35 research outputs found

    Does Faith Has Impact on Investment Return: Evidence From REITs

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    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 z=7−12z=7-12 Obtained with Lyα\alpha Damping Wing Absorptions in 26 Bright Continuum Galaxies

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    We present volume-averaged neutral hydrogen fractions x_{\rm \HI} and ionized bubble radii RbR_{\rm b} measured with Lyα\alpha 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 7<z<127<z<12. We construct 4 composite spectra binned by redshift, and find the clear evolution of spectral flattening towards high redshift at the rest-frame 12161216 \AA\ suggesting the increase of Lyα\alpha damping wing absorption. We estimate Lyα\alpha damping wing absorption in the composite spectra with realistic templates including Lyα\alpha emission and circum-galactic medium absorptions. Assuming the standard inside-out reionization picture having an ionized bubble with RbR_{\rm b} around a galaxy in the inter-galactic medium of x_{\rm \HI}, we obtain x_{\rm \HI} (RbR_{\rm b}) values monotonically increasing (decreasing) from x_{\rm \HI}={0.46}^{+0.36}_{-0.32} to 0.83−0.21+0.12{0.83}^{+0.12}_{-0.21} (Rb=1.49−0.43+0.37×102R_{\rm b}={1.49}^{+0.37}_{-0.43}\times10^2 to 5.04−3.73+8.06{5.04}^{+8.06}_{-3.73} comoving Mpc) at redshift 7.140−0.076+0.0397.140^{+0.039}_{-0.076} to 9.801−1.164+1.5999.801^{+1.599}_{-1.164}. 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 fesc≃0.17f_{\rm esc}\simeq 0.17. Our RbR_{\rm b} measurements are about 20 times larger than the cosmic average values estimated by analytic calculations for a given x_{\rm \HI}, while our RbR_{\rm b} 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 zspec=8.61−13.20z_\mathrm{spec}=8.61-13.20 Confirmed with JWST/NIRSpec

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    We present pure spectroscopic constraints on the UV luminosity functions and cosmic star formation rate (SFR) densities from 25 galaxies at zspec=8.61−13.20z_\mathrm{spec}=8.61-13.20. 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 zspec=8.61−11.40z_\mathrm{spec}=8.61-11.40 including new redshift determinations, and a bright interloper at zspec=4.91z_\mathrm{spec}=4.91 that was claimed as a photometric candidate at z~16. In conjunction with nine galaxies at redshifts up to zspec=13.20z_\mathrm{spec}=13.20 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 Λ\LambdaCDM model due to the removal of the bright interloper, we confirm star-forming galaxies at zspec=11−13z_\mathrm{spec}=11-13 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

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    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

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    We present a first statistical sample of faint type-1 AGNs at z>4z>4 identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at zspec=3.8−8.9z_\mathrm{spec}=3.8-8.9 confirmed with NIRSpec, our systematic search for broad-line emission reveals 10 type-1 AGNs at z=4.015−6.936z=4.015-6.936 whose broad component is only seen in the permitted Hα\alpha line and not in the forbidden [OIII]λ\lambda5007 line that is detected with greater significance than Hα\alpha. The broad Hα\alpha line widths of $\mathrm{FWHM}\simeq1000-6000\ \mathrm{km\ s^{-1}}suggestthattheAGNshavelow−massblackholeswith suggest that the AGNs have low-mass black holes with M_\mathrm{BH}\sim10^6-10^8\ M_\odot,remarkablylowerthanthoseoflow−luminosityquasarspreviouslyidentifiedat, remarkably lower than those of low-luminosity quasars previously identified at z>4withground−basedtelescopes.JWSTandHSThigh−resolutionimagesrevealthatthemajorityofthemshowextendedmorphologiesindicatingsignificantcontributiontothetotallightsfromtheirhostgalaxies,exceptforthreecompactobjectstwoofwhichshowredSEDs,probablyinatransitionphasefromfaintAGNstolowluminosityquasars.CarefulAGN−hostdecompositionanalysesshowthattheirhost′sstellarmassesaresystematicallylowerthanthelocalrelationbetweentheblackholemassandthestellarmass,implyingafastblackholegrowthconsistentwithpredictionsfromtheoreticalsimulations.Ahighfractionofthebroad−lineAGNs( with ground-based telescopes. JWST and HST high-resolution images reveal that the majority of them show extended morphologies indicating significant contribution to the total lights from their host galaxies, except for three compact objects two of which show red SEDs, probably in a transition phase from faint AGNs to low luminosity quasars. Careful AGN-host decomposition analyses show that their host's stellar masses are systematically lower than the local relation between the black hole mass and the stellar mass, implying a fast black hole growth consistent with predictions from theoretical simulations. A high fraction of the broad-line AGNs (\sim5\%),higherthan), higher than z\sim0,indicatesthatanumberdensityofsuchfaintAGNsishigherthananextrapolationofthequasarluminosityfunction,implyingalargepopulationofAGNsincludingtype1andtype2intheearlyuniverse.SuchfaintAGNscontributetocosmicreionization,whilethetotalcontributionisnotlarge,upto, indicates that a number density of such faint AGNs is higher than an extrapolation of the quasar luminosity function, implying a large population of AGNs including type 1 and type 2 in the early universe. Such faint AGNs contribute to cosmic reionization, while the total contribution is not large, up to \sim50\%at at 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

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    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 Hα{\alpha} 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 Hα{\alpha} 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 η{\eta} 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

    Census for the Rest-frame Optical and UV Morphologies of Galaxies at z=4−10z=4-10: First Phase of Inside-Out Galaxy Formation

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    We present the rest-frame optical and UV surface brightness (SB) profiles for 149149 galaxies with Mopt<−19.4M_{\rm opt}< -19.4 mag at z=4z=4-1010 (2929 of which are spectroscopically confirmed with JWST NIRSpec), securing high signal-to-noise ratios of 1010-135135 with deep JWST NIRCam 11-5μ5\mum images obtained by the CEERS survey. We derive morphologies of our high-zz 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., Hα\alpha and [OIII], on optical morphologies with medium-band F410M images. Conducting S\'ersic profile fitting to our high-zz galaxy SBs with GALFIT, we obtain the effective radii of optical re,optr_{\rm e, opt} and UV re,UVr_{\rm e, UV} wavelengths ranging re,opt=0.05r_{\rm e, opt}=0.05-1.61.6 kpc and re,UV=0.03r_{\rm e, UV}=0.03-1.71.7 kpc that are consistent with previous results within large scatters in the size luminosity relations. However, we find the effective radius ratio, re,opt/re,UVr_{\rm e, opt}/r_{\rm e, UV}, is almost unity, 1.01−0.22+0.351.01^{+0.35}_{-0.22}, over z=4z=4-1010 with no signatures of past inside-out star formation such found at z∼0z\sim 0-22. There are no spatial offsets exceeding 3σ3\sigma 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 z≳4z\gtrsim 4 probably experiencing the first phase of inside-out galaxy formation.Comment: 33 pages, 18 figures, 6 table

    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

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    We conduct a comprehensive study on dropout galaxy candidates at z∼9−17z\sim 9-17 using the first 90 arcmin2^2 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-zz determination (Δχ2>4\Delta \chi^2>4). We thus carefully apply a secure photo-zz selection criterion (Δχ2>9\Delta \chi^2>9) and conventional color criteria with confirmations of the ERO NIRSpec spectroscopic redshifts, and obtain a total of 25 dropout galaxies at z∼9−17z\sim 9-17, including two candidates at zphot=16.45−0.32+0.09z_\mathrm{phot}=16.45_{-0.32}^{+0.09} and 16.66−0.34+1.8616.66_{-0.34}^{+1.86}. 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 z∼9−17z\sim 9-17, and confirm that our UV luminosity functions at z∼9z\sim 9 and 1212 agree with those determined by previous HST and JWST studies. The cosmic star-formation rate density decreases from z∼9z\sim 9 to 1212, and perhaps to 1717, but the densities at z∼12−17z\sim12-17 are higher than the constant star formation efficiency model. Interestingly, there are six bright galaxy candidates at z∼11−17z\sim 11-17 with MUV<−19.5M_{\rm UV}<-19.5 whose stellar masses are very high, 108−9M⊙10^{8-9} M_\odot. Because a majority (∼70%\sim 70\%) 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

    Cosmological-scale Lyα Forest Absorption around Galaxies and AGNs Probed with the HETDEX and SDSS Spectroscopic Data

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    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

    The HETDEX Survey: Emission Line Exploration and Source Classification

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    The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is an untargeted spectroscopic survey that aims to measure the expansion rate of the Universe at z∼2.4z \sim 2.4 to 1% precision for both H(z)H(z) and DA(z)D_A(z). HETDEX is in the process of mapping in excess of one million Lyman Alpha emitting (LAE) galaxies and a similar number of lower-z galaxies as a tracer of the large-scale structure. The success of the measurement is predicated on the post-observation separation of galaxies with Lyα\alpha emission from the lower-zz interloping galaxies, primarily [OII], with low contamination and high recovery rates. The Emission Line eXplorer (ELiXer) is the principal classification tool for HETDEX, providing a tunable balance between contamination and completeness as dictated by science needs. By combining multiple selection criteria, ELiXer improves upon the 20 Angstrom rest-frame equivalent width cut commonly used to distinguish LAEs from lower-zz [OII] emitting galaxies. Despite a spectral resolving power, R ∼800\sim800, that cannot resolve the [OII] doublet, we demonstrate the ability to distinguish LAEs from foreground galaxies with 98.1% accuracy. We estimate a contamination rate of Lyα\alpha by [OII] of 1.2% and a Lyα\alpha recovery rate of 99.1% using the default ELiXer configuration. These rates meet the HETDEX science requirements.Comment: 38 pages, 11 figure
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