Supernova Remnant G292 Research Articles

Discovery of X-rays from the supernova remnant G0.9+0.1

During the BeppoSAX survey of the Galactic Center region, we have discovered X-ray emission from the central region of the supernova remnant G0.9+0.1. The high interstellar absorption ( N H ∼ × 10 23 cm −) is consistent with a distance of order of 10 kpc and, correspondingly, an X-ray luminosity of ∼10 35 erg s −1. Although we cannot completely rule out a thermal origin of the X-ray emission, its small angular extent (radius ∼2′), the good fit with a power law, the presence of a flat spectrum radio core, and the estimated SNR age of a few thousand years, favour the interpretation in terms of synchrotron emission powered by a young, energetic pulsar.

Radio continuum and Hi observations of the supernova remnant G296.8–00.3

We present Australia Telescope Compact Array (ATCA) observations of the supernova remnant (SNR) G296.8-00.3. A 1.3-GHz continuum image shows the remnant to have a complex multi-shelled appearance, with an unusual rectangular strip running through its centre. HI absorption yields a kinematic distance to the remnant of 9.6+/-0.6 kpc, from which we estimate an age in the range (2-10) x 10^3 yr. The ATCA's continuum mode allows a measurement of the Faraday rotation across the band, from which we derive a mean rotation measure towards the SNR of 430 rad m^(-2). We consider possible explanations for the morphology of G296.8-00.3, and conclude that it either has a biannular structure, as might be produced through interaction with an asymmetric progenitor wind, or that its appearance is caused by the effects of the surrounding interstellar medium. 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 New Method for the Study of the Spatial Variation of Spectral Indices : Zhang Xi-zhen & L. Higgs Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100080

A new T-T plot method (Convolution Differential-Spectral-Index) for the study of spatial variation of spectral indices in radio astronomy is presented in this paper. The method is independent of DC offset and large scale variation of background in the maps which are used in spectral analysis. An example of the method as applied to the supernova remnant (SNR) G78.2+2.1 is also given.

The X-Ray Source at the Center of G296.5+10.0 as a Young Isolated Neutron Star

view Abstract Citations (55) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The X-Ray Source at the Center of G296.5+10.0 as a Young Isolated Neutron Star Mereghetti, S. ; Bignami, G. F. ; Caraveo, P. A. Abstract We present new X-ray, radio, and optical observations of the unidentified X-ray source 1E 1207.4-5209, which lies at the center of the shell-like supernova remnant G296.5+10.0. On the basis of its high X-ray to optical flux ratio, it had already been suggested that this source is an isolated neutron star associated with the supernova remnant. This is strongly supported by new ROSAT data, which are well fitted with a blackbody spectrum with T ∼ 3 x 106 K, consistent with from a relatively young neutron star (∼104 yr) at the supernova remnant distance of about 1.5 kpc. If confirmed, this would be the second pulsar (after Geminga) not detected at radio wavelengths. Other possible interpretations, involving peculiar low-mass X-ray binaries, are discussed. The alternate possibility that 1E 1207.4-5209 is a BL Lac object is ruled out by a new upper limit of ∼0.1 mJy at 6 cm. Publication: The Astrophysical Journal Pub Date: June 1996 DOI: 10.1086/177370 Bibcode: 1996ApJ...464..842M Keywords: RADIO CONTINUUM: STARS; ISM: INDIVIDUAL ALPHANUMERIC: G296.5+10.0; STARS: NEUTRON; ISM: SUPERNOVA REMNANTS; X-RAYS: STARS full text sources ADS | data products SIMBAD (6) HEASARC (1)

Elemental abundances of the supernova remnant G292.0+1.8: Evidence for a massive progenitor

We present a comprehensive nonequilibrium ionization (NEI) analysis of X-ray spectral data from the Einstein Observatory and EXOSAT for the supernova remnant G292.0+1.8. The spectra are well described by a single-temperature, single-timescale NEI model with kT = 1.64(sub -0.19)(sup +0.29) keV and n(sub e)t = (5.55(sub -1.12)(sup +1.2) x 10(exp 10)s/cu cm, which establishes that this remnant is indeed young and in the ionizing phase of evolution of its X-ray spectrum. We determine the abundances of the elements O, Ne, Mg, Si, S, Ar, and Fe and examine their variation over the allowed range of column density, kT, and n(sub e)t. Numerical calculations of the nucleosynthesis expected for a 25 solar mass progenitor agree best with the fitted abundances; in fact the minimum rms percent difference between this model and the derived abundances is only 15%. From the fitted emission measure and a simple geometric model of the remnant we estimate the mass of X-ray-emitting plasma to be 9.3(sub -6.2)(sup +1.19) solar mass, for an assumed distance of 4.8 +/- 1.6 kpc. Additional errors on this mass estimate, from clumping of the ejecta, for example, may be substantial. No evidence was found for a difference in the thermodynamic state of the plasma as a function of elemental composition based on analysis of the individual ionization timescales of the various species. In this sense then, G292.0+1.8 resembles the remnant Cas A (another product of a massive star supernova), while it is different from the remnants of SN 1572 (Tycho) and SN 1006, both of which are believed to be from Type Ia supernovae.

Unusual interaction of the high-velocity pulsar PSR1757–24 with the supernova remnant G5.4–1.2

The peculiar fan-shaped morphology of the galactic radio source G5.4–1.2 has prompted much speculation about its nature. Here we report high-resolution observations obtained with the Very Large Array, which reveal a compact, highly polarized, flat-spectrum radio nebula on the western edge of G5.4–1.2. We also confirm the presence of a 125-ms pulsar, PSR1757–24, associated with the radio source, and find that it is located near the centre of the newly discovered nebula. We argue that the pulsar is associated with G5.4–1.2, which we identify as a supernova remnant, and that it was born with a high enough velocity, ~ 2,000 kms^(−1), for it to overtake the decelerating supernova shell, creating the peripheral radio nebula. The fortuitous near-coincidence of the pulsar velocity with the shell velocity accounts for the unusual overall shape of the remnant. If the large velocity of the pulsar is confirmed by future observation of its proper motion, the possibility of asymmetric supernova explosions must be taken seriously, and other previously unsuspected associations between pulsars and supernova remnants may emerge.

G54.4–0.3: Interaction of a Supernova Remnant with the Interstellar Medium

AbstractIn our study of the extended supernova remnant G54.4–0.3, we find a CO emission shell at about 40km s−1 radial velocity, in striking alignment with the radio continuum shell. The correspondence in position and size argues strongly for a physical connection, and allows derivation of the kinematic distance as well as the mass and density of the CO shell. The correlation with an OB association supports the value derived for the kinematic distance. Model calculations suggest that the formation of the CO shell results from a stellar wind and that the supernova remnant has expanded into the wind bubble located inside the shell.

The supernova remnant G54.5 - 0.3 and its environs

The supernova remnant G54.5 - 0.3 and its environs

High-resolution study of the supernova remnant G330.2 + 1.0

High-resolution study of the supernova remnant G330.2 + 1.0

CO observations of the supernova remnant G78.2+2.1

CO observations of the supernova remnant G78.2+2.1

The X-ray Structure of the Supernova Remnant G78.2+2.1

The south-eastern portion of the supernova remnant G78.2+2.1, in Cygnus, has been detected as a weak X-ray source by the Einstein Observatory. The X-ray structure is similar to that of the radio filaments in this region, and confirms that X-ray emission in this portion of the “Cygnus super-bubble” does originate in a known supernova remnant. Marginally significant variations in X-ray hardness across the mapped area have been detected and can be related to known radio and optical features of the remnant. In its X-ray properties, G78.2+2.1 resembles IC443.

The Peculiar X-ray Morphology of the SNR G292.0+1.8 : Evidence for an Asymmetric Supernova Explosion

A high resolution X-ray image from the Einstein Observatory of the young supernova remnant G292.0+1.8 (MSH11–54), previously noted as peculiar in terms of its spectral and morphological properties at optical and radio wavelengths, also shows an unusual X-ray morphology. Instead of a limb-brightened X-ray shell characteristic of most SNRs, the remnant consists of a central bar-like feature superposed on an ellipsoidal disc of approximately uniform surface brightness. We attribute the bar emission to a ring of oxygen-rich material ejected in the equatorial plane of a massive rotating progenitor, and the uniform disc component to emission from material with roughly cosmic composition heated by the accompanying blast wave. This interpretation provides observational support for the rotating precursor model of a Type II supernova discussed by Bodenheimer and Woosley.

X-ray line emission from the supernova remnant G292.0 + 1.8

The Solid State Spectrometer on the Einstein Observatory has detected line emission from Mg, Si and S in the thermal X-ray spectrum of the supernova remnant G292.0 + 1.8. An over-abundance of sulfur and a probable under-abundance of iron relative to their solar values is indicated by the data. The X-ray and optical data for this object support an interpretation of emission originating in ejecta from the comparatively recent explosion of a massive (about 20-solar-mass) progenitor star.

High velocity material in the young supernova remnant G292.0 + 1.8

The nebulosity in the direction of the radio/X-ray supernova remnant G 292.0 + 1.8 (MSH11 – 54, H 1122 – 59) has two components. A high velocity component is associated with the bright centre of the SNR (velocity range 2030 km/s); this component exhibits oxygen and neon emission only. The age of the SNR must be less than 1600 yr. A low velocity component of more normal composition (i.e. including Balmer emission) is widely spread in the area of the SNR.

Interstellar scintillation and compact sources in supernova remnants

Interstellar scintillation was detected from a source in or near the supernova remnant G78.1 + 1.8, implying an angular size ≲10−6 arc s, a brightness temperature >1018 K, and a distance of ∼3 kpc. The source does not seem to be a pulsar and is therefore the first source other than a pulsar to show interstellar scintillation. We place limits on the scintillating flux for 15 other galactic and extragalactic objects.

Optical identification and spectrum of the supernova remnant G292.0 + 1.8

Optical identification and spectrum of the supernova remnant G292.0 + 1.8

Soft X-ray spectrum and structure of the supernova remnant G65.2+5.7

The HEAO 1 low energy detectors have observed the supernova remnant G65.2+5.7 in the energy range 0.2-2.5 keV. A strong, extended source of X-ray emission is observed coincident with the eastern side of the optical filamentary structure. The characteristic temperature of the emission is in the range 2-3.8 x 10 to the 6th K, and evidence is found for line emission at about 0.8 keV in the X-ray spectrum. These observations imply a shock velocity (425 km/s) and age (about 20,000 yr) that markedly disagree with the estimates from optical and radio observations.

A synthesis map of the unusual supernova remnant G292.0 + 1.8

High-resolution observations of G292.0 + 1.8 made with the Fleurs synthesis telescope at 1415 MHz give no indication of a shell structure, but show a concentration towards the centre. The source therefore appears to belong to an unusual class of supernova remnants of which the Crab nebula is the best known. Comparisons are made with other supernova remnants of this type.