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Recent observations with the Galaxy Evolution Explorer (GALEX) show strong unexpected ultraviolet (UV) excess in the spectrum of brightest cluster galaxies (BCGs). It is believed that the excess UV signal is produced by old and evolved core-He burning stars, and the UV flux strength could be greatly enhanced if the progenitor stars have a high value of …
The effect of helium sedimentation on cluster mass scaling relations Bulbul, Gul Esra; Abstract. Galaxy cluster masses play an important role in addressing fundamental physical and cosmological problems. A vital tool for the measurement of cluster masses is the diffuse hot intergalactic medium which can be detected primarily through its bright ...
Understanding whether Helium can sediment to the core of galaxy clusters is important for a number of problems in cosmology and astrophysics. All current models addressing this question are one-dimensional and do not account for the fact that magnetic fields can effectively channel ions and electrons, leading to anisotropic transport of …
Understanding whether Helium can sediment to the core of galaxy clusters is important for a number of problems in cosmology and astrophysics. All current models addressing this question are one-dimensional and do not account for the fact that magnetic fields can effectively channel ions and electrons, leading to anisotropic transport of momentum, …
Recent theoretical studies predict that the inner regions of galaxy clusters may have an enhanced helium abundance due to sedimentation over the cluster lifetime. If sedimentation is not suppressed (e.g., by tangled magnetic fields), this may …
Recent observations with the Galaxy Evolution Explorer (GALEX) show strong unexpected ultraviolet (UV) excess in the spectrum of brightest cluster galaxies (BCGs). It is believed that the excess UV signal is produced by old and evolved core-He burning stars, and the UV flux strength could be greatly enhanced if the progenitor stars have a high value of …
The helium concentration profile in galaxy clusters is unfortunately not directly observable. Current models addressing the putative sedimentation are one-dimensional and parametrize the presence of magnetic fields in a crude way, ignoring the weakly collisional, magnetized nature of the medium.
Understanding whether Helium can sediment to the core of galaxy clusters is important for a number of problems in cosmology and astrophysics. All current models addressing this question are one ...
Request PDF | The effect of helium sedimentation on cluster mass scaling relations | Galaxy cluster masses play an important role in addressing fundamental physical and cosmological problems. A ...
Context. Recent theoretical studies predict that the inner regions of galaxy clusters may have an enhanced helium abundance due to sedimentation over the cluster lifetime. If sedimentation is not suppressed (e.g., by tangled magnetic fields), this may significantly affect the cluster mass estimates. Aims: We use Chandra X-ray observations of …
Recent theoretical studies predict that the inner regions of galaxy clusters may have an enhanced helium abundance due to sedimentation over the cluster... Skip to main content. We will keep fighting for all libraries - stand with us! A line drawing of the Internet Archive headquarters building façade. ...
The assumption of a spatially uniform helium distribution in the intracluster medium (ICM) can lead to biases in the estimates of key cluster parameters if composition gradients are present. The helium concentration profile in galaxy clusters is unfortunately not directly observable. Current models addressing the putative sedimentation are one-dimensional …
arXiv:0910.0249v2 [astro-ph.CO] 20 Oct 2009 TheAstrophysicalJournal, 705:L58, 2009 Preprint typeset using LATEX style emulateapj v. 08/22/09 HELIUM SEDIMENTATION AND THE ULTRAVIOLET UPTURN IN ...
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We model the gas density and temperature profiles of nearby cooling core clusters to estimate the gravitational acceleration acting on the helium and show that its sedimentation time scale is too long with respect to the present age of these objects to …
Effect of Helium Sedimentation on X-ray Measurements of Galaxy Clusters. August 2008; The Astrophysical ... X st yle emulateap j v. 10/09/06. EFFECT OF HELIUM SEDIMENT A TION ON X-RA Y ...
Context. Recent theoretical studies predict that the inner regions of galaxy clusters may have an enhanced helium abundance due to sedimentation over the cluster lifetime. If sedimentation is not suppressed (e.g., by tangled magnetic fields), this may significantly affect the cluster mass estimates. Aims. We use Chandra X-ray observations …
Preprint typeset using LATEX style emulateapj v. 08/22/09 HELIUM SEDIMENTATION AND THE ULTRAVIOLET UPTURN IN BRIGHTEST CLUSTER GALAXIES FangPeng1, DaisukeNagai2 The Astrophysical Journal, 705:L58, 2009 ... we point out that helium sedimentation pro-cess can greatly increase the helium abundance in BCGs, making …
Table 2. Best-fit Parameters of the Bulbul et al. (2010) Model Produced Using a Uniform helium Abundance Model (Anders & Grevesse 1989) - "The effect of helium sedimentation on galaxy cluster masses and scaling relations"
Preprint typeset using L ATEX style emulateapj v. 08/22/09. EFFECT OF HELIUM SEDIMENTATION ON X-RAY MEASUREMENTS OF GALAXY CLUSTERS. Fang Peng 1, Daisuke Nagai 2,3. Submitted to the Astrophysical Journal. ABSTRACT.
It is suspected that the ultraviolet (UV) upturn phenomenon in elliptical galaxies and extended horizontal-branch stars in globular clusters have a common origin. An extremely high abundance of helium (Y ~ 0.4) allows for a working hypothesis, but its origin is unclear. Peng & Nagai proposed that primordial helium sedimentation in dark halos over cosmic …
Download PDF Abstract: Recent theoretical studies predict that the inner regions of galaxy clusters are enriched by the sedimentation of Helium (He). We use Chandra X-ray observations of eight relaxed galaxy clusters to investigate the upper limits to the effect of He sedimentation on the measurement of cluster masses and the best-fit …
The uniformity of the helium-to-hydrogen abundance ratio in X-ray emitting intracluster medium (ICM) is one of the commonly adopted assumptions in X-ray analyses of galaxy clusters and cosmological constraints derived from these measurements. In this work, we investigate the effect of He sedimentation on X-ray measurements of galaxy …
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The assumed helium sedimentation model, on average, produces a negligible increase in the gas mass inferred within large radii (r < r500) (1.3 +/- 1.2 per cent) and a (10.2 +/- 5.5) per cent mean decrease in the total mass inferred within r < r500. Significantly stronger effects in the gas mass (10.5 +/- 0.8 per cent) and total mass (25.1 …
The assumed helium sedimentation model, on average, produces a negligible increase in the gas mass inferred within large radii (r < r500) (1.3 ± 1.2%) and a 10.2 ± 5.5% mean decrease in the total mass inferred within r < r500. Significantly stronger effects in the gas mass (10.5 ± 0.8%) and total mass (25.1 ± 1.1%) are seen at small radii ...
Understanding whether Helium can sediment to the core of galaxy clusters is important for a number of problems in cosmology and astrophysics. All current models addressing this question are one-dimensional and do not account for the fact that magnetic fields can effectively channel ions and electrons, leading to anisotropic transport of …
Preprint typeset using LATEX style emulateapj v. 10/09/06 EFFECT OF HELIUM SEDIMENTATION ON X-RAY MEASUREMENTS OF GALAXY CLUSTERS Fang Peng 1, Daisuke Nagai 1,2,3
distribution from numerical simulations of helium sedimentation on a timescale of 11 Gyr. Results.The assumed helium sedimentation model, on average, produces a negligible increase in the gas mass inferred within large radii (r
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