Structure in the Radio Remnant of Supernova 1987A

1993 ◽  
Vol 10 (4) ◽  
pp. 331-334 ◽  
Author(s):  
L. Staveley-Smith ◽  
R.N. Manchester ◽  
M.J. Kesteven ◽  
A.K. Tzioumis ◽  
J.E.R. Reynolds
Keyword(s):  
Radio Emission ◽  
Expansion Velocity ◽  
Synchrotron Emission ◽  
Low Density ◽  
Radial Expansion ◽  
X Ray ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Supernova 1987A ◽  
Compact Array

AbstractThe radio emission associated with SN 1987A appears to be synchrotron emission resulting from the acceleration of electrons at the interface between the outward moving shock wave and clumps of circumstellar material. The Australia Telescope Compact Array is now able to resolve this region, which has dimensions of ~ arcsec, revealing a slight (10%) asphericity in the distribution of the low density gas within the [OIII] circumstellar ring. Assuming that the radio emission arises from a region just behind the shock front, we deduce a mean radial expansion velocity, from 1987 to 1992, of 29 200 kms. First observed contact of the shock with the [OIII] circumstellar ring could occur as early as mid-1993, depending on the deceleration in the intervening gas. This will probably be closely followed by shock-excited optical lines, a strong X-ray outburst and a further increase in the radio emission.

AT Monitoring of SNR 1987A

1991 ◽  
Vol 9 (1) ◽  
pp. 108-108
Author(s):  
L. Staveley-Smith ◽  
R. N. Manchester ◽  
M. J. Kesteven
Keyword(s):  
Radio Emission ◽  
High Velocity ◽  
High Sensitivity ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Upper Limit ◽  
Compact Array

AbstractThe prompt radio emission associated with SN 1987A appeared and disappeared within the space of a few days. The next radio emission is expected as the high velocity ejecta expand into the circumstellar material. The evidence from the timing of the initial UV-flash is that this stage may occur shortly. We have therefore begun to monitor the field around SNR 1987A at high sensitivity with the Australia Telescope Compact Array. At λ6cm, an upper limit to the radio emission of 180μJy has been obtained. Continued observations are planned.

scholarly journals Radio Emission from SN 1987A

1996 ◽  
Vol 145 ◽  
pp. 309-315 ◽  
Author(s):  
L. Staveley-Smith ◽  
R. N. Manchester ◽  
A. K. Tzioumis ◽  
J. E. Reynolds ◽  
D. S. Briggs
Keyword(s):  
Radio Emission ◽  
Radio Observations ◽  
Density Profiles ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Supernova 1987A ◽  
Radio Outburst ◽  
Post Shock ◽  
Two Phases ◽  
Relativistic Particles

We review the first six years of radio observations of Supernova 1987A. The evolution can be divided into two phases: the initial radio outburst which lasted a few weeks, and the period from mid-1990 to the present, during which the radio emission has steadily increased. Both phases can be explained by a small fraction (0.1-0.5%) of the post-shock thermal energy being converted to energy in relativistic particles and magnetic fields, which give rise to synchrotron radiation. The optical depths, densities and density profiles for the pre-shocked circumstellar material are somewhat different for the two phases, but consistent with models of the density structure of the material within the circumstellar ring. New high-resolution radio observations show that the SN shock front is already at about three-quarters of the radius of the circumstellar ring, and that there exists a bright equatorial component of emission aligned with this ring which is probably due to a polar density gradient in the ‘hourglass’ structure.

scholarly journals Simultaneous X-ray and radio observations of the transitional millisecond pulsar candidate CXOU J110926.4–650224

2021 ◽  
Vol 655 ◽  
pp. A52
Author(s):  
F. Coti Zelati ◽  
B. Hugo ◽  
D. F. Torres ◽  
D. de Martino ◽  
A. Papitto ◽  
...  
Keyword(s):  
Radio Emission ◽  
Flux Density ◽  
Millisecond Pulsar ◽  
Radio Emissions ◽  
X Ray ◽  
Link Type ◽  
Upper Limit ◽  
Variability Pattern ◽  
Average Flux ◽  
Compact Array

We present the results of simultaneous observations of the transitional millisecond pulsar (tMSP) candidate CXOU J110926.4–650224 with the XMM-Newton satellite and the MeerKAT telescope. The source was found at an average X-ray luminosity of LX ≃ 7 × 1033 erg s−1 over the 0.3−10 keV band (assuming a distance of 4 kpc) and displayed a peculiar variability pattern in the X-ray emission, switching between high, low and flaring modes on timescales of tens of seconds. A radio counterpart was detected at a significance of 7.9σ with an average flux density of ≃33 μJy at 1.28 GHz. It showed variability over the course of hours and emitted a ≃10-min long flare just a few minutes after a brief sequence of multiple X-ray flares. No clear evidence for a significant correlated or anticorrelated variability pattern was found between the X-ray and radio emissions over timescales of tens of minutes and longer. CXOU J110926.4–650224 was undetected at higher radio frequencies in subsequent observations performed with the Australia Telescope Compact Array, when the source was still in the same X-ray sub-luminous state observed before, down to a flux density upper limit of 15 μJy at 7.25 GHz (at 3σ). We compare the radio emission properties of CXOU J110926.4–650224 with those observed in known and candidate tMSPs and discuss physical scenarios that may account for its persistent and flaring radio emissions.

scholarly journals Thermal X-Rays due to Ejecta/CSM Interaction in SN 1987A

1988 ◽  
Vol 108 ◽  
pp. 450-451
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
H. Itoh ◽  
K. Nomoto ◽  
T. Shigeyama
Keyword(s):  
Light Curve ◽  
Photon Energy ◽  
Thermal Emission ◽  
Circumstellar Matter ◽  
Expansion Velocity ◽  
X Rays ◽  
X Ray ◽  
Sn 1987A ◽  
Inner Radius

The X-ray spectrum observed by Ginga is characterized by a component below 10keV which decreases with increasing photon energy, and a component above 10keV which is nearly flat. This unusual X-ray spectrum may be understood as follows; X-rays below 10keV is likely to be due to thermal emission coming from the shock-heated ejecta, and X-rays above 10keV to be due to γ-ray degradation inside the ejecta. If thermal emission due to the collision of the ejecta with circumstellar matter (CSM) is responsible for X-rays below 10keV, the epoch of the collision can be estimated to be ∼ 0.2yr after the explosion if ∼ 0.5yr is the time when the X-ray flux at ∼ 10keV reaches its maximum. The X-ray light curve then requires the inner radius of CSM to be ∼ 1×1016cm for an expansion velocity, Vex ≃2×109cm s−1.

scholarly journals Radio Emission from Extended Shell-Like SNRs

1998 ◽  
Vol 188 ◽  
pp. 249-250
Author(s):  
A.I. Asvarov
Keyword(s):  
Radio Emission ◽  
Thin Shell ◽  
Large Fraction ◽  
Radiative Cooling ◽  
Interstellar Space ◽  
Low Density ◽  
Shell Formation ◽  
X Ray ◽  
Cooling Effects ◽  
X Ray Background

Observations of the soft X-Ray background and interstellar UV absorption lines have indicated that a large fraction of interstellar space is filled with a high temperature low density “coronal” gas. In such low density environments SNRs will expand up to 200 pc in radius without thin shell formation which occurs due to radiative cooling effects. Such SNRs can occupy a large fraction of volume of Galaxy and can be the main source of background emissions. In the present work we examine the evolution of the radio emission of shell-like SNR evolving in the hot ISM.

scholarly journals A giant radio bridge connecting two clusters in Abell 1758

2020 ◽  
Author(s):  
A Botteon ◽  
R J van Weeren ◽  
G Brunetti ◽  
F de Gasperin ◽  
H T Intema ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Large Scale ◽  
Synchrotron Emission ◽  
X Ray ◽  
Compressed Gas ◽  
Order Of Magnitude ◽  
Thermal Phenomena ◽  
Cluster Pair ◽  
Radio Halos

Abstract Collisions between galaxy clusters dissipate enormous amounts of energy in the intra-cluster medium (ICM) through turbulence and shocks. In the process, Mpc-scale diffuse synchrotron emission in form of radio halos and relics can form. However, little is known about the very early phase of the collision. We used deep radio observations from 53 MHz to 1.5 GHz to study the pre-merging galaxy clusters A1758N and A1758S that are ∼2 Mpc apart. We confirm the presence of a giant bridge of radio emission connecting the two systems that was reported only tentatively in our earlier work. This is the second large-scale radio bridge observed to date in a cluster pair. The bridge is clearly visible in the LOFAR image at 144 MHz and tentatively detected at 53 MHz. Its mean radio emissivity is more than one order of magnitude lower than that of the radio halos in A1758N and A1758S. Interestingly, the radio and X-ray emissions of the bridge are correlated. Our results indicate that non-thermal phenomena in the ICM can be generated also in the region of compressed gas in-between infalling systems.

scholarly journals X-rays and γ-rays from Supernova 1987a

1988 ◽  
Vol 108 ◽  
pp. 394-398
Author(s):  
P. Sutherland ◽  
Y. Xu ◽  
R. McCray ◽  
R. Ross
Keyword(s):  
Circumstellar Matter ◽  
Radioactive Material ◽  
Strong Line ◽  
X Rays ◽  
X Ray ◽  
Monte Carlo Calculations ◽  
Sn 1987A ◽  
Unique Event ◽  
Supernova 1987A ◽  
Γ Rays

SummaryThe observation of X-rays and γ-rays from SN 1987a can provide important constraints on parameters for models of this unique event. We present the results of detailed Monte Carlo calculations of the fluxes to be expected in several X-ray bands and for the strong line at 847 keV associated with the decay of 56Co. Our calculations use Model 10H of Woosley, Pinto, and Ensman(1988), with 0.075M⊙ of radioactive material. If it is assumed that there is no mixing of this material with the layers above, then the X-ray fluxes do not become detectable as early as the observations made by the Ginga team in August, 1987. If these observations correspond to X-rays arising from γ-rays Compton scattered down in energy in the supernova ejecta, rather than the interaction of the ejecta with circumstellar matter, then they can only be explained by mixing outward of radioactive material or an envelope with some combination of less mass or greater kinetic energy per unit mass.

scholarly journals Evolution of the Radio Remnant of SN 1987A: 1990-2001

2002 ◽  
Vol 19 (2) ◽  
pp. 207-221 ◽  
Author(s):  
R. N. Manchester ◽  
B. M. Gaensler ◽  
V. C. Wheaton ◽  
L. Staveley-Smith ◽  
A. K. Tzioumis ◽  
...  
Keyword(s):  
Hot Spots ◽  
Super Resolution ◽  
Radio Spectrum ◽  
Temporal Variations ◽  
Shell Morphology ◽  
Data Set ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Rate Of Increase ◽  
Compact Array

AbstractThe development of the radio remnant of SN 1987A has been followed using the Australia Telescope Compact Array since its first detection in 1990 August. The remnant has been observed at four frequencies, 1.4, 2.4, 4.8, and 8.6 GHz, at intervals of 4–6 weeks since the first detection. These data are combined with the 843 MHz data set of Ball et al. (2001) obtained at Molonglo Observatory to study the spectral and temporal variations of the emission. These observations show that the remnant continues to increase in brightness, with a larger rate of increase at recent times. They also show that the radio spectrum is becoming flatter, with the spectral index changing from −0.97 to −0.88 over the 11 years. In addition, at roughly yearly intervals since 1992, the remnant has been imaged at 9 GHz using super-resolution techniques to obtain an effective synthesised beamwidth of about 0″.5. The imaging observations confirm the shell morphology of the radio remnant and show that it continues to expand at ˜3000 km s−1. The bright regions of radio emission seen on the limb of the shell do not appear to be related to the optical hot spots which have subsequently appeared in surrounding circumstellar material.

Radio Supernova 1987 A

1992 ◽  
Vol 10 (1) ◽  
pp. 38-40 ◽  
Author(s):  
Lewis Ball ◽  
J.G. Kirk
Keyword(s):  
Shock Wave ◽  
Synchrotron Radiation ◽  
Radio Emission ◽  
Density Jump ◽  
Circumstellar Material ◽  
Sn 1987A

AbstractThe reappearance of radio emission from SN 1987A is discussed. We propose a model involving synchrotron radiation from electrons which are accelerated when the expanding supernova shock wave runs into a density jump in the circumstellar material, and which then expand adiabatically.

scholarly journals Hubble Space Telescope Observations of Synchrotron Jets

1994 ◽  
Vol 142 ◽  
pp. 909-916
Author(s):  
W. B. Sparks ◽  
J. A. Biretta ◽  
F. Macchetto
Keyword(s):  
Radio Emission ◽  
Hubble Space Telescope ◽  
Detailed Comparison ◽  
Synchrotron Emission ◽  
Space Telescope ◽  
X Ray ◽  
Radio Lobe ◽  
First Time ◽  
Relativistic Particles ◽  
Single Power

AbstractThe Hubble Space Telescope for the first time enables optical and UV images of jets to be obtained with spatial resolution comparable to radio interferometric techniques. Because synchrotron emission at these wavelengths is a diagnostic of particles several orders of magnitude higher in energy and correspondingly shorter in lifetime than those probed by radio, the sites of particle acceleration may be more readily identified in the optical and UV. Short-lifetime optical synchrotron emission in the SE inner radio lobe of M87 argues strongly for the presence of an invisible counterjet. A detailed comparison of HST and VLA images of the M87 jet shows there are very strong similarities in overall morphology, but that there are also significant differences. The optical and UV radiation is more localized within the knots than the radio emission and appears more confined toward the jet center. These differences may arise from localized shocks, sited at the optical knots with diffusion of relativistic particles away from those knots, or else they may be due to nonuniform magnetic fields and distributed acceleration processes. The UV fluxes of the knots are consistent with a single power law from optical to X-ray. Optical jets in other radio galaxies show diverse properties—the jet of PKS 0521–36 is smoothly resolved by HST while that of 3C 66B shows previously unsuspected filmentary structure. Likewise, the jet of 3C 273 shows newly observed optical filaments and an intensity distribution quite unlike that of the radio emission. Like M87, the optical jet of 3C 273 is narrower than the radio jet. The serendipitous discovery of a new optical synchrotron jet in 3C 264 suggests that optical jets may be relatively common.Subject heading: galaxies: jets

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