| Type |
Journal Article |
| Names |
Claire E. Murray, Robert R. Lindner, Snežana Stanimirović, W. M. Goss, Carl Heiles, John Dickey, Nickolas M. Pingel, Allen Lawrence, Jacob Jencson, Brian L. Babler, Patrick Hennebelle |
| Publication |
The Astrophysical Journal Letters |
| Volume |
781 |
| Pages |
L41 |
| Journal Abbreviation |
The Astrophysical Journal Letters |
| Date |
February 1, 2014 |
| DOI |
10.1088/2041-8205/781/2/L41 |
| ISSN |
0004-637X |
| URL |
http://adsabs.org/2014ApJ.781L.41M |
| Library Catalog |
labs.adsabs.harvard.edu |
| Abstract |
We use the Karl G. Jansky Very Large Array to conduct a high-sensitivity
survey of neutral hydrogen (H I) absorption in the Milky Way. In
combination with corresponding H I emission spectra obtained mostly with
the Arecibo Observatory, we detect a widespread warm neutral medium
component with excitation temperature \langle T_s\rangle =
7200^{+1800}_{-1200}\,K (68% confidence). This temperature lies above
theoretical predictions based on collisional excitation alone, implying
that Lyα scattering, the most probable additional source of
excitation, is more important in the interstellar medium (ISM) than
previously assumed. Our results demonstrate that H I absorption can be
used to constrain the Lyα radiation field, a critical quantity for
studying the energy balance in the ISM and intergalactic medium yet
notoriously difficult to model because of its complicated radiative
transfer, in and around galaxies nearby and at high redshift. |
| Tags |
ISM: clouds, ISM: structure |