* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: Supernova remnant Kes 75


L

Posts: 131433
Date:
RE: Supernova remnant Kes 75
Permalink  
 


Title: Supernova Remnant Evolution in Wind Bubbles: A Closer Look at Kes 27
Authors: Vikram V. Dwarkadas (UChicago), Dan Dewey (MIT)

Massive Stars (> 8 solar masses) lose mass in the form of strong winds. These winds accumulate around the star, forming wind-blown bubbles. When the star explodes as a supernova (SN), the resulting shock wave expands within this wind-blown bubble, rather than the interstellar medium. The properties of the resulting remnant, its dynamics and kinematics, the morphology, and the resulting evolution, are shaped by the structure and properties of the wind-blown bubble. In this article we focus on Kes 27, a supernova remnant (SNR) that has been proposed by Chen et al (2008) to be evolving in a wind-blown bubble, explore its properties, and investigate whether the properties could be ascribed to evolution of a SNR in a wind-blown bubble. Our initial model does not support this conclusion, due to the fact that the reflected shock is expanding into much lower densities.

Read more (1514kb, PDF)



__________________


L

Posts: 131433
Date:
Kes 75
Permalink  
 


Title: Infrared and X-Ray Spectroscopy of the Kes 75 Supernova Remnant Shell: Characterising the Dust and Gas Properties
Authors: Tea Temim, Patrick Slane, Richard G. Arendt, Eli Dwek

We present deep Chandra observations and Spitzer Space Telescope infrared (IR) spectroscopy of the shell in the composite supernova remnant (SNR) Kes 75 (G29.7-0.3). The remnant is composed of a central pulsar wind nebula and a bright partial shell in the south that is visible at radio, IR, and X-ray wavelengths. The X-ray emission can be modelled by either a single thermal component with a temperature of ~ 1.5 keV, or with two thermal components with temperatures of 1.5 and 0.2 keV. Previous studies suggest that the hot component may originate from reverse-shocked SN ejecta. However, our new analysis shows no definitive evidence for enhanced abundances of Si, S, Ar, Mg, and Fe, as expected from supernova (SN) ejecta, or for the IR spectral signatures characteristic of confirmed SN condensed dust, thus favouring a circumstellar or interstellar origin for the X-ray and IR emission. The X-ray and IR emission in the shell are spatially correlated, suggesting that the dust particles are collisionally heated by the X-ray emitting gas. The IR spectrum of the shell is dominated by continuum emission from dust with little, or no line emission. Modelling the IR spectrum shows that the dust is heated to a temperature of ~ 140 K by a relatively dense, hot plasma, that also gives rise to the hot X-ray emission component. The density inferred from the IR emission is significantly higher than the density inferred from the X-ray models, suggesting a low filling factor for this X-ray emitting gas. The total mass of the warm dust component is at least 0.013 solar masses, assuming no significant dust destruction has occurred in the shell. The IR data also reveal the presence of an additional plasma component with a cooler temperature, consistent with the 0.2 keV gas component. Our IR analysis therefore provides an independent verification of the cooler component of the X-ray emission.

Read more (2861kb, PDF)



__________________


L

Posts: 131433
Date:
RE: Supernova remnant Kes 75
Permalink  
 


Title: Chandra Observation of the Pulsar Wind Nebula Powered by the Pulsar J1846-0258 in the Supernova Remnant Kes 75
Authors: C.-Y. Ng, P. O. Slane, B. M. Gaensler, J. P. Hughes
(Version v2)

Read more (490kb, PDF)

__________________


L

Posts: 131433
Date:
Permalink  
 

Title: Deep Chandra Observation of the PulsaR Wind Nebula Powered by the Pulsar J1846-0258 in the Supernova Remnant Kes 75
Authors: C.-Y. Ng, P. O. Slane, B. M. Gaensler, J. P. Hughes

We present the results of detailed spatial and spectral analysis of the pulsar wind nebula (PWN) in supernova remnant Kes 75 (G29.7-0.3) using a deep exposure with Chandra X-ray observatory. The PWN shows a complex morphology with clear axisymmetric structure. We identified a one-sided jet and two bright clumps aligned with the overall nebular elongation, and an arc-like feature perpendicular to the jet direction. Further spatial modeling with a torus and jet model indicates a position angle $207\arcdeg\pm8 \arcdeg$ for the PWN symmetry axis. We interpret the arc as an equatorial torus or wisp and the clumps could be shock interaction between the jets and the surrounding medium. The lack of any observable counter jet implies a flow velocity larger than 0.4c. Comparing to an archival observation 6 years earlier, some small-scale features in the PWN demonstrate strong variability: the flux of the inner jet doubles and the peak of the northern clump broadens and shifts 2" outward. In addition, the pulsar flux increases by 6 times, showing substantial spectral softening from $\Gamma$=1.1 to 1.9 and an emerging thermal component which was not observed in the first epoch. The changes in the pulsar spectrum are likely related to the magnetar-like bursts of the pulsar that occurred 7 days before the Chandra observation, as recently reported from RXTE observations.

Read more (158kb, PDF)

__________________


L

Posts: 131433
Date:
Permalink  
 

Title: Magnetar-like Emission from the Young Pulsar in Kes 75
Authors: F. P. Gavriil, M. E. Gonzalez, E. V. Gotthelf, V. M. Kaspi, M. A. Livingstone, P. M. Woods

We report detection of magnetar-like X-ray bursts from the young pulsar PSR J1846-0258, at the centre of the supernova remnant Kes 75. This pulsar, long thought to be rotation-powered, has an inferred surface dipolar magnetic field of 4.9x10^13 G, higher than those of the vast majority of rotation-powered pulsars, but lower than those of the ~12 previously identified magnetars. The bursts were accompanied by a sudden flux increase and an unprecedented change in timing behaviour. These phenomena lower the magnetic and rotational thresholds associated with magnetar-like behaviour, and suggest that in neutron stars there exists a continuum of magnetic activity that increases with inferred magnetic field strength.

Read more (387kb, PDF)

__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard