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Intracluster medium

About: Intracluster medium is a research topic. Over the lifetime, 2564 publications have been published within this topic receiving 118571 citations.


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TL;DR: In this paper, high-resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year.
Abstract: High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year. X-ray images have revealed giant cavities and shock fronts in the hot gas that provide a direct and relatively reliable means of measuring the energy injected into hot atmospheres by active galactic nuclei (AGN). Average radio jet powers are near those required to offset radiative losses and to suppress cooling in isolated giant elliptical galaxies, and in larger systems up to the richest galaxy clusters. This coincidence suggests that heating and cooling are coupled by feedback, which suppresses star formation and the growth of luminous galaxies. How jet energy is converted to heat and the degree to which other heating mechanisms are contributing, e.g., thermal conduction, are not well understood. Outburst energies require substantial late growth of supermassive black holes. Unless all of the ∼10 62 erg required to suppress star formation is deposited in the cooling regions of clusters, AGN outbursts must alter large-scale properties of the intracluster medium.

1,283 citations

Journal ArticleDOI
TL;DR: The cooling time in the dense gas within 50-300 kpc of the central galaxy in most clusters is found from X-ray images to be less than about 1010 yr as discussed by the authors.
Abstract: The cooling time in the dense gas within 50 – 300 kpc of the central galaxy in most clusters is found from X-ray images to be less than about 1010 yr. The weight of the overlying gas then causes a net inflow which is called a cooling flow. X-ray spectra confirm that the gas is cooling and loses at least 90 per cent of its thermal energy. The rate at which the gas cools ranges from ~ 10 – 500 M⊙ yr−1 . The soft X-ray absorption now discovered in cooling flows suggests that the cooled gas accumulates as very cold, small, gas clouds. Any large-scale star formation must be biased to low mass objects, except in the centres of some flows where some massive star may form, possibly from larger clouds assembled from cloud collisions and aggregation.

1,264 citations

Journal ArticleDOI
TL;DR: In this paper, high-resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year.
Abstract: High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year. X-ray images have revealed giant cavities and shock fronts in the hot gas that provide a direct and relatively reliable means of measuring the energy injected into hot atmospheres by active galactic nuclei (AGN). Average radio jet powers are near those required to offset radiative losses and to suppress cooling in isolated giant elliptical galaxies, and in larger systems up to the richest galaxy clusters. This coincidence suggests that heating and cooling are coupled by feedback, which suppresses star formation and the growth of luminous galaxies. How jet energy is converted to heat and the degree to which other heating mechanisms are contributing, eg. thermal conduction, are not well understood. Outburst energies require substantial late growth of supermassive black holes. Unless all of the approximately 10E62 erg required to suppress star formation is deposited in the cooling regions of clusters, AGN outbursts must alter large-scale properties of the intracluster medium.

865 citations

Journal ArticleDOI
TL;DR: In this article, the authors compared the ICM properties outside cluster cores with the observed X-ray observations of nearby relaxed clusters to assess the impact of galaxy formation, and found that the observed ICM characteristics outside cluster core are well reproduced in the simulations that include cooling and star formation, while the non-radiative simulations predict an overall shape of ICM profiles inconsistent with observations.
Abstract: We present detailed comparisons of the intracluster medium (ICM) in cosmological Eulerian cluster simulations with deep Chandra observations of nearby relaxed clusters. To assess the impact of galaxy formation, we compare two sets of simulations, one performed in the nonradiative regime and another with radiative cooling and several physical processes critical to various aspects of galaxy formation: star formation, metal enrichment, and stellar feedback. We show that the observed ICM properties outside cluster cores are well reproduced in the simulations that include cooling and star formation, while the nonradiative simulations predict an overall shape of the ICM profiles inconsistent with observations. In particular, we find that the ICM entropy in our runs with cooling is enhanced to the observed levels at radii as large as half of the virial radius. We also find that outside cluster cores entropy scaling with the mean ICM temperature in both simulations and Chandra observations is consistent with being self-similar within current error bars. We find that the pressure profiles of simulated clusters are also close to self-similar and exhibit little cluster-to-cluster scatter. We provide analytic fitting formulae for the pressure profiles of the simulated and observed clusters. The X-ray observable mass relations for our simulated sample agree with the Chandra measurements to ≈10%-20% in normalization. We show that this systematic difference could be caused by the subsonic gas motions, unaccounted for in X-ray hydrostatic mass estimates. The much improved agreement of simulations and observations in the ICM profiles and scaling relations is encouraging, and the existence of tight relations of X-ray observables, such as YX, and total cluster mass and the simple redshift evolution of these relations hold promise for the use of clusters as cosmological probes. However, the disagreement between the predicted and observed fractions of cluster baryons in stars remains a major puzzle.

715 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used cosmological gas-dynamic simulations to investigate the accuracy of galaxy cluster mass estimates based on X-ray observations, and they found that the estimated-to-true mass ratio, derived from 174 artificial images constructed from the simulations, is nearly unbiased and has a standard deviation of 14{percent}{endash}29{percent.
Abstract: We use cosmological gasdynamic simulations to investigate the accuracy of galaxy cluster mass estimates based on X-ray observations. The experiments follow the formation of clusters in different cosmological models and include the effects of gravity, pressure gradients, and hydrodynamical shocks. A subset of our ensemble also allows for feedback of mass and energy from galactic winds into the intracluster medium. We find that mass estimates based on the hydrostatic, isothermal {beta}-model are remarkably accurate when evaluated at radii where the cluster mean density is between 500 and 2500 times the critical density. At lower densities, radial temperature information becomes important. In the quoted radial regime, the distribution of the estimated-to-true mass ratio, derived from 174 artificial images constructed from the simulations, is nearly unbiased and has a standard deviation of 14{percent}{endash}29{percent}. The scatter can be considerably reduced (to 8{percent}{endash}15{percent}) by using an alternative mass estimator that exploits the tightness of the mass-temperature relation found in the simulations. The improvement over {beta}-model estimates is due to the elimination of the variance contributed by the gas outer slope parameter. We discuss these findings and their implications for recent measurements of cluster baryon fractions. {copyright} {ital 1996 The American Astronomical Society.}

714 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202363
2022122
2021122
202094
2019103
2018112