An Inverse Compton Process for the Excess Diffuse EUV Emission from the Virgo and Coma Galaxy Clusters

Hwang, Chorng-Yuan

doi:10.1126/science.278.5345.1917

Cited by 59 publications

(61 citation statements)

References 17 publications

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“…These have been found to be unsatisfactory, however, since the cooling times are extremely short (sometimes $10 6 yr; Mittaz et al 1998), so some kind of heating mechanism to sustain the warm gas has to be envisaged (Fabian 1997). On the other hand, if the emission arises from an inverse Compton process (such as suggested by Hwang 1997;Sarazin & Lieu 1998;Ensslin et al 1999), then the radial dependence seen in some clusters can be explained, but the inferred pressure of the required cosmic rays would be perplexedly too high .…”

Section: Introductionmentioning

confidence: 99%

Warm‐hot Intergalactic Medium Emission and the Cluster Soft Excess: A Model Comparison

Mittaz

Lieu

Cen

et al. 2004

ApJ

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The confirmation of the cluster soft excess (CSE) by XMM-Newton has rekindled interest as to its origin. The recent detections of CSE emission at large cluster radii together with reports of O vii line emission associated with the CSE has led many authors to conjecture that the CSE is, in fact, a signature of the warm-hot intergalactic medium ( WHIM ). In this paper we test the scenario by comparing the observed properties of the CSE with predictions based on models of the WHIM. We find that emission from the WHIM in current models is 3-4 orders of magnitude too faint to explain the CSE. We discuss different possibilities for this discrepancy, including issues of simulation resolution and scale and the role of small density enhancements or galaxy groups. Our final conclusion is that it is unlikely that the WHIM alone is able to account for the observed flux of the CSE. Subject heading gs: intergalactic medium -large-scale structure of universe -X-rays: galaxies: clusters

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Section: Introductionmentioning

confidence: 99%

Warm‐hot Intergalactic Medium Emission and the Cluster Soft Excess: A Model Comparison

Mittaz

Lieu

Cen

et al. 2004

ApJ

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“…While the diffuse radio sources in galaxy clusters are universally interpreted as produced by synchrotron emission, the extreme ultraviolet (EUV) and hard X-ray (HXR) excesses have been interpreted as the combined effect of an underlying inverseCompton scattering (ICS) of the cosmic microwave background (CMB) against cluster relativistic electrons that complement the radio halo population (e.g., Hwang 1997;Ensslin & Biermann 1998;Sarazin & Lieu 1998;Blasi & Colafrancesco 1999;Colafrancesco et al 2007;Marchegiani et al 2007;Colafrancesco & Marchegiani 2009;Buote 2001), or thermal emission (Mittaz et al 1998;Cen & Ostriker 1999) from "missing baryons" at sub-virial temperatures (see, e.g., the review of Durret et al 2008). Focusing upon the former interpretation, the role and ramifications of an underlying power law spectrum across the entire X-ray frequency band can be far reaching, with issues concerning cluster merging and central cooling, and also mass and spectroscopic consequences being addressed by Million & Allen (2009), Lagana et al (2010), andProkhorov (2009).…”

Section: Introductionmentioning

confidence: 99%

Dark matter interpretation of the origin of non-thermal phenomena in galaxy clusters

Colafrancesco

Lieu

Marchegiani

et al. 2011

A&A

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Aims. We studied the multi-frequency predictions of various annihilating dark matter (DM) scenarios in order to explore the possibility to interpret the still unknown origin of non-thermal phenomena in galaxy clusters. Methods. We consider three different DM models with light (9 GeV), intermediate (60 GeV), and high (500 GeV) neutralino mass and study their physical effects in the atmosphere of the Coma cluster. The secondary particles created in the neutralino annihilation processes produce a multi-frequency spectral energy distribution (SED) of non-thermal radiation and also heat the intracluster gas, which we test against the observations available for the Coma cluster from radio to gamma-rays. The various DM-produced SEDs are normalized by the condition to fit the Coma radio halo spectrum, thus obtaining best-fit values of the annihilation cross-section σV and of the central magnetic field B 0 . Results. We find that it is not possible to interpret all the non-thermal phenomena observed in galaxy clusters in terms of DM annihilation. The light-mass DM model with 9 GeV mass produces too little power at all other frequencies, while the high-mass DM model with 500 GeV produces a large excess power at all other frequencies. The intermediate-mass DM model with 60 GeV and τ ± composition is marginally consistent with the HXR and gamma-ray observations, but narrowly fails to reproduce the EUV and soft X-ray observations. The intermediate-mass DM model with 60 GeV and bb composition is, on the other hand, always below the observed fluxes. We note that the radio halo spectrum of Coma is well fitted only in the bb or light-and intermediate-mass DM models. We also find that the heating produced by the DM annihilation in the centre of the Coma cluster is always larger than the intracluster gas cooling rate for an NFW DM density profile and it is substantially smaller than the cooling rate only for a cored DM density profile in light-mass DM model with 9 GeV. Conclusions. The possibility of interpreting the origin of non-thermal phenomena in galaxy clusters with DM annihilation scenarios requires a low neutralino mass and a cored DM density profile. If we then consider the multi-messenger constraints to the neutralino annihilation cross-section, it turns out that this scenario would also be excluded unless we introduce a substantial boost factor that represents DM substructures. If we relax the condition to fit the Coma radio halo and we consider the EUV and HXR detections as upper limits for the non-thermal emission, together with the gamma-ray limit, then the limits on σV are less stringent than those obtained by the multi-messenger analysis.

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“…Indeed, Inverse Compton (IC) scattering of Cosmic Background Radiation (CBR) photons by relativistic electrons present in the ICM was proposed to explain the EUV excess in the case of the Coma Cluster (Hwang 1997;Ensslin & Biermann 1998;Ensslin et al 1999). …”

Section: Introductionmentioning

confidence: 99%

EUV excess in the inner Virgo cluster

Paolis

Ingrosso

Nucita

et al. 2003

A&A

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Abstract.Observations with the Extreme UltraViolet Explorer (EUVE) satellite have shown that the inner region of the Virgo cluster (centered in M 87 galaxy) has a strong Extreme UltraViolet (EUV) emission (up to 13 ) in excess to the low-energy tail expected from the hot, diffuse IntraCluster Medium (ICM). Detailed observations of large scale radio emission and upper limits for hard, non-thermal X-ray emission in the 2−10 keV energy band have been also reported. Here we show that all available observations can be accounted for by the existence of two electron Populations (indicated as I and II) in the M 87 Galaxy. The mildly relativistic Population I is responsible for the EUV excess emission via IC scattering of CBR and starlight photons. Population II electrons (with higher energy) are instead responsible for the radio emission through synchrotron mechanism. The same electrons also give rise to hard non-thermal X-ray emission (via IC scattering of CBR photons), but the resulting power is always below the upper bounds placed by present observations. The non-negligible energy budget of the two electron populations with respect to that associated with thermal electrons indicates that the M 87 galaxy is not today in a quiescent (relaxed) phase. Nuclear activity and merging processes could have made available this energy budget that today is released in the form of relativistic electrons.

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An Inverse Compton Process for the Excess Diffuse EUV Emission from the Virgo and Coma Galaxy Clusters

Cited by 59 publications

References 17 publications

Warm‐hot Intergalactic Medium Emission and the Cluster Soft Excess: A Model Comparison

Warm‐hot Intergalactic Medium Emission and the Cluster Soft Excess: A Model Comparison

Dark matter interpretation of the origin of non-thermal phenomena in galaxy clusters

EUV excess in the inner Virgo cluster

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