31 research outputs found
X-Ray Emission from Rotating Elliptical Galaxies
The slow inward flow of the hot gas in elliptical galaxy cooling flows is
nearly impossible to detect directly due to instrumental limitations. However,
in rotating galaxies, if the inflowing gas conserves angular momentum, it will
eventually form a disk. The X-ray signature of this phenomenon is a flattening
of the X-ray isophotes in the inner 1-10 kpc region. This effect is observable,
so we have searched for it in X-ray observations of six rotating and
non-rotating early-type galaxies, obtained mainly with the ROSAT PSPC and HRI
imagers. The ellipticities of the X-ray emission never increase toward the
central region, nor are the X-ray ellipticities significantly greater than the
ellipticities for the optical stellar emission. Central ellipticities in excess
of 0.5 were expected in rotating ellipticals whereas values of 0-0.2 are
measured. The failure to detect the expected signature requires a modification
to the standard cooling flow picture, possibly including partial galactic
winds, rapid mass drop-out, or turbulent redistribution of angular momentum.Comment: 34 postscript pages; ApJ, in press (Feb 10,2000
Hot gas flows on global and nuclear galactic scales
Since its discovery as an X-ray source with the Einstein Observatory, the hot
X-ray emitting interstellar medium of early-type galaxies has been studied
intensively, with observations of improving quality, and with extensive
modeling by means of numerical simulations. The main features of the hot gas
evolution are outlined here, focussing on the mass and energy input rates, the
relationship between the hot gas flow and the main properties characterizing
its host galaxy, the flow behavior on the nuclear and global galactic scales,
and the sensitivity of the flow to the shape of the stellar mass distribution
and the mean rotation velocity of the stars.Comment: 22 pages. Abbreviated version of chapter 2 of the book "Hot
Interstellar Matter in Elliptical Galaxies", Springer 201
Social change and the family: Comparative perspectives from the west, China, and South Asia
This paper examines the influence of social and economic change on family structure and relationships: How do such economic and social transformations as industrialization, urbanization, demographic change, the expansion of education, and the long-term growth of income influence the family? We take a comparative and historical approach, reviewing the experiences of three major sociocultural regions: the West, China, and South Asia. Many of the changes that have occurred in family life have been remarkably similar in the three settings—the separation of the workplace from the home, increased training of children in nonfamilial institutions, the development of living arrangements outside the family household, increased access of children to financial and other productive resources, and increased participation by children in the selection of a mate. While the similarities of family change in diverse cultural settings are striking, specific aspects of change have varied across settings because of significant pre-existing differences in family structure, residential patterns of marriage, autonomy of children, and the role of marriage within kinship systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45661/1/11206_2005_Article_BF01124383.pd