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논문

전체
우리은하 고온기체에서 발생하는 원자외선 방출선의 전천 분포 SCI
  • 조영수; 선광일; 민경욱; 외
  • 2019-07-01
  • ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES 243 1 : 9-1~9-16
We present all-sky maps of two major far-ultraviolet cooling lines, C iv and O vi, of highly ionized gas to investigate the nature of the transition-temperature gas. From the extinction-corrected line intensities of C iv and O vi, we calculated the gas temperature and the emission measure of the transition-temperature gas assuming isothermal plasma in the collisional ionization equilibrium. The gas temperature was found to be more or less uniform throughout the Galaxy with a value of (1.89 ± 0.06) × 105 K. The emission measure of the transition-temperature gas is described well by a disk-like model in which the scale height of the electron density is ${z}_{0}={6}_{-2}^{+3}$ kpc. The total mass of the transition-temperature gas is estimated to be approximately ${6.4}_{-2.8}^{+5.2}\times {10}^{9}{M}_{\odot }$. We also calculated the volume-filling fraction of the transition-temperature gas, which was estimated to be f = 0.26 ± 0.09, and it varies from f ~ 0.37 in the inner Galaxy to f ~ 0.18 in the outer Galaxy. The spatial distribution of C iv and O vi cannot be explained by a simple supernova remnant model or a three-phase model. The combined effects of supernova remnants and turbulent mixing layers can explain the intensity ratio of C iv and O vi. Thermal conduction front models and high-velocity cloud models are also consistent with our observation.