arXiv subjects

Delphine Porquet

Publications and source records attributed to Delphine Porquet.

At least 19 recordsLinked to original sources

arXiv2025

A possible two-fold scenario for the disc-corona of the luminous AGN 1H 0419--577: a high-density disc or a warm corona

[abridged] 1H 0419-577 is a highly-accreting, luminous BLS1 AGN. This study aims to characterise its disc-corona system using, for the first time, simultaneous XMM-Newton and NuSTAR observations, performed in May and November 2018. We conducted high-resolution grating spectroscopy to identify potential soft X-ray absorption and emission features. To measure the hot corona temperatures from the spectral analysis above 3 keV, we also included data from a previous NuSTAR observation from June 2015. We characterised the disc-corona system properties by analysing the broadband spectra and the SED from UV to hard X-rays. 1H 0419-577 was observed in a bare-like high-flux state at both epochs, with negligible neutral and ionised absorption along its line of sight at both Galactic and AGN rest-frames. However, several soft X-ray emission lines were detected, notably a broad and intense OVII line indicating an accretion disc origin at only a few tens of gravitational radii. The broadband X-ray spectra revealed a prominent, absorption-free smooth soft X-ray excess, a weak Fe Kalpha complex, and a lack of a Compton hump. Fitting data above 3 keV yielded apparent moderate hot corona temperatures of ~20-30 keV for the 2018 and 2015 observations, depending on the model applied. The 2018 X-ray broadband spectra were well reproduced by either a relativistic reflection model with a high-density accretion disc (~10^18 cm^-2), or a hybrid model combining warm and hot coronae with relativistic reflection. We performed the SED analysis for the latter scenario, which indicated that both the hot and warm coronae would have a small spatial extent. Both scenarios can successfully reproduce the two 2018 observations of 1H 0419-577, but they imply very different physical conditions, for example, in terms of disc density, temperature and accretion power released in the hot corona and the origin of the UV emission.

astro-ph.HE↗

arXiv2025

The NewAthena mission concept in the context of the next decade of X-ray astronomy

Large X-ray observatories such as Chandra and XMM-Newton have been delivering scientific breakthroughs in research fields as diverse as our Solar System, the astrophysics of stars, stellar explosions and compact objects, accreting super-massive black holes, and large-scale structures traced by the hot plasma permeating and surrounding galaxy groups and clusters. The recently launched observatory XRISM is opening in earnest the new observational window of non-dispersive high-resolution spectroscopy. However, several quests are left open, such as the effect of the stellar radiation field on the habitability of nearby planets, the Equation-of-State regulating matter in neutron stars, the origin and distribution of metals in the Universe, the processes driving the cosmological evolution of the baryons locked in the gravitational potential of Dark Matter and the impact of supermassive black hole growth on galaxy evolution, just to mention a few. Furthermore, X-ray astronomy is a key player in multi-messenger astrophysics. Addressing these quests experimentally requires an order-of-magnitude leap in sensitivity, spectroscopy and survey capabilities with respect to existing X-ray observatories. This paper succinctly summarizes the main areas where high-energy astrophysics is expected to contribute to our understanding of the Universe in the next decade and describes a new mission concept under study by the European Space Agency, the scientific community worldwide and two International Partners (JAXA and NASA), designed to enable transformational discoveries: NewAthena. This concept inherits its basic payload design from a previous study carried out until 2022, Athena.

astro-ph.IM↗

arXiv2024

Active Galaxy Science with the Line Emission Mapper: The Case for High-Resolution Soft X-ray Spectroscopy

This white paper discusses the breadth of science related to active galactic nuclei (AGN) and associated phenomena to be enabled by a mission with microcalorimeter energy resolution in the soft X-ray band, a large collecting area, and wide-field imaging. Such a mission, the Line Emission Mapper (LEM), has been proposed to NASA's 2023 Astrophysics Probe Explorer call. While the science pillars of the PI-led part of the mission focus on galaxy evolution, the PI-led LEM All-Sky Survey (LASS) and General Observer/Investigator opportunities will enable vital discoveries for AGN science in the critical soft X-ray band.

astro-ph.HE↗

arXiv2024

Revealing the burning and soft heart of the bright bare AGN ESO 141-G55: X-ray broadband and SED analysis

[Abridged] ESO 141-G55 is a nearby X-ray bright BLS1, which has been classified as a bare AGN due to the lack of warm absorption along its line-of-sight, providing an unhampered view into its disc-corona system. We aim to probe its disc-corona system thanks to the first simultaneous XMM-Newton and NuSTAR observation obtained on October 1-2, 2022. We carry out the X-ray broadband spectral analysis to determine the dominant process(es) at work, as well as the SED analysis to determine the disc-corona properties. The simultaneous broadband X-ray spectrum of ESO 141-G55 is characterised by the presence of a prominent smooth soft X-ray excess, a broad Fe K emission line and a significant Compton hump. The RGS spectra confirmed the lack of intrinsic warm-absorbing gas along our line of sight in the AGN rest frame, confirming that it is still in a bare state. However, soft X-ray emission lines are observed indicating substantial warm gas out of our line of sight. The intermediate inclination of the disc-corona system, ~43°, may offer us a favourable configuration to observe UFOs from the disc, but none is found in this 2022 observation, contrary to a previous 2007 XMM-Newton one. Relativistic reflection alone on a standard disc is ruled out from the X-ray broadband analysis, while a combination of soft and hard Comptonisation by a warm and hot corona (relagn), plus relativistic reflection (reflkerrd) reproduces its SED quite well. The hot corona temperature is very hot, ~140 keV, much higher than about 80% of the AGNs, whereas the warm corona temperature, ~0.3 keV, is similar to the values found in other sub-Eddington AGNs. ESO 141-G55 is accreting at a moderate Eddington accretion rate (~10--20%). Our analysis points to a significant contribution of an optically-thick warm corona to both the soft X-ray and UV emission in ESO 141-G55.

astro-ph.HE↗

arXiv2023

Probing the face-on disc-corona system of the bare AGN Mrk 110 from UV to hard X-rays: a moderate changing-state AGN?

[Abridged] The X-ray broadband spectra of the bare AGN Mrk 110, obtained by simultaneous XMM-Newton and NuSTAR observations (Nov 2019 and April 2020), are characterised by the presence of a prominent and absorption-free smooth soft X-ray excess, moderately broad OVII and Fe Kalpha emission lines, and a lack of a strong Compton hump. While relativistic reflection as the sole emission is ruled out, a simplified combination of soft and hard Comptonisation from a warm and a hot coronae, plus mild relativistic disc reflection reproduces the data very well. We aim to confirm the physical origin of the soft X-ray excess of Mrk 110 and to determine its disc-corona system properties from its energetics using two new sophisticated models: reXcor and relagn, respectively. At both epochs, the inferred high-values of the warm-corona heating from the X-ray broadband spectral analysis using reXcor confirm that the soft X-ray excess originates mainly from a warm corona rather than relativistic reflection. The intrinsic best-fit SED determined at both epochs using relagn show a high X-ray contribution relative to the UV and are very well reproduced by a warm and hot coronae plus mild relativistic reflection. The outer radii of the hot and warm coronae are located at a few 10s and ~100 Rg, respectively. Moreover, combining the inferred low Eddington ratio (~ a few %) from this work, and previous multi-wavelength spectral and timing studies suggests that Mrk 110 could be classified as a moderate changing-state AGN. Our analysis confirms the existence of a warm corona as a significant contribution to the soft X-ray excess and UV emission in Mrk 110, adding to growing evidence that AGN accretion deviates from standard disc theory. This strengthens the importance of long-term multi-wavelength monitoring on both single targets and large AGN surveys to reveal the real nature of disc-corona system in AGN.

astro-ph.HE↗

arXiv2023

Massive Black Hole Binaries as LISA Precursors in the Roman High Latitude Time Domain Survey

With its capacity to observe $\sim 10^{5-6}$ faint active galactic nuclei (AGN) out to redshift $z\approx 6$, Roman is poised to reveal a population of $10^{4-6}\, {\rm M_\odot}$ black holes during an epoch of vigorous galaxy assembly. By measuring the light curves of a subset of these AGN and looking for periodicity, Roman can identify several hundred massive black hole binaries (MBHBs) with 5-12 day orbital periods, which emit copious gravitational radiation and will inevitably merge on timescales of $10^{3-5}$ years. During the last few months of their merger, such binaries are observable with the Laser Interferometer Space Antenna (LISA), a joint ESA/NASA gravitational wave mission set to launch in the mid-2030s. Roman can thus find LISA precursors, provide uniquely robust constraints on the LISA source population, help identify the host galaxies of LISA mergers, and unlock the potential of multi-messenger astrophysics with massive black hole binaries.

astro-ph.HE↗

arXiv2023

Rapid Variability of the accretion disk wind in the narrow line Seyfert 1, PG 1448+273

PG 1448+273 is a luminous, nearby ($z=0.0645$), narrow line Seyfert 1 galaxy, which likely accretes close to the Eddington limit. XMM-Newton observations of PG 1448+273 in 2017 revealed the presence of an ultra fast outflow, as seen through its blueshifted iron K absorption profile, with an outflow velocity of about $0.1c$. Here, the first NuSTAR observation of PG 1448+273, performed in 2022 and coordinated with XMM-Newton is presented, which shows remarkable variability of its ultra fast outflow. The average count rate is a factor of 2 lower during the last 60 ks of the NuSTAR observation, where a much faster component of the ultra fast outflow was detected with a terminal velocity of $0.26\pm0.04c$. This is significantly faster than the outflow component which was initially detected in 2017, when overall PG 1448+273 was observed at a lower X-ray flux and which implies an order of magnitude increase in the wind kinetic power between the 2017 and 2022 epochs. Furthermore, the rapid variability of the ultra fast outflow in 2022, on timescales down to 10 ks, suggests we are viewing through a highly inhomogeneous disk wind in PG 1448+273, where the passage of a denser wind clump could account for the increase in obscuration in the last 60 ks of the NuSTAR observation.

astro-ph.HE↗

arXiv2023

Astrophysics with the Laser Interferometer Space Antenna

The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and space-born instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA's first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed; ultracompact stellar-mass binaries, massive black hole binaries, and extreme or intermediate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help making progress in the different areas. New research avenues that LISA itself, or its joint exploitation with upcoming studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe.

gr-qc↗

arXiv2023

Origins of the UV/X-ray Relation in Arakelian 120

We explore the accretion geometry in Arakelian 120 using intensive UV and X-ray monitoring from \textit{Swift}. The hard X-rays ($1-10$ keV) show large amplitude, fast (few-day) variability, so we expect reverberation from the disc to produce UV variability from the varying hard X-ray illumination. We model the spectral energy distribution including an outer standard disc (optical), an intermediate warm Comptonisation region (UV and soft X-ray) and a hot corona (hard X-rays). Unlike the lower Eddington fraction AGN (NGC 4151 and NGC 5548 at $L/L_{Edd}\sim 0.02$ and $0.03$ respectively), the SED of Akn 120 ($L\sim 0.05L_{Edd}$) is dominated by the UV, restricting the impact of reverberating hard X-rays by energetics alone. Illumination from a hard X-ray corona with height $\sim10 R_g$ produces minimal UV variability. Increasing the coronal scale height to $\sim 100 R_g$ improves the match to the observed amplitude of UV variability as the disc subtends a larger solid angle, but results in too much fast variability to match the UV data. The soft X-rays (connected to the UV in the warm Comptonisation model) are more variable than the hard, but again contain too much fast variability to match the observed smoother variability seen in the UV. Results on lower Eddington fraction AGN have emphasised the contribution from reverberation from larger scales (the broad line region), but reverberation induces lags on similar timescales to the smoothing, producing a larger delay than is compatible with the data. We conclude that the majority of the UV variability is therefore intrinsic, connected to mass accretion rate fluctuations in the warm Comptonisation region.

astro-ph.HE↗

arXiv2020

The flaring X-ray corona in the quasar PDS 456

New Swift monitoring observations of the variable, radio-quiet quasar, PDS 456, are presented. A bright X-ray flare was captured in September 2018, the flux increasing by a factor of 4 and with a doubling time-scale of 2 days. From the light crossing argument, the coronal size is inferred to be about 30 gravitational radii for a black hole mass of $10^{9} {\rm M}_{\odot}$ and the total flare energy exceeds $10^{51}$ erg. A hardening of the X-ray emission accompanied the flare, with the photon index decreasing from $Γ=2.2$ to $Γ=1.7$ and back again. The flare is produced in the X-ray corona, the lack of any optical or UV variability being consistent with a constant accretion rate. Simultaneous XMM-Newton and NuSTAR observations were performed, $1-3$ days after the flare peak and during the decline phase. These caught PDS 456 in a bright, bare state, where no disc wind absorption features are apparent. The hard X-ray spectrum shows a high energy roll-over, with an e-folding energy of $E_{\rm fold}=51^{+11}_{-8}$ keV. The deduced coronal temperature, of $kT=13$ keV, is one of the coolest measured in any AGN and PDS 456 lies well below the predicted pair annihilation line in X-ray corona. The spectral variability, becoming softer when fainter following the flare, is consistent with models of cooling X-ray coronae. Alternatively, an increase in a non-thermal component could contribute towards the hard X-ray flare spectrum.

astro-ph.HE↗

arXiv2019

Unlocking the Capabilities of Future High-Resolution X-ray Spectroscopy Missions Through Laboratory Astrophysics

Thanks to high-resolution and non-dispersive spectrometers onboard future X-ray missions such as XRISM and Athena, we are finally poised to answer important questions about the formation and evolution of galaxies and large-scale structure. However, we currently lack an adequate understanding of many atomic processes behind the spectral features we will soon observe. Large error bars on parameters as critical as transition energies and atomic cross sections can lead to unacceptable uncertainties in the calculations of e.g., elemental abundance, velocity, and temperature. Unless we address these issues, we risk limiting the full scientific potential of these missions. Laboratory astrophysics, which comprises theoretical and experimental studies of the underlying physics behind observable astrophysical processes, is therefore central to the success of these missions.

astro-ph.HE↗

arXiv2017

A deep X-ray view of the bare AGN Ark 120. III. X-ray timing analysis and multiwavelength variability

We present the spectral/timing properties of the bare Seyfert galaxy Ark 120 through a deep ~420ks XMM-Newton campaign plus recent NuSTAR observations and a ~6-month Swift monitoring campaign. We investigate the spectral decomposition through fractional rms, covariance and difference spectra, finding the mid- to long-timescale (~day-year) variability to be dominated by a relatively smooth, steep component, peaking in the soft X-ray band. Additionally, we find evidence for variable FeK emission red-ward of the FeK-alpha core on long timescales, consistent with previous findings. We detect a clearly-defined power spectrum which we model with a power law with a slope of alpha ~ 1.9. By extending the power spectrum to lower frequencies through the inclusion of Swift and RXTE data, we find tentative evidence of a high-frequency break, consistent with existing scaling relations. We also explore frequency-dependent Fourier time lags, detecting a negative ('soft') lag for the first time in this source with the 0.3-1 keV band lagging behind the 1-4 keV band with a time delay of ~900s. Finally, we analyze the variability in the optical and UV bands using the Optical/UV Monitor on-board XMM-Newton and the UVOT on-board Swift and search for time-dependent correlations between the optical/UV/X-ray bands. We find tentative evidence for the U-band emission lagging behind the X-rays with a time delay of 2.4 +/- 1.8 days, which we discuss in the context of disc reprocessing.

astro-ph.HE↗

arXiv2017

High Resolution X-ray Spectroscopy of the Seyfert 1, Mrk 1040. Revealing the Failed Nuclear Wind with Chandra

High resolution X-ray spectroscopy of the warm absorber in the nearby X-ray bright Seyfert 1 galaxy, Mrk 1040 is presented. The observations were carried out in the 2013-2014 timeframe using the Chandra High Energy Transmission Grating with a total exposure of 200 ks. A multitude of absorption lines from Ne, Mg and Si are detected from a wide variety of ionization states. In particular, the detection of inner K-shell absorption lines from Ne, Mg and Si, from charge states ranging from F-like to Li-like ions, suggests the presence of a substantial amount of low ionization absorbing gas, illuminated by a steep soft X-ray continuum. The observations reveal at least 3 warm absorbing components ranging in ionization parameter from $\logξ= 0-2$ and with column densities of $N_{\rm H} =1.5-4.0 \times 10^{21}$cm$^{-2}$. The velocity profiles imply that the outflow velocities of the absorbing gas are low and within $\pm100$ km s$^{-1}$ of the systemic velocity of Mrk 1040, which suggests any outflowing gas may have stalled in this AGN on large enough scales. The warm absorber is likely located far from the black hole, within 300 pc of the nucleus and is spatially coincident with emission from an extended Narrow Line Region as seen in the HST images. The iron K band spectrum reveals only narrow emission lines, with Fe K$α$ at 6.4 keV consistent with originating from reflection off Compton thick pc-scale reprocessing gas.

astro-ph.HE↗

arXiv2016

A deep X-ray view of the bare AGN Ark 120. I. Revealing the Soft X-ray Line Emission

The Seyfert 1 galaxy, Ark 120, is a prototype example of the so-called class of bare nucleus AGN, whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep ($>400$ ks exposure), high resolution X-ray spectroscopy of Ark 120 is presented, from XMM-Newton observations which were carried out in March 2014, together with simultaneous Chandra/HETG exposures. The high resolution spectra confirmed the lack of intrinsic absorbing gas associated with Ark 120, with the only X-ray absorption present originating from the ISM of our own Galaxy, with a possible slight enhancement of the Oxygen abundance required with respect to the expected ISM values in the Solar neighbourhood. However, the presence of several soft X-ray emission lines are revealed for the first time in the XMM-Newton RGS spectrum, associated to the AGN and arising from the He and H-like ions of N, O, Ne and Mg. The He-like line profiles of N, O and Ne appear velocity broadened, with typical FWHM widths of $\sim5000$ km s$^{-1}$, whereas the H-like profiles are unresolved. From the clean measurement of the He-like triplets, we deduce that the broad lines arise from gas of density $n_{\rm e}\sim10^{11}$ cm$^{-3}$, while the photoionization calculations infer that the emitting gas covers at least 10 percent of $4π$ steradian. Thus the broad soft X-ray profiles appear coincident with an X-ray component of the optical-UV Broad Line Region on sub-pc scales, whereas the narrow profiles originate on larger pc scales, perhaps coincident with the AGN Narrow Line Region. The observations show that Ark 120 is not intrinsically bare and substantial X-ray emitting gas exists out of our direct line of sight towards this AGN.

astro-ph.HE↗

arXiv2015

Study of the X-ray activity of Sgr A* during the 2011 XMM-Newton campaign

In Spring 2011 we observed Sgr A*, the supermassive black hole at the center of our Galaxy, with XMM-Newton with a total exposure of ~226 ks in coordination with the 1.3 mm VLBI. We have performed timing analysis of the X-ray emission from Sgr A* using Bayesian blocks algorithm to detect X-ray flares observed with XMM-Newton. Furthermore, we computed X-ray smoothed light curves observed in this campaign in order to have better accuracy on the position and the amplitude of the flares. We detected 2 X-ray flares on the 2011 March 30 and April 3 which have for comparison a peak detection level of 6.8 and 5.9 sigma in the XMM-Newton/EPIC light curve in the 2-10 keV energy range with a 300 s bin. The former is characterized by 2 sub-flares: the first one is very short (~458 s) with a peak luminosity of ~9.4E34 erg/s whereas the second one is longer (~1542 s) with a lower peak luminosity of ~6.8E34 erg/s. The comparison with the sample of X-ray flares detected during the 2012 Chandra XVP campaign favors the hypothesis that the 2011 March 30 flare is a single flare rather than 2 distinct sub-flares. We model the light curve of this flare with the gravitational lensing of a simple hotspot-like structure but we can not satisfactorily reproduce the large decay of the light curve between the 2 sub-flares with this model. From magnetic energy heating during the rise phase of the first sub-flare and assuming an X-ray photons production efficiency of 1 and a magnetic field of 100 G at 2 r_g, we derive an upper limit to the radial distance of the first sub-flare of 100 r_g. We estimate using the decay phase of the first sub-flare a lower limit to the radial distance of 4 r_g from synchrotron cooling in the infrared. The X-ray emitting region of the first sub-flare is located at a radial position of 4-100 and has a corresponding radius of 1.8-2.87 in r_g unit for a magnetic field of 100 G at 2 r_g.

astro-ph.HE↗

arXiv2013

XIPE: the X-ray Imaging Polarimetry Explorer

X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and temporal variability measurements and to imaging, allows a wealth of physical phenomena in astrophysics to be studied. X-ray polarimetry investigates the acceleration process, for example, including those typical of magnetic reconnection in solar flares, but also emission in the strong magnetic fields of neutron stars and white dwarfs. It detects scattering in asymmetric structures such as accretion disks and columns, and in the so-called molecular torus and ionization cones. In addition, it allows fundamental physics in regimes of gravity and of magnetic field intensity not accessible to experiments on the Earth to be probed. Finally, models that describe fundamental interactions (e.g. quantum gravity and the extension of the Standard Model) can be tested. We describe in this paper the X-ray Imaging Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a small mission with a launch in 2017 but not selected. XIPE is composed of two out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD) filled with a He-DME mixture at their focus and two additional GPDs filled with pressurized Ar-DME facing the sun. The Minimum Detectable Polarization is 14 % at 1 mCrab in 10E5 s (2-10 keV) and 0.6 % for an X10 class flare. The Half Energy Width, measured at PANTER X-ray test facility (MPE, Germany) with JET-X optics is 24 arcsec. XIPE takes advantage of a low-earth equatorial orbit with Malindi as down-link station and of a Mission Operation Center (MOC) at INPE (Brazil).

astro-ph.HE↗

arXiv2013

Modelling the X-ray polarimetric signatures of complex geometry: the case study of the "changing look" AGN NGC 1365

"Changing look" Active Galactic Nuclei (AGN) are a subset of Seyfert galaxies characterized by rapid transitions between Compton-thin and Compton-thick regimes. In their Compton-thin state, the central engine is less obscured, hence spectroscopy or timing observations can probe their innermost structures. However, it is not clear if the observed emission features and the Compton hump are associated with relativistic reflection onto the accretion disc, or complex absorption by distant, absorbing gas clouds passing by the observer's line-of-sight. Here, we investigate these two scenarios under the scope of X-ray polarimetry, providing the first polarisation predictions for an archetypal "changing look" AGN: NGC 1365. We explore the resulting polarisation emerging from lamp-post emission and scattering off an accretion disc in the immediate vicinity of a supermassive black hole. The computed polarisation signatures are compared to the results of an absorption-dominated model, where high column density gas partially covers the central source. While the shape of the polarisation spectrum is similar, the two models differ in net polarisation percentage, with the relativistic reflection scenario producing significantly stronger polarisation. Additionally, the variation of the polarisation position angle is distinctly different between both scenarios: the reflection-dominated model produces smooth rotations of the polarisation angle with photon energy whereas circumnuclear absorption causes an orthogonal switch of the polarisation angle between the soft and the hard X-ray bands. By comparing the predicted polarisation of NGC 1365 to the detectability levels of X-ray polarimetry mission concepts proposed in the past, we demonstrate that with a large, soft X-ray observatory or a medium-sized mission equipped with a hard (6 - 35 keV) polarimeter, the correct interpretation would be unambiguous.

astro-ph.HE↗

arXiv2013

The Hot and Energetic Universe: The close environments of supermassive black holes

Most of the action in Active Galactic Nuclei (AGN) occurs within a few tens of gravitational radii from the supermassive black hole, where matter in the accretion disk may lose up to almost half of its energy with a copious production of X-rays, emitted via Comptonization of the disk photons by hot electrons in a corona and partly reflected by the accretion disk. Thanks to its large effective area and excellent energy resolution, Athena+ contributions in the understanding of the physics of accretion in AGN will be fundamental - and unique - in many respects. It will allow us to map the disk-corona system - which is crucial to understand the mechanism of energy extraction and the relation of the corona with winds and jets - by studying the time lags between reflected and primary photons. These lags have been recently discovered by XMM-Newton, but only Athena+ will have the sensitivity required to fully exploit this technique. Athena+ will also be able e.g. to determine robustly the spin of the black hole in nearby sources (and to extend these measurements beyond the local Universe), to establish the nature of the soft X-ray components, and to map the circumnuclear matter within the AGN inner parsec with unprecedented details.

astro-ph.HE↗