119292105
JETS AND OUTFLOWS IN RADIO GALAXIES: IMPLICATIONS FOR AGN FEEDBACK
One of the main debated astrophysical problems is the role of the AGN feedback in galaxy formation. It is known that massive black holes have a profound effect on the formation and evolution of galaxies, but how black holes and galaxies communicate is still an unsolved problem. For Radio Galaxies, feedback studies have mainly focused on jet/cavity systems in the most massive and X–ray luminous galaxy clusters. The recent high–resolution detection of warm absorbers in some Broad Line Radio Galaxies allow us to investigate the interplay between the nuclear engine and the surrounding medium from a different perspective. We report on the detection of warm absorbers in two Broad Line Radio Galaxies, 3C 382 and 3C 390.3, and discuss the physical and energetic properties of the absorbing gas. Finally, we attempt a comparison between radio–loud and radio–quiet outflows.
73549569
Warm absorber energetics in broad-line radio galaxies
We review the soft X-ray properties of 3C 390.3, 3C 120, 3C 382 and 3C 445, the only broad-line radio galaxies (BLRGs) for which good quality gratings data are currently available. The XMM–Newton/Reflection Grating Spectrometer data of 3C 390.3 and 3C 120 were re-analysed searching for warm absorbers, already discovered in 3C 382 and 3C 445. We confirm the absence of ionized absorption features in 3C 120, but find signatures of outflowing gas (vout∼ 102 km s−1) in 3C 390.3. Its warm absorber (log ξ∼ 2 erg cm s−1, NH∼ 1020 cm−2), similar to that observed in 3C 382, is probably placed in the narrow-line regions. Its gas content is slower and less dense than the accretion disc wind discovered in 3C 445. Independently from the location of the warm gas, the outflowing masses () of BLRGs are significantly (but improbably) predominant with respect to the accretion masses (), suggesting a clumpy configuration of the warm absorber. However, even assuming overestimated values of , the kinetic luminosity of the outflow () is well below 1 per cent of the kinetic power of the jet (Pjet). Thus, the jet remains the major driver of the radio-loud active galactic nucleus (AGN) feedback at least on a parsec scale and beyond. The warm absorber parameters (NH, ξ) of BLRGs span a similar range of values to type 1 radio-quiet AGNs. However, when the mass outflow rate of BLRGs and Seyfert 1s is plotted as a function of the radio loudness, R = log [νLν(5 GHz)/L(2-10 keV)], the mass outflow rate seems to increase with radio power.
118758635
First Results from a XMM-Newton Survey of a Distance-Limited (D<22 Mpc) Sample of Seyfert Galaxies: I- the Agns
We report here preliminary results from a survey of nearby Seyfert galaxies using the EPIC CCDs on board XMM-Newton. The total sample consists of 28 Seyfert galaxies, and constitute a well-defined, complete (B 0 deg.) hemisphere. The survey has been initiated in June, 2001, and we report here the results for the 6 objects analyzed so far, namely: NGC3185, NGC3486, NGC3941, NGC4138, NGC4565, and NGC5033. The main goal of this survey is to obtain a better and unbiased understanding of the ``typical'' Seyfert X-ray spectrum (e.g. the distribution of their absorption column density) in the local Universe. This is crucial to verify the predictions and, thus, to validate unified models, and is a fundamental parameter of synthesis models for the X-ray background. A companion poster (paper II: L. Foschini et al., these proceedings) illustrates how this survey will also allow a comprehensive spectral study of the brightest (highest-luminosity) off-nuclear sources in the galaxies.
15312636
Probing the Hard X-Ray Properties of High-Redshift Radio-Quiet Quasars with ASCA
This paper reports the X-ray spectral analysis of five high-redshift (z≥2), radio-quiet quasars observed by ASCA. A simple power-law continuum plus cold Galactic absorption model well fits all the spectra (typically between ~2 and 30 keV in the sources frame). Neither the X-ray spectral hardening, which is attributed to a reflection component and observed in Seyfert galaxies, nor the excess absorption previously detected in high-redshift, radio-loud quasars have been revealed. Only marginal evidence of a neutral or mildly ionized FeKα line is found in one of the quasars. The average spectral slope in the observed 0.7-10 keV energy range, Γ=1.67 ± 0.11 (dispersion σ ~0.07), appears to be flatter than that of low-z, radio-quiet quasars (Γ 1.9-2) and slightly steeper but consistent with Γ=1.61 ± 0.04 (σ ~0.10) of high-z, radio-loud quasars.
122093176
Broad-Line Radio Galaxies: Jet Contribution to the Nuclear X-Ray Continuum
It is shown that for broad-line radio galaxies the strength of the nonthermal beamed radiation, when present, is always smaller than the accretion flow by a factor of <0.7 in the 2-10 keV band. This result has been obtained using the procedure adopted for disentangling the flat-spectrum radio quasar 3C 273. Although this implies a significantly smaller nonthermal flux in radio galaxies when compared to blazars, the jet component, if present, could be important at very high energies and thus easily detectable with GLAST.
122829632
The INTEGRAL mission
INTEGRAL, the International Gamma-Ray Astrophysics Laboratory, to be launched in 2001, is the second medium-size scientific mission (M2) of the ESA long term programme “Horizon 2000”. INTEGRAL addresses the fine spectroscopy and accurate positioning of celestial gamma-ray sources in the energy range 10 keV to 10 MeV. The observational requirements will be met by a payload utilising coded mask imaging in combination with detector pixel arrays (Imaging) and cooled Germanium detectors (Spectroscopy). INTEGRAL is an ESA led mission in collaboration with Russia and USA. Most of the observing time will be made available to the general scientific community.
21372858
Induced topological phases at the boundary of 3D topological superconductors.
We present tight-binding models of 3D topological superconductors in class DIII that support a variety of winding numbers. We show that gapless Majorana surface states emerge at their boundary in agreement with the bulk-boundary correspondence. At the presence of a Zeeman field, the surface states become gapped and the boundary behaves as a 2D superconductor in class D. Importantly, the 2D and 3D winding numbers are in agreement, signifying that the topological phase of the boundary is induced by the phase of the 3D bulk. Hence, the boundary of a 3D topological superconductor in class DIII can be used for the robust realization of localized Majorana zero modes.
34016084
Abelian Chern-Simons-Maxwell theory from a tight-binding model of spinless fermions.
Abelian Chern-Simons-Maxwell theory can emerge from the bosonization of the (2+1)-dimensional Thirring model that describes interacting Dirac fermions. Here we show how the Thirring model manifests itself in the low energy limit of a two-dimensional tight-binding model of spinless fermions. To establish that, we employ a modification of Haldane's model, where the "doubling" of fermions is rectified by adiabatic elimination. Subsequently, fermionic interactions are introduced that lead to the analytically tractable Thirring model. By local density measurements of the lattice fermions we can establish that for specific values of the couplings the model exhibits the confining (2+1)-dimensional QED phase or a topological ordered phase that corresponds to the Chern-Simons theory. The implementation of the model as well as the measurement protocol are accessible with the current technology of cold atoms in optical lattices.
2580056
Skyrmion Superfluidity in Two-Dimensional Interacting Fermionic Systems
In this article we describe a multi-layered honeycomb lattice model of interacting fermions which supports a new kind of parity-preserving skyrmion superfluidity. We derive the low-energy field theory describing a non-BCS fermionic superfluid phase by means of functional fermionization. Such effective theory is a new kind of non-linear sigma model, which we call double skyrmion model. In the bi-layer case, the quasiparticles of the system (skyrmions) have bosonic statistics and replace the Cooper-pairs role. Moreover, we show that the model is also equivalent to a Maxwell-BF theory, which naturally establishes an effective Meissner effect without requiring a breaking of the gauge symmetry. Finally, we map effective superfluidity effects to identities among fermionic observables for the lattice model. This provides a signature of our theoretical skyrmion superfluidy that can be detected in a possible implementation of the lattice model in a real quantum system.
117979829
A crucial hypothesis for Inflation
As is well known there are many different inflationary models that can explain the accelerated expansion occurred in the early Universe. It is possible that there exists a fundamental property of this period that could provide the corresponding field theory. Our hypothesis is that the Ricci scalar should assume a positive constant value during Inflation. Considering a single scalar field that drives the inflationary phase, we obtain uniquely the scalar potential and the coupling term between the scalar field and spacetime geometry. For this potential, that is well known in the inflationary scenario, the theoretical prediction of the spectral index ns is in perfect agreement with the experimental data. Interestingly in two dimensions, our model is equivalent to Liouville gravity.
118598460
Topological effective field theories for Dirac fermions from index theorem
Dirac fermions have a central role in high energy physics but it is well known that they emerge also as quasiparticles in several condensed matter systems supporting topological order. We present a general method for deriving the topological effective actions of (3+1) massless Dirac fermions living on general backgrounds and coupled with vector and axial-vector gauge fields. The first step of our strategy is standard (in the Hermitian case) and consists in connecting the determinants of Dirac operators with the corresponding analytical indices through the zeta-function regularization. Then, we introduce a suitable splitting of the heat kernel that naturally selects the purely topological part of the determinant (i.e. the topological effective action). This topological effective action is expressed in terms of gauge fields using the Atiyah-Singer index theorem which computes the analytical index in topological terms. The main new result of this paper is to provide a consistent extension of this method to the non Hermitian case where a well-defined determinant does not exist. Quantum systems supporting relativistic fermions can thus be topologically classified on the basis of their response to the presence of (external or emergent) gauge fields through the corresponding topological effective field theories.