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"Tombesi, F"
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Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy
Observations of an ultrafast accretion-disk wind in the X-ray spectrum of a nearby ultraluminous infrared galaxy support the theory that such winds affect the evolution of supermassive black holes and their host galaxies.
Growing in the wind
Francesco Tombesi
et al
. report the detection of a powerful accretion-disk wind with a mildly relativistic velocity in the X-ray spectrum of IRAS F11119+3257, a nearby (
z
= 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The energetics of these winds are consistent with the suggestion that active galactic nuclei winds can provide an efficient way to transfer energy to the interstellar medium and support the theory that such winds affect the evolution of supermassive black holes and their host galaxies.
Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies
1
,
2
. Recent observations of large-scale molecular outflows
3
,
4
,
5
,
6
,
7
,
8
in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models
9
,
10
,
11
,
12
suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete
3
,
4
,
5
,
6
,
7
,
8
because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies
13
,
14
and a few higher-redshift quasars
15
,
16
,
17
,
18
,
19
. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow
6
. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity
6
of 1.5 × 10
46
ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism
9
,
10
,
11
,
12
that is the basis of the quasar feedback
1
in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows).
Journal Article
Frontiers in accretion physics at high X-ray spectral resolution
Microcalorimeters have shown remarkable success in delivering high-spectral-resolution observations of the hot and energetic Universe, and have paved the way to revolutionary new science possibilities in X-ray astronomy. There are several research areas in compact-object science that can only be addressed with energy resolution Δ
E
≲ 5 eV at photon energies of a few kiloelectronvolts, corresponding to a velocity resolution of less than a few hundred kilometres per second, to be ushered in by microcalorimeters. Here we review some of the outstanding questions, focusing on how the research landscape is set to be transformed at the interface between accreting supermassive black holes and their host galaxies, in unravelling the structures of accretion environments, in resolving long-standing issues on the origins of energy and matter feedback, and in testing mass-scaled unification of accretion and feedback. The need to learn lessons from Hitomi and to make improvements in laboratory atomic data precision as well as plasma modelling are highlighted.
Upcoming X-ray microcalorimeter missions should deliver high spectral finesse, and allow detailed studies of accretion processes and feedback mechanisms in growing black holes.
Journal Article
Poynting-Robertson effect on black-hole-driven winds
Layers of ionized plasma, in the form of winds ejected from the accretion disk of Supermassive Black Holes (SMBHs) are frequently observed in Active Galactic Nuclei (AGNs). Winds with a velocity often exceeding \\(0.1c\\) are called Ultra-Fast-Outflows (UFOs) and thanks to their high power they can play a key role in the co-evolution between the SMBH and the host galaxy. In order to construct a proper model of the properties of these winds, it is necessary to consider special relativistic corrections due to their very high velocities. We present a derivation of the Poynting-Robertson effect (P-R effect) and apply it to the description of the dynamics of UFOs. The P-R effect is a special relativistic correction which breaks the isotropy of the radiation emitted by a moving particle funneling the radiation in the direction of motion. As a result of the conservation of the four-momentum, the emitting particles are subjected to a drag force and decelerate. We provide a derivation of the drag force caused by the P-R effect starting from general Lorentz transformations and assuming isotropic emission in the gas reference frame. Then, we derive the equations to easily implement this drag force in future simulations. Finally, we apply them in a toy model in which the gas particles move radially under the influence of the gravitation force, the radiation pressure and the drag due to the P-R effect. P-R effect plays an important role in determining the velocity profile of the wind. For a wind launched from \\(r_0=10r_s\\) (where \\(r_S\\) stands for the Schwarzschild radius), the asymptotic velocity reached by the wind is between \\(10\\)% and \\(24\\)% smaller than the one it would possess if we neglect the effect. This shows that the P-R effect should be taken into account when studying the dynamics of high-velocity, photoionized outflows in general.
Paper
Water megamaser and central black hole masses in a large sample of galaxies
Extragalactic water maser emissions at 22 GHz have been playing vital roles in astrophysics. The limited detection rate of these masers has been motivating researchers to find clues that can help characterise them. The physical environments 22 GHz masers formed in are still ambiguous. Accordingly, statistical studies have been thoroughly used to resolve these favourable environments. This work goes through the essential parameter of Active Galactic Nuclei (AGN), namely, the mass of the central supermassive black hole (MBH) of the maser host galaxy. We study the correlation between maser luminosity (LH2O) and MBH in sub-samples of megamasers (MMs), kilomasers (KMs), and disc masers. The regression line of the relation is also calculated for these sub-samples. Unlike the results of previous works, dividing the maser sample into MMs and KMs gives no privilege to MM galaxies. Contrary to expectation, KMs have weak and low significant LH2O - MBH correlation, while MMs show no correlation. The positive correlation in KMs can be explained by the role of AGN therein, while the diversity of MMs types, with some of which are not strongly related to AGN, may explain the correlation missing. Surprisingly, the 28 disc maser sample, where tight correlation is expected, shows a very weak and low significant LH2O-MBH correlation. Future VLBI studies will eventually lead to a specific classification of a good number of maser galaxies, which is essential to establishing the LH2O-MBH relation.
Paper
The impact of AGN outflows on the surface habitability of terrestrial planets in the Milky Way
It is well-known that active galactic nuclei (AGN) are accompanied by winds and outflows, some of which may reach weakly relativistic speeds of about \\(10\\) percent the speed of light. Yet, in spite of their ubiquity, the impact of AGN outflows in modulating surface habitability of terrestrial planets on galactic scales, using the Milky Way as the basis for comparison, is poorly investigated and inadequately understood. In this work, we address this issue by focusing on two key mechanisms: AGN winds can heat atmospheres and drive atmospheric escape, as well as stimulate the formation of nitrogen oxides and thence cause ozone depletion. By developing simple models, we estimate the maximal distance up to which these deleterious effects are rendered significant for Earth-like planets in the Milky Way, and thereby demonstrate that this value may extend to \\(\\lesssim 1\\) kpc. In the case of quasars hosting larger supermassive black holes, such effects could actually influence the AGN host galaxy as a whole.
Paper
Investigating the nuclear properties of highly accreting active galactic nuclei with XMM-Newton
Our understanding of highly accreting AGNs is hampered by the lack of a complete systematic investigation in terms of their main spectral and variability properties, and by the relative paucity of them in the local Universe, especially those powered by supermassive black holes with \\(M_\\mathrm{BH} > 10^8\\,M_\\odot\\). To overcome this limitation, we present here the X-ray spectral analysis of a new, large sample of 61 highly accreting AGNs named as the \\emph{XMM-Newton} High-Eddington Serendipitous AGN Sample, or X-HESS, obtained by cross-correlating the 11th release of the \\emph{XMM-Newton} serendipitous catalogue and the catalogue of spectral properties of quasars from the SDSS DR14. The X-HESS AGNs are spread across wide intervals with a redshift of \\(0.06
Paper
Linking Macro, Meso, and Micro Scales in Multiphase AGN Feeding and Feedback
Supermassive black hole (SMBH) feeding and feedback processes are often considered as disjoint and studied independently at different scales, both in observations and simulations. We encourage to adopt and unify three physically-motivated scales for feeding and feedback (micro - meso - macro ~ mpc - kpc - Mpc), linking them in a tight multiphase self-regulated loop. We pinpoint the key open questions related to this global SMBH unification problem, while advocating for the extension of novel mechanisms best observed in massive halos (such as chaotic cold accretion) down to low-mass systems. To solve such challenges, we provide a set of recommendations that promote a multiscale, multiwavelength, and interdisciplinary community.
Paper
X-HESS: a large sample of highly accreting serendipitous AGN under the XMM-Newton microscope
The bulk of X-ray spectroscopic studies of active galactic nuclei (AGN) are focused on local (\\(z < 0.1\\)) sources with low-to-moderate (\\(< 0.3\\)) Eddington ratio (\\(\\lambda_\\mathrm{Edd}\\)). It is then mandatory to overcome this limitation and improve our understanding of highly accreting AGN. In this work we present the preliminary results from the analysis of a sample of \\(\\sim70\\) high-\\(\\lambda_\\mathrm{Edd}\\) radio-quiet AGN at \\(0.06 \\leq z \\leq 3.3\\), based on the 10th release of the XMM-Newton serendipitous source catalogue, that we named as XMM-Newton High-Eddington Serendipitous AGN Sample (X-HESS). Almost \\(\\sim35\\%\\) of the X-HESS AGN have multi-epoch archival observations and \\(\\sim70\\%\\) of the sources can rely on simultaneous OM optical data. First results reveal sources showing signatures of ultra-fast outflows and remarkable long- and short-term X-ray flux variations. Indeed in J095847.88+690532.7 (\\(z \\sim 1.3\\)), one of the most densely monitored objects hosting a $\\sim$$10^9\\,M_\\odot\\( supermassive black hole, we discovered a variation of the soft X-ray flux by a factor of > 2 over approximately one week (rest-frame). Large variations in the power-law continuum photon index \\)\\Gamma\\( are also observed, questioning expectations from previously reported \\)\\Gamma - \\lambda_\\mathrm{Edd}\\( relations, for which \\)\\Gamma \\geq 2\\( would be a ubiquitous hallmark of AGN with \\)\\lambda_\\mathrm{Edd} \\sim 1$.
Paper
A Song of Lines and Winds: Tracing the Signatures of AGN Outflows in X-rays
Ultra-fast outflows (UFOs) are highly ionized, mildly relativistic winds seen in the X-ray spectra of active galactic nuclei (AGN) and are thought to contribute to AGN feedback and galaxy evolution. We investigate UFO signatures by analyzing a broad collection of published detections. Our final sample comprises 122 robust (> 2\\(\\sigma\\)) UFO detections in 57 AGN, spanning wide ranges in redshift, luminosity, black hole mass, and Eddington ratio. By combining phenomenological and photoionization modeling of the absorption features, we characterize empirical correlations among UFO properties. We find that line width, equivalent width, and outflow velocity are positively correlated, indicating that the broadest and strongest absorption lines trace the fastest winds, although the \\(\\upsilon_\\mathrm{out} - \\sigma\\) trend is comparatively weak. The large inferred velocity dispersions, often exceeding the uncertainty on the centroid velocity, must be included when estimating wind energetics and scaling relations. From the velocity constraints we derive lower limits on the launching radii, finding a minimum distance consistent with the innermost stable circular orbit of a weakly or non-rotating Schwarzschild black hole. We also assess for the first time how UFO properties depend on AGN class: differences between Seyferts and quasars, bridged by narrow-line Seyfert 1 galaxies, appear to be driven mainly by black hole mass and luminosity. The observed co-variation of velocity, width, and equivalent width supports a picture of clumpy, multi-component winds propagating through a thermally unstable multiphase medium within the chaotic cold accretion (CCA) cycle, and is consistent with both magnetically and line-driven acceleration. High-resolution X-ray spectroscopy with missions such as XRISM and NewAthena will be crucial to resolve the structure, kinematics, and physical origin of these flows.
Paper
Tracing circumnuclear dense gas in H2O maser galaxies
A sample of 30 H2O extra-galactic maser galaxies with their published HCN(J=1-0) and HCO+(J=1-0) observations has been compiled to investigate the dense gas correlation with H2O maser emission. Our sample number exceeds the size of the previous HCN samples studied so far by a factor of three, and it is the first study on the possible relation with the dense gas tracer HCO+. We find a strong correlation between normalized H2O maser emission luminosity (LH2O) and normalized HCO+ line luminosity (LHCO+). Moreover, a weak correlation has been found between LH2O and normalized HCN line luminosity (LHCN). The sample is also studied after excluding Luminous and Ultraluminous infrared galaxy (U)LIRG sources, and the mentioned correlations are noticeably stronger. We show that 'Dense gas' fractions as obtained from HCN and HCO+ molecules tightly correlate with maser emission, especially for galaxies with normal IR luminosity(LIR< 10^11Lsun) and we show that HCO+ is a better 'dense gas' tracer than HCN. Further systematic studies of these dense gas tracers with higher transition level lines are vital to probe megamaser physical conditions and to accurately determining how maser emission interrelates with the dense gas.
Paper