Sydney Work on 21-cm Observations of the HI Galactic Disk
نویسندگان
چکیده
منابع مشابه
Hi Clouds beyond the Galactic Disk
Recent observations in the 21cm line with the Green Bank Telescope have changed our view of the neutral interstellar medium (ISM) in several ways. The new data show that in the inner parts of the Milky Way the disk-halo interface is composed of many discrete HI clouds. The clouds lie in a layer more than one kpc thick and follow Galactic rotation. Their origin and evolution is unknown. In the o...
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Neutral hydrogen traces gravitational potentials. In the nearby universe, 21cm emission-line surveys show that the bulk of the HI resides in well-formed, optically-luminous galaxies. At high redshift, 21cm line absorption against background radio quasars occurs in gas-rich systems identified with the highest HI column densities – the " damped Lyman alpha " quasar absorption-line systems. High s...
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We have made HI 21cm-line absorption measurements using the GMRT towards 15 directions in the Galaxy which are known to have high random velocity clouds as seen in the optical absorption lines of CaII and NaI. For the first time, in 6 out of these 15 directions we detect HI absorption features corresponding to the high random velocity optical absorption lines. The mean optical depth of these de...
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Observations of fluctuations in the redshifted 21 cm radiation from neautral hydrogen (HI) are perceived to be an important future probe of the universe at high redshifts. Under the assimption that at redshifts z ≤ 6 (Post-Reionization Era) the HI traces the underlying dark matter with a possible bias, we investigate the possibility of using observations of redshifted 21 cm radiation to detect ...
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We estimate the number of old, radiative supernova remnants (SNRs) detectable in Hi 21-cm emission line in the Galaxy. We assume that old SNRs consist of expanding Hi shells and that they are visible if the line-of-sight velocities are sufficiently outside the velocity range of the Galactic background Hi emission. This criterion of visibility makes it possible to calculate the background contam...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1958
ISSN: 0074-1809
DOI: 10.1017/s0074180900226612