Power spectrum of HI intensity fluctuations in DDO 210

Abstract

We measure the power spectrum of HI intensity fluctuations in the extremely faint (M_B ~ -10.9) dwarf galaxy DDO 210 using a visibility based estimator that is well suited in very low signal to noise ratio regimes. DDO 210's HI power spectrum is well fit by a power law $P_{H}I(U)=A{U}^{\alpha }$ with $\alpha =-2.75\pm 0.45$ over the length-scales 80 pc to 500 pc. We also find that the power spectrum does not change with an increase in the velocity channel width, indicating that the measured fluctuations correspond mainly to density fluctuations. However, Kolmogorov turbulence (with a velocity structure function spectral slope of 2/3) cannot be ruled out from the present observations. The value of the slope $\alpha$ is similar to that obtained in the Milkyway. In contrast to the Milkyway, DDO 210 has three orders of magnitude less HI, no spiral arms, and also no measurable ongoing star formation. The fact that the power spectrum slope is nonetheless similar in these two galaxies (and also similar to the values measured for the LMC and SMC) suggests that there is some universal, star formation independent, phenomenon responsible for producing fine scale structure in the gas.

5 Pages, 3 Figures. Accepted for publication in MNRAS Letters

References in corpus (1)

• On using visibility correlations to probe the HI distribution from the dark ages to the present epoch I: Formalism and the expected signal

Cited by in corpus (24)

• Foregrounds for redshifted 21 cm studies of reionization: GMRT 153 MHz observations
• Characterizing Foreground for redshifted 21-cm radiation: 150 MHz GMRT observations
• Visibility based angular power spectrum estimation in low frequency radio interferometric observations
• Characterizing gravitational instability in turbulent multi-component galactic discs
• HI power spectrum of the spiral galaxy NGC628
• The Fractal Distribution of HII Regions in Disk Galaxies
• The effect of ISM turbulence on the gravitational instability of galactic discs
• Curvature of magnetic field lines in compressible magnetized turbulence: Statistics, magnetization predictions, gradient curvature, modes and self-gravitating media
• Probing interstellar turbulence in spiral galaxies using HI power spectrum analysis
• The structure and characteristic scales of molecular clouds
• HI 21 cm opacity fluctuations power spectra towards Cassiopeia A
• Magnetohydrodynamic turbulence in supernova remnants
• Tiny scale opacity fluctuations from VLBA, MERLIN and VLA observations of HI absorption toward 3C 138
• The impact of non-Gaussianity on the Epoch of Reionization parameter forecast using 21-cm power spectrum measurements
• 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
• Anomalous compressible mode generation by global frame projections of pure Alfven mode
• Evidence of large scale energy cascade in the spiral galaxy NGC 5236
• Modeling HI distribution and kinematics in the edge-on dwarf irregular galaxy KK250
• Simulated foreground predictions for HI at z = 3.35 with the Ooty Wide Field Array: I. Instrument and the foregrounds
• 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
• Effect of turbulent velocity on the \HI intensity fluctuation power spectrum from spiral galaxies
• Dust and Gas as Seeds for Metal-Poor Star Formation