Radiative Cooling and Heating and Thermal Conduction in M87

Abstract

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.

A diffuse bubble-like radio-halo source MRC 0116+111: imprint of AGN feedback in a low-mass cluster of galaxies

“…The external pressure is p =ρ ICM k T /(μ m H ) (where ρ ICM is the density of ICM, T is the gas temperature, μ= 0.6 the mean molecular weight and m H is mass of the hydrogen atom), which is presently not known for MRC 0116+111. We can obtain an order of magnitude estimate for H cav if we take fiducial values, ρ ICM = 1.67 × 10 −26 gm cm −3 (for a proton number density of 10 −2 cm −3 ) and T = 2.32 × 10 7 K (2 keV), which are typical of the gaseous environment around a miniradio‐halo source like M87 or Perseus A at the centre of a cooling core (Ghizzardi, Molendi & Pizzolato 2004). This gives a pressure p = 5.3 × 10 −11 dynes cm −2 and an enthalpy H cav = 2.06 × 10 60 V 70 erg for a cavity volume V 70 = V /(70 cm 3 ).…”

On the Fe abundance peak formation in cool-core clusters of galaxies: hints from cluster WARPJ1415.1+3612 atz= 1.03

“…We de-project the XMM-Newton profiles of the local clusters in Table 2 following the method described in Ettori (2002) and Ghizzardi et al (2004) and estimate the Fe masses of these clusters within r 2500 with Eq. (1).…”

A thermally stable heating mechanism for the intracluster medium: turbulence, magnetic fields and plasma instabilities

“…Bearing in mind that thermal conduction models routinely fail in the innermost regions of cool cluster cores (e.g. Markevitch et al 2003; Zakamska & Narayan 2003; Ghizzardi et al 2004; Kaastra et al 2004), it is important to note that parallel viscous heating should be especially important in these relatively cold ( T ∼ 1 keV) and strongly magnetized ( B ∼ 10 μG) regions. A balance between parallel viscous heating and radiative cooling, however, does contain the implicit assumption that the thermal conduction is relatively unimportant.…”

“…One advantage is that this ensures smooth gradients for computing the conductive heating rates. The profiles for A478 and A1795 were taken from Dennis & Chandran (2005) and the profiles for M87 were taken from Ghizzardi et al (2004). For A1835 (Sanders et al 2010) and Hydra A (David et al 2001), the electron number density was fitted using with β= 0.593, r c = 32.42 kpc and n 0 = 0.115 cm −3 (for A1835) and β= 0.393, r c = 10.9 kpc and n 0 = 0.0669 cm −3 (for Hydra A).…”