Year: 2001
Type: article
Abstract: A simple model for a hot Local Group halo is constructed using the standard β-model for the halo density and by choosing model parameters based on all available observations of X-ray emission in other groups of galaxies and on optical data of Local Group morphology. From the predicted X-ray intensities, total Local Group mass, and central cooling time of the halo, we derive very conservative upper limits on the central halo density N 0 and global temperature T of N 0 = 5 × 10 -4 cm -3 and kT = 0.5 keV, irrespective of realistic values of the density profile parameters r c and β. A typical poor group value of β = 0.5 requires kT < 0.15 keV and N 0 < 10 -4 cm -3 , from which it is concluded that the Local Group is very unlikely to possess a significant X-ray halo. The prospects for further constraining halo parameters from UV absorption-line observations are considered. We explicitly calculate the ability of the halo to distort the cosmic microwave background (CMB) in terms of the resulting CMB temperature variations and multipole anisotropies.
Source: The Astrophysical Journal
DOI: 10.1086/322380
Authors: Jesper Rasmussen, Kristian Pedersen
Institution: University of Copenhagen
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2004884113