We present a new method which constructs an Hi super-profile of a galaxy which is based on profile decomposition analysis. The decomposed velocity profiles of an Hi data cube with an optimal number of Gaussian components are co-added after being aligned in velocity with respect to their centroid velocities. This is compared to the previous approach where no prior profile decomposition is made for the velocity profiles being stacked. The S/N improved super-profile is useful for deriving the galaxy’s global Hi properties like velocity dispersion and mass from observations which do not provide sufficient surface brightness sensitivity for the galaxy. As a practical test, we apply our new method to 64 high-resolution Hi data cubes of nearby galaxies in the local Universe which are taken from THINGS and LITTLE THINGS. In addition, we also construct two additional Hi super-profiles of the sample galaxies using symmetric and all velocity profiles of the cubes whose centroid velocities are determined from Hermite h3 polynomial fitting, respectively. We find that the Hi super-profiles constructed using the new method have narrower cores and broader wings in shape than the other two super-profiles. This is mainly due to the effect of either asymmetric velocity profiles’ central velocity bias or the removal of asymmetric velocity profiles in the previous methods on the resulting Hi super-profiles. We discuss how the shapes (σn/σb, An/Ab, and An/Atot) of the new Hi super-profiles which are measured from a double Gaussian fit are correlated with star formation rates of the sample galaxies and are compared with those of the other two super-profiles.

1. INTRODUCTION
2. HI SUPER-PROFILES
    2.1. Profile Decomposition
    2.2. Stacking of the Decomposed Velocity Profiles
    2.3. Parameterizing the Shapes of Super-Profiles
    2.4. FittingWeights of 2gfit Analysis
    2.5. Estimating Uncertainties for Super-ProfileParameters
3. COMPARISON WITH PREVIOUS METHODS
    3.1. Profile Analysis of the HI Data Cube of NGC 3521
    3.2. HI Super-Profiles of NGC 3521
4. PRACTICAL APPLICATION OF THEBAYGAUD-BASED HI SUPER-PROFILE TO NEARBYGALAXIES
    4.1. Sample Galaxies and HI Data
    4.2. HI Super-Profiles of the Sample Galaxies
    4.3. Correlations
5. SUMMARY
ACKNOWLEDGMENTS
REFERENCES

• Minsu Kim(Department of Astronomy and Space Science, Sejong University, Seoul 05006, Korea)
• Se-Heon Oh(Department of Astronomy and Space Science, Sejong University, Seoul 05006, Korea/Department of Physics and Astronomy, Sejong University, Seoul 05006, Korea; seheon.oh@sejong.ac.kr)