31 research outputs found
The Complete Infrared View of Active Galactic Nuclei from the 70-month Swift/BAT Catalog
We systematically investigate the near- (NIR) to far-infrared (FIR)
photometric properties of a nearly complete sample of local active galactic
nuclei (AGN) detected in the Swift/Burst Alert Telescope (BAT) all-sky ultra
hard X-ray (14-195 keV) survey. Out of 606 non-blazar AGN in the Swift/BAT
70-month catalog at high galactic latitude of , we obtain IR
photometric data of 604 objects by cross-matching the AGN positions with
catalogs from the WISE, AKARI, IRAS, and Herschel infrared observatories. We
find a good correlation between the ultra-hard X-ray and mid-IR (MIR)
luminosities over five orders of magnitude (). Informed by previous measures of the intrinsic
spectral energy distribution of AGN, we find FIR pure-AGN candidates whose FIR
emission is thought to be AGN-dominated with low starformation activity. We
demonstrate that the dust covering factor decreases with the bolometric AGN
luminosity, confirming the luminosity-dependent unified scheme. We also show
that the completeness of the WISE color-color cut in selecting Swift/BAT AGN
increases strongly with 14-195 keV luminosity.Comment: 24 pages, 11 figures, accepted for publication in ApJ. The full list
of Table 1 is available at
http://www.kusastro.kyoto-u.ac.jp/~ichikawa/table1_MRT.tx
A NuSTAR and XMM-Newton Study of the Two Most Actively Star-forming Green Pea Galaxies (SDSS J0749+3337 and SDSS J0822+2241)
We explore X-ray evidence for the presence of active galactic nuclei (AGNs)
in the two most actively star-forming Green Pea galaxies (GPs), SDSS J0749+3337
and SDSS J0822+2241, which have star-formation rates (SFRs) of
yr and yr, respectively. The GPs have red
mid-infrared (MIR) spectral energy distributions and higher 22 m
luminosities than expected from a proxy of the SFR (H luminosity),
consistent with hosting AGNs with 2-10 keV luminosities of erg
s. We thus obtain and analyze the first hard ( 10 keV) X-ray data
observed with NuSTAR and archival XMM-Newton data below 10 keV. From the NuSTAR
20 ksec data, however, we find no significant hard X-ray emission. By
contrast, soft X-ray emission with 0.5--8 keV luminosities of
erg s is significantly detected in both targets, which can be explained
only by star formation (SF). A possible reason for the lack of clear evidence
is that a putative AGN torus absorbs most of the X-ray emission. Applying a
smooth-density AGN torus model, we determine minimum hydrogen column densities
along the equatorial plane () consistent with the
non-detection. The results indicate
cm for SDSS J0749+3337 and
cm for SDSS J0822+2241. Therefore, the GPs may host such heavily
obscured AGNs. Otherwise, no AGN exists and the MIR emission is ascribed to SF.
Active SF in low-mass galaxies is indeed suggested to reproduce red MIR colors.
This would imply that diagnostics based on MIR photometry data alone may
misidentify such galaxies as AGNs.Comment: 12 pages, 3 tables, 5 figures, accepted for publication in Ap
Discovery of Dying Active Galactic Nucleus in Arp 187: Experience of Drastic Luminosity Decline within years
Arp 187 is one of the fading active galactic nuclei (AGN), whose AGN activity
is currently decreasing in luminosity. We investigate the observational
signatures of AGN in Arp 187, which trace various physical scales from less
than 0.1 pc to the nearly 10 kpc, to estimate the longterm luminosity change
over years. The VLA 5 GHz, 8 GHz, and the ALMA 133 GHz images reveal
bimodal jet lobes with 5 kpc size and the absence of the central
radio-core. The 6dF optical spectrum shows that Arp 187 hosts narrow line
region with the estimated size of 1 kpc, and the line strengths give the
AGN luminosity of erg s. On the other
hand, the current AGN activity estimated from the AGN torus emission gives the
upper bound of erg s. The absence of
the radio-core gives the more strict upper bound of the current AGN luminosity
of erg s, suggesting that the central
engine is already quenched. These multi-wavelength signatures indicate that Arp
187 hosts a "dying" AGN: the central engine is already dead, but the large
scale AGN indicators are still observable as the remnant of the past AGN
activity. The central engine has experienced the drastic luminosity decline by
a factor of fainter within years, which is roughly
consistent with the viscous timescale of the inner part of the accretion disk
within 500 years.Comment: 15 pages, 8 figures, accepted for publication in Ap
Water Soluble Aluminum Paste Using Polyvinyl Alcohol for Silicon Solar Cells
Screen-printing aluminum is still dominantly used in the solar cell fabrication process. Ethyl cellulose is one of the main contents of screen-printing pastes that require dichloromethane for its cleaning process, a substance renowned for being extremely toxic and threatening to the human body. Developing environmental friendly aluminum pastes is essential in order to provide an alternative to the commercial pastes. In this work, new, nontoxic polyvinyl alcohol-based aluminum pastes are introduced. Polyvinyl alcohol was used as a soluble polymer that can be synthesized without saponification and that is also soluble in water. Three different pastes were developed using different recipes including many aluminum particle sizes varying from 3.0 to 45 μm, aluminum oxide with particle sizes between 35 and 50 μm, and acetic acid. Evaluation of the pastes was carried out by Scanning Electron Microscope (SEM) image analysis, sheet resistance measurements, and fabricating silicon solar cells using each paste. Solar cells with 15.6% efficiency were fabricated by nonvacuum processing on CZ-Si p-type wafers using developed aluminum pastes on the back side
NuSTAR Discovery of Dead Quasar Engine in Arp 187
Recent active galactic nucleus (AGN) and quasar surveys have revealed a
population showing rapid AGN luminosity variability by a factor of .
Here we present the most drastic AGN luminosity decline by a factor of constrained by a NuSTAR X-ray observation of the nearby galaxy Arp 187,
which is a promising "dead" quasar whose current activity seems quiet but whose
past activity of erg s is still observable
at a large scale by its light echo. The obtained upper bound of the X-ray
luminosity is ,
corresponding to ,
indicating an inactive central engine. Even if a putative torus model with
cm is assumed, the strong
upper-bound still holds with or . Given the
expected size of the narrow line region, this luminosity decrease by a factor
of must have occurred within yr. This extremely
rapid luminosity/accretion shutdown is puzzling and it requires one burst-like
accretion mechanism producing a clear outer boundary for an accretion disk. We
raise two possible scenarios realizing such an accretion mechanism: a mass
accretion 1) by the tidal disruption of a molecular cloud and/or 2) by the gas
depletion as a result of vigorous nuclear starformation after rapid mass inflow
to the central engine.Comment: 7 pages, 2 figures, accepted for publication in ApJ
Muscle mass, quality, and strength; physical function and activity; and metabolic status in cachectic patients with head and neck cancer
Background & aims: Cancer cachexia is commonly associated with poor prognosis in patients with head and neck cancer (HNC). However, its pathophysiology and treatment are not well established. The current study aimed to assess the muscle mass/quality/strength, physical function and activity, resting energy expenditure (REE), and respiratory quotient (RQ) in cachectic patients with HNC.
Methods: This prospective cross-sectional study analyzed 64 patients with HNC. Body composition was measured via direct segmental multifrequency bioelectrical impedance analysis, and muscle quality was assessed using echo intensity on ultrasonography images. Muscle strength was investigated utilizing handgrip strength and isometric knee extension force (IKEF). Physical function was evaluated using the 10-mwalking speed test and the five times sit-to-stand (5-STS) test. Physical activity was examined using a wearable triaxial accelerometer. REE and RQ were measured via indirect calorimetry. These parameters were compared between the cachectic and noncachectic groups.
Results: In total, 23 (36%) patients were diagnosed with cachexia. The cachectic group had a significantly lower muscle mass than the noncachectic group. Nevertheless, there was no significant difference in terms of fat between the two groups. The cachectic group had a higher quadriceps echo intensity and a lower handgrip strength and IKEF than the noncachectic group. Moreover, they had a significantly slower normal and maximum walking speed and 5 STS speed. The number of steps, total activity time, and time of activity (<3 Mets) did not significantly differ between the two groups. The cachectic group had a shorter time of activity (≥3 Mets) than the noncachectic group. Furthermore, the cachectic group had a significantly higher REE/body weight and REE/fat free mass and a significantly lower RQ than the noncachectic group.
Conclusions: The cachectic group had a lower muscle mass/quality/strength and physical function and activity and a higher REE than the noncachectic group. Thus, REE and physical activity should be evaluated to determine energy requirements. The RQ was lower in the cachectic group than that in the noncachectic group, indicating changes in energy substrate. Further studies must be conducted to examine effective nutritional and exercise interventions for patients with cancer cachexia
Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). III. Discovery of a z = 4.72 Radio Galaxy with Lyman Break Technique
We report a discovery of radio galaxy, HSC J083913.17+011308.1, by
using the Lyman break technique with the Hyper Suprime-Cam Subaru Strategic
Survey (HSC-SSP) catalog for VLA FIRST radio sources. The number of known
high- radio galaxies (HzRGs) at is quite small to constrain the
evolution of HzRGs so far. The deep and wide-area optical survey by HSC-SSP
enables us to apply the Lyman break technique to a large search for HzRGs. For
an HzRG candidate among pre-selected -band dropouts with a radio detection,
a follow-up optical spectroscopy with GMOS/Gemini has been performed. The
obtained spectrum presents a clear Ly emission line redshifted to
. The SED fitting analysis with the rest-frame UV and optical
photometries suggests the massive nature of this HzRG with . The small equivalent width of Ly and the moderately red UV
colors indicate its dusty host galaxy, implying a chemically evolved and dusty
system. The radio spectral index does not meet a criterion for an ultra-steep
spectrum: of and of ,
demonstrating that the HSC-SSP survey compensates for a sub-population of HzRGs
which are missed in surveys focusing on an ultra-steep spectral index.Comment: 10 pages, 5 figures, accepted for publication in A