X-ray Properties of Five Galactic SNRs arXiv: Thomas G. Pannuti et al.

outlines background Sources & data results summary

background Reach et al. (2006): GLIMPSE survey (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) 10◦< |l| <65◦, |b|<1◦, bands: 3.6, 4.5, 5.8 and 8.0 μm 18 of 95 SNRs were detected in IR, coincided (at least partially) with known radio structures. many of the SNRs detected appear to be interacting with relatively dense gas. Evidence : 4.5 μm excess. Such an excess is likely produced by H2 and CO line, associated with molecular shocks. IRS spectroscopy observations revealed H2 emission from all of the SNRs in Reach et al. (2006), suggesting that each of these SNRs are interacting with molecular clouds Several molecular SNRs are detected (like W28, W44 and 3C 391) in the X- ray and all of them belong to the class of sources known as mixed- morphology SNRs (MM SNRs).

background J. Rho (1998): Mixed-Morphology Supernova Remnants

The group of SNRs with shell-like in the radio and centrally filled in the X-ray were termed mixed-morphology, besides shell-like, Crab-like, composite SNRs. Two characterastics: thermal X-ray dominant, emission arises primarily from swept-up ISM than ejecta. The temperature across each remnant is nearly uniform, and the density and pressure are constant or increase toward the remnant center. Strong infrared line emission or OH masers indicates most SNRs are interacting with molecular or HI clouds, suggests their formation requires a denser-than-average ISM. IC443

Sources & data The five SNRs are all detected in the infrared by the Spitzer GLIMPSE survey. 10◦< |l| <65◦, |b|<1◦, bands: 3.6, 4.5, 5.8 and 8.0 μm. (Reach et al.,2006) observationsASCA 99 XMM 05 ASCA 98ASCA 96 XMM 06 Chandra 06 XMM 06

Kes 17 Blue, green and red represent XMM-Newton X-ray (total band), Spitzer MIPS at 24μm and IRAC 4.5μm images

ASCA image of Kes 17

ASCA spectrum of Kes 17

XMM image and spectrum of Kes 17

G the red, green and blue correspond to emission detected at 8μm, 4.5 μm and 3.5μm CO map for the velocity v=39.7 km s^−1.

ASCA image and spectrum of G

G346.6−0.2 Spitzer MIPS at 24 μm, IRAC at 4.6 μm and radio.

ASCA image and spectrum of G346.6−0.2

XMM image and spectrum of CTB 37A G348.5−0.0

Chandra image. Red, green and blue colors correspond to soft ( keV), medium ( keV) and hard ( keV) emission. Chandra ACIS-I spectrum of CXOU J

Discussion--Implications for SNR evolution Simulations have shown that the center-filled thermal X-ray emission as observed in MM SNRs can be produced through anisotropic thermal conduction. SNRs expanding into denser environments tend to be smaller, making it easier for thermal conduction to dictate large changes in the temperatures of their expanding hot gas bubbles. (Tilley et al. 2006). MHD modeling of SNRs expanding through an inhomogeneous ISM also confirms that X-ray emission detected from MM SNRs can be reproduced when both thermal conduction and the reverse shock of the SNR are included in the modeling (Orlando et al. 2009). After the reverse shock has reached the center of the SNR, a maximum in the X-ray emission is seen toward the center of the SNR and the morphology is centrally brightened. Therefore, it is evident that thermal conduction plays a crucial role in producing SNRs of this class.

Summary Spectroscopic analysis of the X-ray properties of five SNRs (Kes 17, G311.5−0.3, G346.6−0.2, CTB 37A and G348.5−0.0) Four of the SNRs are X-ray detected and an upper limit is given on the X-ray luminosity of G348.5−0.0. First published detection of X-ray emission from G311.5−0.3.

The four X-ray detected SNRs all classified as MM SNRs. The X-ray emission from each SNR appears to be thermal in origin. Discussed the plasma conditions of the four X-ray detected SNRs and estimated such properties of the plasma as ne, t and M: these values range from cm−3, ×10^4 yr and Msun. These values are similar to those observed for other MM SNRs.

The results also include the first detailed spatially-resolved spectroscopic study of CTB 37A using Chandra as well as a spectroscopic study of the discrete X-ray source CXOU J −383601, which may be a neutron star associated with CTB 37A. The results help strengthen the link between MM SNRs and interactions between SNRs and molecular clouds: this may help to explain the origin of the center-filled thermal X-ray morphologies of these sources.

Thank you!