Exploring the Kinematics of the Oxygen‐rich Supernova Remnant G292.0+1.8: Ejecta Shells, Fast‐moving Knots, and Shocked Circumstellar Material

Abstract

We present the results of an in-depth optical study of the core-collapse supernova remnant G292.0+1.8 using the Rutgers Fabry-Perot (RFP) imaging spectrometer. Our observations provide a detailed picture of the supernova remnant in the emission lines of [O iii] k5007, H , and [N ii] k6548. The [O iii] Fabry-Perot scans reveal a bright crescent-shaped spur of previously known high-velocity (V radial $ 1500 km s À1 ) O-rich ejecta located on the eastern side of the remnant. The spur consists of a semicoherent structure of mostly redshifted material, along with several clumps that have apparently broken out of the more orderly shell-like expansion. The high-velocity (k600 km s À1 ) component of the spur also displays a scalloped morphology characteristic of Rayleigh-Taylor instabilities. We also find a large number of fast-moving knots (FMKs) of O-rich ejecta undetected in prior photographic plate images and similar to features seen in Cas A. The FMKs are distributed sparsely in the interior of G292.0+1.8 and are seen mostly in blueshifted emission out to V radial % À1700 km s À1 . The position-velocity distribution of the FMKs can be kinematically described as a shell 3A4 in radius expanding at a velocity of 1700 km s À1. Another feature apparent in the [O iii] scans is an equatorial belt consisting of both a barlike structure at zero radial velocity and a clumpy, highvelocity ejecta component seen in projection along the line of sight. Portions of the zero-velocity bar are spatially well correlated with a similar structure seen in the Chandra X-ray image of G292.0+1.8. The bar is also detected in our H RFP images at zero radial velocity, providing further evidence that this structure is of circumstellar origin. We find that the optical and X-ray properties of the bar are consistent with incomplete (partially radiative) shocks in material of moderate densities. There are also a number of faint, elongated structures seen in H at zero radial velocity across the interior of G292.0+1.8 that lack [O iii] and X-ray counterparts. These filaments may be low-density H i clouds photoionized by hard radiation from the interior of the remnant. Overall, these results suggest that G292.0+1.8 is currently interacting with a low-density environment. We find no evidence for high-velocity H or [N ii] emission over the dynamical range sampled by the RFP. Assuming a distance of 6 kpc for G292.0+1.8, we estimate a kinematic age of (3000-3400)d 6 yr for this remnant.

SpitzerIMAGING AND SPECTRAL MAPPING OF THE OXYGEN-RICH SUPERNOVA REMNANT G292.0+1.8

“…This is consistent (based on the discussion in Section 4.1) with a higher overall density in Region 7 than Region 4. (Ghavamian et al 2005), and was shown by Park et al (2002) …”

“…Overall, the regions with the hottest dust in Figure 5 are (not surprisingly) Regions 15, 17, and 18, corresponding to the brightest clumps in the Chandra image of G292.0+1.8. Park et al (2002) found that the equatorial belt (Region 15) had a higher density and slightly lower temperature than the outer shell of G292.0+1.8, while Ghavamian et al (2005) detected faint [O iii] λ5007 emission from the belt. This indicates that the elevated density in the equatorial belt in Region 15 has caused the shocks to become partially radiative at that location.…”

“…These lines are produced in slower, partially radiative shocks in the equatorial belt (Park et al 2002(Park et al , 2004Ghavamian et al 2005). of G292.0+1.8.…”

“…In [O iii] λ5007 optical images G292.0+1.8 is dominated by a distinct, crescentshaped structure approximately 1 in size (hereafter the "Spur") located on the eastern side of the SNR (Goss et al 1979). A collection of localized clumps (fast-moving knots, FMKs, similar to those seen in Cas A) have also been found in the interior of G292.0+1.8 (Ghavamian et al 2005;Winkler & Long 2006). This contrasts with the appearance of the SNR at X-ray (Clark et al 1980;Park et al 2002Park et al , 2004Park et al , 2007Gonzalez & Safi-Harb 2003) and radio (Gaensler & Wallace 2003) wavelengths, where the remnant appears as a slightly elliptical shell approximately 8 across.…”

Six Years of Chandra Observations of Supernova Remnants

“…The X-ray spectrum is modeled with a simple power law, although, as with Vela, (and many other sources) the fit to the data is not unique. From the motions of oxygen-rich optical knots and the size of the remnant, Ghavamian, Hughes, and Williams (2005) recently esti-mated a kinematic age for SNR 292.0+1.8 of 3000-3400 years assuming a distance of 6 kpc. This value is in good agreement with the pulsar spin-down age of 2900 years.…”