ASCA observations of groups at radii of low overdensity. Implications for the cosmic preheating

Details ASCA observations of groups at radii of low overdensity. Implications for the cosmic preheating ASCA observations of groups at radii of low overdensity. Implications for the cosmic preheating

2002-06-20

arxiv.org/abs/astro-ph/0206362v2

Astrophys.J. 578 (2002) 74-89

Astronomy and Astrophysics

Astrophysics

ApJ, v578, in press, 2002, October 10, 17 pages

Scientific paper

10.1086/342472

Through a 3d-modeling of ASCA observations, we performed a spatially resolved X-ray spectroscopic study, extending to radii exceeding 150 kpc, for a sample of 9 groups of galaxies. Combined with published ROSAT results, we conclude that these systems generally exhibit a strong temperature decline at outer radii. In our best case, NGC3268, this corresponds to a flattening of the entropy profile at a level of ~400 keV cm^2. This value is high compared both to the observed entropy floor of ~100 keV cm^2 and to the expected value from gravitational heating. We suggest that the observed entropy profile in most groups at densities exceeding 500 times the critical is purely driven by non-gravitational heating processes. After comparison with a larger sample of groups and clusters, we conclude that there is a variation in the level of non-gravitational heating between ~100 keV cm^2 and ~400 keV cm^2 within every system. Using models of cluster formation as a reference frame, we established that the accreted gas reaches an entropy level of 400 keV cm^2 by redshift 2.0-2.5, while such high entropies where not present at redshifts higher than 2.8-3.5, favoring nearly instantaneous preheating. Adopting galactic winds as a source of preheating, and scaling the released energy by the observed metal abundance, the variation in the preheating could be ascribed mostly to variation in the typical overdensity of the energy injection, ~30 for an entropy floor (100 keV cm^2) and to ~5 for an entropy of 400 keV cm^2.

Affiliated with

Also associated with

No associations

Rating

ASCA observations of groups at radii of low overdensity. Implications for the cosmic preheating 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 ASCA observations of groups at radii of low overdensity. Implications for the cosmic preheating, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ASCA observations of groups at radii of low overdensity. Implications for the cosmic preheating will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-330468