44 research outputs found
Does Faith Has Impact on Investment Return: Evidence From REITs
This paper investigates whether faith has impact on investment returns. Specifically, we choose the Shariah compliance and REITs investment for the purpose of investigation. Synthetic Shariah compliant portfolios are constructed with various interpretation of compliance. We compare the performance of Shariah compliant portfolios with US Equity REIT portfolio during 1993-2017 by examining the abnormal returns using CAPM and Carhart four-factor model. We find no evidence of underperformance or outperformance of the Shariah compliant investments. This is also true during the financial crisis periods which is confirmed by the sub-sample analysis. Our findings suggest that Shariah compliant REIT investor faces no cost or gain in his investments as a result of his faith
JWST Measurements of Neutral Hydrogen Fractions and Ionized Bubble Sizes at Obtained with Ly Damping Wing Absorptions in 26 Bright Continuum Galaxies
We present volume-averaged neutral hydrogen fractions x_{\rm \HI} and
ionized bubble radii measured with Ly damping wing
absorptions of galaxies at the epoch of reionization. We combine JWST/NIRSpec
spectra taken by CEERS, GO-1433, and DDT-2750 programs, and obtain 26 bright
UV-continuum galaxies at . We construct 4 composite spectra binned by
redshift, and find the clear evolution of spectral flattening towards high
redshift at the rest-frame \AA\ suggesting the increase of Ly
damping wing absorption. We estimate Ly damping wing absorption in the
composite spectra with realistic templates including Ly emission and
circum-galactic medium absorptions. Assuming the standard inside-out
reionization picture having an ionized bubble with around a galaxy
in the inter-galactic medium of x_{\rm \HI}, we obtain x_{\rm \HI} () values monotonically increasing (decreasing) from x_{\rm
\HI}={0.46}^{+0.36}_{-0.32} to ( to comoving Mpc)
at redshift to . The
redshift evolution of x_{\rm \HI} indicates moderately late reionization
history consistent with the one suggested from the electron scattering of
cosmic microwave background and the evolution of UV luminosity function with an
escape fraction . Our measurements are
about 20 times larger than the cosmic average values estimated by analytic
calculations for a given x_{\rm \HI}, while our measurements are
comparable with the values for merged ionized bubbles around bright galaxies
predicted by recent numerical simulations
Pure Spectroscopic Constraints on UV Luminosity Functions and Cosmic Star Formation History From 25 Galaxies at Confirmed with JWST/NIRSpec
We present pure spectroscopic constraints on the UV luminosity functions and
cosmic star formation rate (SFR) densities from 25 galaxies at
. By reducing the JWST/NIRSpec spectra taken in
multiple programs of ERO, ERS, GO, and DDT with our analysis technique, we
independently confirm 16 galaxies at including new
redshift determinations, and a bright interloper at that
was claimed as a photometric candidate at z~16. In conjunction with nine
galaxies at redshifts up to in the literature, we make
a sample of 25 spectroscopically-confirmed galaxies in total and carefully
derive the best estimates and lower limits of the UV luminosity functions.
These UV luminosity function constraints are consistent with the previous
photometric estimates within the uncertainties and indicate mild redshift
evolution towards z~12 showing tensions with some theoretical models of rapid
evolution. With these spectroscopic constraints, we obtain firm lower limits of
the cosmic SFR densities and spectroscopically confirm a high SFR density at
z~12 beyond the constant star-formation efficiency models, which supports
earlier claims from the photometric studies. While there are no
spectroscopically-confirmed galaxies with very large stellar masses violating
the CDM model due to the removal of the bright interloper, we confirm
star-forming galaxies at with stellar masses much
higher than model predictions. Our results indicate possibilities of high
star-formation efficiency (>5%), hidden AGN, top-heavy initial mass function
(possibly with Pop-III), and large scatter/variance. Having these successful
and unsuccessful spectroscopy results, we suggest observational strategies for
efficiently removing low redshift interlopers for future JWST programs.Comment: 27 pages, 18 figures, submitted to Ap
Does faith has impact on investment return: evidence from REITs
TThis paper investigates whether faith has impact on investment returns. Specifically, we choose the Shariah compliance and REITs investment for the purpose of investigation. Synthetic Shariah compliant portfolios are constructed with various interpretation of compliance. We compare the performance of Shariah compliant portfolios with US Equity REIT portfolio during 1993–2017 by examining the abnormal returns using CAPM and Carhart four-factor model. We find no evidence of underperformance or outperformance of the Shariah compliant investments. This is also true during the financial crisis periods which is confirmed by the sub-sample analysis. Our findings suggest that Shariah compliant REIT investor faces no cost or gain in his investments as a result of his faith
A JWST/NIRSpec First Census of Broad-Line AGNs at z=4-7: Detection of 10 Faint AGNs with M_BH~10^6-10^8 M_sun and Their Host Galaxy Properties
We present a first statistical sample of faint type-1 AGNs at
identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at
confirmed with NIRSpec, our systematic search for
broad-line emission reveals 10 type-1 AGNs at whose broad
component is only seen in the permitted H line and not in the forbidden
[OIII]5007 line that is detected with greater significance than
H. The broad H line widths of $\mathrm{FWHM}\simeq1000-6000\
\mathrm{km\ s^{-1}}M_\mathrm{BH}\sim10^6-10^8\ M_\odotz>4\sim5\%z\sim0\sim50\%z\sim6$, because of their faint nature.Comment: 24 pages, 16 figures, accepted for publication in Ap
Stellar and AGN Feedback Probed with Outflows in JWST Galaxies at z=3-9: Implications of Frequent Nearly-Spherical Galactic Fountains
We study outflows in 130 galaxies with -22<MUV<-16 at z=3-9 identified in
JWST NIRSpec and NIRCam WFSS data taken by the ERO, CEERS, FRESCO, GLASS, and
JADES programs. We identify 30 out of the 130 galaxies with broad components of
FWHM~200-700 km/s in the emission lines of H and [OIII] that trace
ionized outflows, and find no excesses from the star-formation main sequence.
Four out of the 30 outflowing galaxies are Type 1 AGN whose H
emission lines include line profile components as broad as FWHM>1000 km/s. With
the velocity shift and line widths of the outflow broad lines, we obtain
~80-500 km/s for the outflow velocities. We find that the outflow velocities as
a function of star-formation rate are comparable to or higher than those of
galaxies at z~1, accounting for the selection bias, while the outflow
velocities of AGN are large but not significantly different from the others.
Interestingly, these outflow velocities are typically not high enough to escape
from the galactic potentials, suggestive of fountain-type outflows, which are
concluded on the basis of thorough comparisons with recent JWST results. We
estimate mass loading factors to be 0.1-1 that are not particularly
large, but comparable with those of z~1 outflows. The large fraction of
galaxies with outflows (30% with high resolution data) provides constraints on
outflow parameters, suggesting a wide opening angle of >45 deg and a large
duty-cycle of >30%, which gives a picture of more frequent and spherical
outflows in high-z galaxies.Comment: 16 pages, 11 figures, submitted to the Astrophysical Journa
A Comprehensive Study on Galaxies at z~9-17 Found in the Early JWST Data: UV Luminosity Functions and Cosmic Star-Formation History at the Pre-Reionization Epoch
We conduct a comprehensive study on dropout galaxy candidates at
using the first 90 arcmin JWST/NIRCam images taken by the early release
observations (ERO) and early release science (ERS) programs. With the JWST
simulation images, we find that a number of foreground interlopers are selected
with a weak photo- determination (). We thus carefully
apply a secure photo- selection criterion () and
conventional color criteria with confirmations of the ERO NIRSpec spectroscopic
redshifts, and obtain a total of 25 dropout galaxies at , including
two candidates at and
. We perform thorough comparisons of dropout galaxies
found in our work with recent JWST studies, and conclude that our galaxy sample
is reliable enough for statistical analyses. We derive the UV luminosity
functions at , and confirm that our UV luminosity functions at
and agree with those determined by previous HST and JWST
studies. The cosmic star-formation rate density decreases from to
, and perhaps to , but the densities at are higher than
the constant star formation efficiency model. Interestingly, there are six
bright galaxy candidates at with whose stellar
masses are very high, . Because a majority () of
these galaxies shows no signatures of AGNs in their morphologies, the high
cosmic star-formation rate densities and the existence of these stellar massive
galaxies are explained by no suppression of star-formation by the UV background
radiation at the pre-reionization epoch or an efficient UV radiation production
by Population III-like star formation.Comment: 36 pages, 19 figures. Submitted to ApJS. Comments welcom
Census for the Rest-frame Optical and UV Morphologies of Galaxies at : First Phase of Inside-Out Galaxy Formation
We present the rest-frame optical and UV surface brightness (SB) profiles for
galaxies with mag at - ( of which are
spectroscopically confirmed with JWST NIRSpec), securing high signal-to-noise
ratios of - with deep JWST NIRCam -m images obtained by the
CEERS survey. We derive morphologies of our high- galaxies, carefully
evaluating the systematics of SB profile measurements with Monte Carlo
simulations as well as the impacts of a) AGNs, b) multiple clumps including
galaxy mergers, c) spatial resolution differences with previous HST studies,
and d) strong emission lines, e.g., H and [OIII], on optical
morphologies with medium-band F410M images. Conducting S\'ersic profile fitting
to our high- galaxy SBs with GALFIT, we obtain the effective radii of
optical and UV wavelengths ranging - kpc and - kpc that are consistent
with previous results within large scatters in the size luminosity relations.
However, we find the effective radius ratio, , is
almost unity, , over - with no signatures of
past inside-out star formation such found at -. There are no
spatial offsets exceeding between the optical and UV morphology
centers in case of no mergers, indicative of major star-forming activity only
found near a mass center of galaxies at probably experiencing the
first phase of inside-out galaxy formation.Comment: 33 pages, 18 figures, 6 table
JWST Identification of Extremely Low C/N Galaxies with [N/O] at Evidencing the Early CNO-Cycle Enrichment and a Connection with Globular Cluster Formation
We present chemical abundance ratios of 70 star-forming galaxies at
-10 observed by the JWST/NIRSpec ERO, GLASS, and CEERS programs. Among
the 70 galaxies, we have pinpointed 2 galaxies, CEERS_01019 at and
GLASS_150008 at , with extremely low C/N ([C/N]),
evidenced with CIII]1907,1909, NIII]1750, and
NIV]1483,1486, which show high N/O ratios ([N/O])
comparable with the one of GN-z11 regardless of whether stellar or AGN
radiation is assumed. Such low C/N and high N/O ratios found in CEERS_01019 and
GLASS_150008 (additionally identified in GN-z11) are largely biased towards the
equilibrium of the CNO cycle, suggesting that these 3 galaxies are enriched by
metals processed by the CNO cycle. On the C/N vs. O/H plane, these 3 galaxies
do not coincide with Galactic HII regions, normal star-forming galaxies, and
nitrogen-loud quasars with asymptotic giant branch stars, but globular-cluster
(GC) stars, indicating a connection with GC formation. We compare C/O and N/O
of these 3 galaxies with those of theoretical models, and find that these 3
galaxies are explained by scenarios with dominant CNO-cycle materials, i.e.
Wolf-Rayet stars, supermassive () stars, and tidal
disruption events, interestingly with a requirement of frequent direct
collapses. For all the 70 galaxies, we present measurements of Ne/O, S/O, and
Ar/O, together with C/O and N/O. We identify 4 galaxies with very low Ne/O,
, indicating abundant massive ()
stars.Comment: Accepted for publication in Ap
Cosmological-scale Lyα Forest Absorption around Galaxies and AGNs Probed with the HETDEX and SDSS Spectroscopic Data
We present cosmological-scale three-dimensional neutral hydrogen (H i) tomographic maps at z = 2-3 over a total of 837 deg2 in two blank fields that are developed with Lyα forest absorptions of 14,736 background Sloan Digital Sky Survey (SDSS) quasars at z = 2.08-3.67. Using the tomographic maps, we investigate the large-scale (≳10 h −1 cMpc) average H i radial profiles and two-direction profiles of the line-of-sight (LOS) and transverse directions around galaxies and active galactic nuclei (AGNs) at z = 2-3 identified by the Hobby-Eberly Telescope Dark Energy eXperiment survey and SDSS, respectively. The peak of the H i radial profile around galaxies is lower than the one around AGNs, suggesting that the dark matter halos of galaxies are less massive on average than those of AGNs. The LOS profile of AGNs is narrower than the transverse profile, indicating the Kaiser effect. There exist weak absorption outskirts at ≳30 h −1 cMpc beyond H i structures of galaxies and AGNs found in the LOS profiles that can be explained by the H i gas at ≳30 h −1 cMpc falling toward the source position. Our findings indicate that the H i radial profile of AGNs has transitions from proximity zones (≲a few h −1 cMpc) to the H i structures (∼1-30 h −1 cMpc) and the weak absorption outskirts (≳30 h −1 cMpc). Although there is no significant dependence of AGN types (type 1 vs. type 2) on the H i profiles, the peaks of the radial profiles anticorrelate with AGN luminosities, suggesting that AGNs’ ionization effects are stronger than the gas mass differences