The Velocity Dispersion in the X-Ray Scaling Laws

We used a sample of 20 poor groups of galaxies to study the low mass tail of the relationships among the X-ray temperature T, the X-ray luminosity L^sub x^ and the optical velocity dispersion σ. We obtained redshifts for the fainter members of these groups. We find that X-ray bright groups have more...

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Bibliographic Details
Published in:Astrophysics and space science 2003-01, Vol.285 (1), p.37-42
Main Authors: Zimer, Me, Zabludoff, Ai, Mulchaey, Js
Format: Article
Language:English
Subjects:
Astrophysics
Gases
Kinematics
Luminosity
Monte Carlo simulation
Stars & galaxies
X-rays
Online Access:Get full text
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Summary:We used a sample of 20 poor groups of galaxies to study the low mass tail of the relationships among the X-ray temperature T, the X-ray luminosity L^sub x^ and the optical velocity dispersion σ. We obtained redshifts for the fainter members of these groups. We find that X-ray bright groups have more members and higher velocity dispersions on average. Using the fainter group members and MonteCarlo tests, we define the number of group members required to calculate a robust velocity dispersion. There is a tendency to underestimate the group velocity dispersion for samples of fewer than 10 members that introduces systematic errors in the slope of the relationships among L^sub x^, T, and σ. A comparison with the data of Ponman and Mahdavi shows that our improved velocity dispersions provide better constraints on the relationship between the kinematics of the hot gas and galaxies in these common environments.[PUBLICATION ABSTRACT]
ISSN:0004-640X
1572-946X
DOI:10.1023/A:1024697306665