English to Arabic Science Astronomy & Space

More direct probes of the dark matter are provided by low surface bright-
ness galaxies (LSBs). There is strong dynamical evidence that LSBs have low
baryonic surface density, and thus the disk contributes little to the dynamics
of the galaxy, and the resulting rotation curve is dominated by the dark halo;
the few LSB rotation curves published to date rise remarkably slowly, becoming
asymptotically flat only at several disk scale lengths (Goad & Roberts 1981, de
Blok et al. 1996, Makarov et al. 1997, van Zee et al. 1997, van der Hulst et al.
1993). Furthermore, LSBs span a wide range in mass, and thus can be used to
trace systematic variations in the shapes of dark matter halos as a function of
mass.