The mass estimator used to calculate black hole (BH) masses in broad-line active galactic nuclei (AGNs) relies on a virial coefficient (the "f factor") that is determined by comparing ...reverberation-mapped (RM) AGNs with measured bulge stellar velocity dispersions against the M sub(BH-)sigma* relation of inactive galaxies. It has recently been recognized that only classical bulges and ellipticals obey a tight M sub(BH-)sigma* relation; pseudobulges have a different zero point and much larger scatter. Motivated by these developments, we reevaluate the f factor for RM AGNs with available sigma sub(*) measurements, updated H beta RM lags, and new bulge classifications based on detailed decomposition of high-resolution ground-based and space-based images. Separate calibrations are provided for the two bulge types, whose virial coefficients differ by a factor of ~2: f = 6.3 + or - 1.5 for classical bulges and ellipticals and f = 3.2 + or - 0.7 for pseudobulges. The structure and kinematics of the broad-line region, at least as crudely encoded in the f factor, seems to be related to the large-scale properties or formation history of the bulge. Lastly, we investigate the bulge stellar masses of the RM AGNs, show evidence for recent star formation in the AGN hosts that correlates with Eddington ratio, and discuss the potential utility of the M sub(BH)-M sub(bulge) relation as a more promising alternative to the conventionally used M sub(BH-)sigma* relation for future refinement of the virial mass estimator for AGNs.
This study aims to estimate the transmission potential of mpox in East Asia, focusing on the hardest hit nations: Taiwan, China, Japan, and South Korea.
We utilized six phenomenological dynamic ...growth models to fit the case incidence during the initial 30 epidemic days. The best-fit model was selected to calculate the reproduction number (R
). Additionally, we used the latest case data and a Bayesian framework to compute the instantaneous effective R
by applying the Cori et al.
During the early phase, China demonstrated the highest estimated R
of 2.89 (95% CI: 1.44-3.33); followed by South Korea, 2.18 (95% CI: 0.96-3.57); Japan, 1.73 (95% CI: 0.66-3.94); and Taiwan, 1.36 (95% CI: 0.71-3.30). However, by June 30, 2023, estimated R
dropped below 1.00 in all countries: China at 0.05 (95% credible interval CrI: 0.02-0.10), Japan at 0.32 (95% CrI: 0.15-0.59), South Korea at 0.23 (95% CrI: 0.11-0.42), and Taiwan at 0.41 (95% CrI: 0.31-0.53), indicating the potential decline of the outbreak.
Our analysis shows effective containment by each country. It is crucial to sustain effective management to ensure the ultimate eradication of the outbreak.
One of the most effective methods to achieve high-performance perovskite solar cells has been to include additives that serve as dopants, crystallization agents, or passivate defect sites. Cl-based ...additives are among the most prevalent in literature, yet their exact role is still uncertain. In this work, we systematically study the function of methylammonium chloride (MACl) additive in formamidinium lead iodide (FAPbI3)-based perovskite. Using density functional theory, we provide a theoretical framework for understanding the interaction of MACl with a perovskite. We show that MACl successfully induces an intermediate to the pure FAPbI3 α-phase without annealing. The formation energy is related to the amount of incorporated MACl. By tuning the incorporation of MACl, the perovskite film quality can be significantly improved, exhibiting a 6× increase in grain size, a 3× increase in phase crystallinity, and a 4.3× increase in photoluminescence lifetime. The optimized solar cells achieved a certified efficiency of 23.48%.
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•Improvement of morphology, phase crystallinity, photo-physical property, and efficiency with MACl•Stabilized intermediate to the pure FAPbI3 α-phase with MACl•The formation energy of perovskite structure with the amount of incorporated MACl•Theoretical framework for understanding the interaction of MACl with a perovskite film
Numerous effective methods have been developed toward achieving high-performance perovskite solar cells. The additives are one of the most effective ways of achieving high performance. Cl-based additives are among the most prevalent in literature; however, their exact role is still uncertain.
Herein, we systematically researched the effects of methylammonium chloride (MACl) additive using analysis of photo-physical properties and density functional theory. The highest efficiency achieved was 24.02%, certified as 23.48%, and the resultant devices showed better thermal stabilities and photostabilities than the pristine devices.
Kim and co-workers report systematical studies with methylammonium chloride (MACl) in formamidinium lead iodide (FAPbI3)-based perovskite thin films. The MACl addition could induce the intermediate phase with pure α-phase without annealing, effectively stabilizing the structure, only through cationic site substitution. The film quality can be significantly improved, exhibiting a 6× increase in grain size, a 3× increase in phase crystallinity, and a 4.3× increase in photoluminescence lifetime. The resulting optimized solar cells achieved a peak-scan efficiency of above 24%.
Abstract
We assemble a broadband spectral energy distribution (SED) ranging from the optical to the mid-infrared of nearby active galactic nuclei (AGNs) at
z
< 0.4. The SED fitting analysis is ...performed using semiempirical templates derived from Palomar-Green quasars to classify the sample into normal, warm-dust-deficient (WDD), and hot-dust-deficient (HDD) AGNs. Kolmogorov–Smirnov tests reveal that HDD AGNs exhibit higher AGN luminosity on average than normal and WDD AGNs. The HDD fraction, on the other hand, is only weakly correlated with the black hole mass and inversely correlated with the Eddington ratio. By fixing the other parameters, we conclude that the HDD fraction is primarily connected with the AGN luminosity. This implies that there is a causal connection between the covering factor of the hot dust component and AGN luminosity, possibly due to the sublimation of the innermost dust or the thickening of the intervening gas in the broad-line region. Analysis of the outflow properties traced by the wing of O
iii
λ
5007 suggests that outflows may be related to the formation and maintenance of the hot dust component. Finally, we demonstrate through comparison with previous studies that the classification of HDD AGNs requires careful subtraction of the host galaxy light.
We investigate the triggering mechanism and the structural properties of obscured luminous active galactic nuclei from a detailed study of the rest-frame B and I Hubble Space Telescope images of 29 ...nearby (z 0.04-0.4) optically selected type 2 quasars. Morphological classification reveals that only a minority (34%) of the hosts are mergers or interacting galaxies. More than half (55%) of the hosts contain regular disks, and a substantial fraction (38%), in fact, are disk-dominated (B/T 0.2) late-type galaxies with low Sérsic indices (n < 2), which is characteristic of pseudo bulges. The prevalence of bars in the spiral host galaxies may be sufficient to supply the modest fuel requirements needed to power the nuclear activity in these systems. Nuclear star formation seems to be ubiquitous in the central regions, leading to positive color gradients within the bulges and enhancements in the central surface brightness of most systems.
Abstract
Using the multi-epoch mid-infrared (MIR) photometry from the Wide-field Infrared Survey Explorer spanning a baseline of ∼10 yr, we extensively investigate the MIR variability of nearby ...active galactic nuclei (AGNs) at 0.15 <
z
< 0.4. We find that the ensemble structure function in the W1 band (3.4
μ
m) can be modeled with a broken power law. Type 1 AGNs tend to exhibit larger variability amplitudes than type 2 AGNs, possibly due to the extinction by the torus. The variability amplitude is inversely correlated with the AGN luminosity, consistent with a similar relation known in the optical. Meanwhile, the slope of the power law increases with AGN luminosity. This trend can be attributed to the fact that the inner radius of the torus is proportional to the AGN luminosity, as expected from the size−luminosity relation of the torus. Interestingly, low-luminosity type 2 AGNs, unlike low-luminosity type 1 AGNs, tend to exhibit smaller variability amplitude than do high-luminosity AGNs. We argue that either low-luminosity type 2 AGNs have distinctive central structures due to their low luminosity or their MIR brightness is contaminated by emission from the cold dust in the host galaxy. Our findings suggest that the AGN unification scheme may need to be revised. We find that the variability amplitude of dust-deficient AGNs is systematically larger than that of normal AGNs, supporting the notion that the hot and warm dust in dust-deficient AGNs may be destroyed and reformed according to the strength of the ultraviolet radiation from the accretion disk.
Abstract
We present detailed image analysis of rest-frame optical images of 235 low-redshift (
z
≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the
Hubble Space Telescope
. The ...high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetry of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (H
β
FWHM ≤ 2000 km s
−1
) Type 1 AGNs, in contrast to their broad-line (H
β
FWHM > 2000 km s
−1
) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population.
Abstract
We present bolometric luminosity (
L
bol
) and black hole (BH) mass (
M
BH
) estimators based on mid-infrared (MIR) continuum luminosity (hereafter,
L
MIR
) that are measured from infrared ...(IR) photometric data. The
L
MIR
-based estimators are relatively immune from dust extinction effects, hence they can be used for dust-obscured quasars. To derive the
L
bol
and
M
BH
estimators, we use unobscured quasars selected from the Sloan Digital Sky Survey (SDSS) quasar catalog, which have wide ranges of
L
bol
(10
44.62
–10
46.16
erg s
−1
) and
M
BH
(10
7.14
–10
9.69
M
⊙
). We find empirical relations between (i) continuum luminosity at 5100 Å (hereafter, L5100) and
L
MIR
; (ii)
L
bol
and
L
MIR
. Using these relations, we derive the
L
MIR
-based
L
bol
and
M
BH
estimators. We find that our estimators allow the determination of
L
bol
and
M
BH
at an accuracy of ∼0.2 dex against the fiducial estimates based on the optical properties of the unobscured quasars. We apply the
L
MIR
-based estimators to SDSS quasars at
z
≲ 0.5 including obscured ones. The ratios of
L
bol
from the
L
MIR
-based estimators to those from the optical luminosity-based estimators become larger with the amount of the dust extinction, and a non-negligible fraction (∼15%) of the SDSS quasars exhibits ratios greater than 1.5. This result suggests that dust extinction can significantly affect physical parameter derivations even for SDSS quasars, and that dust extinction needs to be carefully taken into account when deriving quasar properties.
Abstract
We present initial results from a Hubble Space Telescope snapshot imaging survey of the host galaxies of Swift-BAT active galactic nuclei (AGN) at
z
< 0.1. The hard X-ray selection makes ...this sample relatively unbiased in terms of obscuration, compared to optical AGN selection methods. The high-resolution images of 154 target AGN enable us to investigate the detailed photometric structure of the host galaxies, such as the Hubble type and merging features. We find 48% and 44% of the sample to be hosted by early-type and late-type galaxies, respectively. The host galaxies of the remaining 8% of the sample are classified as peculiar galaxies because they are heavily disturbed. Only a minor fraction of host galaxies (18%–25%) exhibit merging features (e.g., tidal tails, shells, or major disturbance). The merging fraction increases strongly as a function of bolometric AGN luminosity, revealing that merging plays an important role in triggering luminous AGN in this sample. However, the merging fraction is weakly correlated with the Eddington ratio, suggesting that merging does not necessarily lead to an enhanced Eddington ratio. Type 1 and Type 2 AGN are almost indistinguishable in terms of their Hubble type distribution and merging fraction. However, the merging fraction of Type 2 AGN peaks at a lower bolometric luminosity compared with those of Type 1 AGN. This result may imply that the triggering mechanism and evolutionary stages of Type 1 and Type 2 AGN are not identical.
Abstract
Although Korean American women have a higher risk of developing cervical cancer, currently there are limited culturally relevant intervention strategies for improving primary prevention of ...cervical cancer by promoting HPV vaccination in this population. This study reports the development of a cross-cultural, cross-generational storytelling HPV intervention using a peer-paired method, in which two storytellers interactively share their stories, as a particular innovation that might resonate with Korean American young women. The acceptability of the intervention was assessed by self-reported satisfaction and endorsement with the intervention in a pilot randomized control trial (RCT). We compared participants’ responses to the intervention by their generation and cultural identity. One hundred and four Korean college women between the ages of 18–26 were recruited from the Northeastern US Participants randomized to the intervention group received a storytelling video (n = 54); the comparison group received written information (n = 50). The acceptability of the intervention was measured immediately post-intervention. The intervention group had significantly greater satisfaction than the comparison group (P < 0.05). Participants reported greater endorsement for videos that reflected their cultural and generational experiences. Future study is needed to examine the impact of such interventions on objective follow-up on HPV vaccination in a large-scale RCT.
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