Broadband X-ray Research Articles

Broad-band X-ray spectral study of nuclear structure in local obscured radio galaxies

ABSTRACT Radio galaxies are a key population to understand the importance of relativistic jets in active galactic nucleus (AGN) feedback. We present the results of a systematic, broad-band X-ray spectral analysis of hard X-ray selected radio galaxies to investigate their nuclear structures. In this study, we focus on the seven most radio-loud, X-ray obscured narrow-line radio galaxies in the Swift/BAT 70 month AGN catalogue. The spectra from 0.5 keV up to 66 keV obtained with Suzaku and NuSTAR of six objects are newly analysed here by utilizing the X-ray clumpy torus model (xclumpy), whereas we refer to the literature for the results of Centaurus A. We find that these radio galaxies have similar torus covering fractions compared with radio-quiet AGNs at the same Eddington ratios (−3 < log λEdd < −1). This result implies that (1) the torus structure is not an important factor that determines the presence of jets and (2) AGN jets have physically little effect on the torus.

Constraint on the Accretion of NGC 6946 X-1 Using Broadband X-Ray Data

We analyze broadband X-ray data of NGC 6946 X-1 and probe plausible accretion scenarios in this ULX. NGC 6946 X-1 is a persistent soft source with broadband continuum spectra described by two thermal disk components. The cool accretion disk temperature T cool ∼ 0.2 keV and the presence of a ∼0.9 keV emission/absorption broad feature suggest evidence of an optically thick wind due to supercritical accretion. The hot geometrically modified accretion disk has an inner temperature of T hot ∼ 2 keV with a radially dependent profile T(r) ∝ r −0.5, expected in a slim-disk scenario. Further, the measurement based on a realistic inclination angle of the disk indicates that the mass of the host compact object is comparable to a ∼6–10 M ⊙ nonrotating black hole or the system hosts a moderately magnetized neutron star with a B ≲ 2 × 1011 G magnetic field. Overall, the detected spectral curvature, high luminosity, flux contribution from two thermal disk components, and estimated accretion rate support the super-Eddington accretion scenario.

X-ray radiative transfer in full 3D with SKIRT

Context. Models of active galactic nuclei (AGN) suggest that their circumnuclear media are complex with clumps and filaments, while recent observations hint towards polar extended structures of gas and dust, as opposed to the classical torus paradigm. The X-ray band could form an interesting observational window to study these circumnuclear media in great detail. Aims. We want to extend the radiative transfer code SKIRT with the X-ray processes that govern the broad-band X-ray spectra of obscured AGN, to study the structure of AGN circumnuclear media in full 3D, based on their reflected X-ray emission. Methods. We extended the SKIRT code with Compton scattering on free electrons, photo-absorption and fluorescence by cold atomic gas, scattering on bound electrons, and extinction by dust. This includes a novel treatment of extreme-forward scattering by dust, and a detailed description of anomalous Rayleigh scattering. To verify our X-ray implementation, we performed the first dedicated benchmark of X-ray torus models, comparing five X-ray radiative transfer codes. Results. The resulting radiative transfer code covers the X-ray to millimetre wavelength range self-consistently, has all the features of the established SKIRT framework, is publicly available, and is fully optimised to operate in arbitrary 3D geometries. In the X-ray regime, we find an excellent agreement with the simulation results of the MYTORUS and REFLEX codes, which validates our X-ray implementation. We find some discrepancies with other codes, which illustrates the complexity of X-ray radiative transfer and motivates the need for a robust framework that can handle non-linear 3D radiative transfer effects. We illustrate the 3D nature of the code by producing synthetic X-ray images and spectra of clumpy torus models. Conclusions. SKIRT forms a powerful new tool to model circumnuclear media in full 3D, and make predictions for the X-ray band in addition to the dust-dominated infrared-to-UV wavelength range. The new X-ray functionalities of the SKIRT code allow for uncomplicated access to a broad suite of 3D X-ray models for AGN that can easily be tested and modified. This will be particularly useful with the advent of X-ray microcalorimeter observations in the near future.

Investigating the Time Evolution of the Thermal Emission from the Putative Neutron Star in SN 1987A for 50+ Years

Observations collected with the Atacama Large Millimeter/submillimeter Array (ALMA) and analysis of broadband X-ray spectra have recently suggested the presence of a central compact object (CCO) in SN 1987A. However, no direct evidence of the CCO has been found yet. Here we analyze Chandra X-ray observations of SN 1987A collected in 2007 and 2018, and synthesize 2027 Chandra and 2037 Lynx spectra of the faint inner region of SN 1987A. We estimate the temporal evolution of the upper limits of the intrinsic luminosity of the putative CCO in three epochs (2018, 2027, and 2037). We find that these upper limits are higher for higher neutron star (NS) kick velocities due to increased absorption from the surrounding cold ejecta. We compare NS cooling models with both the intrinsic luminosity limits obtained from the X-ray spectra and the ALMA constraints with the assumption that the observed blob of SN 1987A is primarily heated by thermal emission. We find that the synthetic Lynx spectra are crucial to constrain the physical properties of the CCO, which will be confirmed by future observations in the 2040s. We draw our conclusions based on two scenarios, namely the nondetection and detection of the NS by Lynx. If the NS is not detected, its kick velocity should be ≃700 km s−1. Furthermore, nondetection of the NS would suggest rapid cooling processes at the age of 40 yr, implying strong crust superfluidity. Conversely, in the case of NS detection, the mass of the NS envelope must be high.

Multi-epoch hard X-ray view of Compton-thick AGN Circinus Galaxy

ABSTRACT The circumnuclear material around active galactic nuclei (AGNs) is one of the essential components of the obscuration-based unification model. However, our understanding of the circumnuclear material in terms of its geometrical shape, structure, and its dependence on accretion rate is still debated. In this paper, we present the multi-epoch broad-band X-ray spectral modelling of a nearby Compton-thick AGN in Circinus galaxy. We utilize all the available hard X-ray (>10 keV) observations taken from different telescopes, i.e. BeppoSAX, Suzaku, NuSTAR, and AstroSat, at 10 different epochs across 22 yr from 1998 to 2020. The 3.0–79 keV broad-band X-ray spectral modelling using physically motivated models, namely MYTorus, borus02, and uxclumpy, infers the presence of a torus with a low covering factor of 0.28, an inclination angle of 77°–81° and Compton-thick line-of-sight column densities (NH,LOS = 4.13–9.26 × 1024 cm−2) in all the epochs. The joint multi-epoch spectral modelling suggests that the overall structure of the torus is likely to remain unchanged. However, we find tentative evidence for the variable line-of-sight column density on time-scales ranging from 1 d to 1 week to a few years, suggesting a clumpy circumnuclear material located at subparsec to tens of parsec scales.

NGC 4117: A New Compton-thick AGN Revealed by Broadband X-Ray Spectral Analysis

In this paper, we present the broadband (0.5–195 keV) X-ray spectral analysis for one of the newly detected AGNs in the Swift-BAT 105 month Hard X-ray Survey Catalog, NGC 4117. According to our ongoing research on low luminosity AGNs from the Swift-BAT 105 month catalog, we examine whether they are indeed low luminosity or heavily obscured AGNs. One of the AGNs in our sample is NGC 4117, where we discover it could be potentially a CTAGN. Therefore to examine NGC 4117 in detail, we combined the high energy Swift-BAT data with low energy data from XMM-Newton and Swift-XRT, and fitted the spectra simultaneously using physically-motivated models. A high absorption occurred at lower energies, i.e., below 3 keV. Past studies suggested that NGC 4117 was heavily obscured with a large column density (∼1023 cm−2). Our fitting suggests that this AGN is in the Compton-thick regime with a predicted line-of-sight column density (N H,los) of 3.82 × 1024 cm−2 and a torus column density (N H,tor) of 3.07 × 1024 cm−2. Both models yield intrinsic luminosity of 1.03 × 1042 erg s−1 at 2–10 keV while our bolometric luminosity is 2.05 × 1043 erg s−1, indicating that NGC 4117 is not an intrinsically low luminosity AGN. Rather, it is a standard AGN. The value of Eddington ratio that we obtained is 0.22, suggesting a very high accretion rate for this AGN.

Research on a laboratory monochromatic micro X-ray fluorescence spectrometer based on polycapillary X-ray lenses and flat crystal

Monochromatic micro X-ray fluorescence (Mμ-XRF) analysis has the advantages of high resolution and low detection limit and is a powerful tool to obtain information on element distribution and concentration in materials. An Mμ-XRF spectrometer for laboratory X-ray tubes is developed in this paper, which mainly composed of an X-ray tube, two polycapillary X-ray lenses and a flat crystal. The polycapillary parallel X-ray lens converts the divergent broadband X-rays emitted by the X-ray tube into quasi-parallel X-rays and projects them onto a flat crystal, where monochromatic X-rays are obtained by crystal diffraction. The monochromatic X-rays are then focused by a polycapillary half-focusing X-ray lens to provide spatial resolution for fluorescence analysis. The combination of the two makes it possible to perform Mμ-XRF under laboratory low-power X-ray tube conditions (5.3 W molybdenum tube). By selecting polycapillary half-focusing X-ray lenses with different parameters, the spectrometer can provide a spatial resolution of tens to hundreds of microns to suit various application requirements. The detection limits of the Mμ-XRF spectrometer are also measured using standard solutions. Experimental results show that the detection limit of Se is 52 μg/L and that the detection limit for light elements such as Mn is 970 μg/L.

Sub-resolution modeling of the apparent mass loss in quantitative broadband X-ray radiography

The quantitative impact of image blur on calculated object mass in X-ray radiography is explored. Radiographed object masses are initially estimated through experimental calibration and compared against their known true mass, with the deviation, or “apparent mass loss”. Apparent mass loss occurs due to the effect of spatial blur on X-ray transmission images that reduces the measured mass because while the image intensity is conserved with spatial blur, the nonlinear conversion to path length is not. A synthetic model is proposed where an object’s apparent mass loss is estimated through the amount of blur present within the radiograph image. The image blur is inferred through a combination of readily available image parameters related to the signal levels, object shape, and experimental extrinsics. A regularized regression model is built that correlates these blur parameters to the expected mass loss. The model is first trained on 2100 and tested on 140 synthetically created objects, and then later verified on two separate experimental setups of type 304 stainless steel objects imaged with a portable tube source at 150 kVp and type 6061 aluminum objects at 80 kVp. The proposed model allows for a simple post hoc reduction in errors of approximately 20% in object mass through X-ray radiography.

PolyX beamline at SOLARIS—Concept and first white beam commissioning results

PolyX is a compact bending magnet beamline under construction at National Synchrotron Radiation Centre SOLARIS, which will be available to users in mid-2023. The beamline is focused on X-ray microimaging and microspectroscopy in the tender/hard (4–15 keV) X-ray energy range. The name PolyX comes from polycapillary X-ray optics that will be extensively used for efficient X-ray focusing and from the possibility of using polychromatic or broadband X-rays to increase the rather low flux from the SOLARIS bending magnet in the hard X-ray energy range. Polycapillary optics will provide focal spots with sizes of 8–200 μm. Single bounce ellipsoidal capillary is expected to provide a ∼2 μm focal spot size. The main experimental techniques at PolyX will be X-ray absorption and phase-contrast imaging and microtomography, micro-X-ray fluorescence imaging and micro-X-ray absorption spectroscopy. This paper presents the concept of PolyX beamline and preliminary “white” beam commissioning results.

A Broadband X-Ray Study of the Rabbit Pulsar Wind Nebula Powered by PSR J1418-6058

We report on broadband X-ray properties of the Rabbit pulsar wind nebula (PWN) associated with the pulsar PSR J1418−6058 using archival Chandra and XMM-Newton data, as well as a new NuSTAR observation. NuSTAR data above 10 keV allowed us to detect the 110 ms spin period of the pulsar, characterize its hard X-ray pulse profile, and resolve hard X-ray emission from the PWN after removing contamination from the pulsar and other overlapping point sources. The extended PWN was detected up to ∼20 keV and is described well by a power-law model with a photon index Γ ≈ 2. The PWN shape does not vary significantly with energy, and its X-ray spectrum shows no clear evidence of softening away from the pulsar. We modeled the spatial profile of X-ray spectra and broadband spectral energy distribution in the radio to TeV band to infer the physical properties of the PWN. We found that a model with low magnetic field strength (B ∼ 10 μG) and efficient diffusion (D ∼ 1027 cm2 s−1) fits the PWN data well. The extended hard X-ray and TeV emission, associated respectively with synchrotron radiation and inverse Compton scattering by relativistic electrons, suggest that particles are accelerated to very high energies (≳500 TeV), indicating that the Rabbit PWN is a Galactic PeVatron candidate.

X-Ray Studies of the Pulsar PSR J1420–6048 and Its TeV Pulsar Wind Nebula in the Kookaburra Region

We present a detailed analysis of broadband X-ray observations of the pulsar PSR J1420−6048 and its wind nebula (PWN) in the Kookaburra region with Chandra, XMM-Newton, and NuSTAR. Using the archival XMM-Newton and new NuSTAR data, we detected 68 ms pulsations of the pulsar and characterized its X-ray pulse profile, which exhibits a sharp spike and a broad bump separated by ∼0.5 in phase. A high-resolution Chandra image revealed a complex morphology of the PWN: a torus-jet structure, a few knots around the torus, one long (∼7′) and two short tails extending in the northwest direction, and a bright diffuse emission region to the south. Spatially integrated Chandra and NuSTAR spectra of the PWN out to 2.′5 are well-described by a power-law model with a photon index Γ ≈ 2. A spatially resolved spectroscopic study, as well as NuSTAR radial profiles of the 3–7 keV and 7–20 keV brightness, showed a hint of spectral softening with increasing distance from the pulsar. A multiwavelength spectral energy distribution (SED) of the source was then obtained by supplementing our X-ray measurements with published radio, Fermi-LAT, and H.E.S.S. data. The SED and radial variations of the X-ray spectrum were fit with a leptonic multizone emission model. Our detailed study of the PWN may be suggestive of (1) particle transport dominated by advection, (2) a low magnetic-field strength (B ∼ 5 μG), and (3) electron acceleration to ∼PeV energies.

Capturing the lowest luminosity state of the supergiant fast X-ray transient XTE J1739−302

Here, we report the results of our analysis of recent Chandra, XMM-Newton, and NuSTAR observations of the supergiant fast X-ray transient XTE J1739−302. The source was caught in a low X-ray luminosity state, from a few 1031–1034 erg s−1 (0.5–10 keV). A very low X-ray luminosity was captured during an XMM-Newton observation performed in October 2022, at a few 1031 erg s−1 (0.5–10 keV), which had never been observed before in XTE J1739−302. The XMM-Newton spectrum could be well fitted either by an absorbed, steep power-law model (photon index of 3.5) or by a collisionally ionized diffuse gas with a temperature of 0.7 keV that would very likely have been produced by shocks in the supergiant donor wind. These observations covered different orbital phases, but they all appear compatible with the low luminosity level expected from the orbital INTEGRAL light curve. The absorbing column density is variable in the range between 1022 and 1023 cm−2. The broadband X-ray spectrum was feasibly investigated at 1034 erg s−1 (0.5–30 keV) for the first time in XTE J1739−302 with non-simultaneous (albeit at similar orbital phases) Chandra and NuSTAR data, showing a power-law spectral shape with a photon index of ∼2.2 and an absorbing column density of ∼1023 cm−2. Remarkably, owing to the XMM-Newton observation, the amplitude of the X-ray variability now exceeds five orders of magnitude, making XTE J1739−302 one of the most extreme SFXTs.

Evaluating the jet/accretion coupling of Aql X-1: probing the contribution of accretion flow spectral components

ABSTRACTThe coupling between radio and X-ray luminosity is an important diagnostic tool to study the connection between the accretion inflow and jet outflow for low-mass X-ray binaries (LMXBs). The radio/X-ray correlation for individual neutron star (NS) LMXBs is scattered, whereas for individual black hole (BH) LMXBs a more consistent correlation is generally found. Furthermore, jet quenching is observed for both types of LMXBs, but it is unclear whether jets in NS-LMXBs quench as strongly as those in BH-LMXBs. While additional soft X-ray spectral components can be detected in NS-LMXB spectra due to the presence of the NS surface, disentangling the individual X-ray spectral components has thus far not been considered when studying the radio/X-ray coupling. Here we present eleven epochs of Swift/XRT observations matched with quasi-simultaneous archival radio observations of the 2009 November outburst of Aql X-1. We decompose the thermal and Comptonized spectral components in the Swift/XRT spectra, with the aim of studying whether the presence of additional thermal emission affects the coupling of the radio/X-ray luminosity. We find that there is no evidence of a significant thermal contribution in Swift/XRT spectra that could cause scatter in the radio/X-ray coupling. To explore the role of potential spectral degeneracies in the X-ray models and consider the improvements from including hard X-rays, we perform joint fits with quasi-simultaneous RXTE/PCA spectra. Follow-up research using more sensitive, broad-band X-ray observations and densely sampled near-simultaneous radio observations is required to study this in more detail.

Broad-band X-ray properties of black holes GRS 1758−258 and 1E 1740.7−2942: AstroSat and NuSTAR results

ABSTRACT We present the results on broad-band X-ray properties of persistent black hole binaries GRS 1758−258 and 1E 1740.7−2942 using AstroSat, NuSTAR, and Swift–XRT observations carried out during 2016–2022. We perform spectral modelling of both sources after eliminating the contamination in their LAXPC spectra from nearby X-ray sources. Preliminary spectral modelling using Comptonization and line emission (∼6.4 keV) models suggest that GRS 1758−258 occupies both dim-soft state (kTbb = 0.37 ± 0.01 keV, Γ ∼ 5.9, $L_{bol}=1{{\ \rm per\ cent}}$ of Eddington luminosity LEdd) and hard state (Γ = 1.64–2.22, kTe = 4–45 keV, Lbol = 1–5 per cent LEdd) that requires a multicolour disc blackbody model (kTin = 0.54 ± 0.01 keV) occasionally. 1E 1740.7−2942 instead is found only in hard state (Γ = 1.67–2.32, kTe = 5–16 keV, Lbol = 1–2 per cent LEdd). Reflection properties of both sources are studied by applying relativistic reflection model RELXILL to the broad-band spectra. Our results from AstroSat and NuSTAR consistently unveiled the presence of a Comptonizing region along with an ionized reflection region (ionization parameter log ξ = 2.7–3.8 and 2.7–4.7 erg cm s−1 in GRS 1758−258 and 1E 1740.7−2942, respectively) in both sources. Reflection modelling revealed GRS 1758−258 to have a high metal abundance ($A_{fe}=3.9^{+0.4}_{-0.3}$ times solar metal abundance) and inclination angle (i) of 61 ± 2°. In case of 1E 1740.7−2942, i is constrained to be 55 ± 1°. Finally, we discuss the implication of our findings in the context of accretion dynamics by comparing our results with the previous studies.

The Complex X-Ray Obscuration Environment in the Radio-loud Type 2 Quasar 3C 223

3C 223 is a radio-loud, Type 2 quasar at z = 0.1365 with an intriguing X-ray Multi-mirror Mission (XMM)-Newton spectrum that implicated it as a rare, Compton-thick (N H ≳ 1.25 × 1024 cm−2) active galactic nucleus (AGN). We obtained contemporaneous XMM-Newton and Nuclear Spectroscopic Telescope Array (NuSTAR) spectra to fit the broadband X-ray spectrum with the physically motivated MYTorus and borus02 models. We confirm earlier results that the obscuring gas is patchy with both high (though not Compton-thick) levels of obscuration (N H > 1023 cm−2) and gas clouds with column densities up to an order of magnitude lower. The spectral fitting results indicate additional physical processes beyond those modeled in the spectral grids of MYTorus and borus02 impact the emergent spectrum: the Compton-scattering region may be extended beyond the putative torus; a ring of heavy Compton-thick material blocks most X-ray emission along the line of sight; or the radio jet is beamed, boosting the production of Fe Kα line photons in the global medium compared with what is observed along the line of sight. We revisit a recent claim that no radio-loud Compton-thick AGN have yet been conclusively shown to exist, finding three reported cases of radio-loud AGN with global average (but not line-of-sight) column densities that are Compton thick. Now that it is possible to separately determine line-of-sight and global column densities, inhomogeneity in the obscuring medium has consequences for how we interpet the spectrum and classify an AGN as “Compton thick.”

Investigating the variability of Swift-BAT blazars with NICER

ABSTRACT We present results of X-ray spectral and time-domain variability analyses of four faint, ‘quiescent’ blazars from the Swift-BAT 105-month catalogue. We use observations from a recent, 5-month long NICER campaign, as well as archival BAT data. Variations in the 0.3–2 keV flux are detected on minute, ∼weekly, and monthly time-scales, but we find that the fractional variability Fvar on these time-scales is <25 per cent and decreases on longer time-scales, implying generally low-amplitude variability across all sources and showing very low variability on monthly time-scales ($F_{\rm var}\lesssim 13{{\ \rm per\ cent}}$), which is at odds with previous studies that show that blazars are highly variable in the X-rays on a wide range of time-scales. Moreover, we find that the flux variability on very short time-scales appears to be characterized by long periods of relative quiescence accompanied by occasional short bursts, against the relatively time-stationary nature of the variability of most other AGN light curves. Our analysis also shows that the broadband X-ray spectra (0.3–195 keV) of our sources can be described with different power-law models. As is the case with most blazars, we find that two sources (2MASS J09343014-1721215 and PKS 0312-770) are well-modelled with a simple power law, while the remaining two (1RXS J225146.9-320614 and PKS 2126-15) exhibit curvature in the form of a log-parabolic power law. We also find that, in addition to the continuum, PKS 2126-15 requires significant absorption at the soft X-rays (≲1 keV) to fully describe the observed curvature, possibly due to absorption from the intergalactic medium.

Discovery of two cyclotron resonance scattering features in X-ray pulsar cen X-3 by Insight-HXMT

ABSTRACT We present the results of the neutron star X-ray binary system Cen X-3 performed by Insight-HXMT with two observations during 2017 and 2018. During these two observations, the source reached a X-ray luminosity of ∼1038 erg s−1 from 2–105 keV. The analysis of the broadband X-ray spectrum reports the presence of two cyclotron resonance scattering features (CRSFs) with the fundamental line at ∼ 28 keV and the harmonic line at ∼47 keV. The multiple lines exist by fittings with different continuum models, like the absorbed negative and positive power-law with an exponential cutoff (NPEX) model and a power-law with high energy exponential cutoff model. This is the first time that both fundamental and harmonic lines are detected in Cen X-3. We also show evidence of two cyclotron lines in the phase-resolved spectrum of Cen X-3. The CRSF and continuum spectral parameters show evolution with the pulse profile, and the two line centroid energy ratio does not change significantly and locates in a narrow value range of 1.6−1.7 over the pulse phase. The implications of the discovering two cyclotron absorption features and phase-resolved spectral properties are discussed.

Imaging suprathermal x-rays from a laboratory plasma jet using PIN-diode-based and scintillator-based 1D pinhole/coded aperture cameras.

A PIN-diode-based 1D x-ray camera and a scintillator-based 1D x-ray camera, both with a microsecond to submicrosecond time resolution, have been developed to perform time-resolved imaging of transient, low-intensity, suprathermal x-rays associated with magnetohydrodynamic instabilities disrupting a plasma jet. These cameras have a high detection efficiency over a broad x-ray band, a wide field of view, and the capability to produce >50 time-resolved frames with a ≤1 μs time resolution. The x-ray images are formed by a pinhole or by a coded aperture placed outside a vacuum chamber in which the plasma jet is launched. The 1D imaging shows that the location of the x-ray source is either a few centimeters away from an inner disk electrode or near a spatially translatable metal frame that is 30-40cm away from the electrode. Compared to a pinhole, a coded aperture increases the signal collection efficiency but also introduces unwanted artifacts.

X-Ray Properties of NGC 253's Starburst-driven Outflow

We analyze image and spectral data from ≈365 ks of observations from the Chandra X-ray Observatory of the nearby, edge-on starburst galaxy NGC 253 to constrain properties of the hot phase of the outflow. We focus our analysis on the −1.1 to +0.63 kpc region of the outflow and define several regions for spectral extraction where we determine best-fit temperatures and metal abundances. We find that the temperatures and electron densities peak in the central ∼250 pc region of the outflow and decrease with distance. These temperature and density profiles are in disagreement with an adiabatic spherically expanding starburst wind model and suggest the presence of additional physics such as mass loading and nonspherical outflow geometry. Our derived temperatures and densities yield cooling times in the nuclear region of a few million years, which may imply that the hot gas can undergo bulk radiative cooling as it escapes along the minor axis. Our metal abundances of O, Ne, Mg, Si, S, and Fe all peak in the central region and decrease with distance along the outflow, with the exception of Ne, which maintains a flat distribution. The metal abundances indicate significant dilution outside of the starburst region. We also find estimates of the mass outflow rates, which are 2.8 M ⊙ yr−1 in the northern outflow and 3.2 M ⊙ yr−1 in the southern outflow. Additionally, we detect emission from charge exchange and find it makes a significant contribution (20%–42%) to the total broadband (0.5–7 keV) X-ray emission in the central and southern regions of the outflow.

Multiwavelength Analysis of a Nearby Heavily Obscured AGN in NGC 449

We present the multiwavelength analysis of a heavily obscured active galactic nucleus (AGN) in NGC 449. We first constructed a broadband X-ray spectrum using the latest NuSTAR and XMM-Newton data. Its column density (≃1024 cm−2) and photon index (Γ ≃ 2.4) were reliably obtained by analyzing the broadband X-ray spectrum. However, the scattering fraction and the intrinsic X-ray luminosity could not be well constrained. Combined with the information obtained from the mid-infrared spectrum and spectral energy distribution fitting, we derived its intrinsic X-ray luminosity (≃8.54 × 1042 erg s−1) and scattering fraction (f scat ≃ 0.26%). In addition, we also derived the following results. (1) The mass accretion rate of the central AGN is about 2.54 × 10−2 M ⊙ yr−1, and the Eddington ratio is 8.39 × 10−2. (2) The torus of this AGN has a high gas-to-dust ratio (N H/A V = 8.40 × 1022 cm−2 mag−1). (3) The host galaxy and central AGN are both in the early stage of coevolution.