arXiv subjects

Satoshi Yamada

Publications and source records attributed to Satoshi Yamada.

At least 19 recordsLinked to original sources

arXiv2026

The Geometry of Ultra-Fast Outflows Probed by Soft X-ray Variability in PDS 456

Constraining the location and geometry of ultra-fast outflows (UFOs) is essential for identifying where they are launched and how they are accelerated. We investigate the soft X-ray variability of the luminous quasar PDS 456 using simultaneous March 2024 observations with XRISM/Xtend and NuSTAR. A model-independent comparison between the flare and quiescent phases reveals spectral variability around 1 keV in the rest frame, while the hard X-ray spectral shape remains nearly unchanged. Broadband spectral fitting shows that the soft X-ray structure is well described by a partial-covering low-ionization UFO with $\log (\xi/(\mathrm{erg~cm~s^{-1}})) \simeq 3.1$ and $v_{\mathrm{out}} \simeq 0.30c$. Time-sliced spectral analysis further reveals significant variability in the covering fraction of this absorber. Interpreting this variability as transverse motion across the X-ray source, we constrain the crossing velocity to be $v_{\mathrm{cross}} \lesssim 5 \times 10^{-3}c$ and derive a lower limit on the absorber distance of $r \gtrsim 4 \times 10^3 R_{\mathrm{g}}$. This location is substantially farther out than the high-ionization UFO previously inferred at ~200-600 $R_{\mathrm{g}}$, while the two phases have comparable outflow velocities. The resulting velocity-distance structure disfavors a self-similar magnetocentrifugal wind and instead suggests either radiation-pressure acceleration following a Castor-Abbott-Klein-like velocity law or compact magnetic acceleration through magnetic reconnection. These results demonstrate that soft X-ray partial-covering variability can provide a geometrical probe of UFOs and directly connect spectral variability to wind acceleration.

astro-ph.HE↗

arXiv2026

XRISM Resolves the Circum-nuclear Environment of NGC 4945

Compton-thick Active Galactic Nuclei (AGN) represent one of the most elusive phases of massive black hole growth, yet are expected to contribute substantially to the Cosmic X-ray Background and the integrated growth of massive black holes. NGC 4945 is the closest Compton-thick AGN and amongst the brightest AGN in the hard X-ray sky, making it an important benchmark for more distant Compton-thick AGN. We present the first high-resolution X-ray spectral analysis of NGC 4945 using XRISM/Resolve. The entire 4-15 keV Resolve spectrum, including a strong Fe K$\alpha$ doublet and weak Compton Shoulder, is well described by a de-coupled dual-obscurer model. The model features a low-covering-factor Compton-thick primary obscurer intersecting the line-of-sight that permits the rapidly variable, direct transmitted coronal continuum to dominate above 10 keV. A Compton-thin secondary reprocessor with a high covering factor dominates the reprocessed emission between $\sim$4-10 keV. Assuming that virial motion accounts for line broadening, the secondary reprocessor can exist at $\sim$0.12 pc, and could help explain the weak high-ionisation optical and infrared emission lines observed in NGC 4945. If such obscuration geometries are common among more distant and/or fainter Compton-thick AGN, our results suggest that simpler coupled X-ray spectral modelling could substantially over-estimate Compton-thick covering factors and under-estimate intrinsic X-ray luminosities.

astro-ph.GA↗

arXiv2026

Vigorous turbulence driven by quasar-mode feedback in a cluster core

Quasars are among the most luminous objects. They are powered by accretion onto supermassive black holes. They are thought to impact cosmological evolution primarily through energetic winds, known as quasar-mode feedback, yet the efficiency and spatial extent of this process remain poorly constrained. Here we present X-Ray Imaging and Spectroscopy Mission (XRISM) observations of H1821+643---the nearest galaxy cluster with a central quasar (redshift z = 0.297)---which was a rare opportunity to directly probe quasar-mode feedback in the intracluster medium. High-resolution spectroscopy reveals exceptionally broadened Fe XXV emission lines from the intracluster medium, with a velocity dispersion of approximately 300 km/s, far exceeding values observed in nearby cluster cores. These lines originate predominantly at radii of 20-100 kpc from the centre. Assuming that turbulence from a quasar-driven shock led to the broadening of the lines, the energy injected by the quasar beyond galactic scales ($\gtrsim$20 kpc) is estimated to be $\gtrsim$1-10% of its radiative energy. Notably, this feedback efficiency exceeds previous multiwavelength estimates by orders of magnitude ($\lesssim$0.01%) and reaches the levels required by the latest cosmological hydrodynamical simulations. This finding of vigorous turbulence indicates that quasar-mode feedback plays a central role in regulating galaxy and cluster evolution at high redshift.

astro-ph.GA↗

arXiv2026

Kinetic structure of the intracluster medium across nearby clusters observed with XRISM

XRISM/Resolve is building a sample of galaxy clusters with directly measured ICM gas motions, revealing diverse projected dynamical states. We compile 45 XRISM/Resolve measurements in 19 nearby galaxy clusters and place them on a common, emission-weighted effective line-of-sight scale, $\ell_{\rm eff}$. We compare the line-of-sight velocity dispersion $\sigma_v$, bulk velocity amplitude $|v_{\rm bulk}|$, their ratio $R_v \equiv |v_{\rm bulk}|/\sigma_v$, and non-thermal pressure proxies. Disturbed non-cool-core systems are not simply higher-dispersion counterparts of relaxed cool-core regions. Instead, differences among cool-core centers, cool-core outer regions, and non-cool-core systems are driven mainly by coherent line-of-sight motion relative to unresolved line broadening: $R_v$ tends to remain below unity in cool-core regions but often exceeds unity in non-cool-core systems, with the mean $R_v$ rising from 0.45 in cool-core centers to 1.6 in non-cool-core systems. These diagnostics help separate local central line broadening, likely associated with AGN feedback in some cool cores, from larger-scale coherent motions associated with sloshing, mergers, and halo assembly. Comparison with forward-modeled TNG-Cluster predictions suggests that many cool-core measurements occupy the lower part of the predicted non-thermal pressure range, consistent with small hydrostatic-mass corrections in relaxed systems and larger corrections in disturbed ones. XRISM is thus beginning to resolve the projected kinetic structure of the ICM across cluster environments, rather than tracing a single sequence of increasing turbulence.

astro-ph.CO↗

arXiv2026

XRISM Time-resolved Fe K$\alpha$ Spectroscopy of NGC 4395: Time-variable Inner-disk Emission

We report the first XRISM observation of the low-mass AGN in the nearby dwarf galaxy NGC 4395 ($M_{\rm BH}\sim10^{4-5}\,M_\odot$), complemented by a simultaneous NuSTAR observation. We constrained the continuum by jointly fitting the XRISM/Resolve (2-12 keV) and NuSTAR (3-30 keV) spectra while excluding the Fe K band (5.5-7.5 keV). Relative to this baseline continuum, the time-averaged Resolve spectrum revealed an unresolved neutral Fe K$\alpha$ core with a velocity width of $\lesssim$110 km s$^{-1}$ and an adjacent redward wing. The red wing was well reproduced by an additional relativistically broadened Fe K component. Furthermore, time-resolved spectroscopy with $\approx$87 ks bins showed that the diskline profile varied significantly over the $\sim$400 ks observation. This evolution can be interpreted in terms of changes in the inner radius of the line-emitting region, together with a possible inclination modulation with a period of $\approx$210 ks. If interpreted as Lense-Thirring precession of a tilted inner flow, the observed period would favor the low end of the black hole mass estimates ($M_{\rm BH}\approx9\times10^3\,M_\odot$) and imply a moderate spin ($a\gtrsim0.6$). These results highlight the capability of XRISM to track relativistic disk dynamics in AGNs.

astro-ph.HE↗

arXiv2026

Decoupled Kinematics and Excitation in the Compton-thick AGN NGC 6552: Spatially Resolved KOOLS-IFU Observations

Hard X-ray selected Compton-thick AGNs provide a relatively obscuration-resistant census of accretion, but optical line diagnostics can be strongly shaped by extinction and geometry. Spatially resolved integral-field spectroscopy can mitigate these effects and provides direct constraints on outflow kinematics and ionization state on kiloparsec scales. We present KOOLS-IFU optical integral-field spectroscopy of NGC 6552 obtained on the 3.8 m Seimei Telescope. Using spatially resolved emission-line ratios and non-parametric [O III]5007 kinematics over the central ~2 kpc, we test whether ionized-gas kinematics are locally coupled to excitation. The [O III]5007 width W80 is broadly elevated across the inner region (~530-830 km/s) and declines monotonically with projected galactocentric distance, consistent with a centrally concentrated outflow that decelerates at larger radii. Despite this clear kinematic structure, neither W80 nor the velocity asymmetry parameter dv shows a statistically significant correlation with [O III]5007/Hbeta. Order-of-magnitude outflow energetics yield Edot_K/L_bol ~ 0.01%-0.28% (for assumed n_e = 50-1000 cm^-3), consistent with [O III]-based estimates tracing only the ionized phase of a multi-phase outflow. We conclude that in NGC 6552 both the total line broadening traced by W80 and dv are consistent with being governed primarily by spatial dynamical structure and line-of-sight superposition of multiple kinematic components, with no statistically significant coupling to excitation-driven processes detected at our sensitivity level. A positive W80-[O III]5007/Hbeta coupling does emerge in the small subset of bins for which the two-component fit is most strongly favored statistically, which deeper observations will be needed to confirm.

astro-ph.GA↗

arXiv2026

A XRISM Study of Highly Ionized Iron Emission Lines from the Low-Eddington-ratio AGN in NGC 7213

We present an analysis of XRISM and NuSTAR data obtained for the nearby low-Eddington active galactic nucleus NGC 7213. Our goal is to examine whether its He-like and H-like iron emission lines can be reproduced by photoionization or collisional ionization processes. Using the broad-band energy coverage of our data (2-60 keV), we first constrained the continuum shape. Then, we focused on the iron-K band in the Resolve spectrum. Gaussian fits to Fe XXV He$\alpha$ and Fe XXVI Ly$\alpha$ lines suggest that they may have different velocity widths: $v_\sigma=790^{+370}_{-240}$ km s$^{-1}$ for Fe XXV and $v_\sigma=2610^{+1700}_{-1580}$ km s$^{-1}$ for Fe XXVI. In this case, the He$\alpha$ resonance line (w) and forbidden line (z) have similar intensities of $\approx0.5$-$0.6\times10^{-5}$ ph s$^{-1}$ cm$^{-2}$, while the intercombination lines (x+y) are not significantly detected with upper limits of $\lesssim 0.2\times10^{-5}$ ph s$^{-1}$ cm$^{-2}$. Motivated by the possible difference in the line widths, we tested one- and two-zone photoionized and collisionally ionized models. Our results show that the additional ionized component is not significantly required, and the current data cannot uniquely determine whether photoionization or collisional ionization dominates. Moreover, if the Fe XXV He$\alpha$ complex implies that the weak x+y lines are suppressed relative to the w and z lines, such a structure is difficult to reproduce with either ionization model adopted. Finally, by comparing NGC 7213 with M 81$^\ast$, accreting at a much lower Eddington ratio of $\lambda_{\rm Edd}\sim 10^{-5}$, we found a decrease in the density of the gas responsible for highly ionized iron emission, which may imply that the density decreases with decreasing $\lambda_{\rm Edd}$.

astro-ph.HE↗

arXiv2026

Complex Nuclear Structure in Seyfert 2 Galaxy NGC 4388 Revealed by XRISM Observation

We report results from the simultaneous XRISM (183 ks) and NuSTAR (62 ks) observations of the Seyfert-2 galaxy NGC 4388. This AGN has the brightest Fe K$\alpha$ line among Compton-thin, obscured sources. To model the reflection continuum and fluorescent lines, we employ an updated version of XCLUMPY and a broad line region model with a disk-like geometry. The profile of the neutral Fe-K fluorescent line is well described as the sum of three components convolved with Gaussians with FWHM values of $\sim 290\ \mathrm{km\ s^{-1}}$, $\sim 1470\ \mathrm{km\ s^{-1}}$, and $\sim 11100\ \mathrm{km\ s^{-1}}$. These line widths correspond to radii of 1.5 pc, 0.060 pc, and $1.0\times10^{-3}$ pc by assuming Keplerian motion, which we interpret as the dusty torus, its inner edge region, and the BLR, respectively. The data suggest that the Fe K$\alpha$ BLR component is larger than that of H$\alpha$ (FWHM of 4500 $\mathrm{km\ s^{-1}}$) in the polarized optical spectrum, implying that the velocity field of the BLR is dominated by that parallel to the equatorial plane. In addition, Fe XXVI Ly$\alpha$ and Fe XXV absorption lines are detected, characterized by $\log{\xi} \sim 3.50~\mathrm{erg\ cm\ s^{-1}}$, $\log{N_{\mathrm{H}}} \sim 22.1~\mathrm{cm^{-2}}$, $v_{\mathrm{out}} \sim 40\ \mathrm{km\ s^{-1}}$, and $\sigma_v \sim 160\ \mathrm{km\ s^{-1}}$. We infer that the absorber is gravitationally bound and is possibly associated with a failed wind, consistent with a radiation-driven fountain flow.

astro-ph.HE↗

arXiv2026

Blackbody Quasar and Radio Source (BBQSORS): A Candidate of Transitional Little Red Dots with a $T\sim10^4\ K$ Blackbody Spectrum

We report Subaru/PFS spectroscopic follow-up of a radio-loud quasar at $z=1.715$ from the UNVEIL radio AGN catalog and with X-ray detections. The PFS spectrum displays a broad MgII emission line with an $\mathrm{FWHM}\gtrsim4000\ km/s$, accompanied by a narrow absorption feature. The spectrum reveals a characteristic $\Lambda$-shape over the rest-frame wavelength ranging $\sim1500-3500\ \r{A}$. This underlying UV continuum is too curved to be reproduced by simply applying dust extinction to the spectrum of typical unobscured quasars. Alternatively, it is well described by a blackbody spectrum with a temperature of $T\approx10000\ K$. This result is in good agreement with its UV to MIR photometry that can be well modeled by three blackbody components representing the SMBH envelope ($\mathit{T}\approx9700\ K$), dust torus ($T\approx1500\ K$), and host galaxy dust ($T\approx80\ K$). The source is marginally detected in the GALEX NUV, revealing a potential V-shaped spectral energy distribution around $1400\ \r{A}$, reminiscent of the spectral feature reported for recently discussed LRDs whose V-shapes occur around $3000-4000\ \r{A}$. This wavelength shift is broadly consistent with the temperature contrast between our blackbody component, with $T\sim10^4\ K$, and the lower effective temperature of $T\sim5000\ K$ expected for an optically thick photosphere surrounding the SMBH in LRDs. These properties suggest that this source might be caught in a transient evolutionary phase in which the dense gas envelope characteristic of LRD has begun to fragment, allowing us to witness the emergence of a quasar from an LRD-like state.

astro-ph.GA↗

arXiv2026

Winds of Change: XRISM Resolve X-ray spectroscopy of NGC 4051

NGC 4051 is a nearby (16.7 Mpc), Narrow Line Seyfert 1 galaxy (NLS1), which has a low black hole mass of $10^6$ M$_{\odot}$. It is also known for its rapid X-ray variability, on timescales of kilo-seconds and has a complex, multi component wind in both the soft X-ray and Fe K bands. Here we present the first high resolution XRISM Resolve spectrum of NGC 4051, which was captured in a historically bright state for a 150 ks exposure. XRISM resolves two blue-shifted Fe K shell absorption troughs in the mean spectrum, which can be ascribed to H-like iron and arises from two outflow components with outflow velocities of 0.025c and 0.04c. A time dependent spectral analysis shows that the iron K absorption is variable on timescales of less than a day, increasing in velocity over the duration of the observation. The velocity changes may be explained either by the passage of two separate transiting absorbers, of different velocities, or by a single accelerating outflow of approximately constant column density. In the latter case, the wind acceleration is likely to be too large to be caused by radiation pressure and instead magnetic driving is favored to accelerate the wind up to 0.04c. The outflow can originate from an accretion disk wind, whose kinetic power is sub-Eddington in contrast to recent examples of winds from powerful, luminous quasars observed by XRISM.

astro-ph.HE↗

arXiv2026

Resolving the Multiple Component Outflows in PG 1211+143: II. The Soft X-ray View of the Ultra Fast Outflow

The nearby quasar, PG 1211+143, has one of the prototype examples of an ultra fast outflow (UFO), as seen in several past XMM-Newton and Chandra observations. In December 2024, PG 1211+143 was observed simultaneously with XRISM Resolve and XMM-Newton, allowing both the Fe K and soft X-ray outflows to be examined at high resolution simultaneously. The Resolve spectrum revealed a forest of Fe K band absorption lines from the UFO (Mizumoto et al. 2026), comprising of up to six discrete velocity components ranging from $v/c=-0.074$ to $v/c=-0.40$. Here we present the simultaneous XMM-Newton RGS (Reflection Grating Spectrometer) spectrum, where three lower ionization counterparts of the Fe K velocity zones are observed; at $v/c=-0.074, -0.12$ and $-0.33$. The soft X-ray absorbers tend to be somewhat less ionized than their Fe K counterparts, with their opacity mainly arising from Fe L shell lines and highly ionized Oxygen. From comparing the Resolve and RGS absorbers, we show that the outflow can be parameterized with a density profile varying with radius as $r^{-5/3}$, while the lower ionization zones likely originate from denser clumps of gas. Pure electron scattering appears insufficient to provide enough thrust to power the wind, unless sufficient low ionization gas capable of radiative line driving exists outside of the line of sight. Overall, PG 1211+143 provides further evidence for the clumpy nature of accretion disk winds, as was recently revealed in the quasar PDS 456 with XRISM.

astro-ph.HE↗

arXiv2026

Diverse Origins of Broad H$\alpha$ Lines in Heavily Obscured AGNs Revealed by Multi-epoch Spectroscopy

According to the classical AGN model, broad emission lines originate from the broad-line region (BLR) and are observable only when the attenuation by the dusty torus is small. However, we recently found several heavily-obscured ($A_V > 50$ mag) AGNs with broad H$\alpha$ detections: MCG -3-34-64, UGC 5101, and Mrk 268. To investigate the origin of the observed broad line in these AGNs, we performed multi-epoch optical spectroscopic observations to search for flux variability of the broad H$\alpha$ line. For MCG -3-34-64 and UGC 5101, no significant variability was detected, suggesting that the broad line of these AGNs may arise from sources other than the BLR. Spectral fitting analysis suggests possible large contribution of ionized outflows to the observed broad component of MCG -3-34-64, while both the outflow and scattering by polar material can explain that of UGC 5101. For Mrk 268, we detected a significant ($4.3\sigma$) flux variation of the broad H$\alpha$ line by using the flux ratio of the H$\alpha$ complex and the [SII]$\lambda\lambda6716$, 6731 doublet, indicating that the broad line originates directly from the BLR. The lack of significant flux variation in the optical continuum implies that the line of sight to the nucleus of Mrk 268 is mildly obscured. Our results demonstrate that the observed broad H$\alpha$ lines in obscured AGNs likely have multiple origins. Such complexity may introduce additional uncertainties in black hole mass measurements of distant AGNs revealed by e.g., JWST.

astro-ph.GA↗

arXiv2026

XRISM finds the Changing-Look AGN NGC 1365 in an extended low state: A dense, highly ionized outflow obscures the central source

We present the first XRISM/Resolve observations of the active galactic nucleus, NGC 1365, obtained in 2024 February and July. NGC 1365 is known for rapid transitions between Compton-thick and Compton-thin states, along with strong absorption from a highly ionized wind. During our observations, the source is found in a persistent low-flux state, characterized by a decrease in hard-X-ray luminosity and significant line-of-sight obscuration. In this state, XRISM/Resolve reveals clear Fe\,\textsc{xxv} and Fe\,\textsc{xxvi} absorption lines together with, for the first time in this source, corresponding emission lines. These features may arise either from reemission from a photoionized wind (P Cygni profile) or from collisionally ionized gas associated with outflow-driven shocks in the interstellar medium. We estimate the wind launch radius to be approximately $10^{16}~\mathrm{cm}$ ($\sim 10^4 R_{\mathrm{g}}$), consistent with the location of the X-ray broad-line region. We also resolve a broadened Fe K$\alpha$ line by $\sigma \sim 1300$ km s$^{-1}$ placing it at similar scales to the wind, consistent with radii inferred from disk-broadening models and the variability of the Fe K$\alpha$ broad line. The similarity of the Fe K$\alpha$ profile to the H$\beta$ wing and broad Pa$\alpha$ width indicates that the X-ray-emitting region is likely cospatial with the optical/IR broad-line region and originates from the same gas.

astro-ph.HE↗

arXiv2025

Delving into the depths of NGC 3783 with XRISM III. Birth of an ultrafast outflow during a soft flare

The 2024 X-ray/UV observation campaign of NGC 3783, led by XRISM, revealed the launch of an ultrafast outflow (UFO) with a radial velocity of 0.19c (57000 km/s). This event is synchronized with the sharp decay, within less than half a day, of a prominent soft X-ray/UV flare. Accounting for the look-elsewhere effect, the XRISM Resolve data alone indicate a low probability of 2e-5 that this UFO detection is due to random chance. The UFO features narrow H-like and He-like Fe lines with a velocity dispersion of 1000 km/s, suggesting that it originates from a dense clump. Beyond this primary detection, there are hints of weaker outflow signatures throughout the rise and fall phases of the soft flare. Their velocities increase from 0.05c to 0.3c over approximately three days, and they may be associated with a larger stream in which the clump is embedded. The radiation pressure is insuffcient to drive the acceleration of this rapidly evolving outflow. The observed evolution of the outflow kinematics instead closely resembles that of solar coronal mass ejections, implying magnetic driving and, conceivably, reconnection near the accretion disk as the likely mechanisms behind both the UFO launch and the associated soft flare.

astro-ph.HE↗

arXiv2025

The dynamic central environment of NGC 3516 revealed by XRISM

We present a detailed, time-resolved analysis of the Fe K band of the Seyfert 1.5 galaxy NGC 3516 observed with XRISM. The 249 ks observation spanning $\sim$310 ks in elapsed time reveals an exceptionally rich and time-variable absorption spectrum. Six distinct absorption components are detected across multiple ionization states, spanning more than an order of magnitude in ionization parameter and a wide range of systemic velocities, from a potential inflow ($+4300~\rm km~s^{-1}$) to a mildly relativistic ultra-fast outflow ($-9800~\rm km~s^{-1}$). Despite their diversity, the components exhibit relatively small broadening ($\lesssim$$400~\rm km~s^{-1}$), implying comparable internal dynamics within a medium of a complex structure. Time-resolved spectroscopy reveals pronounced variability in three highly ionized absorbers, with Fe XXV$-$Fe XXVI features that appear and disappear on timescales of tens of kiloseconds. This behavior likely reflects a combination of geometrical transits of clumpy gas and ionization-state changes driven by continuum variability. An additional temporary absorption feature in the red wing of the Fe K$\alpha$ line, consistent with Fe XXV absorption, indicates a possible transient ultra-fast inflow at $\sim$$15\,000~\rm km~s^{-1}$ ($\sim$5% $c$). Finally, the continuum light curve exhibits a tentative $\sim$40 ks oscillatory pattern, accompanied by correlated shifts of a weak, narrow Fe K$\alpha$ emission feature, suggesting dynamic coupling between the continuum and the line-emitting region. Together, these results reveal that the nuclear environment of NGC 3516 is dominated by rapidly evolving, multi-phase gas flows, where accretion, ejection, and ionization processes are tightly coupled on sub-parsec scales.

astro-ph.GA↗

arXiv2025

Resolving the Multiple Component Outflows in PG 1211+143: I. The Fe-K Absorption Structure and UFO Forest

We present the initial high-resolution X-ray spectroscopic observations of the Fe-K absorption structure in the luminous nearby quasar PG 1211+143, utilizing the X-ray Imaging and Spectroscopy Mission (XRISM). The primary objective is to characterize the Fe-K absorption features due to Ultra-Fast Outflow (UFO) in this Eddington-luminosity source. Observations were conducted with XRISM's Resolve and Xtend instruments, complemented by simultaneous data from XMM-Newton and NuSTAR. A historically bright phase was captured. The Resolve spectra clearly reveal a prominent P Cygni profile and resolves the Fe-K absorption into six distinct velocity components, ranging from $v = -0.074c$ to $-0.405c$. A similar superposition of multiple UFOs has been reported in PDS~456, suggesting that such a ``UFO forest'' structure may be a common feature of near Eddington-luminosity sources. Some UFO components exhibit narrow line widths of approximately $\sigma \sim 200\,\mathrm{km\,s^{-1}}$, which may indicate that the outflows have reached their terminal velocities, thereby resulting in a smaller velocity shear. The mass outflow rate is estimated to be $\dot{M}_\mathrm{out} \sim 1~M_{\odot}~\text{yr}^{-1}$, which is of the order of the Eddington accretion rate. This suggests a physically plausible scenario where the outflow is a significant channel for mass ejection.

astro-ph.HE↗

arXiv2025

Discovery of an X-ray Luminous Radio-Loud Quasar at $z=3.4$: A Possible Transitional Super-Eddington Phase

We report the multiwavelength properties of eFEDS J084222.9+001000 (hereafter ID830), a quasar at $z=3.4351$, identified as the most X-ray luminous radio-loud quasar in the eROSITA Final Equatorial Depth Survey (eFEDS) field. ID830 shows a rest-frame 0.5-2 keV luminosity of $\log (L_\mathrm{0.5-2\,keV}/\mathrm{erg}~\mathrm{s}^{-1}) = 46.20 \pm 0.12$, with a steep X-ray photon index ($\Gamma =2.43 \pm 0.21$), and a significant radio counterpart detected with VLA/FIRST 1.4 GHz and VLASS 3 GHz bands. The rest-frame UV to optical spectra from SDSS and Subaru/MOIRCS $J$-band show a dust reddened quasar feature with $A_\mathrm{V} = 0.39 \pm 0.08$ mag and the expected bolometric AGN luminosity from the dust-extinction-corrected UV luminosity reaches $L_\mathrm{bol,3000}= (7.62 \pm 0.31) \times 10^{46}$ erg s$^{-1}$. We estimate the black hole mass of $M_\mathrm{BH} = (4.40 \pm 0.72) \times 10^{8} M_{\odot}$ based on the MgII$\lambda$2800 emission line width, and an Eddington ratio from the dust-extinction-corrected UV continuum luminosity reaches $\lambda_\mathrm{Edd,UV}=1.44 \pm 0.24$ and $\lambda_{\mathrm{Edd,X}} = 12.8 \pm 3.9$ from the X-ray luminosity, both indicating the super-Eddington accretion. ID830 shows a high ratio of UV-to-X-ray luminosities, $\alpha_\mathrm{OX}=-1.20 \pm 0.07$ (or $\alpha_\mathrm{OX}=-1.42 \pm 0.07$ after correcting for jet-linked X-ray excess), higher than quasars and little red dots in super-Eddington phase with similar UV luminosities, with $\alpha_\mathrm{OX}<-1.8$. Such a high $\alpha_\mathrm{OX}$ suggests the coexistence of a prominent radio jet and X-ray corona, in this high Eddington accretion phase. We propose that ID830 may be in a transitional phase after an accretion burst, evolving from a super-Eddington to a sub-Eddington state, which could naturally describe the high $\alpha_\mathrm{OX}$.

astro-ph.GA↗

arXiv2025

Discovery of Powerful Multi-Velocity Ultra-Fast Outflows in the Starburst Merger Galaxy IRAS 05189$-$2524 with XRISM

We observed the X-ray-bright ultra-luminous infrared galaxy, IRAS 05189$-$2524, with XRISM during its performance verification phase. The unprecedented energy resolution of the onboard X-ray microcalorimeter revealed complex spectral features at $\sim$7$-$9 keV, which can be interpreted as blueshifted Fe XXV/XXVI absorption lines with various velocity dispersions, originating from ultra-fast outflow (UFO) components with multiple bulk velocities of $\sim0.076c$, $\sim0.101c$, and $\sim0.143c$. In addition, a broad Fe-K emission line was detected around $\sim7$ keV, forming a P Cygni profile together with the absorption lines. The onboard X-ray CCD camera revealed a 0.4$-$12 keV broadband spectrum characterized by a neutrally absorbed power-law continuum with a photon index of $\sim2.3$, and intrinsic flare-like variability on timescales of $\sim10$ ksec, both of which are likely associated with near-Eddington accretion. We also found potential variability of the UFO parameters on a timescale of $\sim140$ ksec. Using these properties, we propose new constraints on the outflow structure and suggest the presence of multiple outflowing regions on scales of about tens to a hundred Schwarzschild radii, located within roughly two thousand Schwarzschild radii. Since both the estimated momentum and energy outflow rates of the UFOs exceed those of galactic molecular outflows, our results indicate that powerful, multi-velocity UFOs are already well developed during a short-lived evolutionary phase following a major galaxy merger, characterized by intense starburst activity and likely preceding the quasar phase. This system is expected to evolve into a quasar, sustaining strong UFO activity and suppressing star formation in the host galaxy.

astro-ph.HE↗