THE SHAPES OF THE H I VELOCITY PROFILES OF THE THINGS GALAXIES
- Max-Planck Institut fuer Astronomie, Koenigstuhl 17, D-69117, Heidelberg (Germany)
We analyze the shapes of the H I velocity profiles of The H I Nearby Galaxy Survey to study the phase structure of the neutral interstellar medium and its relation to global galaxy properties. We use a method analogous to the stacking method sometimes used in high-redshift H I observations to construct high-signal-to-noise (S/N) profiles. We call these high-S/N profiles super profiles. We analyze and discuss possible systematics that may change the observed shapes of the super profiles. After quantifying these effects and selecting a subsample of unaffected galaxies, we find that the super profiles are best described by a narrow and a broad Gaussian component, which are evidence of the presence of the cold neutral medium and the warm neutral medium. The velocity dispersion of the narrow component ranges from {approx}3.4 to {approx}8.6 km s{sup -1} with an average of 6.5 {+-} 1.5 km s{sup -1}, whereas that of the broad component ranges from {approx}10.1 to {approx}24.3 km s{sup -1} with an average of 16.8 {+-} 4.3 km s{sup -1}. We find that the super profile parameters correlate with star formation indicators such as metallicity, far-UV-near-UV colors, and H{alpha} luminosities. The flux ratio between the narrow and broad components tends to be highest for high-metallicity, high-star-formation-rate galaxies. We show that the narrow component identified in the super profiles is associated with the presence of star formation, and possibly with molecular hydrogen.
- OSTI ID:
- 22089869
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 144, Issue 4; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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