X-Ray Expansion of the Southern Rim of the Vela Jr. Supernova Remnant
Abstract
Vela Jr. is the brightest steady source in the sky above 1 TeV, and is one of the rare class of supernova remnants (SNRs) whose shell morphology has been resolved in gamma-rays, with others being RX J1713.7-3946, SN 1006, HESS J1731-347, RCW 86, and HESS J1534-571. It is thus a remarkable laboratory where we can study the mechanisms through which SNRs accelerate particles up to the highest energies, and thier role in the long-standing enigma of the origin of Galactic cosmic-rays. The most plausible estimates of the age (and distance) of this remnant are based on the expansion measurements, using XMM-Newton (Katsuda et al. 2008) and Chandra (Allen et al. 2015). Both of the two measurements focused on the brightest northwestern rim, providing a slow expansion of 0.42+/-0.10 arcsec/yr (this is the Chandra result which is about half the value reported for an analysis of XMM-Newton). If we assume that the Chandra rate is representative of the remnant as a whole, then the results of a hydrodynamic analysis suggest that the age of Vela Jr. is between 2.4 kyr and 5.1 kyr. However, it has been unclear if such an assumption is valid, especially because the northwestern rim seems to be interacting with a massive HI gas entirely and molecular clouds partially (Fukui et al. 2017). Here, we report on our results of expansion measurements for the southern rim of the remnant. The first- and second-epoch observations were taken with XMM-Newton on 2001-04-24 and with Chandra on 2007-10-17, respectively. Because the southern rim is not very sharp, we can directly compare the radial profiles from the two distinct satellites. We derived the proper motion to be 0.59+/-0.42 arcsec/yr, which is similar to that obtained in the northwestern rim. Our result supports the assumption that the remnant is expanding uniformly, providing further evidence that the age of Vela Jr. is about a few thousand years old.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1458K