Discovery of a new supernova remnant G150.3+4.5

Abstract

Context. Large-scale radio continuum surveys have good potential for discovering new Galactic supernova remnants (SNRs). Surveys of the Galactic plane are often limited in the Galactic latitude of |b| ∼ 5 • . SNRs at high latitudes, such as the Cygnus Loop or CTA 1, cannot be detected by surveys in such limited latitudes. Aims. Using the available Urumqi λ6 cm Galactic plane survey data, together with the maps from the extended ongoing λ6 cm medium latitude survey, we wish to discover new SNRs in a large sky area. Methods. We searched for shell-like structures and calculated radio spectra using the Urumqi λ6 cm, Effelsberg λ11 cm, and λ21 cm survey data. Radio polarized emission and evidence in other wavelengths are examined for the characteristics of SNRs. Results. We discover an enclosed oval-shaped object G150.3+4.5 in the λ6 cm survey map. It is about 2.• 5 wide and 3 • high. Parts of the shell structures can be identified well in the λ11 cm, λ21 cm, and λ73.5 cm observations. The Effelsberg λ21 cm total intensity image resembles most of the structures of G150.3+4.5 seen at λ6 cm, but the loop is not closed in the northwest. High resolution images at λ21 cm and λ73.5 cm from the Canadian Galactic Plane Survey confirm the extended emission from the eastern and western shells of G150.3+4.5. We calculated the radio continuum spectral indices of the eastern and western shells, which are β ∼ −2.4 and β ∼ −2.7 between λ6 cm and λ21 cm, respectively. The shell-like structures and their non-thermal nature strongly suggest that G150.3+4.5 is a shell-type SNR. For other objects in the field of view, G151.4+3.0 and G151.2+2.6, we confirm that the shell-like structure G151.4+3.0 very likely has a SNR origin, while the circular-shaped G151.2+2.6 is an H ii region with a flat radio spectrum associated with optical filamentary structure, Hα, and infrared emission.

Discovery of a new supernova remnant G21.8−3.0

“…Using the data of the Sino-German λ6 cm polarisation survey of the Galactic plane 1 (Sun et al 2007;Gao et al 2010;Sun et al 2011;Xiao et al 2011), we discovered three new SNRs: G25.1−2.3 and G178.2−4.2 by Gao et al (2011) and G150.3+4.5 by Gao & Han (2014). Here we report the discovery of a new shell-like SNR, G21.8−3.0.…”

CO(J = 1–0) Observations of a Filamentary Molecular Cloud in the Galactic Region Centered at l = 150°, b = 3.°5

“…This elongated cloud is located to the west of a giant molecular cloud (GMC), and it covers an area within 148 • ≤ l ≤ 153 • and 1 • ≤ b ≤ 6 • (see Figure 1). A few supernova remnants (SNRs) identified by radio observations are also located in this area, like G149.5+3.2 and G150.8+3.8 (Gerbrandt et al 2014), and G150.3+4.5 (Gao & Han 2014). Three velocity components can be roughly resolved in the longitude-velocity map of this elongated cloud (see Figure 2), with two GMCs located in the east and west.…”

Detection of GeV Gamma-Rays from HESS J1534−571 and Multiwavelength Implications for the Origin of the Nonthermal Emission

“…Non-thermal X-rays are expected to decrease as a SNR evolves (Nakamura et al 2012) and even though the evolution of the downstream magnetic field in a SNR is not well understood, it is expected to decrease with decreasing shock speeds (e.g., Völk et al 2005). Other similar objects could include the relatively faint SNR G150.3+4.5 (Gao & Han 2014;Ackermann et al 2016). Follow up observations of HESS J1534-571 and modeling are necessary to confirm this scenario.…”