Simulating the evolution of the local universe is important for studying galaxies and the intergalactic medium in a way free of cosmic variance. Here we present a method to reconstruct the initial ...linear density field from an input nonlinear density field, employing the Hamiltonian Markov Chain Monte Carlo (HMC) algorithm combined with Particle-mesh (PM) dynamics. The HMC+PM method is applied to cosmological simulations, and the reconstructed linear density fields are then evolved to the present day with iV-body simulations. These constrained simulations accurately reproduce both the amplitudes and phases of the input simulations at various z. Using a PM model with a grid cell size of 0.75 h super(-1) Mpc and 40 time steps in the HMC can recover more than half of the phase information down to a scale k ~ 0.85 h Mpc super(-1) at high z and to k ~ 3.4 h Mpc super(-1) at z = 0, which represents a significant improvement over similar reconstruction models in the literature, and indicates that our model can reconstruct the formation histories of cosmic structures over a large dynamical range. Adopting PM models with higher spatial and temporal resolutions yields even better reconstructions, suggesting that our method is limited more by the availability of computer resource than by principle. Dynamic models of structure evolution adopted in many earlier investigations can induce non-Gaussianity in the reconstructed linear density field, which in turn can cause large systematic deviations in the predicted halo mass function. Such deviations are greatly reduced or absent in our reconstruction.
Abstract
We present a new H
i
mass estimator that relates
log
10
(
M
HI
/
M
*
) to a linear combination of four galaxy properties: stellar surface mass density, color index
u
−
r
, stellar mass, and ...concentration index, with the scatter of individual galaxies around the mean H
i
mass modeled with a Gaussian distribution function. We calibrate the estimator using the xGASS sample, including both H
i
detection and nondetection, and constrain the model parameters through Bayesian inferences. Tests with mock catalogs demonstrate that our estimator provides unbiased H
i
masses for optical samples like SDSS. We apply our estimator to the SDSS spectroscopic sample to estimate the H
i
mass function (HIMF) of local galaxies, as well as the conditional H
i
mass function in galaxy groups and the H
i
–halo mass relation. Our HIMF agrees with the ALFALFA measurements at
M
HI
≳ 5 × 10
9
M
⊙
, but with higher amplitude and a steeper slope at lower masses. We show that this discrepancy is caused primarily by the cosmic variance, which is corrected for the SDSS sample but not for ALFALFA. The total CHIMFs for all halo masses can be described by a single Schechter function, while those of central galaxies show a double-Gaussian profile. The total H
i
mass in a group increases monotonically with halo mass, but for central galaxies, the H
i
mass shows weak dependence on halo mass when
M
h
≳ 10
12
M
☉
. The observed H
i
–halo mass relation is not reproduced by current hydrodynamic simulations and semianalytic models of galaxy formation.
•We proposed an electromagnetic incremental forming (EMIF) method.•Simulation the electromagnetic incremental forming process by remeshing the air meshes.•The simulation method considers the effect ...of the workpiece deformation and movement of coil on magnetic analysis.•Two consecutive discharges in a fixed position are needed to produce large parts using EMIF technology.•There exists suitable overlap ratio in two adjacent discharge regions, which corresponds to best forming quality.
Large parts cannot be shaped by conventional electromagnetic forming method due to the limitation of the strength of working coil and the capacity of capacitor bank. In this paper, based on the principle of single point incremental forming, a new method named electromagnetic incremental forming (EMIF) has been proposed. The method makes use of a small coil and small discharge energy to cause workpiece local deformation in a high speed. Finally, all local deformations accumulate into large parts. For the electromagnetic incremental sheet forming, the effect factors of processing parameters namely discharge voltage, vent hole, discharging times in a fixed position and the number of discharge region, on final sheet shape are investigated by using AA3003 aluminum alloy parts. In addition, two different simulation strategies are proposed to predict electromagnetic incremental sheet and tube forming process. For method 1: the technology like “birth–death element” is used to indirectly describe the movement of the coil and the morphing technology is used to make the air change with the workpiece deformation. For method 2: the coil can directly move to a special position and the remesh technology is used to consider the effect of the workpiece deformation and the movement of coil on magnetic analysis. It is found that method 1 cannot be used for electromagnetic incremental sheet forming process if overlap region exists in two adjacent discharge regions. However, method 1 can successfully predict electromagnetic incremental tube forming. And method 2 can be used for electromagnetic incremental sheet or tube forming. Both of the experimental and simulation results demonstrate that this new technology is feasible to produce large part.
We extend the real-space mapping method developed in Shi et al. so that it can be applied to flux-limited galaxy samples. We use an ensemble of mock catalogs to demonstrate the reliability of this ...extension, showing that it allows for an accurate recovery of the real-space correlation functions and galaxy biases. We also demonstrate that, using an iterative method applied to intermediate-scale clustering data, we can obtain an unbiased estimate of the growth rate of structure , which is related to the clustering amplitude of matter, to an accuracy of ∼10%. Applying this method to the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), we construct a real-space galaxy catalog spanning the redshift range 0.01 ≤ z ≤ 0.2, which contains 584,473 galaxies in the northern Galactic cap. Using these data, we infer at a median redshift z = 0.1, which is consistent with the WMAP9 cosmology at the 1 level. By combining this measurement with the real-space clustering of galaxies and with galaxy-galaxy weak lensing measurements for the same sets of galaxies, we are able to break the degeneracy between f, 8, and b. From the SDSS DR7 data alone, we obtain the following cosmological constraints at redshift z = 0.1: f = , 8 = , and b = , , , and for galaxies within different absolute magnitude bins , −22, 0, −21.0, −21.0, −20.0, and −20.0, −19.0, respectively.
Abstract
We perform full spectrum fitting stellar population analysis and Jeans Anisotropic modelling of the stellar kinematics for about 2000 early-type galaxies (ETGs) and spiral galaxies from the ...MaNGA DR14 sample. Galaxies with different morphologies are found to be located on a remarkably tight mass plane which is close to the prediction of the virial theorem, extending previous results for ETGs. By examining an inclined projection (‘the mass–size’ plane), we find that spiral and early-type galaxies occupy different regions on the plane, and their stellar population properties (i.e. age, metallicity, and stellar mass-to-light ratio) vary systematically along roughly the direction of velocity dispersion, which is a proxy for the bulge fraction. Galaxies with higher velocity dispersions have typically older ages, larger stellar mass-to-light ratios and are more metal rich, which indicates that galaxies increase their bulge fractions as their stellar populations age and become enriched chemically. The age and stellar mass-to-light ratio gradients for low-mass galaxies in our sample tend to be positive (centre < outer), while the gradients for most massive galaxies are negative. The metallicity gradients show a clear peak around velocity dispersion log10 σe ≈ 2.0, which corresponds to the critical mass ∼3 × 1010 M⊙ of the break in the mass–size relation. Spiral galaxies with large mass and size have the steepest gradients, while the most massive ETGs, especially above the critical mass Mcrit ≳ 2 × 1011 M⊙, where slow rotator ETGs start dominating, have much flatter gradients. This may be due to differences in their evolution histories, e.g. mergers.
ABSTRACT
We propose an efficient and robust method to estimate the halo concentration based on the first moment of the density distribution, which is $R_1\equiv \int _0^{r_{\rm vir}}4\pi r^3\rho ...(r)\mathrm{ d}r/M_{\rm vir}/r_{\rm vir}$. We find that R1 has a monotonic relation with the concentration parameter of the Navarro–Frenk–White (NFW) profile, and that a cubic polynomial function can fit the relation with an error $\lesssim 3~{{\ \rm per\ cent}}$. Tests on ideal NFW haloes show that the conventional NFW profile fitting method and the Vmax/Vvir method produce biased halo concentration estimation by $\approx 10~{{\ \rm per\ cent}}$ and $\approx 30~{{\ \rm per\ cent}}$, respectively, for haloes with 100 particles. In contrast, the systematic error for our R1 method is smaller than 0.5 per cent even for haloes containing only 100 particles. Convergence tests on realistic haloes in N-body simulations show that the NFW profile fitting method underestimates the concentration parameter for haloes with ≲300 particles by $\gtrsim 20~{{\ \rm per\ cent}}$, while the error for the R1 method is $\lesssim 8~{{\ \rm per\ cent}}$. We also show other applications of R1, including estimating Vmax and the Einasto concentration ce ≡ rvir/r−2. The calculation of R1 is efficient and robust, and we recommend including it as one of the halo properties in halo catalogues of cosmological simulations.
The kinematics of satellite galaxies reflect the masses of the extended dark matter haloes in which they orbit, and thus shed light on the mass–luminosity relation (MLR) of their corresponding ...central galaxies. In this paper, we select a large sample of centrals and satellites from the Sloan Digital Sky Survey and measure the kinematics (velocity dispersions) of the satellite galaxies as a function of the r-band luminosity of the central galaxies. Using the analytical framework presented in More, van den Bosch & Cacciato, we use these data to infer both the mean and the scatter of the MLR of central galaxies, carefully taking account of selection effects and biases introduced by the stacking procedure. As expected, brighter centrals on average reside in more massive haloes. In addition, we find that the scatter in halo masses for centrals of a given luminosity, σlog M, also increases with increasing luminosity. As we demonstrate, this is consistent with σlog L, which reflects the scatter in the conditional probability function P(Lc|M), being independent of halo mass. Our analysis of the satellite kinematics yields σlog L= 0.16 ± 0.04, in excellent agreement with constraints from clustering and group catalogues, and with predictions from a semi-analytical model of galaxy formation. We thus conclude that the amount of stochasticity in galaxy formation, which is characterized by σlog L, is well constrained, independent of halo mass and in a good agreement with current models of galaxy formation.
Primary cutaneous γδ T cell lymphomas (PCGDTLs) represent a heterogeneous group of uncommon but aggressive cancers. Herein, we perform genome-wide DNA, RNA, and T cell receptor (TCR) sequencing on 29 ...cutaneous γδ lymphomas. We find that PCGDTLs are not uniformly derived from Vδ2 cells. Instead, the cell-of-origin depends on the tissue compartment from which the lymphomas are derived. Lymphomas arising from the outer layer of skin are derived from Vδ1 cells, the predominant γδ cell in the epidermis and dermis. In contrast, panniculitic lymphomas arise from Vδ2 cells, the predominant γδ T cell in the fat. We also show that TCR chain usage is non-random, suggesting common antigens for Vδ1 and Vδ2 lymphomas respectively. In addition, Vδ1 and Vδ2 PCGDTLs harbor similar genomic landscapes with potentially targetable oncogenic mutations in the JAK/STAT, MAPK, MYC, and chromatin modification pathways. Collectively, these findings suggest a paradigm for classifying, staging, and treating these diseases.
The zinc (Zn) diffusion effects on metal–organic chemical vapor deposition grown flexible inverted metamorphic (IMM) GaInP/GaAs/InGaAs triple junction solar cell performance have been investigated. ...By studying electrical and spectral properties of solar cells with different configuration, it was found out that the Zn diffusion from GaAs middle cell AlGaAs:Zn back surface field (BSF) layer into AlGaAs/GaAs tunnel junction is the main reason for I–V curve inflection and low fill factor. Besides, the thermal annealing effects caused by the long epitaxial growth time also has significant effect on Zn diffusion and degrades the overall cell performance. These adverse effects caused by Zn diffusion was suppressed by replacing Zn with carbon as the p-type dopant source in BSF layer, and the thermal annealing effects was solved by fine tuning InGaAs bottom subcell base layer thickness. A large area, 4 × 2 cm2, flexible IMM GaInP/GaAs/InGaAs triple junction solar cell with 34.52% efficiency under AM 1.5D solar spectrum has been successfully fabricated.
•Zinc diffusion effects on GaInP/GaAs/InGaAs solar cell have been investigated.•Zn diffusion into tunnel junction is the reason for I–V curve inflection and low FF.•Prolonged epitaxial growth time enhances the Zn diffusion effect.•Zn diffusion effects was suppressed by using carbon as the p-type dopant source.•Cell efficiency increased by adjusting InGaAs bottom subcell base layer thickness.
Abstract
A clear transition feature of galaxy quenching is identified in the multi-parameter space of stellar mass (
M
*
), bulge-to-total mass ratio (
B
/
T
m
), halo mass (
M
h
) and halo-centric ...distance (
r
/
r
180
). For a given halo mass, the characteristic stellar mass (
) for the transition is about one-fifth of that of the corresponding central galaxy, and almost independent of
B
/
T
m
. Once
B
/
T
m
is fixed, the quenched fraction of galaxies with
increases with
M
h
, but decreases with
M
*
in the inner part of halos (
r
/
r
180
< 0.5). In the outer part (
r
/
r
180
> 0.5), the trend with
M
h
remains but the correlation with
M
*
is absent or becomes positive. For galaxies above
and with
B
/
T
m
fixed, the quenched fraction increases with
, but depends only weakly on
M
h
in both the inner and outer regions. At fixed
B
/
T
m
and
M
*
, the quenched fraction increases with decreasing
r
/
r
180
for galaxies with
, and depends only weakly on
r
/
r
180
for galaxies with
. Our finding provides a physically motivated way to classify galaxies in halos into two classes based on their quenching properties: an “upper class” with
and a “lower class” with
. Environmental quenching is important for “lower class” galaxies, while internal quenching plays the dominating role for the “upper class.”
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