Spatially resolved Fe K spectroscopy of NGC 4945

We present the imaging and spectroscopic analysis of the combined Chandra ACIS-S observations of the Compton-thick Seyfert 2 galaxy NGC 4945. We performed a spatially-resolved spectroscopy of the circumnuclear environment of the source, picturing the innermost 200 parsecs around the highly absorbed nucleus. The additional 200 ks ACIS-S data with respect to the previous campaign allowed us to map with even greater detail the central structure of this source and to discover an enhanced iron emission in the innermost nuclear region, with respect to the associated Compton reflection continuum. We revealed that the Equivalent Width of the iron K$\alpha$ line is spatially variable (ranging from 0.5 to 3 keV), on scales of tens of parsecs, likely due to the ionization state and orientation effects of the reprocessing material, with respect to the central X-ray illuminating source. A clump of highly ionized Fe XXV He-$\alpha$ is also detected, 40 parsecs east to the nucleus. When observations taken years apart are considered, the central unresolved reflected emission is found to remain constant.Comment: 10 pages, 6 figures, 4 tables, accepted for publication in MNRA

Linear response theory for long-range interacting systems in quasistationary states

Long-range interacting systems, while relaxing to equilibrium, often get trapped in long-lived quasistationary states which have lifetimes that diverge with the system size. In this work, we address the question of how a long-range system in a quasistationary state (QSS) responds to an external perturbation. We consider a long-range system that evolves under deterministic Hamilton dynamics. The perturbation is taken to couple to the canonical coordinates of the individual constituents. Our study is based on analyzing the Vlasov equation for the single-particle phase space distribution. The QSS represents stable stationary solution of the Vlasov equation in the absence of the external perturbation. In the presence of small perturbation, we linearize the perturbed Vlasov equation about the QSS to obtain a formal expression for the response observed in a single-particle dynamical quantity. For a QSS that is homogeneous in the coordinate, we obtain an explicit formula for the response. We apply our analysis to a paradigmatic model, the Hamiltonian mean-field model, that involves particles moving on a circle under Hamilton dynamics. Our prediction for the response of three representative QSSs in this model (the water-bag QSS, the Fermi-Dirac QSS, and the Gaussian QSS) is found to be in good agreement with $N$-particle simulations for large $N$. We also show the long-time relaxation of the water-bag QSS to the Boltzmann-Gibbs equilibrium state.Comment: 13 pages, 4 figures; v2: typos fixed; v3: small changes, close to the published versio

Value Matters: The Long-run Behavior of Stock Index Returns

We present a simple dynamical model of stock index returns grounded on the ability of the Cyclically Adjusted Price Earning valuation ratio devised by Robert Shiller to predict long-horizon performances of the market. Specifically, within the model returns are driven by a fundamental term and an autoregressive component perturbed by external random disturbances. The autoregressive component arises from the agents\u2019 belief that expected returns are higher in bullish markets than in bearish ones. The fundamental value, towards which fundamentalists expect that the current price should revert, varies in time and depends on the initial averaged Price-to- Earnings ratio. We demonstrate both analytically and by means of numerical experiments that the long-run behavior of the stylized dynamics agrees with empirical evidences reported in literature

Kinetic theory for non-equilibrium stationary states in long-range interacting systems

We study long-range interacting systems perturbed by external stochastic forces. Unlike the case of short-range systems, where stochastic forces usually act locally on each particle, here we consider perturbations by external stochastic fields. The system reaches stationary states where external forces balance dissipation on average. These states do not respect detailed balance and support non-vanishing fluxes of conserved quantities. We generalize the kinetic theory of isolated long-range systems to describe the dynamics of this non-equilibrium problem. The kinetic equation that we obtain applies to plasmas, self-gravitating systems, and to a broad class of other systems. Our theoretical results hold for homogeneous states, but may also be generalized to apply to inhomogeneous states. We obtain an excellent agreement between our theoretical predictions and numerical simulations. We discuss possible applications to describe non-equilibrium phase transitions.Comment: 11 pages, 2 figures; v2: small changes, close to the published versio

Age-related co-morbidities in people living with HIV

Abstracts of the Ninth International Congress on Drug Therapy in HIV Infection Meeting abstracts – A single PDF containing all abstracts in this Supplement is available here . http://www.biomedcentral.com/content/pdf/1758-2652-11-S1-info.pd

The lively accretion disc in NGC 2992. III. Tentative evidence of rapid Ultra Fast Outflow variability

We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert galaxy NGC 2992, observed at one of its highest flux levels in the X-rays. The time-averaged spectra of the two XMM-Newton orbits show Ultra Fast Outflows (UFOs) absorbing structures above 9 keV with $> 3 \sigma$ significance. A detailed investigation of the temporal evolution on a $\sim$5 ks time scale reveals UFO absorption lines at a confidence level $>$95% (2$\sigma$) in 8 out of 50 XMM-Newton segments, estimated via Monte Carlo simulations. We observe a wind variability corresponding to a length scale of 5 Schwarzschild radii $r_S$. Adopting the novel Wind in the Ionised Nuclear Environment (WINE) model, we estimate the outflowing gas velocity ($v=0.21-0.45 c$), column density ($N_H=4-8\cdot 10^{24} cm^{-2}$) and ionisation state ($\log(\xi_0/erg\ cm\ s^{-1})=3.7-4.7$), taking into account geometrical and special relativity corrections. These parameters lead to instantaneous mass outflow rates$\dot{M}_{out}\simeq0.3-0.8 M_{\odot} yr^{-1}$, with associated outflow momentum rates$\dot{p}_{out}\simeq 20-90 L_{Bol}/c$and kinetic energy rates$\dot{E}_K \simeq 2-25 L_{Bol}$. We estimate a wind duty cycle$\approx$12and a total mechanical power$\approx$2 times the AGN bolometric luminosity, suggesting the wind may drive significant feedback effects between the AGN and the host galaxy. Notably, we also provide an estimate for the wind launching radius and density$\approx 5 r_S, 10^{11} {cm}^{-3}$, respectively.Comment: Accepted for publication in the Astrophysical Journal. 21 pages, 11 figure

Supermassive black hole winds in X-rays: SUBWAYS: I. Ultra-fast outflows in quasars beyond the local Universe

We present a new X-ray spectroscopic study of 22 luminous (2 × 1045 ¿ Lbol/erg s-1 ¿ 2 × 1046) active galactic nuclei (AGNs) at intermediate redshifts (0.1 ¿ z ¿ 0.4), as part of the SUpermassive Black hole Winds in the x-rAYS (SUBWAYS) sample, mostly composed of quasars and type 1 AGNs. Here, 17 targets were observed with XMM-Newton in 2019–2020, and the remaining 5 are from previous observations. The aim of this large campaign (1.45 Ms duration) is to characterise the various manifestations of winds in the X-rays driven from supermassive black holes in AGNs. In this paper we focus on the search for and characterisation of ultra-fast outflows (UFOs), which are typically detected through blueshifted absorption troughs in the Fe K band (E > 7 keV). By following Monte Carlo procedures, we confirm the detection of absorption lines corresponding to highly ionised iron (e.g. Fe¿XXV Ha and Fe¿XXVI Lya) in 7 out of 22 sources at the ¿95% confidence level (for each individual line). The global combined probability of such absorption features in the sample is > 99.9%. The SUBWAYS campaign, based on XMM-Newton, extends to higher luminosities and redshifts than previous local studies on Seyferts. We find a UFO detection fraction of ~30% of the total sample, which is in agreement with previous findings. This work independently provides further support for the existence of highly ionised matter propagating at mildly relativistic speeds (¿0.1c) in a considerable fraction of AGNs over a broad range of luminosities, which is believed to play a key role in the self-regulated AGN feeding-feedback cycle, as also supported by hydrodynamical multi-phase simulations.Peer ReviewedPostprint (published version