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2021 ◽  
Vol 923 (2) ◽  
pp. 252
Author(s):  
Kelly N. Sanderson ◽  
Moire M. K. Prescott ◽  
Lise Christensen ◽  
Johan Fynbo ◽  
Palle Møller

Abstract Recent wide-field integral-field spectroscopy has revealed the detailed properties of high-redshift Lyα nebulae, most often targeted due to the presence of an active galactic nucleus (AGN). Here, we use VLT/MUSE to resolve the morphology and kinematics of a nebula initially identified due to strong Lyα emission at z ∼ 3.2 (LABn06). Our observations reveal a two-lobed Lyα nebula, at least ∼173 pkpc in diameter, with a light-weighted centroid near a mid-infrared source (within ≈17.2 pkpc) that appears to host an obscured AGN. The Lyα emission near the AGN is also coincident in velocity with the kinematic center of the nebula, suggesting that the nebula is both morphologically and kinematically centered on the AGN. Compared to AGN-selected Lyα nebulae, the surface-brightness profile of this nebula follows a typical exponential profile at large radii (>25 pkpc), although at small radii, the profile shows an unusual dip at the location of the AGN. The kinematics and asymmetry are similar to, and the C iv and He ii upper limits are consistent with, other AGN-powered Lyα nebulae. Double-peaked and asymmetric line profiles suggest that Lyα resonant scattering may be important in this nebula. These results support the picture of the AGN being responsible for powering a Lyα nebula that is oriented roughly in the plane of the sky. Further observations will explore whether the central surface-brightness depression is indicative of either an unusual gas or dust distribution or variation in the ionizing output of the AGN over time.


2021 ◽  
Vol 922 (2) ◽  
pp. 249
Author(s):  
Yongmin Yoon ◽  
Changbom Park ◽  
Haeun Chung ◽  
Kai Zhang

Abstract We study how stellar rotation curves (RCs) of galaxies are correlated on average with morphology and stellar mass (M star) using the final release of Sloan Digital Sky Survey IV MaNGA data. We use the visually assigned T-types for the morphology indicator, and adopt a functional form for the RC that can model non-flat RCs at large radii. We discover that within the radial coverage of the MaNGA data, the popularly known flat rotation curve at large radii applies only to the particular classes of galaxies, i.e., massive late types (T-type ≥ 1, M star ≳ 1010.8 M ⊙) and S0 types (T-type = −1 or 0, M star ≳ 1010.0 M ⊙). The RC of late-type galaxies at large radii rises more steeply as M star decreases, and its slope increases to about +9 km s−1 kpc−1 at M star ≈ 109.7 M ⊙. By contrast, elliptical galaxies (T-type ≤ −2) have descending RCs at large radii. Their slope becomes more negative as M star decreases, and reaches as negative as −15 km s−1 kpc−1 at M star ≈ 1010.2 M ⊙. We also find that the inner slope of the RC is highest for elliptical galaxies with M star ≈ 1010.5 M ⊙, and decreases as T-type increases or M star changes away from 1010.5 M ⊙. The velocity at the turnover radius R t is higher for higher M star, and R t is larger for higher M star and later T-types. We show that the inner slope of the RC is coupled with the central surface stellar mass density, which implies that the gravitational potential of central regions of galaxies is dominated by baryonic matter. With the aid of simple models for matter distribution, we discuss what determines the shapes of RCs.


2021 ◽  
Vol 13 (15) ◽  
pp. 2902
Author(s):  
Yuan Gao ◽  
Jie Zhang ◽  
Jian Sun ◽  
Changlong Guan

The spaceborne synthetic aperture radar (SAR) is an effective tool to observe tropical cyclone (TC) wind fields at very high spatial resolutions. TC wind speeds can be retrieved from cross-polarization signals without wind direction inputs. This paper proposed methodologies to retrieve TC intensity parameters; for example, surface maximum wind speed, TC fullness (TCF) and central surface pressure from the European Space Agency Sentinel-1 Extra Wide swath mode cross-polarization data. First, the MS1A geophysical model function was modified from 6 to 69 m/s, based on three TC samples’ SAR images and the collocated National Oceanic and Atmospheric Administration stepped frequency microwave radiometer wind speed measurements. Second, we retrieved the wind fields and maximum wind speeds of 42 TC samples up to category 5 acquired in the last five years, using the modified MS1A model. Third, the TCF values and central surface pressures were calculated from the 1-km wind retrievals, according to the radial curve fitting of wind speeds and two hurricane wind-pressure models. Three intensity parameters were found to be dependent upon each other. Compared with the best-track data, the averaged bias, correlation coefficient (Cor) and root mean-square error (RMSE) of the SAR-retrieved maximum wind speeds were –3.91 m/s, 0.88 and 7.99 m/s respectively, showing a better result than the retrievals before modification. For central pressure, the averaged bias, Cor and RMSE were 1.17 mb, 0.77 and 21.29 mb and respectively, indicating the accuracy of the proposed methodology for pressure retrieval. Finally, a new symmetric TC wind field model was developed with the fitting function of the TCF values and maximum wind speeds, radial wind curve and the Rankine Vortex model. By this model, TC wind field can be simulated just using the maximum wind speed and the radius of maximum wind speed. Compared with wind retrievals, averaged absolute bias and averaged RMSE of all samples’ wind fields simulated by the new model were smaller than those of the Rankine Vortex model.


2021 ◽  
Vol 14 (3) ◽  
Author(s):  
Heri Purwoto ◽  
Ratih Dwi Ismawanti ◽  
Harianto Harianto ◽  
M. Jusuf Djafar ◽  
Widya Dwi Rukmi Putri ◽  
...  

Plastic packaging has dominated the waste and the number is increasing every year. Candy plastic packaging waste is most often considered trivial because of its small size so it is usually disposed of carelessly. Every year the candy packaging waste contributes 0.3 billion. Due to its nonbiodegradable, it causes environmental pollution. Edible filmpackaging is an alternative to reduce the impact of candy packaging waste pollution.The purpose of this study was to obtain the optimum formula of edible film between based maize starch, carrageenan and rice bran as a hard candy packaging with the Response Surface Methodology (RSM) Central Surface Composite Design using the Design Expert 10.0.7. The prediction data obtained is then verified and tested by t-test at a 5% reliance interval.The optimum formulation of RSM results is 3,4% of maize starch, 1,1% of carrageenan and 0,38% of rice bran with predicted response of water content of 14,51%, WVTR 61,06 g/m2/hour, viscosity of 258,8 cP, tensile strength of 107,9 kgf/cm2, elongation of 19,41%, and modulus of response young 586,28 kgf/cm2. The verification had a moisture content of 14,37%, WVTR 63,34 g/m2/hour, viscosity of 244,9 cP, tensile strength of 96,9 kgf/cm2, elongation of 20,96%, and young modulus of 462,49 kgf/cm2


Author(s):  
A Leveque ◽  
M Giersz ◽  
M Paolillo

Abstract Over the last few decades, exhaustive surveys of extra Galactic globular clusters (EGGCs) have become feasible. Only recently, limited kinematical information of globular clusters (GCs) were available through Gaia DR2 spectroscopy and also proper motions. On the other hand, simulations of GCs can provide detailed information about the dynamical evolution of the system. We present a preliminary study of EGGCs- properties for different dynamical evolutionary stages. We apply this study to 12 Gyr-old GCs simulated as part of the MOCCA Survey Database. Mimicking observational limits, we consider only a subssample of the models in the database, showing that it is possible to represent observed Milky Way GCs. In order to distinguish between different dynamical states of EGGCs, at least three structural parameters are necessary. The best distinction is achieved by considering the central parameters, those being observational core radius, central surface brightness, ratio between central and half-mass velocity dispersion, or similarly considering the central color, the central V magnitude and the ratio between central and half-mass radius velocity dispersion, although such properties could be prohibitive with current technologies. A similar but less solid result is obtained considering the average properties at the half-light radius, perhaps accessible presently in the Local Group. Additionally, we mention that the color spread in EGGCs due to internal dynamical models, at fixed metallcity, could be just as important due to the spread in metallicity.


2020 ◽  
Vol 10 (1) ◽  
pp. 82
Author(s):  
Michele Lanza ◽  
Luigi De Rosa ◽  
Sandro Sbordone ◽  
Rosa Boccia ◽  
Ugo Antonello Gironi Carnevale ◽  
...  

The purpose of the study is to evaluate the corneal biomechanical properties (CBP) and their behaviors after myopic refractive surgery both with Ocular Response Analyzer (ORA) and Corvis ST (CST). This retrospective study included 145 eyes of 145 patients with a mean age of 33.13 ± 9.24 years, who underwent myopic photorefractive keratectomy (PRK) for a refractive defect, measured as spherical equivalent, of mean −4.69 ± 2.04 D and have been evaluated before surgery and at 1, 3 and 6 months follow-up. Corneal hysteresis (CH) and corneal resistance factor (CRF) values significantly decreased after 1 month and remained statistically stable during further follow-ups. CST parameters had a different evolution: only second applanation time (AT2) differences showed a significant variation after 1 month that did not statistically change over time. Highest concavity deformation amplitude (HCDA), highest concavity peak distance (HCPD), first applanation time (AT1) and velocity (AV1) showed continuous significant differences both after 3 and after 6 months. This study suggests that after central surface ablation surgery, such as myopic PRK, corneal shape is remodeling, and its deformation parameters are going to change even at 6 months follow-up. This indicates that it should be important to evaluate refractive surgery patients during a longer follow-up because this could allow earlier diagnosis and better management of late-onset complications.


2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Juqi Zhang ◽  
Yatao Ren ◽  
Yanmei Yin ◽  
Hong Qi

Abstract Corneal laser surgery is a widely used method for the treatment of ocular myopia, hyperopia, and astigmatism. Although it is a well-established technique, the photothermal properties of the cornea are often overlooked, causing unexpected changes in temperature during laser irradiation. Therefore, there is a need for further investigation of the temperature response of the cornea under laser irradiation. In the present work, a photothermal corneal numerical model is presented, assuming the stratification of the cornea with laser ablation in an uncoagulated layer, a coagulated layer, a dehydrating layer, a dried layer, and a carbonized layer. The modified Pennes' bioheat transfer equation and Lambert-Beer's law are applied to simulate heat transfer in the corneal tissue during laser irradiation. And the corneal dynamic photothermal parameters are considered in the proposed model. The central surface temperature, the boundary and thickness of each layer, and the thermal damage during laser irradiation are investigated. From the model, it was found that in the steady-state process, the thickness of the coagulated layer was 2.6, 14.4, and 52.4 times larger than that of the dehydrating layer, the dried layer, and the carbonized layer, respectively. The thickness of the corneal thermal damage gradually increased, and reached a peak of 0.196 mm at about 18.2 ms. Subsequently, it sharply decreased by 0.01 mm before stabilizing. On this basis, the influence of laser intensity is investigated. The parametric investigation and analysis presented provide a theoretical basis for corneal laser surgery, which can be used to improve our understanding of laser-tissue surgery.


2020 ◽  
Vol 501 (2) ◽  
pp. 1591-1602
Author(s):  
T Parsotan ◽  
R K Cochrane ◽  
C C Hayward ◽  
D Anglés-Alcázar ◽  
R Feldmann ◽  
...  

ABSTRACT The galaxy size–stellar mass and central surface density–stellar mass relationships are fundamental observational constraints on galaxy formation models. However, inferring the physical size of a galaxy from observed stellar emission is non-trivial due to various observational effects, such as the mass-to-light ratio variations that can be caused by non-uniform stellar ages, metallicities, and dust attenuation. Consequently, forward-modelling light-based sizes from simulations is desirable. In this work, we use the skirt  dust radiative transfer code to generate synthetic observations of massive galaxies ($M_{*}\sim 10^{11}\, \rm {M_{\odot }}$ at z = 2, hosted by haloes of mass $M_{\rm {halo}}\sim 10^{12.5}\, \rm {M_{\odot }}$) from high-resolution cosmological zoom-in simulations that form part of the Feedback In Realistic Environments project. The simulations used in this paper include explicit stellar feedback but no active galactic nucleus (AGN) feedback. From each mock observation, we infer the effective radius (Re), as well as the stellar mass surface density within this radius and within $1\, \rm {kpc}$ (Σe and Σ1, respectively). We first investigate how well the intrinsic half-mass radius and stellar mass surface density can be inferred from observables. The majority of predicted sizes and surface densities are within a factor of 2 of the intrinsic values. We then compare our predictions to the observed size–mass relationship and the Σ1−M⋆ and Σe−M⋆ relationships. At z ≳ 2, the simulated massive galaxies are in general agreement with observational scaling relations. At z ≲ 2, they evolve to become too compact but still star forming, in the stellar mass and redshift regime where many of them should be quenched. Our results suggest that some additional source of feedback, such as AGN-driven outflows, is necessary in order to decrease the central densities of the simulated massive galaxies to bring them into agreement with observations at z ≲ 2.


2020 ◽  
Vol 500 (4) ◽  
pp. 4989-5008
Author(s):  
Q Ni ◽  
W N Brandt ◽  
G Yang ◽  
J Leja ◽  
C-T J Chen ◽  
...  

ABSTRACT Recent studies show that a universal relation between black hole (BH) growth and stellar mass (M⋆) or star formation rate (SFR) is an oversimplification of BH–galaxy coevolution, and that morphological and structural properties of host galaxies must also be considered. Particularly, a possible connection between BH growth and host-galaxy compactness was identified among star-forming (SF) galaxies. Utilizing ≈6300 massive galaxies with I814W  <  24 at z < 1.2 in the Cosmic Evolution Survey (COSMOS) field, we perform systematic partial correlation analyses to investigate how sample-averaged BH accretion rate ($\rm \overline{BHAR}$) depends on host-galaxy compactness among SF galaxies, when controlling for morphology and M⋆ (or SFR). The projected central surface mass density within 1 kpc, Σ1, is utilized to represent host-galaxy compactness in our study. We find that the $\rm \overline{BHAR}$–Σ1 relation is stronger than either the $\rm \overline{BHAR}$–M⋆ or $\rm \overline{BHAR}$–SFR relation among SF galaxies, and this $\rm \overline{BHAR}$–Σ1 relation applies to both bulge-dominated galaxies and galaxies that are not dominated by bulges. This $\rm \overline{BHAR}$–Σ1 relation among SF galaxies suggests a link between BH growth and the central gas density of host galaxies on the kpc scale, which may further imply a common origin of the gas in the vicinity of the BH and in the central ∼kpc of the galaxy. This $\rm \overline{BHAR}$–Σ1 relation can also be interpreted as the relation between BH growth and the central velocity dispersion of host galaxies at a given gas content (i.e. gas mass fraction), indicating the role of the host-galaxy potential well in regulating accretion on to the BH.


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