349 research outputs found
THE THERMAL SUNYAEV-ZEL'DOVICH TOMOGRAPHY
No full textThe thermal Sunyaev-Zel'dovich (tSZ) effect directly measures the thermal pressure of free electrons integrated along the line of sight and thus contains valuable information on the thermal history of the universe. However, the redshift information is entangled in the projection along the line of sight. This projection effect severely degrades the power of the tSZ effect to reconstruct the thermal history. We investigate the tSZ tomography technique to recover this otherwise lost redshift information by cross-correlating the tSZ effect with galaxies of known redshifts, or alternatively with matter distribution reconstructed from weak-lensing tomography. We investigate in detail the three-dimensional distribution of the gas thermal pressure and its relation with the matter distribution, through our adiabatic hydrodynamic simulation and the one with additional gastrophysics including radiative cooling, star formation, and supernova feedback. (1) We find a strong correlation between the gas pressure and matter distribution, with a typical cross-correlation coefficient r greater than or similar to 0.7 at k less than or similar to 3 h Mpc(-1) and z < 2. This tight correlation will enable robust cross-correlation measurement between SZ surveys such as Planck, ACT, and SPT and lensing surveys such as DES and LSST, at greater than or similar to 20 sigma-100 sigma level. (2) We propose a tomography technique to convert the measured cross-correlation into the contribution from gas in each redshift bin to the tSZ power spectrum. Uncertainties in gastrophysics may affect the reconstruction at similar to 2% level, due to the similar to 1% impact of gastrophysics on r found in our simulations. However, we find that the same gastrophysics affects the tSZ power spectrum at similar to 40% level, so it is robust to infer the gastrophysics from the reconstructed redshift-resolved contribution
QUENCHING DEPENDS ON MORPHOLOGIES: IMPLICATIONS FROM THE ULTRAVIOLET-OPTICAL RADIAL COLOR DISTRIBUTIONS IN GREEN VALLEY GALAXIES
No full textIn this Letter, we analyze the radial ultraviolet-optical color distributions in a sample of low redshift green valley galaxies, with the Galaxy Evolution Explorer (GALEX)+Sloan Digital Sky Survey (SDSS) images, to investigate how the residual recent star formation is distributed in these galaxies. We find that the dust-corrected u - r colors of early-type galaxies (ETGs) are flat out to R-90, while the colors monotonously turn blue when r > 0.5 R-50 for late-type galaxies (LTGs). More than half of the ETGs are blue-cored and have remarkable positive NUV - r color gradients, suggesting that their star formations are centrally concentrated. The rest have flat color distributions out to R-90. The centrally concentrated star formation activity in a large portion of ETGs is confirmed by the SDSS spectroscopy, showing that similar to 50% of the ETGs have EW(H alpha) > 6.0 angstrom. Of the LTGs, 95% show uniform radial color profiles, which can be interpreted as a red bulge plus an extended blue disk. The links between the two kinds of ETGs, e.g., those objects having remarkable "blue-cores" and those having flat color gradients, are less known and require future investigations. It is suggested that the LTGs follow a general model by which quenching first occurs in the core regions, and then finally extend to the rest of the galaxy. Our results can be re-examined and have important implications for the IFU surveys, such as MaNGA and SAMI
Peculiar velocity decomposition, redshift space distortion and velocity reconstruction in redshift surveys. II. Dark matter velocity statistics
No full textAdaptability and Life Satisfaction: The Moderating Role of Social Support
No full textThe purpose of this study was to investigate the moderating role of social support in the relationship between adaptability and life satisfaction. Data were collected from 99 undergraduate freshmen in a Chinese university using a lagged design with a 1-month interval. Results demonstrated that social support moderated the relation between adaptability and life satisfaction, such that the positive relation between adaptability and life satisfaction was stronger for individuals with higher levels of social support than for individuals with lower levels of social support. The theoretical and practical implications of this result are discussed.National Natural Science Foundation of China [71502086, 71532005][email protected]
Gaussianizing the non-Gaussian lensing convergence field: The performance of the Gaussianization
No full textMotivated by recent works of Neyrinck et al. 2009 and Scherrer et al. 2010, we proposed a Gaussian transformation to Gaussianize the non-Gaussian lensing convergence field kappa. It performs a local monotonic transformation kappa -> y pixel by pixel to make the fine-scale one-point probability distribution function of the new variable y Gaussian. We tested whether the whole y field is Gaussian through N-body simulations. (1) We found that the proposed Gaussianization suppresses the non-Gaussianity by orders of magnitude, in measures of the skewness, the kurtosis, the 5th- and 6th-order cumulants of the y field smoothed over various angular scales, relative to that of the corresponding smoothed kappa field. The residual non-Gaussianities are often consistent with zero within the statistical errors. (2) The Gaussianization significantly suppresses the bispectrum. Furthermore, the residual scatters about zero, depending on the configuration in the Fourier space. (3) The Gaussianization works with even better performance for the 2D fields of the matter density projected over similar to 300h(-1) Mpc distance interval centered at z is an element of (0, 2), which can be reconstructed from the weak lensing tomography. (4) We identified imperfectness and complexities of the proposed Gaussianization. We noticed weak residual non-Gaussianity in the y field. We verified the widely used logarithmic transformation as a good approximation to the Gaussian transformation. However, we also found noticeable deviations
Gaussianizing the non-Gaussian lensing convergence field II. The applicability to noisy data
No full textIn paper I (Yu et al. [1]), we showed through N-body simulation that a local monotonic Gaussian transformation can significantly reduce non-Gaussianity in a noise-free lensing convergence field. This makes the Gaussianization a promising theoretical tool to understand high-order lensing statistics. Here we present a study of its applicability in lensing data analysis, in particular when shape measurement noise is presented in lensing convergence maps. (i) We find that shape measurement noise significantly degrades the Gaussianization performance and the degradation increases for shallower surveys. (ii) The Wiener filter is efficient in reducing the impact of shape measurement noise. The Gaussianization of the Wiener-filtered lensing maps is able to suppress skewness, kurtosis, and the 5th- and 6th-order cumulants by a factor of 10 or more. It also works efficiently to reduce the bispectrum to zero
Discovering Chinese economic history from footnotes : the living tale of a private merchant archive (1800-1850)
No full textThis article recounts our unique encounter –through the last seven years of our
research - with the Tong Taisheng (统泰升) merchant account books in the Ninjing county of
Northern China in 1800-1850. By tracing the personal history of the original owner or donor,
we address a large historiographical and epistemological issue behind the current Great
Divergence debate on why Industrial Revolution occurred in England but not in China. Our
article showcases how the development of political ideology and academic discipline in the
modern era impacts our understanding of historical statistics and realities of the early modern
era, a critical issue largely neglected in the current Great Divergence debate
Wording effects and the dimensionality of the General Health Questionnaire (GHQ-12)
No full textThere has been a debate about the structure of the 12-item General Health Questionnaire (GHQ-12). While some researchers believe it taps two or three dimensions, others think its multidimensionality is merely an artifact of wording effects. To directly test these competing views, we had 855 Chinese employees take one of three versions of the GHQ-12: either the original version, which is comprised of six positively worded and six negatively worded items; or one of two alternative versions that are comprised of 12 positively worded or 12 negatively worded items. Analyses indicated that the GHQ-12 had a unidimensional factor structure after controlling wording effects. The substantive meaning of the factor analysis results is further discussed based on their correlations with a string of personality and organization behavior variables. (C) 2011 Elsevier Ltd. All rights reserved.Psychology, SocialSSCI6ARTICLE7,SI1056-10615
BULK FLOW OF HALOS IN Lambda CDM SIMULATION
No full textAnalysis of the Pangu N-body simulation validates that the bulk flow of halos follows a Maxwellian distribution with variance that is consistent with the prediction of the linear theory of structure formation. We propose that the consistency between the observed bulk velocity and theories should be examined at the effective scale of the radius of a spherical top-hat window function yielding the same smoothed velocity variance in linear theory as the sample window function does. We compared some recently estimated bulk flows from observational samples with the prediction of the Lambda CDM model we used; some results deviate from expectation at a level of similar to 3 sigma, but the discrepancy is not as severe as previously claimed. We show that bulk flow is only weakly correlated with the dipole of the internal mass distribution, that the alignment angle between the mass dipole and the bulk flow has a broad distribution peaked at similar to 30 degrees-50 degrees, and also that the bulk flow shows little dependence on the mass of the halos used in the estimation. In a simulation of box size 1 h(-1) Gpc, for a cell of radius 100 h(-1) Mpc the maximal bulk velocity is >500 km s(-1); dipoles of the environmental mass outside the cell are not tightly aligned with the bulk flow, but are rather located randomly around it with separation angles similar to 20 degrees-40 degrees. In the fastest cell there is a slightly smaller number of low-mass halos; however, halos inside are clustered more strongly at scales greater than or similar to 20 h(-1) Mpc, which might be a significant feature since the correlation between bulk flow and halo clustering actually increases in significance beyond such scales
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