of this remnant being associated with a pulsar wind nebulae (PWN). The tail of this remnant isn't seen in the radio-continuum images and is only seen in the optical and X-ray images.

A multiwavelength study of the supernova remnant G296.8-0.3

Astrophysics and Space Science, 2012

We report XMM-Newton observations of the Galactic supernova remnant G296.8−0.3, together with complementary radio and infrared data. The spatial and spectral properties of the X-ray emission, detected towards G296.8−0.3, was investigated in order to explore the possible evolutionary scenarios and the physical connexion with its unusual morphology detected at radio frequencies. G296.8−0.3 displays diffuse X-ray emission correlated with the peculiar radio morphology detected in the interior of the remnant and with the shell-like radio structure observed to the northwest side of the object. The X-ray emission peaks in the soft/medium energy range (0.5-3.0 keV). The Xray spectral analysis confirms that the column density is high (N H ∼0.64×10 22 cm −2 ) which supports a distant location (d>9 kpc) for the SNR. Its X-ray spectrum can be well represented by a thermal (PSHOCK)

Out of the frying pan: a young pulsar with a long radio trail emerging from SNR G315. 9-0.0

2009

The faint radio supernova remnant SNR G315.9-0.0 is notable for a long and thin trail that extends outward perpendicular from the edge of its approximately circular shell. In a search with the Parkes telescope we have found a young and energetic pulsar that is located at the tip of this collimated linear structure. PSR J1437-5959 has period P = 61 ms, characteristic age τ c = P/(2Ṗ) = 114 kyr, and spin-down luminosityĖ = 1.4 × 10 36 erg s −1. It is very faint, with a flux density at 1.4 GHz of about 75 µJy. From its dispersion measure of 549 pc cm −3 , we infer d ≈ 8 kpc. At this distance and for an age comparable to τ c , the implied pulsar velocity in the plane of the sky is V t = 300 km s −1 for a birth at the center of the SNR, although it is possible that the SNR/pulsar system is younger than τ c and that V t > 300 km s −1. The highly collimated linear feature is evidently the pulsar wind trail left from the supersonic passage of PSR J1437-5959 through the interstellar medium surrounding SNR G315.9-0.0.