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X-ray emission signatures of galactic feedback in the hot circumgalactic medium: predictions from cosmological hydrodynamical simulations

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arxiv 2506.17440 v1 pith:PNG7JOFL submitted 2025-06-20 astro-ph.GA astro-ph.HE

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keywords feedbackgalaxiesoutflowssimulationsx-rayemissioncosmicgalactic
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abstract

Little is currently known about the physical properties of the hot circumgalactic medium (CGM) surrounding massive galaxies. Next-generation X-ray observatories will enable detailed studies of the hot CGM in emission. To support these future efforts, we make predictions of the X-ray emission from the hot CGM using a sample of 28 $\sim$Milky Way-mass disk galaxies at $z=0$ from seven cosmological hydrodynamical simulation suites incorporating a wide range of galactic feedback prescriptions. The X-ray surface brightness (XSB) morphology of the hot CGM varies significantly across simulations. XSB-enhanced outflows and bubble-like structures are predicted in many galaxies simulated with AGN feedback and in some stellar-feedback-only galaxies, while other galaxies exhibit more isotropic XSB distributions at varying brightnesses. Galaxies simulated without cosmic ray physics exhibit radial XSB profiles with similar shapes ($\propto r^{-3}$ within $20-200$ kpc), with scatter about this slope likely due to underlying feedback physics. The hot CGM kinematics also differ substantially: velocity maps reveal signatures of bulk CGM rotation and high-velocity biconical outflows, particularly in simulations incorporating AGN feedback. Some stellar-feedback-only models also generate similar AGN-like outflows, which we postulate is due to centrally-concentrated star formation. Simulations featuring AGN feedback frequently produce extended temperature enhancements in large-scale galactic outflows, while simulations incorporating cosmic ray physics predict the coolest CGM due to pressure support being provided by cosmic rays rather than hot CGM. Individually-resolved X-ray emission lines further distinguish hot CGM phases, with lower-energy lines (e.g., O VII) largely tracing volume-filling gas, and higher-energy lines (e.g., Fe XVII) highlighting high-velocity feedback-driven outflows.

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Works this paper leans on

92 extracted references · 8 canonical work pages

  1. [1]

    E., & Bregman, J

    Anderson, M. E., & Bregman, J. N. 2011, ApJ, 737, 22, doi: 10.1088/0004-637X/737/1/22

  2. [2]

    E., Bregman, J

    Anderson, M. E., Bregman, J. N., & Dai, X. 2013, ApJ, 762, 106, doi: 10.1088/0004-637X/762/2/106

  3. [3]

    E., Gaspari, M., White, S

    Anderson, M. E., Gaspari, M., White, S. D. M., Wang, W., & Dai, X. 2015, MNRAS, 449, 3806, doi: 10.1093/mnras/stv437 Astropy Collaboration, Robitaille, T. P., Tollerud, E. J., et al. 2013, A&A, 558, A33, doi: 10.1051/0004-6361/201322068 Astropy Collaboration, Price-Whelan, A. M., Sip˝ ocz, B. M., et al. 2018, AJ, 156, 123, doi: 10.3847/1538-3881/aabc4f

  4. [4]

    R., Chervenak, J

    Bandler, S. R., Chervenak, J. A., Datesman, A. M., et al. 2019, Journal of Astronomical Telescopes, Instruments, and Systems, 5, 021017, doi: 10.1117/1.JATIS.5.2.021017

  5. [5]

    2018, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol

    Barret, D., Lam Trong, T., den Herder, J.-W., et al. 2018, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray, ed. J.-W. A. den Herder, S. Nikzad, & K. Nakazawa, 106991G, doi: 10.1117/12.2312409

  6. [6]

    2013, MNRAS, 430, 3292, doi: 10.1093/mnras/stt131 Bogd´ an,´A., Bourdin, H., Forman, W

    Bertone, S., Aguirre, A., & Schaye, J. 2013, MNRAS, 430, 3292, doi: 10.1093/mnras/stt131 Bogd´ an,´A., Bourdin, H., Forman, W. R., et al. 2017, ApJ, 850, 98, doi: 10.3847/1538-4357/aa9523 Bogd´ an,´A., Forman, W. R., Vogelsberger, M., et al. 2013, ApJ, 772, 97, doi: 10.1088/0004-637X/772/2/97

  7. [7]

    N., Hodges-Kluck, E., Qu, Z., et al

    Bregman, J. N., Hodges-Kluck, E., Qu, Z., et al. 2022, ApJ, 928, 14, doi: 10.3847/1538-4357/ac51de

  8. [8]

    L., Norman, M

    Bryan, G. L., Norman, M. L., O’Shea, B. W., et al. 2014, ApJS, 211, 19, doi: 10.1088/0067-0049/211/2/19

Show all 92 references
  1. [9]

    2020, MNRAS, 497, 1712, doi: 10.1093/mnras/staa1960

    Springel, V. 2020, MNRAS, 497, 1712, doi: 10.1093/mnras/staa1960

  2. [10]

    N., Rubin, K

    Burchett, J. N., Rubin, K. H. R., Prochaska, J. X., et al. 2021, ApJ, 909, 151, doi: 10.3847/1538-4357/abd4e0

  3. [11]

    N., Tripp, T

    Burchett, J. N., Tripp, T. M., Bordoloi, R., et al. 2016, ApJ, 832, 124, doi: 10.3847/0004-637X/832/2/124

  4. [12]

    N., Tripp, T

    Burchett, J. N., Tripp, T. M., Prochaska, J. X., et al. 2019, ApJL, 877, L20, doi: 10.3847/2041-8213/ab1f7f

  5. [13]

    S., & Quinn, T

    Butsky, I. S., & Quinn, T. R. 2018, ApJ, 868, 108, doi: 10.3847/1538-4357/aaeac2

  6. [14]

    2018, ApJL, 861, L3, doi: 10.3847/2041-8213/aacce6

    Cai, Z., Hamden, E., Matuszewski, M., et al. 2018, ApJL, 861, L3, doi: 10.3847/2041-8213/aacce6

  7. [15]

    D., et al

    Chadayammuri, U., Bogd´ an,´A., Oppenheimer, B. D., et al. 2022, ApJL, 936, L15, doi: 10.3847/2041-8213/ac8936

  8. [16]

    K., Kereˇ s, D., Gurvich, A

    Chan, T. K., Kereˇ s, D., Gurvich, A. B., et al. 2022, MNRAS, 517, 597, doi: 10.1093/mnras/stac2236

  9. [17]

    K., Kereˇ s, D., Hopkins, P

    Chan, T. K., Kereˇ s, D., Hopkins, P. F., et al. 2019, MNRAS, 488, 3716, doi: 10.1093/mnras/stz1895

  10. [18]

    2001, MNRAS, 323, 93, doi: 10.1046/j.1365-8711.2001.04090.x

    Churazov, E., Haehnelt, M., Kotov, O., & Sunyaev, R. 2001, MNRAS, 323, 93, doi: 10.1046/j.1365-8711.2001.04090.x

  11. [19]

    Kacprzak, G. G. 2013, ApJ, 779, 87, doi: 10.1088/0004-637X/779/1/87

  12. [20]

    2022, A&A, 666, A156, doi: 10.1051/0004-6361/202243101

    Comparat, J., Truong, N., Merloni, A., et al. 2022, A&A, 666, A156, doi: 10.1051/0004-6361/202243101

  13. [21]

    2022, Nature Astronomy, 6, 1035, doi: 10.1038/s41550-022-01719-7

    Connor, L., & Ravi, V. 2022, Nature Astronomy, 6, 1035, doi: 10.1038/s41550-022-01719-7

  14. [22]

    A., & van de Voort, F

    Crain, R. A., & van de Voort, F. 2023, ARA&A, 61, 473, doi: 10.1146/annurev-astro-041923-043618

  15. [23]

    A., Schaye, J., Bower, R

    Crain, R. A., Schaye, J., Bower, R. G., et al. 2015, MNRAS, 450, 1937, doi: 10.1093/mnras/stv725

  16. [24]

    Dalcin, L., & Fang, Y.-L. L. 2021, Computing in Science and Engineering, 23, 47, doi: 10.1109/MCSE.2021.3083216

  17. [25]

    2020, ApJ, 897, 63, doi: 10.3847/1538-4357/ab93d2

    Das, S., Mathur, S., & Gupta, A. 2020, ApJ, 897, 63, doi: 10.3847/1538-4357/ab93d2

  18. [26]

    2019, ApJ, 885, 108, doi: 10.3847/1538-4357/ab48df Dav´ e, R., Angl´ es-Alc´ azar, D., Narayanan, D., et al

    Das, S., Mathur, S., Gupta, A., et al. 2019, ApJ, 885, 108, doi: 10.3847/1538-4357/ab48df Dav´ e, R., Angl´ es-Alc´ azar, D., Narayanan, D., et al. 2019, MNRAS, 486, 2827, doi: 10.1093/mnras/stz937

  19. [27]

    J., Crain, R

    Davies, J. J., Crain, R. A., Oppenheimer, B. D., & Schaye, J. 2020, MNRAS, 491, 4462, doi: 10.1093/mnras/stz3201

  20. [28]

    2018, MNRAS, 473, 1930, doi: 10.1093/mnras/stx2482 Faucher-Gigu` ere, C.-A., & Oh, S

    El-Badry, K., Quataert, E., Wetzel, A., et al. 2018, MNRAS, 473, 1930, doi: 10.1093/mnras/stx2482 Faucher-Gigu` ere, C.-A., & Oh, S. P. 2023, ARA&A, 61, 131, doi: 10.1146/annurev-astro-052920-125203

  21. [29]

    J., Chatzikos, M., Guzm´ an, F., et al

    Ferland, G. J., Chatzikos, M., Guzm´ an, F., et al. 2017, RMxAA, 53, 385, doi: 10.48550/arXiv.1705.10877

  22. [30]

    R., Ji, L., Smith, R

    Foster, A. R., Ji, L., Smith, R. K., & Brickhouse, N. S. 2012, ApJ, 756, 128, doi: 10.1088/0004-637X/756/2/128

  23. [31]

    F., Wetzel, A., et al

    Garrison-Kimmel, S., Hopkins, P. F., Wetzel, A., et al. 2018, MNRAS, 481, 4133, doi: 10.1093/mnras/sty2513

  24. [32]

    R., Millman, K

    Harris, C. R., Millman, K. J., van der Walt, S. J., et al. 2020, Nature, 585, 357, doi: 10.1038/s41586-020-2649-2

  25. [33]

    2016, ApJ, 828, 49, doi: 10.3847/0004-637X/828/1/49

    Hayes, M., Melinder, J., ¨Ostlin, G., et al. 2016, ApJ, 828, 49, doi: 10.3847/0004-637X/828/1/49

  26. [34]

    Hopkins, P. F. 2015, MNRAS, 450, 53, doi: 10.1093/mnras/stv195 —. 2017, arXiv e-prints, arXiv:1712.01294, doi: 10.48550/arXiv.1712.01294

  27. [35]

    F., Chan, T

    Hopkins, P. F., Chan, T. K., Ji, S., et al. 2021, MNRAS, 501, 3640, doi: 10.1093/mnras/staa3690

  28. [36]

    F., Kereˇ s, D., O˜ norbe, J., et al

    Hopkins, P. F., Kereˇ s, D., O˜ norbe, J., et al. 2014, MNRAS, 445, 581, doi: 10.1093/mnras/stu1738 28

  29. [37]

    F., Quataert, E., Ponnada, S

    Hopkins, P. F., Quataert, E., Ponnada, S. B., & Silich, E. 2025, arXiv e-prints, arXiv:2501.18696. https://arxiv.org/abs/2501.18696

  30. [38]

    F., & Raives, M

    Hopkins, P. F., & Raives, M. J. 2016, MNRAS, 455, 51, doi: 10.1093/mnras/stv2180

  31. [39]

    F., Wetzel, A., Kereˇ s, D., et al

    Hopkins, P. F., Wetzel, A., Kereˇ s, D., et al. 2018, MNRAS, 480, 800, doi: 10.1093/mnras/sty1690

  32. [40]

    F., Chan, T

    Hopkins, P. F., Chan, T. K., Garrison-Kimmel, S., et al. 2020, MNRAS, 492, 3465, doi: 10.1093/mnras/stz3321

  33. [41]

    B., Bryan, G

    Hummels, C. B., Bryan, G. L., Smith, B. D., & Turk, M. J. 2013, MNRAS, 430, 1548, doi: 10.1093/mnras/sts702

  34. [42]

    B., Smith, B

    Hummels, C. B., Smith, B. D., Hopkins, P. F., et al. 2019, ApJ, 882, 156, doi: 10.3847/1538-4357/ab378f

  35. [43]

    J., Buote, D

    Humphrey, P. J., Buote, D. A., Canizares, C. R., Fabian, A. C., & Miller, J. M. 2011, ApJ, 729, 53, doi: 10.1088/0004-637X/729/1/53

  36. [44]

    Hunter, J. D. 2007, Computing in Science and Engineering, 9, 90, doi: 10.1109/MCSE.2007.55

  37. [45]

    P., & Masterson, P

    Ji, S., Oh, S. P., & Masterson, P. 2019, MNRAS, 487, 737, doi: 10.1093/mnras/stz1248

  38. [46]

    K., Hummels, C

    Ji, S., Chan, T. K., Hummels, C. B., et al. 2020, MNRAS, 496, 4221, doi: 10.1093/mnras/staa1849

  39. [47]

    2019, MNRAS, 482, 4972, doi: 10.1093/mnras/sty2992

    Khabibullin, I., & Churazov, E. 2019, MNRAS, 482, 4972, doi: 10.1093/mnras/sty2992

  40. [48]

    2022, arXiv e-prints, arXiv:2211.09827, doi: 10.48550/arXiv.2211.09827

    Kraft, R., Markevitch, M., Kilbourne, C., et al. 2022, arXiv e-prints, arXiv:2211.09827, doi: 10.48550/arXiv.2211.09827

  41. [49]

    Anderson, M. E. 2018, ApJL, 855, L24, doi: 10.3847/2041-8213/aab2af

  42. [50]

    N., Wang, Q

    Li, J.-T., Bregman, J. N., Wang, Q. D., et al. 2017, ApJS, 233, 20, doi: 10.3847/1538-4365/aa96fc

  43. [51]

    S., Kereˇ s, D., Hopkins, P

    Lu, Y. S., Kereˇ s, D., Hopkins, P. F., et al. 2025, arXiv e-prints, arXiv:2505.13597, doi: 10.48550/arXiv.2505.13597

  44. [52]

    L., Kereˇ s, D., Faucher-Gigu` ere, C.-A., et al

    Muratov, A. L., Kereˇ s, D., Faucher-Gigu` ere, C.-A., et al. 2015, MNRAS, 454, 2691, doi: 10.1093/mnras/stv2126

  45. [53]

    2019, MNRAS, 490, 3234, doi: 10.1093/mnras/stz2306

    Nelson, D., Pillepich, A., Springel, V., et al. 2019, MNRAS, 490, 3234, doi: 10.1093/mnras/stz2306

  46. [54]

    Murphy, M. T. 2013, ApJ, 776, 114, doi: 10.1088/0004-637X/776/2/114

  47. [55]

    D., & Schaye, J

    Oppenheimer, B. D., & Schaye, J. 2013, MNRAS, 434, 1043, doi: 10.1093/mnras/stt1043

  48. [56]

    D., Crain, R

    Oppenheimer, B. D., Crain, R. A., Schaye, J., et al. 2016, MNRAS, 460, 2157, doi: 10.1093/mnras/stw1066

  49. [57]

    E., Hayward, C

    Orr, M. E., Hayward, C. C., Medling, A. M., et al. 2020, MNRAS, 496, 1620, doi: 10.1093/mnras/staa1619

  50. [58]

    S., Corlies, L., Tumlinson, J., et al

    Peeples, M. S., Corlies, L., Tumlinson, J., et al. 2019, ApJ, 873, 129, doi: 10.3847/1538-4357/ab0654

  51. [59]

    2021, MNRAS, 508, 4667, doi: 10.1093/mnras/stab2779

    Pillepich, A., Nelson, D., Truong, N., et al. 2021, MNRAS, 508, 4667, doi: 10.1093/mnras/stab2779

  52. [60]

    2018, MNRAS, 473, 4077, doi: 10.1093/mnras/stx2656

    Pillepich, A., Springel, V., Nelson, D., et al. 2018, MNRAS, 473, 4077, doi: 10.1093/mnras/stx2656

  53. [61]

    2019, MNRAS, 490, 3196, doi: 10.1093/mnras/stz2338

    Pillepich, A., Nelson, D., Springel, V., et al. 2019, MNRAS, 490, 3196, doi: 10.1093/mnras/stz2338

  54. [62]

    2024, MNRAS, 535, 1721, doi: 10.1093/mnras/stae2165 Planck Collaboration, Ade, P

    Pillepich, A., Sotillo-Ramos, D., Ramesh, R., et al. 2024, MNRAS, 535, 1721, doi: 10.1093/mnras/stae2165 Planck Collaboration, Ade, P. A. R., Aghanim, N., et al. 2014, A&A, 571, A16, doi: 10.1051/0004-6361/201321591 —. 2016, A&A, 594, A13, doi: 10.1051/0004-6361/201525830

  55. [63]

    B., Panopoulou, G

    Ponnada, S. B., Panopoulou, G. V., Butsky, I. S., et al. 2022, Monthly Notices of the Royal Astronomical Society, 516, 4417, doi: 10.1093/mnras/stac2448

  56. [64]

    S., Kilbourne, C

    Porter, F. S., Kilbourne, C. A., Chiao, M., et al. 2024, in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, Vol. 13093, Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, ed. J.-W. A. den Herder, S. Nikzad, & K. Nakazawa, 130931K,...

  57. [65]

    2019, ApJ, 872, 88, doi: 10.3847/1538-4357/aafb30 Roca-F` abrega, S., Kim, J.-H., Hausammann, L., et al

    Ravi, V. 2019, ApJ, 872, 88, doi: 10.3847/1538-4357/aafb30 Roca-F` abrega, S., Kim, J.-H., Hausammann, L., et al. 2021, ApJ, 917, 64, doi: 10.3847/1538-4357/ac088a

  58. [66]

    Rupke, D. S. N., Coil, A., Geach, J. E., et al. 2019, Nature, 574, 643, doi: 10.1038/s41586-019-1686-1

  59. [67]

    Salem, M., & Bryan, G. L. 2014, MNRAS, 437, 3312, doi: 10.1093/mnras/stt2121

  60. [68]

    L., & Corlies, L

    Salem, M., Bryan, G. L., & Corlies, L. 2016, MNRAS, 456, 582, doi: 10.1093/mnras/stv2641

  61. [69]

    A., Bower, R

    Schaye, J., Crain, R. A., Bower, R. G., et al. 2015, MNRAS, 446, 521, doi: 10.1093/mnras/stu2058

  62. [70]

    A., et al

    Schellenberger, G., Bogd´ an,´A., ZuHone, J. A., et al. 2024, ApJ, 969, 85, doi: 10.3847/1538-4357/ad4548

  63. [71]

    Raymond, J. C. 2001, ApJL, 556, L91, doi: 10.1086/322992

  64. [72]

    2010, MNRAS, 401, 791, doi: 10.1111/j.1365-2966.2009.15715.x

    Springel, V. 2010, MNRAS, 401, 791, doi: 10.1111/j.1365-2966.2009.15715.x

  65. [73]

    C., Adelberger, K

    Steidel, C. C., Adelberger, K. L., Shapley, A. E., et al. 2000, ApJ, 532, 170, doi: 10.1086/308568

  66. [74]

    2021, ApJ, 911, 88, doi: 10.3847/1538-4357/abd776

    Stern, J., Faucher-Gigu` ere, C.-A., Fielding, D., et al. 2021, ApJ, 911, 88, doi: 10.3847/1538-4357/abd776

  67. [75]

    T., Keeney, B

    Stocke, J. T., Keeney, B. A., Danforth, C. W., et al. 2013, ApJ, 763, 148, doi: 10.1088/0004-637X/763/2/148

  68. [76]

    F., Hayward, C

    Su, K.-Y., Hopkins, P. F., Hayward, C. C., et al. 2017, MNRAS, 471, 144, doi: 10.1093/mnras/stx1463

  69. [77]

    2015, MNRAS, 448, 895, doi: 10.1093/mnras/stu2762 29

    Suresh, J., Bird, S., Vogelsberger, M., et al. 2015, MNRAS, 448, 895, doi: 10.1093/mnras/stu2762 29

  70. [78]

    2021, MNRAS, 508, 1563, doi: 10.1093/mnras/stab2638

    Hernquist, L. 2021, MNRAS, 508, 1563, doi: 10.1093/mnras/stab2638

  71. [79]

    2023, MNRAS, 525, 1976, doi: 10.1093/mnras/stad2216

    Truong, N., Pillepich, A., Nelson, D., et al. 2023, MNRAS, 525, 1976, doi: 10.1093/mnras/stad2216

  72. [80]

    S., & Werk, J

    Tumlinson, J., Peeples, M. S., & Werk, J. K. 2017, ARA&A, 55, 389, doi: 10.1146/annurev-astro-091916-055240

  73. [81]

    K., et al

    Tumlinson, J., Thom, C., Werk, J. K., et al. 2011, Science, 334, 948, doi: 10.1126/science.1209840 —. 2013, ApJ, 777, 59, doi: 10.1088/0004-637X/777/1/59

  74. [82]

    J., Smith, B

    Turk, M. J., Smith, B. D., Oishi, J. S., et al. 2011, ApJS, 192, 9, doi: 10.1088/0067-0049/192/1/9 van de Voort, F., Springel, V., Mandelker, N., van den

  75. [83]

    C., & Pakmor, R

    Bosch, F. C., & Pakmor, R. 2019, MNRAS, 482, L85, doi: 10.1093/mnrasl/sly190 van der Walt, S., Colbert, S. C., & Varoquaux, G. 2011, Computing in Science and Engineering, 13, 22, doi: 10.1109/MCSE.2011.37

  76. [84]

    K., Prochaska, J

    Werk, J. K., Prochaska, J. X., Thom, C., et al. 2013, ApJS, 204, 17, doi: 10.1088/0067-0049/204/2/17

  77. [85]

    K., Prochaska, J

    Werk, J. K., Prochaska, J. X., Tumlinson, J., et al. 2014, ApJ, 792, 8, doi: 10.1088/0004-637X/792/1/8

  78. [86]

    K., Prochaska, J

    Werk, J. K., Prochaska, J. X., Cantalupo, S., et al. 2016, ApJ, 833, 54, doi: 10.3847/1538-4357/833/1/54

  79. [87]

    A., Schaye, J., & Oppenheimer, B

    Wijers, N. A., Schaye, J., & Oppenheimer, B. D. 2020, MNRAS, 498, 574, doi: 10.1093/mnras/staa2456

  80. [88]

    C., Tumlinson, J., Peeples, M

    Wright, A. C., Tumlinson, J., Peeples, M. S., et al. 2024, ApJ, 970, 70, doi: 10.3847/1538-4357/ad49a3

  81. [89]

    2023, ApJ, 945, 87, doi: 10.3847/1538-4357/acbc7d

    Wu, X., & McQuinn, M. 2023, ApJ, 945, 87, doi: 10.3847/1538-4357/acbc7d

  82. [90]

    2024, arXiv e-prints, arXiv:2401.17308, doi: 10.48550/arXiv.2401.17308

    Zhang, Y., Comparat, J., Ponti, G., et al. 2024, arXiv e-prints, arXiv:2401.17308, doi: 10.48550/arXiv.2401.17308

  83. [91]

    A., & Hallman, E

    ZuHone, J. A., & Hallman, E. J. 2016, pyXSIM: Synthetic X-ray observations generator. http://ascl.net/1608.002

  84. [92]

    A., Schellenberger, G., Ogorza lek, A., et al

    ZuHone, J. A., Schellenberger, G., Ogorza lek, A., et al. 2024, ApJ, 967, 49, doi: 10.3847/1538-4357/ad36c1 30 APPENDIX A. THE NEED FOR PHOTOIONIZATION IN X-RAY EMISSIVITY CALCULATIONS In the low-density warm/hot CGM, photoionization by the cosmic UV/X-ray background radiation...

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