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A general relativistic hydrostatic model for a galaxy

Technical Report:

Abstract

The existence of huge amounts of mass laying at the center of some galaxies has been inferred by data gathered at different wavelengths. It seems reasonable then, to incorporate general relativity in the study of these objects. A general relativistic hydrostatic model for a galaxy is studied. We assume that the galaxy is dominated by the dark mass except at the nucleus, where the luminous matter prevails. It considers four different concentric spherically symmetric regions, properly matched and with a specific equation of state for each of them. It yields a slowly raising orbital velocity for a test particle moving in the background gravitational field of the dark matter region. In this sense we think of this model as representing a spiral galaxy. The dependence of the mass on the radius in cluster and field spiral galaxies published recently, can be used to fix the size of the inner luminous core. A vanishing pressure at the edge of the galaxy and the assumption of hydrostatic equilibrium everywhere generates a jump in the density and the orbital velocity at the shell enclosing the galaxy. This is a prediction of this model. The ratio between the size core and the shells introduced  More>>
Authors:
Hojman, R; [1]  Pena, L; Zamorano, N [2] 
  1. International Centre for Theoretical Physics, Trieste (Italy)
  2. Chile Univ., Santiago (Chile). Dept. de Fisica
Publication Date:
Aug 01, 1991
Product Type:
Technical Report
Report Number:
IC-91/244
Reference Number:
SCA: 661300; PA: AIX-23:015353; SN: 92000647070
Resource Relation:
Other Information: PBD: Aug 1991
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; GALAXIES; COSMOLOGICAL MODELS; GENERAL RELATIVITY THEORY; GRAVITATIONAL FIELDS; 661300; OTHER ASPECTS OF PHYSICAL SCIENCE
OSTI ID:
10113335
Research Organizations:
International Centre for Theoretical Physics (ICTP), Trieste (Italy)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ON: DE92615233; TRN: XA9130254015353
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
INIS
Size:
35 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Hojman, R, Pena, L, and Zamorano, N. A general relativistic hydrostatic model for a galaxy. IAEA: N. p., 1991. Web.
Hojman, R, Pena, L, & Zamorano, N. A general relativistic hydrostatic model for a galaxy. IAEA.
Hojman, R, Pena, L, and Zamorano, N. 1991. "A general relativistic hydrostatic model for a galaxy." IAEA.
@misc{etde_10113335,
title = {A general relativistic hydrostatic model for a galaxy}
author = {Hojman, R, Pena, L, and Zamorano, N}
abstractNote = {The existence of huge amounts of mass laying at the center of some galaxies has been inferred by data gathered at different wavelengths. It seems reasonable then, to incorporate general relativity in the study of these objects. A general relativistic hydrostatic model for a galaxy is studied. We assume that the galaxy is dominated by the dark mass except at the nucleus, where the luminous matter prevails. It considers four different concentric spherically symmetric regions, properly matched and with a specific equation of state for each of them. It yields a slowly raising orbital velocity for a test particle moving in the background gravitational field of the dark matter region. In this sense we think of this model as representing a spiral galaxy. The dependence of the mass on the radius in cluster and field spiral galaxies published recently, can be used to fix the size of the inner luminous core. A vanishing pressure at the edge of the galaxy and the assumption of hydrostatic equilibrium everywhere generates a jump in the density and the orbital velocity at the shell enclosing the galaxy. This is a prediction of this model. The ratio between the size core and the shells introduced here are proportional to their densities. In this sense the model is scale invariant. It can be used to reproduce a galaxy or the central region of a galaxy. We have also compared our results with those obtained with the Newtonian isothermal sphere. The luminosity is not included in our model as an extra variable in the determination of the orbital velocity. (author). 29 refs, 10 figs.}
place = {IAEA}
year = {1991}
month = {Aug}
}