Abundances in the ICM from XMM (original) (raw)
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XMM Observations of Abundances in the Intracluster Medium
Symposium - International Astronomical Union, 2004
Based on XMM-Newton observations of M 87 and the Centaurus cluster, abundance profiles of various elements of the intracluster medium (ICM) are derived. The abundances of Si and Fe show strong decreasing gradients. In contrast, the O and Mg abundances are about half of the Si abundance at the center.From the gas mass to stellar mass ratio and the comparison of Mg abundance with the stellar metallicity, the stellar mass loss from the central galaxies is indicated to be the main source of gas in the very central region of the clusters.The observed O, Si and Fe abundance pattern determines the contribution of supernova (SN) Ia and SN II, with the abundance pattern of ejecta of SN Ia. Most of the Si and Fe of the ICM in the central region of the clusters comes from SN Ia which occured in the central galaxies. In order to explain the observed O/Si ratio of a half solar, SN Ia products should have similar abundances of Si and Fe, which may reflect dimmer SN Ia observed in old stellar syst...
Astronomy & Astrophysics, 2006
The abundances of O, Mg, Si, and Fe in the intracluster medium of the Centaurus cluster are derived. The Fe abundance has a negative radial gradient. In solar units, the Si abundance is close to the Fe abundance, while the O and Mg abundances are much lower. The high Fe/O and Si/O ratios indicate that the metal supply from supernovae Ia is important and that supernovae Ia synthesize Si as does Fe. Within 2 , the O and Mg abundances are consistent with the stellar metallicity of the cD galaxy derived from the Mg 2 index. This result indicates that the central gas is dominated by the gas from the cD galaxy. The observed abundance pattern of the Centaurus cluster resembles those observed in the center of other clusters and groups of galaxies. However, the central Fe abundance and the Si/Fe ratio are 40% higher and 30% lower than those of M 87, respectively. Since the accumulation timescale of the supernovae Ia is greater in the Centaurus cluster, these differences imply a time dependence of nucleosynthesis by the supernovae Ia.
Metal abundances in the ICM as a diagnostics of the cluster history
Advances in Space Research, 2005
Galaxy clusters with a dense cooling core exhibit a central increase in the metallicity of the intracluster medium. Recent XMM-Newton studies with detailed results on the relative abundances of several heavy elements show that the high central abundances are mostly due to the contribution from supernovae type Ia. The dominant source is the stellar population of the central cluster galaxy.
Astronomy & Astrophysics
The hot intra-cluster medium (ICM) permeating galaxy clusters and groups is not pristine, as it has been continuously enriched by metals synthesised in Type Ia (SNIa) and core-collapse (SNcc) supernovae since the major epoch of star formation (z 2-3). The cluster/group enrichment history and mechanisms responsible for releasing and mixing the metals can be probed via the radial distribution of SNIa and SNcc products within the ICM. In this paper, we use deep XMM-Newton/EPIC observations from a sample of 44 nearby cool-core galaxy clusters, groups, and ellipticals (CHEERS) to constrain the average radial O, Mg, Si, S, Ar, Ca, Fe, and Ni abundance profiles. The radial distributions of all these elements, averaged over a large sample for the first time, represent the best constrained profiles available currently. Specific attention is devoted to a proper modelling of the EPIC spectral components, and to other systematic uncertainties that may affect our results. We find an overall decrease of the Fe abundance with radius out to ∼0.9 r 500 and ∼0.6 r 500 for clusters and groups, respectively, in good agreement with predictions from the most recent hydrodynamical simulations. The average radial profiles of all the other elements (X) are also centrally peaked and, when rescaled to their average central X/Fe ratios, follow well the Fe profile out to at least ∼0.5 r 500. As predicted by recent simulations, we find that the relative contribution of SNIa (SNcc) to the total ICM enrichment is consistent with being uniform at all radii, both for clusters and groups using two sets of SNIa and SNcc yield models that reproduce the X/Fe abundance pattern in the core well. In addition to implying that the central metal peak is balanced between SNIa and SNcc, our results suggest that the enriching SNIa and SNcc products must share the same origin and that the delay between the bulk of the SNIa and SNcc explosions must be shorter than the timescale necessary to diffuse out the metals. Finally, we report an apparent abundance drop in the very core of 14 systems (∼32% of the sample). Possible origins of these drops are discussed.
X-MAS2: Study systematics on the ICM metallicity measurements
Astrophysical Journal Letters, 2008
The X-ray measurements of the intra-cluster medium metallicity are becoming more and more frequent due to the availability of powerful X-ray telescope with excellent spatial and spectral resolutions. The information which can be extracted from the measurements of the α-elements, like Oxygen, Magnesium and Silicon with respect to the Iron abundance is extremely important to better understand the stellar formation and its evolutionary history. In this paper we investigate possible source of bias or systematic effects connected to the plasma physics when recovering metal abundances from X-ray spectra. To do this we analyze 6 simulated galaxy clusters processed through the new version of our X-ray MAp Simulator (X-MAS), which allows to create mock XMM-Newton EPIC MOS1 and MOS2 observations. By comparing the spectroscopic results inferred by the X-ray spectra to the expected values directly obtained from the original simulation we find that: i) the Iron is recovered with high accuracy for both hot (T > 3 keV) and cold (T < 2 keV) systems; at intermediate temperatures, however, we find a systematic overestimate which depends inversely on the number counts; ii) Oxygen is well recovered in cold clusters, while in hot systems the X-ray measurement may overestimate the true value by a factor up to 2-3; iii) Being a weak line, the measurement of Magnesium is always difficult; despite of this, for cold systems (i.e. with T < 2 keV) we do not find any systematic behavior, while for very hot systems (i.e. with T > 5 keV) the spectroscopic measurement may strongly overestimate the true value up to a factor of 4; iv) Silicon is well recovered for all the clusters in our sample. We investigate in detail the nature of the systematic effects and biases found performing XSPEC simulations. We conclude that they are mainly connected with the multi-temperature nature of the projected observed spectra and to the intrinsic limitation of the XMM-Newton-EPIC spectral resolution that does not always allow to disentangle among the emission lines produced by different elements.
Enrichment of the Hot Intracluster Medium: Observations
Space Science Reviews
Four decades ago, the firm detection of an Fe-K emission feature in the X-ray spectrum of the Perseus cluster revealed the presence of iron in its hot intracluster medium (ICM). With more advanced missions successfully launched over the last 20 years, this discovery has been extended to many other metals and to the hot atmospheres of many other galaxy clusters, groups, and giant elliptical galaxies, as evidence that the elemental bricks of life-synthesized by stars and supernovae-are also found at the largest scales of the Universe. Because the ICM, emitting in X-rays, is in collisional ionisation equilibrium, its elemental abundances can in principle be accurately measured. These abundance measurements, in turn, are valuable to constrain the physics and environmental conditions of the Type Ia and core-collapse supernovae that exploded and enriched the ICM over the entire cluster volume. On the other hand, the spatial distribution of metals across the ICM constitutes a remarkable signature of the chemical history and evolution of clusters, groups, and ellipticals. Here, we summarise the most significant achievements in measuring elemental abundances in the ICM, from the very first attempts up to the era of XMM-Newton, Chandra, and Suzaku and the unprecedented results obtained by Hitomi. We also discuss the current systematic limitations of these measurements and how the future missions XRISM and Athena will further improve our current knowledge of the ICM enrichment.
Recovering true metal abundances of the ICM
2001
Recovering the true average abundance of the intracluster medium (ICM) is crucial for estimates of its global metal content, which in turn is linked to its past evolution and to the star formation history of the stellar component of the cluster. We analyze here how abundance gradients affect commonly adopted estimates of the average abundance, assuming various plausible ICM density and temperature profiles. We find that, adopting the observed abundance gradients, the true average mass weighted abundance is less than (although not largely deviating from) the commonly used emission weighted abundance.
Intermediate‐Element Abundances in Galaxy Clusters
The Astrophysical Journal, 2005
We present the average abundances of the intermediate elements obtained by performing a stacked analysis of all the galaxy clusters in the archive of the X-ray telescope ASCA. We determine the abundances of Fe, Si, S, and Ni as a function of cluster temperature (mass) from 1 -10 keV, and place strong upper limits on the abundances of Ca and Ar. In general, Si and Ni are overabundant with respect to Fe, while Ar and Ca are very underabundant. The discrepancy between the abundances of Si, S, Ar, and Ca indicate that the α-elements do not behave homogeneously as a single group. We show that the abundances of the most well-determined elements Fe, Si, and S in conjunction with recent theoretical supernovae yields do not give a consistent solution for the fraction of material produced by Type Ia and Type II supernovae at any temperature or mass. The general trend is for higher temperature clusters to have more of their metals produced in Type II supernovae than in Type Ias. The inconsistency of our results with abundances in the Milky Way indicate that spiral galaxies are not the dominant metal contributors to the intracluster medium (ICM). The pattern of elemental abundances requires an additional source of metals beyond standard SN Ia and SN II enrichment. The properties of this new source are well matched to those of Type II supernovae with very massive, metal-poor progenitor stars. These results are consistent with a significant fraction of the ICM metals produced by an early generation of population III stars.
X-Ray Properties of Young Early-Type Galaxies. II. Abundance Ratio in the Hot Interstellar Matter
The Astrophysical Journal, 2012
Using Chandra X-ray observations of young, post-merger elliptical galaxies, we present X-ray characteristics of age-related observational results, by comparing them with typical old elliptical galaxies in terms of metal abundances in the hot interstellar matter (ISM). While the absolute element abundances may be uncertain because of unknown systematic errors and partly because of the smaller amount of hot gas in young ellipticals, the relative abundance ratios (e.g., the α-element to Fe ratio, most importantly Si/Fe ratio) can be relatively well constrained. We find that in two young elliptical galaxies (NGC 720 and NGC 3923) the Si to Fe abundance ratio is super-solar (at a 99% significance level), in contrast to typical old elliptical galaxies where the Si to Fe abundance ratio is close to solar. Also the O/Mg ratio is close to solar in the two young elliptical galaxies, as opposed to the sub-solar O/Mg ratio reported in old elliptical galaxies. Both features appear to be less significant outside the effective radius (roughly 30'' for the galaxies under study), consistent with the observations that confine to the centermost regions the signatures of recent star formation in elliptical galaxies. Observed differences between young and old elliptical galaxies can be explained by the additional contribution from SNe II ejecta in the former. In young elliptical galaxies, the later star formation associated with recent mergers would have a dual effect, resulting both in galaxy scale winds-and therefore smaller observed amounts of hot ISM-because of the additional SNII heating, and in different metal abundances, because of the additional SNII yields.
Astronomy and Astrophysics, 2003
Based on a detailed study of the temperature structure of the intracluster medium in the halo of M 87, abundance profiles of 7 elements, O, Mg, Si, S, Ar, Ca, and Fe are derived. In addition, abundance ratios are derived from the ratios of line strengths, whose temperature dependences are small within the temperature range of the ICM of M 87. The abundances of Si, S, Ar, Ca and Fe show strong decreasing gradients outside 2 ′ and become nearly constant within the radius at ∼ 1.5 solar. The Fe/Si ratio is determined to be 0.9 solar with no radial gradient. In contrast, the O abundance is less than a half of the Si abundance at the center and has a flatter gradient. The Mg abundance is ∼1 solar within 2 ′ , which is close to stellar abundance within the same radius. The O/Si/Fe pattern of M 87 is located at the simple extension of that of Galactic stars. The observed Mg/O ratio is about 1.25 solar, which is also the same ratio as for Galactic stars. The O/Si/Fe ratio indicates that the SN Ia contribution to Si and Fe becomes important towards the center and SN Ia products have similar abundances of Si and Fe at least around M 87, which may reflect dimmer SN Ia observed in old stellar systems. The S abundance is similar to the Si abundance at the center, but has a steeper gradient. This result suggests that the S/Si ratio of SN II products is much smaller than the solar ratio.