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Register a new userKinematics of the Galactic SNR G109.1-1.0 (CTB 109)
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M\\'onica S\\'anchez Cruces
Publication date
2017
fields
Physics
and research's language is
English
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We present direct images in the H$alpha$ and [SII]$lambda lambda$6717,6731 $text{AA}$ lines of the Galactic Supernova Remnant G109.1-1.0 (CTB 109). We confirm that the filaments detected are the optical counterpart of the X-ray and radio supernova remnant due to their high [SII]/H$alpha$ line-ratios. We study for the first time the kinematics of the optical counterpart of SNR CTB 109 using the UNAM scanning Fabry-Perot interferometer PUMA. We estimate a systemic velocity of V$_{LSR}$=-50$pm$6 km s$^{-1}$ for this remnant and an expansion velocity of V$_{exp}$=230$pm$5 km s$^{-1}$. From this velocity value and taking into account previous studies about the kinematics of objects at that Galactic longitude we derive a distance to the SNR CTB 109 of 3.1$pm$0.2 kpc, locating it in the Perseus arm. Using the [SII]$lambda$6717/[SII]$lambda$6731 line-ratio we find an electronic density value around n$_e$= 580 cm$^{-3}$. Considering that this remnant is evolving in a low density medium with higher density cloudlets responsible of the optical emission, we determine the age and energy deposited in the ISM by the supernova explosion (E$_0$) in both the Sedov-Taylor phase and the radiative phase. For both cases the age is of thousands of years and the E$_0$ is rather typical of SNRs containing simple pulsars so that, the energy released to the ISM cannot be used to distinguish between supernova remnants hosting typical pulsars from those hosting powerful magnetars as in the case of CTB 109.
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We report the detection of molecular clouds around the X-ray bright interior feature in the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0). This feature, called the Lobe, has been previously suggested to be the result of an interaction of the SNR shock wave with a molecular cloud complex. We present new high resolution X-ray data from the Chandra X-ray Observatory and new high resolution CO data from the Five College Radio Observatory which show the interaction region with the cloud complex in greater detail. The CO data reveal three clouds around the Lobe in the velocity interval -57 < v < -52 km s^-1. The velocity profiles of 12CO at various parts of the east cloud are well fit with a Gaussian; however, at the position where the CO cloud and the Lobe overlap, the velocity profile has an additional component towards higher negative velocities. The molecular hydrogen density in this part of the cloud is relatively high (N_H2 = 1.9 x 10^20 cm^-2), whereas the foreground absorption in X-rays (N_H = 4.5 x 10^21 cm^-2), obtained from Chandra data, is lower than in other parts of the cloud and in the north and south cloud. These results indicate that this cloud has been hit by the SNR blast wave on the western side, forming the bright X-ray Lobe.
Context: We study the X-ray emission of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0), which is well-known for its enigmatic half-shell morphology both in radio and in X-rays and is associated with the anomalous X-ray pulsar (AXP) 1E2259+586. Aims: We want to understand the origin of the X-ray bright feature inside the SNR called the Lobe and the details of the interaction of the SNR shock wave with the ambient interstellar medium (ISM). Methods: The Lobe and the northeastern part of the SNR were observed with Chandra ACIS-I. We analysed the spectrum of the X-ray emission by dividing the entire observed emission into small regions. The X-ray emission is best reproduced with one-component or two-component non-equilibrium ionisation models depending on the position. In the two-component model one emission component represents the shocked ISM and the other the shocked ejecta. Results: We detect enhanced element abundances, in particular for Si and Fe, in and around the Lobe. There is one particular region next to the Lobe with a high Si abundance of 3.3 (2.6 - 4.0) times the solar value. This is the first, unequivocal detection of ejecta in CTB 109. Conclusions: The new Chandra data confirm that the Lobe was created by the interaction of the SNR shock and the supernova ejecta with dense and inhomogeneous medium in the environment of SNR CTB 109. The newly calculated age of the SNR is t ~ 1.4 x 10^4 yr.
We suggest a revised distance to the supernova remnant (SNR) G109.1-1.0 (CTB 109) and its associated anomalous X-ray pulsar (AXP) 1E 2259+586 by analyzing 21cm HI-line and 12CO-line spectra of CTB 109, HII region Sh 152, and the adjacent molecular cloud complex. CTB 109 has been established to be interacting with a large molecular cloud (recession velocity at v=-55 km s^-1). The highest radial velocities of absorption features towards CTB 109 (-56 km s^-1) and Sh 152 (-65 km s^-1) are larger than the recombination line velocity (-50 km s^-1) of Sh 152 demonstrating the velocity reversal within the Perseus arm. The molecular cloud has cold HI column density large enough to produce HI self-absorption (HISA) and HI narrow self-absorption (HINSA) if it was at the near side of the velocity reversal. Absence of both HISA and HINSA indicates that the cloud is at the far side of the velocity reversal within the Perseus Arm, so we obtain a distance for CTB 109 of 4+/-0.8 kpc. The new distance still leads to a normal explosion energy for CTB 109/AXP 1E 2259+586.
We present a radio polarization study of the supernova remnant CTB 80 based on images at 1420 MHz from the Canadian Galactic plane survey, at 2695 MHz from the Effelsberg survey of the Galactic plane, and at 4800 MHz from the Sino-German 6cm polarization survey of the Galactic plane. We obtained a rotation measure (RM) map using polarization angles at 2695 MHz and 4800 MHz as the polarization percentages are similar at these two frequencies. RM exhibits a transition from positive values to negative values along one of the shells hosting the pulsar PSR B1951+32 and its pulsar wind nebula. The reason for the change of sign remains unclear. We identified a partial shell structure, which is bright in polarized intensity but weak in total intensity. This structure could be part of CTB 80 or part of a new supernova remnant unrelated to CTB 80.
Ages of the magnetar 1E 2259+586 and the associated supernova remnant CTB~109 were studied. Analyzing the Suzaku data of CTB~109, its age was estimated to be $sim$14~kyr, which is much shorter than the measured characteristic age of 1E 2259+586, 230 kyr. This reconfirms the previously reported age discrepancy of this magnetar/remnant association, and suggests that the characteristic ages of magnetars are generally over-estimated as compared to their true ages. This discrepancy is thought to arise because the former are calculated without considering decay of the magnetic fields. This novel view is supported independently by much stronger Galactic-plane concentration of magnetars than other pulsars. The process of magnetic field decay in magnetars is mathematically modeled. It is implied that magnetars are much younger objects than previously considered, and can dominate new-born neutron stars.
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