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The information content of the autocorrelation function (ACF) of intensity fluctuations of the X-ray background (XRB) is analyzed. The tight upper limits set by ROSAT deep survey data on the ACF at arcmin scales imply strong constraints on…

天体物理学 · 物理学 2009-10-22 L. Danese , L. Toffolatti , A. Franceschini , J. M. Martin-Mirones , G. De Zotti

Almost all massive galaxies today are understood to contain supermassive black holes (SMBH) at their centers. SMBHs grew by accreting material from their surroundings, emitting X-rays as they did so. X-ray Luminosity Functions (XLFs) of…

星系天体物理 · 物理学 2023-01-16 Ahlam Alqasim , Mat J. Page

In an effort to search for faint sources of emission over arbitrary timescales, we present a novel method for analyzing forced photometry light curves in difference imaging from optical surveys. Our method "ATLAS Clean'' or ATClean,…

We employ the Chandra Multiwavelength Project (ChaMP) and the Sloan Digital Sky Survey (SDSS) to study the fraction of X-ray-active galaxies in the field out to z = 0.7. We utilize spectroscopic redshifts from SDSS and ChaMP, as well as…

高能天体物理现象 · 物理学 2015-05-18 Daryl Haggard , Paul J. Green , Scott F. Anderson , Anca Constantin , Tom L. Aldcroft , Dong-Woo Kim , Wayne A. Barkhouse

Fluorescence correlation and cross-correlation spectroscopy (FCS, FCCS) are widely used techniques to study the diffusion properties and interactions of fluorescent molecules. Autocorrelation (ACFs) and cross-correlation functions (CCFs)…

Structure and dynamics at soft-matter interfaces play an important role in nature and technical applications. Optical single-molecule investigations are non-invasive and capable to reveal heterogeneities at the nanoscale. In this work we…

Collaborative filtering methods based on graph neural networks (GNNs) have witnessed significant success in recommender systems (RS), capitalizing on their ability to capture collaborative signals within intricate user-item relationships…

信息检索 · 计算机科学 2024-04-16 Wei Wu , Chao Wang , Dazhong Shen , Chuan Qin , Liyi Chen , Hui Xiong

It is important to quantify the underestimation of rms photometric errors returned by the commonly used $\emph APPHOT$ algorithm in the $\emph IRAF$ software, in the context of differential photometry of point-like AGN, because of the…

宇宙学与河外天体物理 · 物理学 2015-06-16 Arti Goyal , Mukul Mhaskey , Gopal-Krishna , Paul J. Wiita , C. S. Stalin , Ram Sagar

Based on the analysis of a small sample of BATSE and Konus gamma-ray bursts (GRBs) with know redshift it has been reported that the width of the autocorrelation function (ACF) shows a remarkable bimodal distribution in the rest-frame of the…

天体物理学 · 物理学 2008-11-26 L. Borgonovo , F. Frontera , C. Guidorzi , E. Montanari , L. Vetere , P. Soffitta

We investigate the evolution of the 0.5-2 keV soft X-ray luminosity function (SXLF) of active galactic nuclei (AGN) using results from ROSAT surveys of various depth, ranging from shallow large-area ROSAT All-Sky Survey -based samples to…

天体物理学 · 物理学 2007-05-23 Takamitsu Miyaji , Guenther Hasinger , Maarten Schmidt

In deep X-ray surveys, active galactic nuclei (AGNs) with a broad range of luminosities have been identified. However, cosmologically distant low-luminosity AGN (LLAGN, $L_{\mathrm{X}} \lesssim 10^{42}$ erg s$^{-1}$) identification still…

Fluorescence Correlation Spectroscopy (FCS) yields measurement parameters (number of molecules, diffusion time) that characterize the concentration and kinetics of fluorescent molecules within a supposedly known observation volume. Absolute…

生物物理 · 物理学 2011-12-23 Charles Edouard Leroux , Irène Wang , Jacques Derouard , Antoine Delon

Many synoptic surveys are observing large parts of the sky multiple times. The resulting lightcurves provide a wonderful window to the dynamic nature of the universe. However, there are many significant challenges in analyzing these light…

应用统计 · 统计学 2016-02-04 Julian Faraway , Ashish Mahabal , Jiayang Sun , Xiaofeng Wang , Yi , Wang , Lingsong Zhang

Deep learning-based change detection (CD) using remote sensing images has received increasing attention in recent years. However, how to effectively extract and fuse the deep features of bi-temporal images for improving the accuracy of CD…

计算机视觉与模式识别 · 计算机科学 2024-01-18 Yuanxin Ye , Mengmeng Wang , Liang Zhou , Guangyang Lei , Jianwei Fan , Yao Qin

The variability of active galactic nuclei (AGN) has long held the promise of shedding light on their detailed structure, and possibly other astrophysical phenonema. Different emission mechanisms lead to different patterns of variability in…

天体物理学 · 物理学 2009-11-07 M. R. S. Hawkins

Robust velocity and position estimation is crucial for autonomous robot navigation. The optical flow based methods for autonomous navigation have been receiving increasing attentions in tandem with the development of micro unmanned aerial…

机器人学 · 计算机科学 2018-12-06 Chen Wang , Tete Ji , Thien-Minh Nguyen , Lihua Xie

The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify…

宇宙学与河外天体物理 · 物理学 2015-06-03 M. Young , W. N. Brandt , Y. Q. Xue , M. Paolillo , D. M. Alexander , F. E. Bauer , B. D. Lehmer , B. Luo , O. Shemmer , D. P. Schneider , C. Vignali

In this paper, standard accretion disk models of AGNs are tested using light curves of 26 objects well observed for reverberation mapping. Time scales of variations are estimated by the most common definition of the variability time scale…

天体物理学 · 物理学 2014-01-10 H. T. Liu , J. M. Bai , X. H. Zhao , L. Ma

Continuum and emission-line variability of active galactic nuclei provides a powerful probe of microarcsecond scale structures in the central regions of these sources. In this contribution, we review basic concepts and methodologies used in…

天体物理学 · 物理学 2016-11-03 Bradley M. Peterson

Amorphous graphene or amorphous monolayer carbon (AMC) is a family of carbon films that exhibit a surprising sensitivity of electronic conductance to morphology. We combine deep learning-enhanced simulation techniques with percolation…

介观与纳米尺度物理 · 物理学 2025-04-30 Nicolas Gastellu , Ata Madanchi , Lena Simine