Discovery of non-equilibrium ionization plasma associated with the North Polar Spur and Loop I
Open accessAbstract
We investigated the detailed plasma condition of the North Polar Spur (NPS)/Loop I using archival Suzaku data. In previous research, collisional ionization equilibrium (CIE) have been assumed for X-ray plasma state, but we also assume non-equilibrium ionization (NEI) to check the plasma condition in more detail. We found that most of the plasma in the NPS/Loop I favors the state of NEI, and has the density-weighted ionization timescale of net ∼ 1011–12 s cm−3 and the electron number density ne ∼ a few × 10−3 cm−3. The plasma shock age, t, or the time elapsed after the shock front passed through the plasma, is estimated to be on the order of a few $\rm {Myr}$ for the NPS/Loop I, which puts a strict lower limit to the age of the whole NPS/Loop I structure. We found that NEI results in significantly higher temperature and lower emission measure than those currently derived under CIE assumption. The electron temperature under NEI is estimated to be as high as 0.5 keV toward the brightest X-ray NPS ridge at Δθ = −20○, which decreases to 0.3 keV at −10○, and again increases to ∼0.6 keV towards the outer edge of Loop I at Δθ ∼ 0○, about twice the currently estimated temperatures. Here, Δθ is the angular distance from the outer edge of Loop I. We discuss the implication of introducing NEI for the research in plasma states in astrophysical phenomena.
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Wind-driven bubbles with power L_wind ∼10^42 erg/s are also consistent with the estimated non-equilibrium temperature (∼0.7 keV) from the Suzaku telescope.
“More recently, Fujita (2023) showed that wind-driven bubbles with power, L wind ∼ 10 42 erg s -1 ) are also consistent with the estimated non-equilibrium temperature ( ∼ 0 . 7 keV) from the Suzaku telescope (Yamamoto et al. 2022).”
From The Fermi/eROSITA bubbles: a look into the nuclear outflow from the Milky Way (2024) · cites this paper as Yamamoto et al. 2022
Yamamoto et al. use Suzaku data and report non-equilibrium plasma temperatures reaching approximately 0.6 keV near the outer edge of Loop I (Section 3.2, p. 4), rather than the cited estimate of approximately 0.7 keV. The wind-driven bubble power and consistency result are attributed in the citing sentence to Fujita (2023), not to Yamamoto et al. (LLM, conf=0.85)
Experimental — accuracy not yet measuredYamamoto et al. found that the Suzaku spectra of the NPS are consistent with a temperature of 0.5-0.6 keV and contain signatures of non-equilibrium ionization.
“Interestingly, Yamamoto et al. (2022) find that the Suzaku spectra of the NPS are consistent with a temperature of 0 . 5 -0 . 6 keV and that the spectra contain signatures of non-equilibrium ionization.”
From The Fermi/eROSITA bubbles: a look into the nuclear outflow from the Milky Way (2024) · cites this paper as Yamamoto et al. 2022
Further analysis of Suzaku data in that region indicates the presence of a hot (about 0.7 keV) component.
“Further analysis of Suzaku data in this region indicates the presence of a hot ( ≃ 0 . 7 keV) component, similar to the findings by Yamamoto et al. (2022) in that region.”
From The Fermi/eROSITA bubbles: a look into the nuclear outflow from the Milky Way (2024) · cites this paper as Yamamoto et al. 2022
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Cites
Data Reduction and Error Analysis for the Physical Sciences
Bevington, P. R., Robinson, D. K., Blair, J. M., Mallinckrodt, A. J., & McKay, S. R. (1993) · Computers in Physics · doi:10.1063/1.4823194 · Cited by 14,992 · see citing works
Physics of Fully Ionized Gases
Spitzer, L., & Seeger, R. J. (1963) · American Journal of Physics · doi:10.1119/1.1969155 · Cited by 5,665 · see citing works
Dickey, J. M., & Lockman, F. J. (1990) · Annual Review of Astronomy and Astrophysics · doi:10.1146/annurev.aa.28.090190.001243 · Cited by 4,521 · see citing works
THE LARGE AREA TELESCOPE ON THE <i>FERMI GAMMA-RAY SPACE TELESCOPE</i> MISSION
Atwood, W. B., Abdo, A. A., Ackermann, M., Althouse, W., Anderson, B., Axelsson, M., Baldini, L., Ballet, J., Band, D. L., Barbiellini, G., et al. (2009) · The Astrophysical Journal · doi:10.1088/0004-637x/697/2/1071 · Cited by 4,198 · see citing works
Data Reduction and Error Analysis for the Physical Sciences.
C., E. L., & Bevington, P. R. (1972) · Journal of the American Statistical Association · doi:10.2307/2284752 · Cited by 3,586 · see citing works
X-Ray Imaging Spectrometer (XIS) on Board Suzaku
Koyama, K., Tsunemi, H., Dotani, T., Bautz, M. W., Hayashida, K., Tsuru, T. G., Matsumoto, H., Ogawara, Y., Ricker, G. R., Doty, J., et al. (2007) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/59.sp1.s23 · Cited by 1,045 · see citing works
Mitsuda, K., Bautz, M. W., Inoue, H., Kelley, R. L., Koyama, K., Kunieda, H., Makishima, K., Ogawara, Y., Petre, R., Takahashi, T., et al. (2007) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/59.sp1.s1 · Cited by 1,007 · see citing works
Self-citationThe eROSITA X-ray telescope on SRG
Predehl, P., Andritschke, R., Arefiev, V., Babyshkin, V., Batanov, O., Becker, W., Böhringer, H., Bogomolov, A., Boller, T., Borm, K., et al. (2021) · Astronomy & Astrophysics · doi:10.1051/0004-6361/202039313 · Cited by 897 · see citing works
GIANT GAMMA-RAY BUBBLES FROM FERMI-LAT: ACTIVE GALACTIC NUCLEUS ACTIVITY OR BIPOLAR GALACTIC WIND?
Su, M., Slatyer, T., & Finkbeiner, D. (2010) · The Astrophysical Journal · doi:10.1088/0004-637x/724/2/1044 · Cited by 756 · see citing works
The eROSITA X-ray telescope on SRG
Predehl, P., Andritschke, R., Arefiev, V., Babyshkin, V., Batanov, O. V., Becker, W., Böhringer, H., Bogomolov, A., Böller, T., Borm, K., et al. (2021) · Springer Link (Chiba Institute of Technology) · doi:10.1051/0004-6361/202039313/pdf · Cited by 647 · see citing works
Hard X-Ray Detector (HXD) on Board Suzaku
Takahashi, T., Abe, K., Endo, M., Endo, Y., Ezoe, Y., Fukazawa, Y., Hamaya, M., Hirakuri, S., Hong, S., Horii, M., et al. (2007) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/59.sp1.s35 · Cited by 644 · see citing works
Self-citationIshisaki, Y., Maeda, Y., Fujimoto, R., Ozaki, M., Ebisawa, K., Takahashi, T., Ueda, Y., Ogasaka, Y., Ptak, A., Mukai, K., et al. (2007) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/59.sp1.s113 · Cited by 469 · see citing works
Supernova Remnants in the Sedov Expansion Phase: Thermal X‐Ray Emission
Borkowski, K. J., Lyerly, W. J., & Reynolds, S. P. (2001) · The Astrophysical Journal · doi:10.1086/319011 · Cited by 430 · see citing works
Reproducibility of Non-X-Ray Background for the X-Ray Imaging Spectrometer aboard Suzaku
Tawa, N., Hayashida, K., Nagai, M., Nakamoto, H., Tsunemi, H., Yamaguchi, H., Ishisaki, Y., Miller, E. D., Mizuno, T., Dotani, T., et al. (2008) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/60.sp1.s11 · Cited by 332 · see citing works
Microwave Interstellar Medium Emission Observed by the<i>Wilkinson Microwave Anisotropy Probe</i>
Finkbeiner, D. P. (2004) · The Astrophysical Journal · doi:10.1086/423482 · Cited by 331 · see citing works
Small‐Scale Structure of the SN 1006 Shock withChandraObservations
Bamba, A., Yamazaki, R., Ueno, M., & Koyama, K. (2003) · The Astrophysical Journal · doi:10.1086/374687 · Cited by 315 · see citing works
The Large‐Scale Bipolar Wind in the Galactic Center
Bland‐Hawthorn, J., & Cohen, M. (2003) · The Astrophysical Journal · doi:10.1086/344573 · Cited by 301 · see citing works
First Maps of the Soft X-Ray Diffuse Background from the ROSAT XRT/PSPC All-Sky Survey
Snowden, S. L., Freyberg, M. J., Plucinsky, P. P., Schmitt, J. H. M. M., Truemper, J. E., Voges, W. H., Edgar, R. J., McCammon, D., & Sanders, W. T., III (1995) · The Astrophysical Journal · doi:10.1086/176517 · Cited by 270 · see citing works
Study of the X-Ray Background Spectrum and Its Large-Scale Fluctuation with ASCA
Kushino, A., Ishisaki, Y., Morita, U., Yamasaki, N. Y., Ishida, M., Ohashi, T., & Ueda, Y. (2002) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/54.3.327 · Cited by 263 · see citing works
Detection of large-scale X-ray bubbles in the Milky Way halo
Predehl, P., Sunyaev, R. A., Becker, W., Brunner, H., Burenin, R., Bykov, A., Cherepashchuk, A., Chugai, N., Churazov, E., Doroshenko, V., et al. (2020) · Nature · doi:10.1038/s41586-020-2979-0 · Cited by 234 · see citing works
Detection of large-scale X-ray bubbles in the Milky Way halo
Predehl, P., Sunyaev, R., Becker, W., Brunner, H., Burenin, R., Bykov, A. M., Cherepashchuk, A. M., Чугай, Н. Н., Churazov, E., Doroshenko, V., et al. (2020) · RePEc: Research Papers in Economics · Cited by 188 · see citing works
Energy Spectra of the Soft X-Ray Diffuse Emission in Fourteen Fields Observed with Suzaku
Yoshino, T., Mitsuda, K., Yamasaki, N. Y., Takei, Y., Hagihara, T., Masui, K., Bauer, M., McCammon, D., Fujimoto, R., Wang, Q. D., et al. (2009) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/61.4.805 · Cited by 181 · see citing works
X-ray spectral imaging and Doppler mapping of Cassiopeia A
Willingale, R., Bleeker, J. A. M., van der Heyden, K. J., Kaastra, J. S., & Vink, J. (2002) · Astronomy and Astrophysics · doi:10.1051/0004-6361:20011614 · Cited by 161 · see citing works
IONIZATION EQUILIBRIUM TIMESCALES IN COLLISIONAL PLASMAS
Smith, R. K., & Hughes, J. P. (2010) · The Astrophysical Journal · doi:10.1088/0004-637x/718/1/583 · Cited by 148 · see citing works
The Suzaku High Resolution X-Ray Spectrometer
Kelley, R. L., Mitsuda, K., Allen, C. A., Arsenovic, P., Audley, M. D., Bialas, T. G., Boyce, K. R., Boyle, R. F., Breon, S. R., Brown, G. V., et al. (2007) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/59.sp1.s77 · Cited by 148 · see citing works
Self-citation<i>SUZAKU</i>OBSERVATIONS OF THE DIFFUSE X-RAY EMISSION ACROSS THE FERMI BUBBLES' EDGES
Kataoka, J., Tahara, M., Totani, T., Sofue, Y., Stawarz, Ł., Takahashi, Y., Takeuchi, Y., Tsunemi, H., Kimura, M., Takei, Y., et al. (2013) · The Astrophysical Journal · doi:10.1088/0004-637x/779/1/57 · Cited by 118 · see citing works
Self-citationSofue, Y. (2000) · The Astrophysical Journal · doi:10.1086/309297 · Cited by 102 · see citing works
Self-citationTHE INTERACTION OF THE FERMI BUBBLES WITH THE MILKY WAY’S HOT GAS HALO
Miller, M. J., & Bregman, J. N. (2016) · The Astrophysical Journal · doi:10.3847/0004-637x/829/1/9 · Cited by 91 · see citing works
THE STRUCTURE OF THE LOCAL HOT BUBBLE
Liu, W., Chiao, M., Collier, M. R., Cravens, T., Galeazzi, M., Koutroumpa, D., Kuntz, K. D., Lallement, R., Lepri, S. T., McCammon, D., et al. (2016) · The Astrophysical Journal · doi:10.3847/1538-4357/834/1/33 · Cited by 90 · see citing works
Panoramic Views of the Cygnus Loop
Levenson, N. A., Graham, J. R., Keller, L. D., & Richter, M. J. (1998) · The Astrophysical Journal Supplement Series · doi:10.1086/313136 · Cited by 88 · see citing works
Polarized radio filaments outside the Galactic plane
Vidal, M., Dickinson, C., Davies, R. D., & Leahy, J. P. (2015) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/stv1328 · Cited by 88 · see citing works
Planck Intermediate Results. IX. Detection of the Galactic haze with Planck
Ade, P. A. R., Aghanim, N., Arnaud, M., Ashdown, M., Atrio-Barandela, F., Aumont, J., Baccigalupi, C., Balbi, A., Banday, A. J., Barreiro, R. B., et al. (2013) · LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) · doi:10.1051/0004-6361/201220271 · Cited by 70 · see citing works
New $\mathsf{\lambda}$6 cm observations of the Cygnus Loop
Sun, X. H., Reich, W., Han, J. L., Reich, P., & Wielebinski, R. (2006) · Astronomy and Astrophysics · doi:10.1051/0004-6361:20054133 · Cited by 58 · see citing works
Suzaku Observations of the North Polar Spur: Evidence for Nitrogen Enhancement
Miller, E. D., Tsunemi, H., Bautz, M. W., McCammon, D., Fujimoto, R., Hughes, J. P., Katsuda, S., Kokubun, M., Mitsuda, K., Porter, F. S., et al. (2008) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/60.sp1.s95 · Cited by 50 · see citing works
X-ray and Gamma-ray Observations of the Fermi Bubbles and NPS/Loop I Structures
Kataoka, J., Sofue, Y., Inoue, Y., Akita, M., Nakashima, S., & Totani, T. (2018) · Galaxies · doi:10.3390/galaxies6010027 · Cited by 43 · see citing works
Self-citationGLOBAL STRUCTURE OF ISOTHERMAL DIFFUSE X-RAY EMISSION ALONG THE FERMI BUBBLES
Kataoka, J., Tahara, M., Totani, T., Sofue, Y., Inoue, Y., Nakashima, S., & Cheung, C. C. (2015) · The Astrophysical Journal · doi:10.1088/0004-637x/807/1/77 · Cited by 41 · see citing works
Self-citationMagnetic Fields in the Galactic Spurs
Bingham, R. (1967) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/137.2.157 · Cited by 40 · see citing works
PRESSURE EQUILIBRIUM BETWEEN THE LOCAL INTERSTELLAR CLOUDS AND THE LOCAL HOT BUBBLE
Snowden, S. L., Chiao, M. P., Collier, M. R., Porter, F. S., Thomas, N. E., Cravens, T. E., Robertson, I. P., Galeazzi, M., Uprety, Y., Ursino, E., et al. (2014) · The Astrophysical Journal Letters · doi:10.1088/2041-8205/791/1/l14 · Cited by 38 · see citing works
Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data
Panopoulou, G. V., Dickinson, C., Readhead, A. C. S., Pearson, T. J., & Peel, M. (2021) · The Astrophysical Journal · doi:10.3847/1538-4357/ac273f · Cited by 38 · see citing works
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Sofue, Y. (2015) · Monthly Notices of the Royal Astronomical Society · doi:10.1093/mnras/stu2661 · Cited by 37 · see citing works
Self-citationGIANT LOBES OF CENTAURUS A RADIO GALAXY OBSERVED WITH THE SUZAKU X-RAY SATELLITE
Stawarz, Ł., Tanaka, Y., Madejski, G. M., O’Sullivan, S. P., Cheung, C. C., Feain, I., Fukazawa, Y., Gandhi, P., Hardcastle, M. J., Kataoka, J., et al. (2013) · The Astrophysical Journal · doi:10.1088/0004-637x/766/1/48 · Cited by 36 · see citing works
Self-citationTosaki, T., Shioya, Y., Kuno, N., Hasegawa, T., Nakanishi, K., Matsushita, S., & Kohno, K. (2007) · Publications of the Astronomical Society of Japan · doi:10.1093/pasj/59.1.33 · Cited by 29 · see citing works
Henley, D. B., & Shelton, R. L. (2015) · The Astrophysical Journal · doi:10.1088/0004-637x/808/1/22 · Cited by 26 · see citing works
An Analysis of the North Polar Spur Using HaloSat
LaRocca, D. M., Kaaret, P., Kuntz, K. D., Hodges-Kluck, E., Zajczyk, A., Bluem, J., Ringuette, R., & Jahoda, K. M. (2020) · The Astrophysical Journal · doi:10.3847/1538-4357/abbdfd · Cited by 26 · see citing works
Diffuse X-Ray Emission from the Northern Arc of Loop I Observed with Suzaku
Akita, M., Kataoka, J., Arimoto, M., Sofue, Y., Totani, T., Inoue, Y., & Nakashima, S. (2018) · Astrophysical Journal · doi:10.3847/1538-4357/aacd08 · Cited by 15 · see citing works
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Kataoka, J., Yamamoto, M., Nakamura, Y., Ito, S., Sofue, Y., Inoue, Y., Nakamori, T., & Totani, T. (2021) · The Astrophysical Journal · doi:10.3847/1538-4357/abdb31 · Cited by 14 · see citing works
Self-citationInteraction of the galactic-centre super bubbles with the gaseous disc
Sofue, Y., & Kataoka, J. (2021) · Monthly notices of the Royal Astronomical Society · doi:10.1093/mnras/stab1857 · Cited by 11 · see citing works
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“Interestingly, Yamamoto et al. (2022) find that the Suzaku spectra of the NPS are consistent with a temperature of 0 .”
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- Authors
- Yamamoto, M., Kataoka, J., & Sofue, Y.
- Affiliations
- Waseda University (JP)
- The University of Tokyo (JP)
- Corresponding author
- Yamamoto, Marino
- Venue
- Monthly Notices of the Royal Astronomical Society
- Publisher
- Oxford University Press (OUP)
- Published
- 2022-03-04
- Volume
- 512
- Issue
- 2
- Pages
- 2034-2043
- ISSN
- 0035-8711 (ISSN-L)
- 1365-2966
- OpenAlex
- W4214870434
- Cited by
- 8
- References
- 47
- Citations by year
- 2026: 1 · 2025: 1 · 2024: 3 · 2023: 2 · 2022: 1
- FWCI
- 0.22
- Type
- journal article
- Language
- en
- Open access
- green
- arxiv.org
- Licence
- academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model (vor)
- Locations
- Monthly Notices of the Royal Astronomical Society (publishedVersion)
- arXiv (Cornell University) (submittedVersion)
- arXiv (Cornell University)
- Funders
- JST
- ERATO (JPMJER2102)
- JSPS (JP20K20923)
- Topics
- Physical Sciences › Physics and Astronomy › Nuclear and High Energy Physics › Astrophysics and Cosmic Phenomena
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysical Phenomena and Observations
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Solar and Space Plasma Dynamics
- Keywords
- North Polar Spur, Loop I, non-equilibrium ionization, collisional ionization equilibrium, electron density, electron temperature, emission measure, Suzaku
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