Cold molecular gas has recently been detected in several cooling flow clusters of galaxies containing huge optical nebula. These optical filaments are tightly linked to cooling flows and related phenomena, such as rising bubbles of relativistic plasma fed by radio jets. We present here a map, in the CO(2-1) rotational line, of the cold molecular gas associated with some of the Hα filaments surrounding the central galaxy of the Perseus cluster: NGC 1275. The map, extending to about 50 kpc (135 arcsec) from the center of the galaxy, has been made with the 18-receiver array HERA at the focus of the IRAM 30 m telescope. Although most of the cold gas is concentrated to the center of the galaxy, the CO emission is also clearly associated with the extended filaments conspicuous in ionised gas, and could trace a possible reservoir fueling the star formation there. Some of the CO emission is also found where the X-ray gas could cool down more efficiently at the rims of the central X-ray cavities (where the hot gas is thought to have been pushed out and compressed by the expanding radio lobes of the central AGN). The CO global kinematics do not show any rotation in NGC 1275. The cold gas is probably a mixture of gas falling down on the central galaxy and of uplifted gas dragged out by a rising bubble in the intracluster medium. As recently suggested in other cluster cores, the cold gas peculiar morphology and kinematics argue for the picture of an intermittent cooling flow scenario where the central AGN plays an important role.

We show that Eddington-limited black hole luminosities can be sufficient to deplete a galaxy bulge of gas through radiation pressure, when the ionization state of the gas and the presence of dust are properly taken into account. Once feedback starts to be effective it can consistently drive all the gas out of the whole galaxy. We estimate the amount by which the effect of radiation pressure on dusty gas boosts the mass involved in the Eddington limit and discuss the expected column density at which the gas is ejected. An example is shown of the predicted observed nuclear spectrum of the system at the end of an early, obscured phase of growth when the remaining column density NH ~ f * 1e24 cm^-2 where f is the gas fraction in the bulge.Comment: correct corrupted figures in pdf version, MNRAS accepted, 5 pages, 3 figure

The lobes of radio galaxies and quasars, fed by jets and hot spots, represent a significant, and currently illconstrained, source of energy input into the intergalactic medium (IGM). How much energy is input into the IGM depends on the minimum energy to which the power-law distribution of relativistic particles is accelerated in the hot spots. This has hitherto been unknown to within 3 orders of magnitude. We present direct evidence for the discovery of this low-energy cutoff in the lobe of a megaparsec-sized radio galaxy via the existence of extended X-ray emission, inverse Compton-scattered from aged radio plasma, and its separation by 80 kpc from regions containing freshly accelerated plasma from the hot spot. The low-energy cutoff of in the hot 4 g ∼ 10 spot is higher than previously thought but reconciles discrepancies with magnetic field estimates that had been systematically lower than equipartition values. The inverse Compton scattering of the spent synchrotron plasma is at the expense of cosmic microwave background (CMB) photons; we comment on the importance of such giant radio galaxies as contaminants of CMB anisotropies.

We present Chandra observations of two relatively high redshift FRII radio galaxies, 3C 432 and 3C 191 (z=1.785 and z=1.956 respectively), both of which show extended X-ray emission along the axis of the radio jet or lobe. This X-ray emission is most likely to be due to inverse-Compton scattering of Cosmic Microwave Background (CMB) photons. Under this assumption we estimate the minimum energy contained in the particles responsible. This can be extrapolated to determine a rough estimate of the total energy. We also present new, deep radio observations of 3C 294, which confirm some association between radio and X-ray emission along the NE-SW radio axis and also that radio emission is not detected over the rest of the extent of the diffuse X-ray emission. This, together with the offset between the peaks of the X-ray and radio emissions may indicate that the jet axis in this source is precessing.Comment: definitive version is on MNRAS online early, 9 pages, 6 figures - here misleading text removed and typos correcte

We present new XMM–Newton data of the high‐redshift (z= 1.883), Mpc‐sized giant radio galaxy 6C 0905+39. The larger collecting area and longer observation time for our new data means that we can better characterize the extended X‐ray emission, in particular its spectrum, which arises from cosmic microwave background photons scattered into the X‐ray band by the energetic electrons in the spent synchrotron plasma of the (largely) radio‐quiet lobes of 6C 0905+39. We calculate the energy that its jet‐ejected plasma has dumped into its surroundings in the last 3 × 107 yr and discuss the impact that similar, or even more extreme, examples of spent, radio‐quiet lobes would have on their surroundings. Interestingly, there is an indication that the emission from the hotspots is softer than the rest of the extended emission and the core, implying it is due to synchrotron emission. We confirm our previous detection of the low‐energy turnover in the eastern hotspot of 6C 0905+39.