Kinematics of the Galactic Supernova Remnant G109.1-1.0 (CTB 109)

MNRAS 473, 1705–1717 (2018) doi:10.1093/mnras/stx2460 Kinematics of the Galactic Supernova Remnant G109.1-1.0 (CTB 109) M. Sánchez-Cruces,1‹ M. Rosado,2‹ I. Fuentes-Carrera1‹ and P. Ambrocio-Cruz3 1 Escuela Superior de Fı́sica y Matemáticas, Instituto Politécnico Nacional, U.P. Adolfo López Mateos, C.P. 07738, Ciudad de México, México 2 Instituto de Astronomı́a, Universidad Nacional Autónoma de México, Circuito Exterior, C.U., A. Postal 70-264, 04510 Ciudad de México, México 3 Escuela Superior de Tlahuelilpan, Universidad Autónoma del Estado de Hidalgo, Ex-Hacienda de San Servando s/n, Col. Centro, 42780 Tlahuelilpan Hgo., México Accepted 2017 September 21. Received 2017 August 25; in original form 2016 November 16 We present direct images in the H α and [S II] λλ6717,6731 Å lines of the Galactic supernova remnant (SNR) G109.1-1.0 (CTB 109). We confirm that the filaments detected are the optical counterpart of the X-ray and radio SNR due to their high [S II]/H α line ratios. We study for the first time the kinematics of the optical counterpart of SNR CTB 109 using the Universidad Nacional Autónoma de México scanning Fabry–Perot interferometer PUMA. We estimate a systemic velocity of VLSR = −50 ± 6 km s−1 for this remnant and an expansion velocity of Vexp = 230 ± 5 km s−1 . From this velocity and taking into account previous studies of the kinematics of objects at that Galactic longitude, we derive a distance to SNR CTB 109 of 3.1 ± 0.2 kpc, locating it in the Perseus arm. Using the [S II] λ6717/[S II] λ6731 line ratio, we find an electronic density value around ne = 580 cm−3 . Considering that this remnant is evolving in a low-density medium with higher-density cloudlets responsible for the optical emission, we determine the age and energy deposited in the ISM by the supernova explosion (E0 ) in both the Sedov–Taylor phase and the radiative phase. For both cases, the age is thousands of years and E0 is rather typical of SNRs containing simple pulsars, so that the energy released to the ISM cannot be used to distinguish between SNRs hosting typical pulsars from those hosting powerful magnetars, like CTB 109. Key words: ISM: kinematics and dynamics – ISM: supernova remnants-G109.1-1.0CTB 109. 1 I N T RO D U C T I O N A supernova remnant (SNR) is the region confined by the shock wave generated by a supernova (SN) explosion. It contains both shocked interstellar medium (ISM) and the material ejected by the explosion. Depending on the mass of the progenitor star and the circumstellar environment at the moment of the explosion (core collapse of massive stars or thermonuclear explosion in a binary system), a compact object can remain. The energy deposited in the ISM is of the order of 1050 to 1051 erg. The SNR G109.1-1.0 (CTB 109) is located at α (J2000) = 23h 01m 35s , δ (J2000) = +58◦ 53 according to its source centroid (Green Catalogue, Green 2014). Its morphology shows a semicircular shell both in radio emission (Hughes, Harten & van den Bergh 1981) and X-ray (Gregory & Fahlman 1980), where it was discovered. The X-ray emission detected by ROSAT HRI (Hurford & Fesen 1995), XMM–Newton (Sasaki et al. 2004) and Chandra (Sasaki et al. 2013) reveal the shell-type and semicircular morphology of SNR CTB 109.  E-mail: (MS-C); margarit@astro. unam.mx (MR); (IF-C) In the Sloan survey data, there is no appreciable optical emission from the X-ray-emitting hemispherical shell (see Fig. 1). Optical emission of this remnant was detected a long time after the X-ray and radio emissions by Fesen & Hurford (1995), who found H α filaments whose spectra showed [S II]/H α ratios consistent with shocks. CO and H I studies have not been successful in detecting shocked molecular or neutral material directly associated with the SNR. Nevertheless, the molecular gas observations show an anticorrelation between the X-ray hemispherical shell and the CO clouds, suggesting a possible interaction (see Tatematsu et al. 1987; Kothes, Uyaniker & Yar 2002; Sasaki et al. 2006; Tian, Leahy & Li 2010; Kothes & Foster 2012). In the ROSAT and XMM–Newton images, it is possible to see the anomalous X-ray pulsar (AXP) 1E 2259+586. This pulsar is also known as MG J2301+5852 in the McGill magnetar catalogue (Olausen & Kaspi 2014) and as AXP J2301+5852. This central source was discovered by Gregory & Fahlman (1980) as an X-ray point source. One year later, the central source was reported as an X-ray pulsar (Fahlman & Gregory 1981). Now this source is considered to be a magnetar (Kaspi, Gavriil & Woods 2002; Gavriil, Kaspi & Woods 2004; Woods et al. 2004) with a magnetic field of 5.9 × 1013 G (Tendulkar, Cameron & Kulkarni 2013). The measured period is 6.97 s (Morini et al. 1988).  C 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society ABSTRACT 1706 M. Sánchez-Cruces et al. No radio or optical emission has been detected for the magnetar. Magnetars and pulsars differ in their periods and surface magnetic fields. Typically, the magnetic field of a magnetar is about 1013 –1015 G (Woods & Thompson 2006; Mereghetti 2008; Harding 2013) while the magnetic field of a pulsar is about 1012 G (Popov et al. 2010). The period of a magnetar is >1 s while that of a pulsar is less than or about 1 s. Fig. 1 shows that for SNR CTB 109, there is a strong correlation between X-ray emission and radio emission. No optical emission was detected in the DSS image1 at that level associated with 1 SkyView Survey metadata. Data taken by Royal Observatory Edinburgh and Anglo-Australian Observatory, CalTech. Compression and distribution were done by the Space Telescope Science Institute. MNRAS 473, 1705–1717 (2018) the SNR. The X-ray magnetar AXP 1E 2259+586 (marked with a × symbol) and the geometric centre of the remnant given by Kothes et al. (2006) (marked with a +) do not match. If we assume that the SNR expanded symmetrically, this mismatch could suggest a transverse motion of the magnetar. 1.1 Previous distance estimates In this section, we present a brief summary of the previous distance determinations to SNR CTB 109 and to the magnetar AXP 1E 2259+586. Given that SNR CTB 109 is in the direction of the Perseus arm, distance estimates based on the kinematics should be checked with other distance indicators. Large differences between the radial velocities and the distance estimated by other than the kinematic Figure 1. Top left: X-ray image of SNR CTB 109 taken from ROSAT HRI (Hurford & Fesen 1995). Top right: Radio continuum image (at 325 MHz or 92 cm) taken from the Westerbork Northern Sky Survey (Rengelink et al. 1997). Bottom left: Optical image taken from the DSS data base. Bottom right: Combined image of X-ray (red) and radio continuum (blue). The multiplication sign (×) indicates the location of the X-ray magnetar AXP 1E 2259+586 and the plus (+) is the geometrical centre of the almost hemispherical emitting gas (Kothes et al. 2006). Galactic Super (...truncated)