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PreprintarXiv licencearXiv

Studying the absorption signatures of H I Lyman-α in the warm-hot circumgalactic medium with TNG50

  • P. Aparicio Marcos
  • P. Richter
  • M. Sparre
  • F. Rünger
  • D. Nelson
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Abstract

In this study, we investigate the spectral signatures of neutral hydrogen Lyman-α absorption arising from the warm-hot gas component of the circumgalactic medium (CGM) around z=0 Milky Way (MW)-like galaxies using the high-resolution TNG50 cosmological simulation. We used synthetic absorption spectra to identify and characterise coronal broad Lyα absorbers (CBLAs), which represent H I absorption features produced by the warm-hot CGM at temperatures above 105 K. Our study implies that CBLAs have a significant absorption cross-section, fc, around MW-like galaxies. Based on an analysis of 75 sightlines intersecting the CGM of 15 galaxies in the mass range 1011.7 M⊙ ≤ M200 ≤ 1012.3 M⊙, we find fc ≈ 0.8 for log NHI ≥ 13, where CBLAs span a total column-density range log NHI=11.6−15.4. Therefore, CBLAs provide a significant contribution to the overall H I optical depth in the CGM with ∼ 50% of the CGM absorbers being dominated by CBLA absorption. Furthermore, we find that CBLAs trace warm-hot gas in a temperature range T=105.2−6.4 K, which accounts for ∼ 7% of the overall baryon budget in the TNG50 galaxies and ∼ 25% of the total CGM mass. Finally, we identify a population of strong CBLAs that exhibit substantial H I column densities up to log NHI=14.9. This population represents a new absorber class tracing massive warm-hot circumgalactic structures at large radial distances. In conclusion, our study demonstrates that CBLAs represent an important absorber class that needs to be considered when interpreting the H I absorption signatures from the multi-phase CGM of MW-like galaxies at low redshift.

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Cite

BibTeXRIS
BibTeX
@misc{marcos2026studying,
  title = {{Studying the absorption signatures of H I Lyman-α in the warm-hot circumgalactic medium with TNG50}},
  author = {P. Aparicio Marcos and P. Richter and M. Sparre and F. Rünger and D. Nelson},
  howpublished = {arXiv},
  year = {2026},
  month = jun,
  doi = {10.48550/arxiv.2606.04083},
  eprint = {2606.04083},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2606.04083},
}
RIS
TY  - UNPB
TI  - Studying the absorption signatures of H I Lyman-α in the warm-hot circumgalactic medium with TNG50
AU  - P. Aparicio Marcos
AU  - P. Richter
AU  - M. Sparre
AU  - F. Rünger
AU  - D. Nelson
PY  - 2026
DA  - 2026/06/02
PB  - arXiv
DO  - 10.48550/arxiv.2606.04083
UR  - https://arxiv.org/abs/2606.04083
AB  - In this study, we investigate the spectral signatures of neutral hydrogen Lyman-α absorption arising from the warm-hot gas component of the circumgalactic medium (CGM) around z=0 Milky Way (MW)-like galaxies using the high-resolution TNG50 cosmological simulation. We used synthetic absorption spectra to identify and characterise coronal broad Lyα absorbers (CBLAs), which represent H I absorption features produced by the warm-hot CGM at temperatures above 10^5 K. Our study implies that CBLAs have a significant absorption cross-section, f_c, around MW-like galaxies. Based on an analysis of 75 sightlines intersecting the CGM of 15 galaxies in the mass range 10^11.7 M_⊙ ≤ M_200 ≤ 10^12.3 M_⊙, we find f_c ≈ 0.8 for log N_HI ≥ 13, where CBLAs span a total column-density range log N_HI=11.6−15.4. Therefore, CBLAs provide a significant contribution to the overall H I optical depth in the CGM with ∼ 50% of the CGM absorbers being dominated by CBLA absorption. Furthermore, we find that CBLAs trace warm-hot gas in a temperature range T=10^5.2−6.4 K, which accounts for ∼ 7% of the overall baryon budget in the TNG50 galaxies and ∼ 25% of the total CGM mass. Finally, we identify a population of strong CBLAs that exhibit substantial H I column densities up to log N_HI=14.9. This population represents a new absorber class tracing massive warm-hot circumgalactic structures at large radial distances. In conclusion, our study demonstrates that CBLAs represent an important absorber class that needs to be considered when interpreting the H I absorption signatures from the multi-phase CGM of MW-like galaxies at low redshift.
ER  -