2009/05/12 by Prasun Dutta, Ayesha Begum, Somnath Bharadwaj +1 · 2 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Dwarf galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Interstellar medium #Length scale #Physics #Power law #Spectral density #Spiral galaxy #Star formation #Statistics #Stellar, planetary, and galactic studies #Turbulence #astro-ph.GA
paper · pdf · doi:10.1111/j.1365-2966.2009.15105.x
24 pages 10 figures and 2 tables. Accepted for publication in Mon. Not. of Royal Astron. Soc
arxiv created 2009/05/12 · openalex publication_date 2009/08/10 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We estimate the power spectrum of H i intensity fluctuations for a sample of eight galaxies (seven dwarf and one spiral). The power spectrum can be fitted to a power-law for six of these galaxies, indicating turbulence is operational. The estimated best-fitting value for the slope ranges from ∼−1.5 (AND IV, NGC 628, UGC 4459 and GR 8) to ∼−2.6 (DDO 210 and NGC 3741). We interpret this bi-modality as being due to having effectively 2D turbulence on length-scales much larger than the scale-height of the galaxy disc and 3D otherwise. This allows us to use the estimated slope to set bounds on the scale-heights of the face-on galaxies in our sample. We also find that the power-law slope remains constant as we increase the channel thickness for all these galaxies, suggesting that the fluctuations in H i intensity are due to density fluctuations and not velocity fluctuations, or that the slope of the velocity structure function is ∼0. Finally, for the four galaxies with ‘2D turbulence’ we find that the slope α correlates with the star formation rate (SFR) per unit area, with larger SFRs leading to steeper power laws. Given our small sample size, this result needs to be confirmed with a larger sample.