499 research outputs found
Mass Dependence of Galaxy-Halo Alignment in LOWZ and CMASS
We measure the galaxy-ellipticity (GI) correlations for the Slogan Digital
Sky Survey DR12 LOWZ and CMASS samples with the shape measurements from the
DESI Legacy Imaging Surveys. We model the GI correlations in an N-body
simulation with our recent accurate stellar-halo mass relation from the
Photometric object Around Cosmic webs (PAC) method. The large data set and our
accurate modeling turns out an accurate measurement of the alignment angle
between central galaxies and their host halos. We find that the alignment of
central {\textit {elliptical}} galaxies with their host halos increases
monotonically with galaxy stellar mass or host halo mass, which can be well
described by a power law for the massive galaxies. We also find that central
elliptical galaxies are more aligned with their host halos in LOWZ than in
CMASS, which might indicate an evolution of galaxy-halo alignment, though
future studies are needed to verify this is not induced by the sample
selections. In contrast, central {\textit {disk}} galaxies are aligned with
their host halos about 10 times more weakly in the GI correlation. These
results have important implications for intrinsic alignment (IA) correction in
weak lensing studies, IA cosmology, and theory of massive galaxy formation.Comment: 9 pages, 4 figures. Accepted for publication in Ap
Structural analysis and evolutionary exploration based on the research topic network of a field: a case in high-frequency trading
This study aims to systematically analyze the distribution dynamics of research topics and uncover the development state of the research in the specific field, which will provide a practical reference for developing professional subject knowledge services in the era of big data. The research topic network is constructed and analyzed using methods and tools of scientometrics. Basic statistics on network characteristics are performed to reveal the research status. Community detection, node ordering, and other steps are conducted to generate the evolutionary alluvial diagram. Then, relevant results are analyzed to explore the knowledge structure of the specific field and evolutionary context of research topics. Visualization analysis on the network structure of the latest period is executed to distinguish related concepts and predict the research trends. Taking high-frequency trading (HFT) as a case, this study achieves diversified scientometrics analysis of the research topic network and multi-dimensional evolution exploration of the relevant research topics in the specific field, which obtaining some knowledge insights. (1) Six major topics in HFT: liquidity & market microstructure, market efficiency, financial market, incomplete market, cointegration & price discovery, and event study. (2) The research focus about markets gradually transferred from international to emerging, meanwhile continuous attention to volatility/risk related issues. (3) The emphasis will change from theory to practice, technologies (big data, etc.) and theories (behavioral finance, etc.) will have more interaction with HFT. An effective research idea is proposed to reveal the knowledge structure of field and analyze the evolutionary context of research topics, which demonstrating the knowledge insights
Links Assignment Scheme based on Potential Edges Importance in Dual-layer Wavelength Routing Optical Satellite Networks
With the development of the massive satellite constellation and the on-orbit
laser-based communication equipment, the wavelength routing optical satellite
network (WROSN) becomes a potential solution for on-orbit, high-capacity, and
high-speed communication. Since the inter-satellite links (ISLs) are
time-varying, one of the fundamental considerations in the construction of the
WROSN is assigning limited laser communication terminals for each satellite to
establish ISLs with the visible satellites. Therefore, we propose a links
assignment scheme (LAS) based on the potential edges importance matrix (PEIM)
algorithm to construct a temporarily stable topology of the ISLs for a
dual-layer constellation. The simulation results showed that the LAS based on
the PEIM algorithm is better than LAS based on the random or Greedy algorithm
in terms of node-to-node distance, node pair connectivity, wavelength demand,
and transmission delay. The node pair connectivity and wavelength demand in
WROSN is a trade-off problem. The research in this paper also brings a novel
method for reduction of the cost of the on-board resources, that is through
designing topology of the ISLs with links assignment algorithm.Comment: This is the manuscript version that was submitted to the
International Journal of Satellite Communications and Networking
(SAT-23-0018
Photometric Objects Around Cosmic Webs (PAC) Delineated in a Spectroscopic Survey. IV. High Precision Constraints on the Evolution of Stellar-Halo Mass Relation at Redshift
Taking advantage of the Photometric objects Around Cosmic webs (PAC) method
developed in Paper I, we measure the excess surface density
of photometric objects around spectroscopic objects
down to stellar mass , and
in the redshift ranges of , and
respectively, using the data from the DESI Legacy Imaging Surveys
and the spectroscopic samples of Slogan Digital Sky Survey (i.e. Main, LOWZ and
CMASS samples). We model the measured in N-body
simulation using abundance matching method and constrain the stellar-halo mass
relations (SHMR) in the three redshift ranges to percent level. With the
accurate modeling, we demonstrate that the stellar mass scatter for given halo
mass is nearly a constant, and that the empirical form of Behroozi et al
describes the SHMR better than the double power law form at low mass. Our SHMR
accurately captures the downsizing of massive galaxies since , while
it also indicates that small galaxies are still growing faster than their host
halos. The galaxy stellar mass functions (GSMF) from our modeling are in
perfect agreement with the {\it model-independent} measurements in Paper III,
though the current work extends the GSMF to a much smaller stellar mass. Based
on the GSMF and SHMR, we derive the stellar mass completeness and halo
occupation distributions for the LOWZ and CMASS samples, which are useful for
correctly interpreting their cosmological measurements such as galaxy-galaxy
lensing and redshift space distortion.Comment: 18 + 9 (appendix) pages, 12 + 7 (appendix) figures. Main results in
Figure 6-9. Submitted to ApJ. arXiv admin note: text overlap with
arXiv:2207.1242
- …