The spatial power spectrum of galactic neutral hydrogen from observations of the 21-cm emission line
J. Crovisier, J. M. Dickey;
AaA, 1983, 122, 282
ABSTRACT:A statistical study of the small-scale structure of interstellar hydrogen based on
observations of the power spectrum (PS) of its 21-cm brightness distribution is
presented.
The observations and reductions are discussed, including the telescope
parameters, the data obtained from a map developed with a Fourier inversion, and
corrections applied to the PS to account for noise and weak continuum radiation in
the field.
The resulting spatial PS of the 21-cm brightness temperature
as a function of velocity is discussed.
There is a high degree of
azimuthal symmetry on the u,v plane; the log of the spatial PS is roughly a linear
function of the log of the spatial frequency with spectral index around -3 for the
interferometer observation, but around -2 for the single-dish data.
These spectral
indices appear to be independent of velocity; using the Schmidt model to
convert velocity to distance, the brightness temperature statistics are
found to be independent of distance to the limits of sensitivity.
KEYWORDS: astronomical spectroscopy, hydrogen clouds, interstellar gas, milky way galaxy, radio astronomy, autocorrelation, brightness temperature, centimeter waves, data reduction, line spectra, power spectra, radio interferometers
PERSOKEY:turbulence, h_i, statistical analysis, 21 cm, ,
CODE: crovisier83