Engineering topics

Ueda, Yoshihiro

Publications and source records attributed to Ueda, Yoshihiro.

11 records

DOE OSTI2023

AGN number fraction in galaxy groups and clusters at z < 1.4 from the Subaru Hyper Suprime-Cam survey

Abstract One of the key questions on active galactic nuclei (AGN) in galaxy clusters is how AGN could affect the formation and evolution of member galaxies and galaxy clusters in the history of the Universe. To address this issue, we investigate the dependence of AGN number fraction (fAGN) on cluster redshift (zcl) and distance from the cluster center (R$/$R200). We focus on more than 27000 galaxy groups and clusters at 0.1 < zcl < 1.4 with more than 1 million member galaxies selected from the Subaru Hyper Suprime-Cam. By combining various AGN selection methods based on infrared (IR), radio, and X-ray data, we identify 2688 AGN. We find that (i) fAGN increases with zcl and (ii) fAGN decreases with R$/$R200. The main contributors to the rapid increase of fAGN towards high-z and cluster center are IR- and radio-selected AGN, respectively. These results indicate that the emergence of the AGN population depends on the environment and redshift, and galaxy groups and clusters at high z play an important role in AGN evolution. We also find that cluster–cluster mergers may not drive AGN activity in at least the cluster center, while we have tentative evidence that cluster–cluster mergers could enhance AGN activity in the outskirts of (particularly massive) galaxy clusters.

Hashiguchi, Aoi↗

DOE OSTI2023

eROSITA Final Equatorial-Depth Survey (eFEDS) eFEDS X-ray view of WERGS radio galaxies selected by the Subaru/HSC and VLA/FIRST survey

We constructed the eROSITA X-ray catalog of radio galaxies discovered by the WERGS survey, made by cross-matching the wide area Subaru/Hyper Suprime-Cam (HSC) optical survey and VLA/FIRST 1.4 GHz radio survey. We report finding 393 eROSITA detected radio galaxies in the 0.5-2 keV band in the eFEDS field covering 140 deg 2 . Thanks to the wide and medium depth eFEDS X-ray survey down to f 0.5 - 2 keV = 6.5 × 10 -15 erg s -1 cm -2 , the sample contains the rare and most X-ray luminous radio galaxies above the knee of the X-ray luminosity function, spanning 44 < log(L 0.5-2 keV (abs,corr) /erg s -1 ) < 46.5 at 1 < z < 4. The sample also contains the sources around and below the knee for the sources 41 < log(L 0.5-2 keV (abs,corr) /erg s -1 ) < 45 at z < 1. Based on the X-ray properties obtained by the spectral fitting, 37 sources show obscured active galactic nucleus (AGN) signatures with log(N H /cm -2 ) > 22. These obscured and radio AGN reside in 0.4 < z < 3.2, indicating that they are obscured counterparts of the radio-loud quasar, which were missed in the previous optical quasar surveys. By combining radio and X-ray luminosities, we also investigated the jet production efficiency η jet = η rad P jet /L AGN,bol by utilizing the jet power of P jet . We find that there are 14 sources with extremely high jet production efficiency at η jet ≈ 1. This high η jet value might be a result of the decreased radiation efficiency of η rad < 0.1, due to the low accretion rate for those sources, and/or of the boosting due to the decline of L AGN,bol by a factor of 10-100 by keeping P jet constant in the previous Myr, indicating the experience of the AGN feedback. Finally, inferring the BH masses from the stellar mass, we find that X-ray luminous sources show the excess of the radio emission with respect to the value estimated from the fundamental plane. This radio emission excess cannot be explained by the Doppler boosting alone, and therefore the disk–jet connection of X-ray luminous eFEDS-WERGS is fundamentally different from the conventional fundamental plane which mainly covers the low-accretion regime.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

BASS XXXII: Studying the Nuclear Millimeter-wave Continuum Emission of AGNs with ALMA at Scales ≲100–200 pc

To understand the origin of nuclear (≲100 pc) millimeter-wave (mm-wave) continuum emission in active galactic nuclei (AGNs), we systematically analyzed subarcsecond resolution Band-6 (211–275 GHz) Atacama Large Millimeter/submillimeter Array data of 98 nearby AGNs (z < 0.05) from the 70 month Swift/BAT catalog. The sample, almost unbiased for obscured systems, provides the largest number of AGNs to date with high mm-wave spatial resolution sampling (~1–200 pc), and spans broad ranges of 14–150 keV luminosity {$40\lt \mathrm{log}[{L}_{14-150}/(\mathrm{erg}\,{{\rm{s}}}^{-1})]\lt 45$}, black hole mass $[5\lt \mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })\lt 10$], and Eddington ratio ($-4\lt \mathrm{log}{\lambda }_{\mathrm{Edd}}\lt 2$). We find a significant correlation between 1.3 mm (230 GHz) and 14–150 keV luminosities. Its scatter is ≈0.36 dex, and the mm-wave emission may serve as a good proxy of the AGN luminosity, free of dust extinction up to N H ~ 10 26 cm –2 . While the mm-wave emission could be self-absorbed synchrotron radiation around the X-ray corona according to past works, we also discuss different possible origins of the mm-wave emission: AGN-related dust emission, outflow-driven shocks, and a small-scale (<200 pc) jet. The dust emission is unlikely to be dominant, as the mm-wave slope is generally flatter than expected. Also, due to no increase in the mm-wave luminosity with the Eddington ratio, a radiation-driven outflow model is possibly not the common mechanism. Furthermore, we find independence of the mm-wave luminosity on indicators of the inclination angle from the polar axis of the nuclear structure, which is inconsistent with a jet model whose luminosity depends only on the angle.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

BASS. XXIV. The BASS DR2 Spectroscopic Line Measurements and AGN Demographics

We present the second catalog and data release of optical spectral line measurements and active galactic nucleus (AGN) demographics of the BAT AGN Spectroscopic Survey, which focuses on the Swift-BAT hard X-ray detected AGNs. We use spectra from dedicated campaigns and publicly available archives to investigate spectral properties of most of the AGNs listed in the 70 month Swift-BAT all-sky catalog; specifically, 743 of the 746 unbeamed and unlensed AGNs (99.6%). We find a good correspondence between the optical emission line widths and the hydrogen column density distributions using the X-ray spectra, with a clear dichotomy of AGN types for N H = 10 22 cm –2 . Based on optical emission-line diagnostics, we show that 48%–75% of BAT AGNs are classified as Seyfert, depending on the choice of emission lines used in the diagnostics. The fraction of objects with upper limits on line emission varies from 6% to 20%. Roughly 4% of the BAT AGNs have lines too weak to be placed on the most commonly used diagnostic diagram, [O iii ]λ5007/Hβ versus [N ii ]λ6584/Hα, despite the high signal-to-noise ratio of their spectra. This value increases to 35% in the [O iii ]λ5007/[O ii ]λ3727 diagram, owing to difficulties in line detection. Compared to optically selected narrow-line AGNs in the Sloan Digital Sky Survey, the BAT narrow-line AGNs have a higher rate of reddening/extinction, with Hα/Hβ > 5 (~36%), indicating that hard X-ray selection more effectively detects obscured AGNs from the underlying AGN population. Finally, we present a subpopulation of AGNs that feature complex broad lines (34%, 250/743) or double-peaked narrow emission lines (2%, 17/743).

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

The eROSITA Final Equatorial-Depth Survey (eFEDS)

Here, we investigate the physical properties – such as the stellar mass (M * ), star-formation rate, infrared (IR) luminosity (L IR ), X-ray luminosity (L X ), and hydrogen column density (N H ) – of mid-IR (MIR) galaxies and active galactic nuclei (AGN) at z < 4 in the 140 deg 2 field observed by eROSITA on SRG using the Performance-and-Verification-Phase program named the eROSITA Final Equatorial Depth Survey (eFEDS). By cross-matching the WISE 22 μm (W4)-detected sample and the eFEDS X-ray point-source catalog, we find that 692 extragalactic objects are detected by eROSITA. We have compiled a multiwavelength dataset extending from X-ray to far-IR wavelengths. We have also performed (i) an X-ray spectral analysis, (ii) spectral-energy-distribution fitting using X-CIGALE, (iii) 2D image-decomposition analysis using Subaru Hyper Suprime-Cam images, and (iv) optical spectral fitting with QSFit to investigate the AGN and host-galaxy properties. For 7088 WISE 22 μm objects that are undetected by eROSITA, we have performed an X-ray stacking analysis to examine the typical physical properties of these X-ray faint and probably obscured objects. We find that (i) 82% of the eFEDS–W4 sources are classified as X-ray AGN with log L X > 42 erg s –1 ; (ii) 67 and 24% of the objects have log(L IR /L ⊙ ) > 12 and 13, respectively; (iii) the relationship between L X and the 6 μm luminosity is consistent with that reported in previous works; and (iv) the relationship between the Eddington ratio and N H for the eFEDS–W4 sample and a comparison with a model prediction from a galaxy-merger simulation indicates that approximately 5.0% of the eFEDS–W4 sources in our sample are likely to be in an AGN-feedback phase, in which strong radiation pressure from the AGN blows out the surrounding material from the nuclear region. Thanks to the wide area coverage of eFEDS, we have been able to constrain the ranges of the physical properties of the WISE 22 μm-selected sample of AGNs at z < 4, providing a benchmark for forthcoming studies on a complete census of MIR galaxies selected from the full-depth eROSITA all-sky survey.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2016

A Broadband X-Ray Imaging Spectroscopy with High-Angular Resolution: the FORCE Mission

We are proposing FORCE (Focusing On Relativistic universe and Cosmic Evolution) as a future Japan-lead X-ray observatory to be launched in the mid 2020s. Hitomi (ASTRO-H) possesses a suite of sensitive instruments enabling the highest energy-resolution spectroscopy in soft X-ray band, a broadband X-ray imaging spectroscopy in soft and hard X-ray bands, and further high energy coverage up to soft gamma-ray band. FORCE is the direct successor to the broadband X-ray imaging spectroscopy aspect of Hitomi (ASTRO-H) with significantly higher angular resolution. The current design of FORCE defines energy band pass of 1-80 keV with angular resolution of <15" in half-power diameter, achieving a 10 times higher sensitivity above 10 keV compared to any previous missions with simultaneous soft X-ray coverage. Our primary scientific objective is to trace the cosmic formation history by searching for "missing black holes" in various mass-scales: "buried supermassive black holes (SMBHs)" (> 10(exp 4) Stellar Mass) residing in the center of galaxies in a cosmological distance, "intermediate-mass black holes" (10(exp 2)-(10(exp 4) Stellar Mass) acting as the possible seeds from which SMBHs grow, and "orphan stellar-mass black holes" (< 10(exp 2) Stellar Mass) without companion in our Galaxy. In addition to these missing BHs, hunting for the nature of relativistic particles at various astrophysical shocks is also in our scope, utilizing the broadband X-ray coverage with high angular-resolution. FORCE are going to open a new era in these fields. The satellite is proposed to be launched with the Epsilon vehicle that is a Japanese current solid-fuel rocket. FORCE carries three identical pairs of Super-mirror and wide-band X-ray detector. The focal length is currently planned to be 10 m. The silicon mirror with multi-layer coating is our primary choice to achieve lightweight, good angular optics. The detector is a descendant of hard X-ray imager onboard Hitomi (ASTRO-H) replacing its silicon strip detector with SOI-CMOS silicon pixel detector, allowing an extension of the low energy threshold down to 1 keV or even less.

Hard X-ray↗

NASA NTRS2013

Suzaku View of the Swift/BAT Active Galactic Nuclei. V. Torus Structure of Two Luminous Radio-Loud Active Galactic Nuclei (3C 206 and PKS 0707-35)

We present the results from broadband X-ray spectral analysis of 3C 206 and PKS 0707−35 with Suzaku and Swift/BAT, two of the most luminous unobscured and obscured radio-loud active galactic nuclei (AGNs) with hard X-ray luminosities of 10(sup 45.5) erg per second and 10(sup 44.9) erg per second (14-195 keV), respectively. Based on the radio core luminosity, we estimate that the X-ray spectrum of 3C 206 contains a significant (∼60% in the 14-195 keV band) contribution from the jet, while it is negligible in PKS 0707−35.We can successfully model the spectra with the jet component (for 3C 206), the transmitted emission, and two reflection components from the torus and the accretion disk. The reflection strengths from the torus are found to be R(sub torus)(≡Omega/2pi) = 0.29 +/- 0.18 and 0.41 +/- 0.18 for 3C 206 and PKS 0707−35, respectively, which are smaller than those in typical Seyfert galaxies. Utilizing the torus model by Ikeda et al., we quantify the relation between the half-opening angle of a torus (theta(sub oa)) and the equivalent width of an iron-K line. The observed equivalent width of 3C 206, less than 71 eV, constrains the column density in the equatorial plane to N(sup eq)(sub H) lesst han 10(sup 23) per square centimeter, or the half-opening angle to theta(sub oa) greater than 80 deg. if N(sup eq)(sub H) = 10(sup 24) per square centimeter is assumed. That of PKS 0707−35, 72 +/- 36 eV, is consistent with N(sup eq)(sub H) ∼ 10(sup 23) per square centimeter. Our results suggest that the tori in luminous radio-loud AGNs are only poorly developed. The trend is similar to that seen in radio-quiet AGNs, implying that the torus structure is not different between AGNs with jets and without jets.

Suzaku↗

NASA NTRS2011

Combined Spectral and Timing Analysis of the Black Hole Candidate MAXI J1659-152 Discovered by MAXI and Swift

We report on X-ray spectral and timing results of the new black hole candidate (BHC) MAXI J1659-152 with the orbital period of 2.41 hours (shortest among BHCs) in the 2010 outburst from 65 Rossi X-ray Timing Explorer (RXTE) observations and 8 simultaneous Swift and RXTE observations. According to the definitions of the spectral states in Remillard & McClintock (2006), most of the observations have been classified into the intermediate state. All the X-ray broadband spectra can be modeled by a multi-color disk plus a power-law with an exponential cutoff or a multi-color disk plus a Comptonization component. During the initial phase of the outburst, a high energy cutoff was visible at 30-40 keV. The innermost radius of the disk gradually decreased by a factor of more than 3 from the onset of the outburst and reached a constant value of 35 d(sub 10)cos(i sup −1/2) km, where d(sub 10) is the distance in units of 10 kpc and i is the inclination. The type-C quasi-periodic oscillation (QPO) frequency varied from 1.6 Hz to 7.3 Hz in association with a change of the innermost radius, while the innermost radius remained constant during the type-B QPO detections at 1.6-4.1 Hz. Hence, we suggest that the origin of the type-B QPOs is different from that of type-C QPOs, the latter of which would originate from the disk truncation radius. Assuming the constant innermost radius in the latter phase of the outburst as the innermost stable circular orbit, the black hole mass in MAXI J1659-152 is estimated to be 3.6-8.0 solar mass for a distance of 5.3-8.6 kpc and an inclination angle of 60-75 degrees.

Timing↗

NASA NTRS2009

Suzaku View of the Swift/BAT Active Galactic Nuclei (I): Spectral Analysis of Six AGNs and Evidence for Two Types of Obscured Population

We present a systematic spectral analysis with Suzaku of six AGNs detected in the Swift/BAT hard X-ray (15-200 keV) survey, Swift J0138.6-4001, J0255.2-0011, J0350.1-5019, J0505.7-2348, J0601.9-8636, and J1628.1-5145. This is considered to be a representative sample of new AGNs without X-ray spectral information before the BAT survey. We find that the 0.5-200 keV spectra of these sources can be uniformly fit with a base model consisting of heavily absorbed (log NH >23.5/sq cm) transmitted components, scattered lights, a reflection component, and an iron-K emission line. There are two distinct groups, three "new type" AGNs (including the two sources reported by Ueda et al. 2007) with an extremely small scattered fraction (f(sub scat) < 0:5%) and strong reflection component (R = omega/2pi > or equal to 0.8 where omega is the solid angle of the reflector), and three "classical type" ones with f(sub scat > 0.5% and R < or approx. 0.8. The spectral parameters suggest that the new type has an optically thick torus for Thomson scattering (N(sub H) approx. 10(exp 25)/sq cm) with a small opening angle theta approx. 20deg viewed in a rather face-on geometry, while the classical type has a thin torus (N(sub H) approx. 10(exp 23-24)/sq cm) with theta > or approx. 30deg. We infer that a significant number of new type AGNs with an edge-on view is missing in the current all-sky hard X-ray surveys. Subject headings: galaxies: active . gamma rays: observations . X-rays: galaxies . X-rays: general

Eguchi, Satoshi↗

NASA NTRS2001

ASCA Observation of the Superluminal Jet Source GRO J1655-40 in the 1997 Outburst

We report on the results of an ASCA observation of the Galactic jet source GRO 51655-40 performed from 1997 February 25 to February 28 covering a full orbital period (2.62 d). The averaged 2-10 keV flux was about 1.1 Crab. An absorption line feature centered at 6.8 keV was detected both in the GIS and SIS spectra. We interpret this as a blend of two resonance-absorption K alpha lines from H-like and He-like iron ions. We can consistently explain both the ASCA spectra and the simultaneous RXTE/PCA spectrum by a combination of K-absorption lines and K-absorption edges of iron ions. The fact that the absorption line is stably present over the whole orbital phase implies that the distribution of the highly ionized plasma is not affected by the companion star, which is consistent with its presence around the black hole. A curve of growth analysis shows that the plasma contains velocity dispersion along the line-of-sight larger than 300 km/s attributed to bulk motions. It is probably a part of a geometrically thick accretion flow in turbulent motions with velocities of 500-1600 km/s at an estimated radius of sim 10(exp 10)/cm.

Yamaoka, Kazutaka↗

NASA NTRS1994

Spectral study of GX 339-4 in the low-intensity state observed with Ginga

The energy spectra of the black-hole candidate GX 339-4 in the low-intensity state were observed on four occasions through 1989 to 1991 with the Large Area Counter on board the Ginga satellite. The spectra showed significant deviations from a power-law, with an iron K(sub alpha) emission line at approximetaly 6.4 keV and a broad iron K-edge structure above approximately 7 keV. The enrgy spectra above approximately 4 keV were successfully explained with a reflection model, in which part of the incident X-rays with a power-law spectrum is Compton reflected by optically thick matter, resulting in a harder continuum component with iron K-edge absorption and an iron flourescent line. The line equivalent width with respect to the reflection component decreases as the source flux increases. This is consistent with an increase in the ionization state of the material, so that resonant absorption followed by Auger ionization depletes the line. The photon-index of the power-law component was clearly variable, and it correlated with the relative amount of the reflection component. Such a correlation may be explained in the context of the anisotropic Comptonization models of Haardt et al. (1993), or by a variation of the relative geometry of the source and disk.

Ueda, Yoshihiro↗