Physics
Scientific paper
Jan 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993egte.conf..117m&link_type=abstract
In its The Evolution of Galaxies and Their Environment p 117-118 (SEE N93-26706 10-90)
Physics
Dark Matter, Disk Galaxies, Galactic Halos, Lyman Spectra, Red Shift, Background Radiation, Emissivity, Hubble Space Telescope, Irregular Galaxies, Space Density, Spiral Galaxies
Scientific paper
Recent observations using the Hubble Space Telescope of the z = 0.156 QSO 3C 273 have discovered a surprisingly large number of Ly-alpha absorption lines. In particular, Morris et al. found 9 certain and 7 possible Ly-alpha lines with equivalent widths above 25 mA. This is much larger (by a factor of 5-10) than the number expected from extrapolation of the high-redshift behavior of the Ly-alpha forest. Within the context of pressure-confined models for the Ly-alpha clouds, this behavior can be understood if the ionizing background declines sharply between z is approximately 2 and z is approximately 0. However, this requires that the ionizing photon flux drop as rapidly as the QSO volume emissivity; moreover, the absorbers must have a space density n(sub O) is approximately 2.6(N/10)h/((D/100 kpc)(sup 2)) Mpc(sup -3) where D is the present-day diameter of the absorbers. It is somewhat surprising that such necessarily fragile objects could have survived in such numbers to the present day. It is shown that it is plausible that the atomic hydrogen extents of spiral and irregular galaxies are large enough to produce the observed number of Ly-alpha absorption lines toward 3C 273, and that the neutral column densities and doppler b-values expected under these conditions fall in the range found by Morris et al. (1991).
No associations
LandOfFree
Low redshift Lyman alpha absorption lines and the dark matter halos of disk galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Low redshift Lyman alpha absorption lines and the dark matter halos of disk galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low redshift Lyman alpha absorption lines and the dark matter halos of disk galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1259526