Astronomy and Astrophysics – Astronomy
Scientific paper
Sep 2006
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006aspc..352..241f&link_type=abstract
New Horizons in Astronomy: Frank N. Bash Symposium ASP Conference Series, Vol. 352, Proceedings of the Conference Held 16-18 Oct
Astronomy and Astrophysics
Astronomy
Scientific paper
The study of elliptical galaxy dark halos at large radii is important because it is the region where dark matter is thought to dominate the galaxy mass and can therefore provide the best constraints on observed dark halo properties. We present axisymmetric orbit-superposition models of the dark halo in the elliptical galaxy NGC 821 using line-of-sight velocity distributions obtained to ˜100 arcsec (over 2 effective radii) with long-slit spectroscopy from the Hobby-Eberly Telescope. We fit models with a range of dark halo density profiles and find that a power-law dark halo with a constant density of 0.0105 Msun/pc3 is the best-fitting model ruling out both the no dark halo and the Navarro, Frenk, & White (1996; NFW) models at a greater than 3 σ confidence level. We show the internal moments σr, σθ, and σφ and find that the model with no dark halo is radially anisotropic at small radii and tangentially anisotropic at large radii while the best-fit halo models are slightly radially anisotropic at all radii. The dark halo we find is inconsistent with previous claims of little to no dark matter halo in this galaxy based on planetary nebula measurements.
Forestell Amy Dove
Gebhardt Karl
No associations
LandOfFree
The Dark Halo in NGC 821 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Dark Halo in NGC 821, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Dark Halo in NGC 821 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-996370