Is the Gum Nebula an important interstellar scattering disk of background pulsars?  

作　　者：Rui Wang Zhen Yan Zhiqiang Shen Ke Jia Lee Yajun Wu Rongbing Zhao Zhipeng Huang Xiaowei Wang Jie Liu 

机构地区：[1]Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai,200030,China [2]School of Astronomy and Space Sciences,University of Chinese Academy of Sciences,Beijing,100049,China [3]Key Laboratory of Radio Astronomy and Technology,Chinese Academy of Sciences,Beijing,100101,China [4]School of Physical Science and Technology,ShanghaiTech University,Shanghai,201210,China [5]Department of Astronomy,School of Physics,Peking University,Beijing,100871,China [6]Kavli Institute for Astronomy and Astrophysics,Peking University,Beijing,100871,China [7]Department of Physics and Astronomy,Hubei University of Education,Wuhan,430205,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2025年第3期175-186,共12页中国科学:物理学、力学、天文学(英文版)

基　　金：supported by the National SKA Program of China(Grant No.2020SKA0120104);the National Key R&D Program of China(Grant No.2022YFA1603104);the National Natural Science Foundation of China(Grant Nos.U2031119,and 12041301);The image of the Gum Nebula comes from the Southern H-Alpha Sky Survey Atlas(SHASSA),which is supported by the National Science Foundation。

摘　　要：The Gum Nebula is a faint supernova remnant extending about 40°across the southern sky,potentially affecting tens of background pulsars.Though the view that the Gum Nebula acts as a potential scattering screen for background pulsars has been recurrently mentioned over the past five decades,it has not been directly confirmed.We chose the strong background pulsar PSR B0740-28 as a probe and monitored its diffractive interstellar scintillation(DISS)at 2.25&8.60 GHz simultaneously for about two years using the Shanghai Tian Ma Radio Telescope(TMRT).DISS was detected at both frequencies and quantified by two-dimensional autocorrelation analysis.We calculated their scattering spectral indexαand found that 9/21 of the observations followed the theoretical predictions,while 4/21 of them clearly showedα<4.This finding provides strong support for anomalous scattering along the pulsar line of sight,due to the large frequency lever arm and the simultaneous features of our dual-frequency observations.In comparison to the 2.25 GHz observations,scintillation arcs were observed in 10/21 of the secondary spectrum plots for 8.60 GHz observations.Consequently,the highest frequency record for pulsar scintillation arc detection was updated to 8.60 GHz.Our fitting results were the most direct evidence for the view that the Gum Nebula acts as the scattering screen for background pulsars,because both the distance(245_(-72)^(+69)pc)and transverse speed(22.4_(-4.2)^(+4.1)km s^(-1))of the scintillation screen are comparable with related parameters of the Gum Nebula.Our findings indicated that anisotropic scattering provides a superior explanation for the annual modulation of scintillation arcs than isotropic scattering.Additionally,the orientation of its long axis was also fitted.

关 键 词：pulsar interstellar scintillation Gum Nebula 

分 类 号：P145.6[天文地球—天体物理]