Heated Cooling Flows

Brighenti, Fabrizio; Mathews, William G.

doi:10.1086/340763

Cited by 64 publications

(141 citation statements)

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“…In particular, Brighenti & Mathews (2002) analyzed several heating mechanisms induced by the central AGN and concluded that no simple mechanism is able to quench the cooling flow. Moreover, the required mechanism needs a finely tuned heating source.…”

Section: Introductionmentioning

confidence: 99%

Radiative Cooling and Heating and Thermal Conduction in M87

Ghizzardi

Molendi

Pizzolato

et al. 2004

ApJ

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The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observations of galaxy clusters has led to the development of several models that explore different heating processes in order to assess whether they can quench the cooling flow. Among the most appealing mechanisms are thermal conduction and heating through buoyant gas deposited in the intracluster medium (ICM) by active galactic nuclei (AGNs). We combine Virgo/M87 observations of three satellites (Chandra, XMM-Newton, and BeppoSAX ) to inspect the dynamics of the ICM in the center of the cluster. Using the spectral deprojection technique, we derive the physical quantities describing the ICM and determine the extra heating needed to balance the cooling flow, assuming that thermal conduction operates at a fixed fraction of the Spitzer value. We assume that the extra heating is due to buoyant gas, and we fit the data using the model developed by Ruszkowski and Begelman. We derive a scale radius for the model of $5 kpc, which is comparable with the M87 AGN jet extension, and a required luminosity of the AGN of a few ; 10 42 ergs s À1 , which is comparable to the observed AGN luminosity. We discuss a scenario in which the buoyant bubbles are filled with relativistic particles and magnetic field, which are responsible for the radio emission in M87. The AGN is supposed to be intermittent and to inject populations of buoyant bubbles through a succession of outbursts. We also study the X-ray-cool component detected in the radio lobes and suggest that it is structured in blobs that are tied to the radio buoyant bubbles.

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Section: Introductionmentioning

confidence: 99%

Radiative Cooling and Heating and Thermal Conduction in M87

Ghizzardi

Molendi

Pizzolato

et al. 2004

ApJ

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“…The location of the temperature maximum in M87 is at an unusually large radius presumably because of the relatively high ambient temperature (2-3 keV) in the Virgo Cluster. The central cooling of the gas can be understood as the mixing of hot inflowing gas from the Virgo Cluster with gas lost from evolving stars in M87, which orbit with a lower virial temperature than that of the surrounding cluster (Brighenti & Mathews 1999a). The characteristic deep central temperature minimum in M87 indicates that most of the gas in M87 has not been substantially heated by the jet and radio source.…”

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confidence: 99%

Spatial Diffusion of X-Ray Emission Lines in the M87 Cooling Flow; Evidence for Absorption

Mathews

Buote

Brighenti

2001

The Astrophysical Journal

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Recent XMM-Newton observations of the cooling flow in M87 indicate sharply decreasing oxygen, iron, and silicon abundances within ∼5 kpc of the galactic center. This result is unexpected since stellar mass loss and Type Ia supernovae are expected to produce pronounced central abundance maxima for all three elements. However, it has been suggested that many of the strong X-ray lines are optically thick and diffuse to larger radii in the cooling flow before escaping, falsifying the central abundances. We verify with radiation transfer calculations that this effect does indeed occur in the M87 cooling flow but that it is insufficient to account for the M87 observations. We suggest that some source of continuous opacity is required to reduce the central X-ray line emission, perhaps by warm gas at K. The radial surface brightness profiles of X-ray resonance lines 5 6T ∼ 10 -10 are also sensitive to turbulence in cooling flows, which reduces the line center optical depths considerably. Turbulence may provide sufficient energy to continuously heat the warm absorbing gas. Subject headings: cooling flows -galaxies: elliptical and lenticular, cD -galaxies: ISM -X-rays: galaxies -X-rays: galaxies: clustersThis estimate of the diffusion of X-ray line photons in M87 has been motivated by the exceptionally low abundances of iron, silicon, and oxygen within ∼5 kpc of the center of M87 as recently observed by Böhringer et al. (2001) with XMMNewton. We explore the possibility that these abundance variations are artifacts of the outward diffusion of optically thick X-ray lines as suggested by Gil'franov, Sunyaev, & Churazov (1987), Tawara et al. (1997), Shigeyama (1998), andBöhringer et al. (2001). We find that the expected outward migration of line photons does occur but is insufficient to account for the central photon depletion observed. Instead, an additional source of continuous absorption is indicated, as suggested by Buote (2001), and we speculate about its physical nature. Before discussing our results, we begin with a review of the properties of the M87 cooling flow and describe our line transfer calculation. VARIATION OF GAS TEMPERATURE AND DENSITYThe electron density distribution in the M87 cooling flow is taken from Nulsen & Böhringer (1995), corrected to distance 17 Mpc ( kpc): density distribution is based on ROSAT HRI observations reported in Böhringer (1999). Since the central X-ray emission in M87 is known to be partly nonthermal (and time variable), this latter density determination may be uncertain. Nevertheless, in the following we assume that is given by the n (r) e maximum of and , which intersect at 11.9 kpc.The (single-phase) gas temperature distribution is found by combining the results of Böhringer et al. (2001) ; all radii are in units of . This temperature profile rises 0.22 r e from the center toward a broad maximum, similar to thermal profiles in other well-observed bright elliptical galaxy cooling flows (Brighenti & Mathews 1997). The location of the temperature maximum in M87 is at an u...

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“…Recent numerical simulations show that heating the ICM near the cluster core can also give rise to bubble-like features that resemble those seen in the Chandra images (e.g., Churazov et al 2001;Quilis, Bower, & Balogh 2001;Brighenti & Mathews 2002a). However, it still is not clear how the AGNs or the bubbles they produce could heat up cooling flows, e.g., through shocks, cosmic rays, or Compton heating or whether this heating would be sufficient to offset the radiative losses and establish the observed high minimum temperature (see, e.g., Fabian et al 2002a andBrighenti &Mathews 2002b). We speculate that there could be an even simpler connection between the bubbles, "cooling flow" clusters, and the high minimum temperatures of clusters.…”

Section: Introductionmentioning

confidence: 86%

On the Relationship between Cooling Flows and Bubbles

McCarthy

Babul

Katz

et al. 2003

ApJ

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A common feature of the X-ray bubbles observed in Chandra images of some "cooling flow" clusters is that they appear to be surrounded by bright, cool shells. Temperature maps of a few nearby luminous clusters reveal that the shells consist of the coolest gas in the clusters-much cooler than the surrounding medium. Using simple models, we study the effects of this cool emission on the inferred cooling flow properties of clusters. We find that the introduction of bubbles into model clusters that do not have cooling flows results in temperature and surface brightness profiles that resemble those seen in nearby "cooling flow" clusters. They also approximately reproduce the recent XMM-Newton and Chandra observations of a high minimum temperature of ∼1-3 keV. Hence, bubbles, if present, must be taken into account when inferring the physical properties of the intracluster medium. In the case of some clusters, bubbles may account entirely for these observed features, calling into question their designation as clusters with cooling flows. However, since not all nearby "cooling flow" clusters show bubble-like features, we suggest that there may be a diverse range of physical phenomena that give rise to the same observed features.

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Heated Cooling Flows

Cited by 64 publications

References 77 publications

Radiative Cooling and Heating and Thermal Conduction in M87

Radiative Cooling and Heating and Thermal Conduction in M87

Spatial Diffusion of X-Ray Emission Lines in the M87 Cooling Flow; Evidence for Absorption

On the Relationship between Cooling Flows and Bubbles

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