The \HI column density power spectrum of six nearby spiral galaxies

Abstract

We propose a method to determine the power spectrum of \HI column density fluctuations using radio-interferometric observations of 21-cm emission from the ISM of galaxies. We have used this to estimate the power spectra of six nearly face on nearby spiral galaxies. Earlier work has shown that these power spectra are well fitted by power laws with slopes around -1.6 across length-scales $\sim 1\mathrm{kpc}$ to $\sim 10\mathrm{kpc}$, the amplitude however was undetermined. In the present work we have determined the amplitude of the \HI column density power spectrum. We find that the \HI column density $N_{\mathrm{HI}}$ expressed in units of $10^{20}{\mathrm{cm}}^{-2}$ has mean square fluctuations in the range $\sim 0.03$ to $\sim 20$. The amplitude of the power spectrum is found to be tightly correlated with the \HI mass fraction of the galaxies. The physical process responsible for these scale-invariant fluctuations is, however, at present not known.

12 pages, 4 figures, accepted for publication; MNRAS lett. (2013)

References in corpus (6)

• High-Resolution Rotation Curves and Galaxy Mass Models from THINGS
• Power spectrum of HI intensity fluctuations in DDO 210
• HI power spectrum of the spiral galaxy NGC628
• Probing interstellar turbulence in spiral galaxies using HI power spectrum analysis
• HI 21 cm opacity fluctuations power spectra towards Cassiopeia A
• On the Origin of the High Column Density Turnover in the HI Column Density Distribution

Cited by in corpus (14)

• The impact of stellar feedback on the density and velocity structure of the interstellar medium
• The SATIN project I: Turbulent multi-phase ISM in Milky Way simulations with SNe feedback from stellar clusters
• Spatial Power Spectra of Dust across the Local Group: No Constraint on Disc Scale Height
• The structure and characteristic scales of the HI gas in galactic disks
• Evidence of large scale energy cascade in the spiral galaxy NGC 5236
• An Image-based Tapered Gridded Estimator (ITGE) for the angular power spectrum
• Probing galaxy evolution through HI 21-cm emission and absorption: current status and prospects with the Square Kilometre Array
• Calibration requirements for Epoch of Reionization 21-cm signal observations -- II. Analytical estimation of the bias and variance with time-correlated residual gains
• Visibility moments and power spectrum of turbulence velocity
• Effect of turbulent velocity on the \HI intensity fluctuation power spectrum from spiral galaxies
• Estimating statistics of sky brightness using radio interferometric observations
• HI column density statistics of the cold neutral medium from absorption studies
• Calibration requirement for Epoch of Reionization 21-cm signal observation -- III. Bias and variance in uGMRT ELAIS-N1 field power spectrum
• Power spectrum to probe turbulence in Interstellar medium using 21cm line