TY - JOUR
T1 - Origin of galactic spurs
T2 - New insight from radio/X-ray all-sky maps
AU - Kataoka, Jun
AU - Yamamoto, Marino
AU - Nakamura, Yuki
AU - Ito, Soichiro
AU - Sofue, Yoshiaki
AU - Inoue, Yoshiyuki
AU - Nakamori, Takeshi
AU - Totani, Tomonori
N1 - Funding Information:
We thank an anonymous referee for his/her constructive comments to improve this manuscript. This research made use of Astropy, a community-developed core Python package for Astronomy (The Astropy Collaboration et al. 2018, 2013). J.K. acknowledges the support from JSPS KAKENHI grant No. JP20K20923. Y.I. is supported by JSPS KAKENHI grant Nos. JP18H05458 and JP19K14772. T.T. was supported by JSPS/ MEXT KAKENHI grant Nos. 18K03692 and 17H06362.
Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/2/10
Y1 - 2021/2/10
N2 - In this study, we analyze giant Galactic spurs seen in both radio and X-ray all-sky maps to reveal their origins. We discuss two types of giant spurs: one is the brightest diffuse emission near the map's center, which is likely to be related to Fermi bubbles (NPSs/SPSs, north/south polar spurs, respectively), and the other is weaker spurs that coincide positionally with local spiral arms in our Galaxy (LAS, Local Arm spur). Our analysis finds that the X-ray emissions, not only from the NPS but also from the SPS, are closer to the Galactic center by ~5° compared with the corresponding radio emission. Furthermore, larger offsets of 10°-20° are observed in the LASs; however, they are attributed to different physical origins. Moreover, the temperature of the X-ray emission is kT ≃ 0.2 keV for the LAS, which is systematically lower than those of the NPS and SPS (kT ≃ 0.3 keV) but consistent with the typical temperature of Galactic halo gas. We argue that the radio/X-ray offset and the slightly higher temperature of the NPS/SPS X-ray gas are due to the shock compression/heating of halo gas during a significant Galactic explosion in the past, whereas the enhanced X-ray emission from the LAS may be due to the weak condensation of halo gas in the arm potential or star formation activity without shock heating.
AB - In this study, we analyze giant Galactic spurs seen in both radio and X-ray all-sky maps to reveal their origins. We discuss two types of giant spurs: one is the brightest diffuse emission near the map's center, which is likely to be related to Fermi bubbles (NPSs/SPSs, north/south polar spurs, respectively), and the other is weaker spurs that coincide positionally with local spiral arms in our Galaxy (LAS, Local Arm spur). Our analysis finds that the X-ray emissions, not only from the NPS but also from the SPS, are closer to the Galactic center by ~5° compared with the corresponding radio emission. Furthermore, larger offsets of 10°-20° are observed in the LASs; however, they are attributed to different physical origins. Moreover, the temperature of the X-ray emission is kT ≃ 0.2 keV for the LAS, which is systematically lower than those of the NPS and SPS (kT ≃ 0.3 keV) but consistent with the typical temperature of Galactic halo gas. We argue that the radio/X-ray offset and the slightly higher temperature of the NPS/SPS X-ray gas are due to the shock compression/heating of halo gas during a significant Galactic explosion in the past, whereas the enhanced X-ray emission from the LAS may be due to the weak condensation of halo gas in the arm potential or star formation activity without shock heating.
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U2 - 10.3847/1538-4357/abdb31
DO - 10.3847/1538-4357/abdb31
M3 - Article
AN - SCOPUS:85101544789
SN - 0004-637X
VL - 908
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - abdb31
ER -