A Suzaku X-ray study of the mixed-morphology supernova remnant Kes 69 and searching for its gamma-ray counterpart

Abstract

Kes 69 is a mixed-morphology (MM) supernova remnant (SNR) that is known to be interacting with molecular clouds based on 1720 MHz hydroxyl (OH) maser emission observations in the northeastern and southeastern regions. We present an investigation of Kes 69 using ∼67 ks Suzaku observation. The X-ray spectrum of the whole SNR is well fitted by a non-equilibrium ionization model with an electron temperature of kT e ∼ 2.5 keV, ionization time-scale of τ ∼ 4.1×10 10 cm −3 s and absorbing column density of N H ∼ 3.1×10 22 cm −2 . We clearly detected the Fe-Kα line at ∼6.5 keV in the spectra. The plasma shows slightly enhanced abundances of Mg, Si, S and Fe indicating that the plasma is likely to be of ejecta origin. We find no significant feature of a recombining plasma in this SNR. In order to characterize radial variations in the X-ray spectral parameters, we also analyze annular regions in the remnant. We investigate the explosive origin of Kes 69 and favor the core-collapse origin. Additionally, we report a lack of significant gamma-ray emission from Kes 69, after analyzing the GeV gamma-ray data taken for about 9 years by the Large Area Telescope on board Fermi. Finally, we discuss the properties of Kes 69 in the context of other interacting MM SNRs.

Can the Fe K-alpha Line Reliably Predict Supernova Remnant Progenitors?

“…The difference is that in G344.7-0.1, the range of variations was fully confined to the Type Ia region elucidated by Y14. For Kes 79, Sezer et al (2018) report a variation of 50 eV between different concentric regions, also confined to the Type Ia region. In 3C 397 however, the centroid energies of the different regions fall on either side of the Y14 dividing line, while also overlapping the centroid energy of SNR G292.0+1.8, a CC remnant with a known pulsar (see Figure 3).…”

“…While the centroid energy-luminosity correlation can be seen in both theoretical modeling and Y14, many recent studies (Sezer et al 2018;Bhalerao et al 2019;Sawada et al 2019;Quirola-Vásquez et al 2019;Martínez-Rodríguez et al 2020) have continued to treat the Fe Kα line centroid as the sole discriminant. The Y14 calibration appears to hold for many SNRs.…”