arXiv subjects

D. Ł. Król

Publications and source records attributed to D. Ł. Król.

10 recordsLinked to original sources

arXiv2026

Local Heavily Obscured Active Galaxies Observed With Chandra (I): Spectral Properties of the Nuclear and Extended X-ray Emission

The Chandra X-ray Observatory has revealed that kiloparsec-scale extended X-ray emission is commonly associated with heavily absorbed ($\log (N_{H}$/cm$^{-2})\,>\, 23$) Active Galactic Nuclei (AGN) in the local Universe. We present a homogeneous spatially resolved spectral analysis of a sample of nearby obscured AGN observed with deep ($>100$~ks) Chandra/ACIS exposures and all associated with extra-nuclear extended emission. Exploiting the sub-arcsecond resolution of Chandra, we separate unresolved nuclear emission from physically distinct extended regions and model their spectra using photoionized and thermal plasma components. The extended emission is spectrally complex, requiring a combination of photoionized and collisionally ionized components in most regions. The spectral parameters exhibit systematic radial variations, with nuclear regions typically hosting higher-column and higher-ionization components, while extended regions span similarly broad but overlapping ranges without a simple monotonic radial progression. Hard ($>3$ keV) X-ray emission in excess of nuclear PSF spillover is detected in 19/20 sources, while extended Fe~K$α$ emission is observed in 12/20 systems. These results establish a uniform baseline for the X-ray properties of heavily obscured AGN and provide constraints on the geometry and physical conditions of AGN-driven feedback in the local Universe.

astro-ph.GA↗

arXiv2026

Directly tracking the re-brightening of a supermassive black hole accretion disk

Accretion onto supermassive black holes powers the most luminous persistent sources in the Universe, the so-called active galactic nuclei, whose emission is characterized by two distinct spectral components: thermal optical/ultraviolet radiation from an optically thick accretion disk and a power-law X-ray tail from a corona located in the innermost regions of the accretion flow. Yet, how radiatively efficient accretion disks develop and couple to the hot corona remains poorly understood. Using six years of simultaneous ultraviolet and X-ray monitoring of the nearby active galaxy ESO 511-G030, we witness a dramatic evolution of the broadband spectral energy distribution, driven by an increase of the ultraviolet flux from the disk by more than an order of magnitude over a time scale of less than three years. The overall behavior is unlikely to track an uncovering event, and is instead compatible with a progressive recovery of the optically thick component of the accretion flow. At accretion rates higher than approximately one per cent of the Eddington limit, ultraviolet and X-ray data are tightly coupled and follow the well-defined, non-linear correlation between disk and corona found in the more luminous quasars. Below this threshold, the relation apparently breaks down, as expected in case of evaporation of the inner accretion disk into a geometrically thick, optically thin hot flow. This is a strong hint of an accretion-state transition analogous to those observed in stellar-mass black holes, and confirms the need for a paradigm change in the models of radiatively efficient accretion flows around supermassive black holes.

astro-ph.HE↗

arXiv2026

Tracking down the broadband polarimetric properties of PG 1553+113

We report on a nine-month monitoring campaign of the blazar PG 1553+113, relying on three observations carried out in 2025 with the Imaging X-ray Polarimetry Explorer (IXPE) and supported by multi-wavelength facilities. The source displayed pronounced variability across the electromagnetic spectrum, with X-ray flux changes by up to a factor of $\sim5$ and complex evolution of the optical polarization properties, including one of the largest (exceeding $150^{\circ}$) and fastest rotations in the electric vector position angle (EVPA) ever recorded. This swing of the EVPA was also accompanied by a temporary drop of the optical polarization degree to nearly zero. Significant X-ray polarization was observed during the third IXPE pointing, with a polarization degree $Π_{\rm X}\,=(\,18.4\,\pm\,5.8)\%$ and $Ψ_{\rm X}\,=\,74^{\circ} \pm 9^{\circ}$ in the 2--8~keV band, while only upper limits were obtained in the first two epochs. The optical data show that the second IXPE observation occurred shortly after a dramatic optical polarization event characterized by a rapid EVPA swing and strong depolarization. Two possible scenarios may explain the broadband polarimetric behavior: (i) the superposition of two emitting regions with nearly orthogonal magnetic field configurations and variable relative contributions, and (ii) the interaction of a single emitting region with a shock that temporarily reorders the magnetic field. In both cases, the data support a picture in which the X-ray and optical emissions arise from closely related but not strictly co-spatial regions within a dynamically evolving, magnetically structured jet.

astro-ph.HE↗

arXiv2026

Ultra-thick warm absorbers: Enlarging the parameter space of AGN ionised outflows

The analysis of X-ray absorption features in active galactic nuclei (AGN) provides a wealth of information about the physical properties of the matter surrounding supermassive black holes (SMBHs). While standard correlations between the ionisation state, column density, and velocity typically distinguish between disc winds and warm absorbers, some sources exhibit properties that significantly deviate from these trends. We investigate a class of X-ray absorbers, which we define as ultra-thick warm absorbers (UTWAs), identified in a sample of 12 AGN. These absorbers are characterised by exceptionally high column densities and ionisation parameters (($\log (N_{\rm H}/\rm cm^{-2})\gtrsim22.5$ and $0.5 \lesssim \log(ξ/\rm erg~cm~s^{-1})$ $ \lesssim 2.5$)) that lie outside the typical ranges observed in standard warm absorbers. We performed detailed X-ray spectral analyses of both unpublished and archival {\it XMM-Newton}, {\it NuSTAR}, and {\it Swift} datasets to characterise the physical properties of UTWAs in four of these twelve sources. We studied their variability on timescales ranging from days to years and explored their connection with other spectral features. All AGN hosting UTWAs in our sample exhibit extreme soft X-ray variability, in some cases up to an order of magnitude, primarily driven by changes in the absorbing gas. In a subset of these sources (four out of 12), the UTWAs are accompanied by signatures of ultra-fast outflows (UFOs) in the Fe K$α$ energy range. UTWAs represent a rare but crucial phase of AGN feedback. We discuss their physical origin, their potential connection with UFOs, and provide insights into why these high-column density, unusually ionised absorbers appear so rarely in local AGN samples.

astro-ph.HE↗

arXiv2026

Active Galactic Nuclei-driven Metallicity Enrichment in the Interstellar Medium of Mrk 573

We present the first spatially resolved at $\sim20$ pc scale application of AGN-specific metallicity diagnostics for the nearby Compton-thick Seyfert 2 galaxy Mrk 573 ($z = 0.017$). We use Hubble Space Telescope narrow-band imaging, MUSE integral-field spectroscopy and apply AGN strong-line metallicity diagnostics based on [O III], [S II], H$β$, H$α$, and [N II] emission lines. We construct maps of $12 + \log$(O/H) for two different metallicity calibrations and two different N/O-O/H scaling relations out to $\sim1$ kpc and down to $\sim20$ pc scales. Our analysis reveals metallicity enhancement in AGN-dominated regions, with oxygen abundances reaching up to few times Solar. The metallicity shows a patchy spatial distribution, varying on $\sim100$ pc scales, appears to trace the high Seyfert/LINER index (SLI) value regions and the VLA 6 cm jet/radio lobe emission. These spatial correspondences and the lack of evidence for star formation in the bicone region suggest that the enrichment originates from metals transported from the nuclear AGN regions by winds, outflows, or jets.

astro-ph.GA↗

arXiv2026

High Resolution (<100pc) Ionization Structures in the ISM of AGN ESO~137-G34

We present a detailed, spatially resolved { Veilleux \& Osterbrock (VO) diagram} analysis of ESO\,137-G034, a Compton-thick Active Galactic Nucleus (AGN), based on narrowband {\it HST} imaging in [O~III], [S~II], H$α$, and H$β$ emission lines. The narrowband optical emission exhibits a bi-conical morphology and traces the diffuse X-ray emission observed with \textit{Chandra}. We dissect the Interstellar Medium (ISM) into Seyfert-, LINER-, and H~II-dominated regions with a resolution of $\sim0.1^{\prime\prime}$ ($\sim20$\,pc at $z=0.009$). To { visualize} the fine spatial structure of the { ISM excitation}, we introduce a new parameter: the Seyfert/LINER Index (SLI), defined as the perpendicular distance of each point in the { VO} diagram from the Seyfert/LINER division line. { SLI mapping reveals fine spatial structures in the ISM excitation especially in the Seyfert ionization bi-cones where the statistical significance of our data is higher.} Most of the emission within the bi-cones is Seyfert-like, with SLI values consistent with regions of the { VO} diagram that can be modeled with AGN photoionization. In the North-West Seyfert cone three radial SLI peaks suggest episodic nuclear outbursts, with estimated timescales of a few $10^3$\,yrs and $<100$\,yrs duration. The South-East cone shows inhomogeneous excitation, with a higher SLI region in its inner part, coinciding with a wider region of enhanced soft X-ray emission at the radio lobe inner edge. This region is characterized by line ratios consistent with fast shocks ($>1000$\,km\,s$^{-1}$) induced excitation. The North-West cone is surrounded by a smooth LINER ``cocoon''. The LINER region in the SE cone appears more irregular, with inter-cone LINER points likely shaped by both local ISM structure and shocks. Our findings highlight the complex interplay of different AGN feedback mechanisms in the ISM.

astro-ph.GA↗

arXiv2026

Probing AGN-ISM Feedback through Extended X-ray Emission in ESO 137-G034

We present a detailed analysis of the X-ray emission of the Compton-thick (CT) AGN ESO\,137-G034 based on deep ($\sim230$\,ks) Chandra observations. As in other CT AGNs, the morphology of the emission is elongated, approximately following the [O III] ionization bicone. With spatially resolved spectral modeling, we show that the extended emission within the bi-cone regions { is most readily explained} as from a mixture of photo-ionized gas and shock-heated plasma, reflecting the combined effects of radiative and kinematic AGN feedback. By comparing the morphology of the { X-ray emission in narrow spectral bands and that of the 3\,cm radio jet, we find suggestive evidence of thermal, possibly shocked emission associated with the SE termination of the radio jet. This interpretation is also supported by the lack of [O~III] relative to the $0.3-3.0$ keV flux in the inner $3^{\prime\prime}$ ($\sim600$\,pc) of the SE cone, which would be consistent with an additional thermal X-ray component on top of the photonized emission of an outflowing wind. A similar effect is only seen within the inner $1^{\prime\prime}$ ($200$\,pc) of the NW cone. In the radial profile of the [OIII]/X-ray flux ratio and the X-ray hardness ratio within the inner $\sim3^{\prime\prime}$ ($\sim600$\,pc) of the SE cone we see an asymmetry, with no counterpart in the NW cone. We detect soft extended X-ray emission in the cross-cones which may originate from the interaction of an embedded radio jet with a clumpy interstellar medium (ISM). }These results highlight the { importance of both} radiative and mechanical feedback in shaping the circumnuclear environment of ESO\,137-G034.

astro-ph.HE↗

arXiv2025

The X-ray Emission of NGC 5005: An Unobscured Low-Luminosity AGN with a Weakly Accreting Broad-Line Region

We present deep Chandra X-ray observations of NGC 5005, a LINER-dominated galaxy previously reported to host a broad H$α$ emission line. The diffuse soft X-ray emission ($<$3 keV) extends out to $\sim$800 pc, while harder emission ($>$3 keV) is confined to the central $\sim$400 pc. Spatially resolved spectroscopy of the nuclear ($r<150$ pc) and extended ($150<r<500$ pc) regions reveals that these are best described by models including both photoionized and thermal plasma components, consistent with excitation by a low-luminosity AGN and shock-heated gas. Narrow-band imaging and excitation maps from the Hubble Space Telescope (HST) support this interpretation, closely matching the X-ray morphology and ionization structure. The detection of a faint hard X-ray nuclear source with Chandra, combined with stringent upper limits from NuSTAR and Swift, and consistency with the X-ray luminosity predicted from the HST [O III]$λ$5007 emission, indicates that NGC 5005 hosts an intrinsically low-luminosity ($L_{\rm bol} \sim 10^{41}$ erg s$^{-1}$), unobscured AGN. Despite the extremely low Eddington ratio inferred from our measurements ($λ_{\rm Edd} \sim 5 \times 10^{-6}$), the presence of a broad H$α$ line in the optical spectrum suggests the persistence of a thin accretion disk, challenging standard paradigms of accretion flow configurations at such low accretion rates.

astro-ph.GA↗

arXiv2022

Possible Gravitational Microlensing Events in the Optical Lightcurve of Active Galaxy S5 0716+714

A well-known active galaxy of the blazar type, S5 0716+714, is characterized by a particularly high variability duty cycle on short-time scales at optical frequencies. As such, the source was subjected to numerous monitoring programs, including both ground-based as well as space-borne telescopes. On closer inspection of the most recent accumulation of the data provided by the Transiting Exoplanet Survey Satellite, we have noticed several conspicuous events with `volcano-like' symmetric shape, lasting all for several hours, which closely resemble the achromatic events detected with the previous Whole Earth Blazar Telescope campaigns targeting the source. We propose that those peculiar features could be due to the gravitational micro-lensing of the innermost segments of the precessing jet in the system, by a binary lens. We study the magnification pattern of the lens with the inverse-ray shooting method, and the source trajectory parameters with the Python package MuLensModel. In this way, we were able to fit successfully all the selected events with a single lens, adjusting slightly only the source trajectory parameters for each lensing event. Based on the fit results, we postulate the presence of a massive binary lens, containing an intermediate-mass black hole, possibly even a super-massive one, and a much less massive companion (by a factor of $\lesssim 0.01$), located within the host galaxy of the blazar, most likely the central kiloparsec region. We discuss the major physical implications of the proposed scenario regarding the quest for the intermediate-mass and dual supermassive black holes in active galaxies.

astro-ph.HE↗

arXiv2020

Evolution of black hole mass and spin in collapsars

We investigate the collapsar scenario for the long gamma ray bursts. The energetics % of explosions in the $γ$-ray band are consistent with the binding energy of a progenitor star. The events duration times, lightcurve profiles, variability, and connection with supernovae, are still subject of many studies. In our scenario, the evolved progenitor star is collapsing onto a spinning black hole formed from the compact core. The accretion via rotationally supported torus powers the ejection of relativistic jets. The rotational energy of the black hole is presumably transported to the remote jet and mediated by magnetic fields. The rotation of pre-supernova star is a key property of the model. In our study, we investigate different accretion scenarios and various distributions of initial angular momentum in the envelope, that affect the spinning up the black hole and its mass increment.

astro-ph.HE↗