Repository logo

Infoscience

  • English
  • French
Log In
Logo EPFL, École polytechnique fédérale de Lausanne

Infoscience

  • English
  • French
Log In
  1. Home
  2. Academic and Research Output
  3. Journal articles
  4. On the distribution of the cold neutral medium in galaxy discs
 
research article

On the distribution of the cold neutral medium in galaxy discs

Smith, Rowan J.
•
Tress, Robin  
•
Soler, Juan D.
Show more
July 4, 2023
Monthly Notices Of The Royal Astronomical Society

The cold neutral medium (CNM) is an important part of the galactic gas cycle and a precondition for the formation of molecular and star-forming gas, yet its distribution is still not fully understood. In this work, we present extremely high resolution simulations of spiral galaxies with time-dependent chemistry such that we can track the formation of the CNM, its distribution within the galaxy, and its correlation with star formation. We find no strong radial dependence between the CNM fraction and total neutral atomic hydrogen (H i) due to the decreasing interstellar radiation field counterbalancing the decreasing gas column density at larger galactic radii. However, the CNM fraction does increase in spiral arms where the CNM distribution is clumpy, rather than continuous, overlapping more closely with H-2. The CNM does not extend out radially as far as H i, and the vertical scale height is smaller in the outer galaxy compared to H i with no flaring. The CNM column density scales with total mid-plane pressure and disappears from the gas phase below values of P-T/k(B) = 1000 K cm(-3). We find that the star formation rate density follows a similar scaling law with CNM column density to the total gas Kennicutt-Schmidt law. In the outer galaxy, we produce realistic vertical velocity dispersions in the H i purely from galactic dynamics, but our models do not predict CNM at the extremely large radii observed in H i absorption studies of the Milky Way. We suggest that extended spiral arms might produce isolated clumps of CNM at these radii.

  • Files
  • Details
  • Metrics
Loading...
Thumbnail Image
Name

document.pdf

Type

Publisher's Version

Version

http://purl.org/coar/version/c_970fb48d4fbd8a85

Access type

openaccess

License Condition

CC BY

Size

2.43 MB

Format

Adobe PDF

Checksum (MD5)

28607dd1aeca44445b0df14a1c729bc7

Logo EPFL, École polytechnique fédérale de Lausanne
  • Contact
  • infoscience@epfl.ch

  • Follow us on Facebook
  • Follow us on Instagram
  • Follow us on LinkedIn
  • Follow us on X
  • Follow us on Youtube
AccessibilityLegal noticePrivacy policyCookie settingsEnd User AgreementGet helpFeedback

Infoscience is a service managed and provided by the Library and IT Services of EPFL. © EPFL, tous droits réservés