XMM-Newtondetection of the supernova remnant G304.6 + 0.1 (Kes 17)

Abstract

Aims. We report the first detailed X-ray study of the supernova remnant (SNR) G304.6+0.1, achieved with the XMM-Newton mission. Methods. The powerful imaging capability of XMM-Newton was used to study the X-ray characteristics of the remnant at different energy ranges. The X-ray morphology and spectral properties were analyzed. In addittion, radio and mid-infrared data obtained with the Molonglo Observatory Synthesis Telescope and the Spitzer Space Telescope were used to study the association with the detected X-ray emission and to understand the structure of the SNR at differents wavelengths. Results. The SNR shows an extended and arc-like internal structure in the X-ray band without a compact point-like source inside the remnant. We find a high column density of N H in the range 2.5-3.5 × 10 22 cm −2 , which supports a relatively distant location (d ≥ 9.7 kpc). The X-ray spectrum exhibits at least three emission lines, indicating that the X-ray emission has a thin thermal plasma origin, although a non-thermal contribution cannot be discarded. The spectra of three different regions (north, center and south) are well represented by a combination of a non-equilibrium ionization (PSHOCK) and a power-law (PL) model. The mid-infrared observations show a bright filamentary structure along the north-south direction coincident with the NW radio shell. This suggests that Kes 17 is propagating in a non-uniform environment with high density and that the shock front is interacting with several adjacent massive molecular clouds. The good correspondence of radio and mid-infrared emissions suggests that the filamentary features are caused by shock compression. The X-ray characteristics and well-known radio parameters indicate that G304.6+0.1 is a middle-aged SNR (2.8−6.4) × 10 4 yr old and a new member of the recently proposed group of mixed-morphology SNRs.

A deep X-ray observation of the supernova remnant G304.6+0.1 (Kes 17) using Suzaku

“…As seen from Table 2, the spectral parameters for the three regions are almost similar. We obtained a high absorbing column density N H in the range of (3.2-4.2) × 10 22 cm −2 , which is consistent with the previous work of Combi et al (2010), in the range of (2.5-3.5) × 10 22 cm −2 . This gives support for the large distance d ≥ 9.7 kpc to the remnant adopted by Caswell et al (1975).…”

“…Considering all these cases, it is still difficult to explain the origin of the non-thermal emission using Suzaku data. Combi et al (2010) also obtained non-thermal emission from this remnant with a photon index value in the range of 1.8-3.1 with an XMM-Newton observation, which is softer than our photon index value. This indicates particle acceleration in shock fronts.…”

“…This gives support for the large distance d ≥ 9.7 kpc to the remnant adopted by Caswell et al (1975). Our N H value is larger than that of Combi et al (2010) and therefore, throughout our calculations, we have used d = 10 kpc. From the emission measure (EM = n e n H V, where n e is the electron density, n H is the hydrogen density and V is the volume of the X-ray emitting plasma), we estimate the electron density of the plasma, taking into account n e = 1.2n H for the mean charge state with normal composition.…”

“…G304.6+0.1 (Kes 17), a new MM member (Combi et al 2010), was first detected at 408 MHz and 5 GHz with the Parkes and Molonglo radio telescopes by Shaver & Goss (1970). Caswell et al (1975) gave a lower limit of 9.7 kpc to the distance of the remnant by measuring the 21-cm absorption profiles with the Parkes hydrogenline interferometer.…”

“…Hewitt et al (2009) have obtained sensitive low-resolution spectroscopy from 5 to 35 μm for this remnant with the Spitzer Infrared Spectrograph (IRS) and they found evidence of shocked molecular gas. The first detailed multiwavelength (radio, mid-IR and X-ray) study of G304.6+0.1 has been conducted by Combi et al (2010). Using XMM-Newton data (26.8 ks), they have found that the X-ray emission is dominated by thermal radiation (PSHOCK) plus a small fraction of non-thermal radiation (power law) in the northern, central and southern regions.…”