For refcode 1993ApJ...412..443F: Retrieve 38 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by American Astronomical Society.
Reproduced by permission
1993ApJ...412..443F
ROTATION CURVES FROM BARYONIC INFALL: DEPENDENCE ON DISKTOHALO RATIO,
INITIAL ANGULAR MOMENTUM, AND CORE RADIUS, AND COMPARISON WITH DATA'
RICARDO FLORES
Department of Physics and Astronomy, University of Missouri, Saint Louis,
MO 63121
JOEL R. PRIMACK
Santa Cruz Institute for Particle Physics, University of California,
Santa Crux CA 95064
GEORGE R. BLUMENTHAL
University of California Observatories/Lick Observatory, Board of Studies
in Astronomy and Astrophysics, University of California,
Santa Cruz, CA 95064
AND
S. M. FABER
University of California Observatories/Lick Observatory, Board of Studies
in Astronomy and Astrophysics, University of California,
Santa Cruz, CA 95064
Received 1992 June 29; accepted 1992 December 18
ABSTRACT
Using a simple analytic model of the response of dark matter halos to
the dissipative infall of the luminous material to form an exponential
disk, we explore the dependence of the final rotation curves on all the
relevant parameters: the ratio F = M_b_/M of the dissipative baryonic
mass M_b_ to the total galaxy mass M including dark matter; the ratio b/R
of the disk exponential scale length b to the truncation radius R (beyond
which infall can be neglected); the core radius r_core_ of the isothermal
halo in the absence of dissipation; and the dimensionless angular
momentum parameter {lambda} = JE^1/2^G^1^M^5/2^ (where J and E are
the total angular momentum and energy of the galaxy). We explore in
particular the final rotation curves expected in the tidal torque theory
of angular momentum, in which <{lambda}> ~ 0.05. For {lambda} = 0.05, we
find the final rotation curve to be flat when the gravitational effect of
the infalling baryonic material on the dark halo is included and if
F ~ 0.05, the value suggested by nucleosynthesis constraints if the
Hubble parameter H_0_ ~ 50 km s^1^ Mpc^1^. Also, the mass inside a
"Holmberg" radius R_H_ = 4.5b is about half luminous and half dark as
observations indicate. These results are quite insensitive to r_core_
provided it is sufficiently large, and are characteristic of any theory
in which <{lambda}> ~ F. The key results are that for F ~ 0.05 the
dispersion in {lambda} expected in the tidal torque theory,
0.02 <~ {lambda} <~ 0.1, (a) leads to rotation curves for bright galaxies
whose systematics are much like those of the galaxies for which H I data
are available when consistent baryonic disk scale lengths are used
throughout; and (b) the mass inside R_H_ shows a spread of values
consistent with observations except possibly for the smallest galaxies,
which may have suffered significant gas loss. With this range of
{lambda}values, the distribution of outer rotation curve slopes for a
given maximum rotation velocity is inconsistent with the data if F is
substantially larger or smaller than 0.05, or if r_core_/R is substantially
smaller than 0.2.
Subject headings: dark matter  elementary particles  galaxies:
formation  galaxies: kinematics and dynamics
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