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Changing-Look AGN (CL-AGN) are AGN which transition between Seyfert types, challenging AGN unification models. Most CL-AGN have been identified via repeat spectroscopy, making it difficult to determine the duration and magnitude of the…

We present a determination of the optical/UV AGN luminosity function and its evolution, based on a large sample of faint (R<24) QSOs identified in the COMBO-17 survey. Using multi-band photometry in 17 filters within 350nm < lambda_obs <…

Astrophysics · Physics 2010-04-06 C. Wolf , L. Wisotzki , A. Borch , S. Dye , M. Kleinheinrich , K. Meisenheimer

Point cloud segmentation is the foundation of 3D environmental perception for modern intelligent systems. To solve this problem and image segmentation, conditional random fields (CRFs) are usually formulated as discrete models in label…

Computer Vision and Pattern Recognition · Computer Science 2021-10-13 Fei Yang , Franck Davoine , Huan Wang , Zhong Jin

A key feature of active galactic nuclei (AGN) is their variability across all wavelengths. Typically, AGN vary by a few tenths of a magnitude or more over periods lasting from hours to years. By contrast, extreme variability of AGN -- large…

High Energy Astrophysical Phenomena · Physics 2024-03-12 Summer A. J. McLaughlin , James R. Mullaney , Stuart P. Littlefair

Personalized recommendation is widely used in the web applications, and graph contrastive learning (GCL) has gradually become a dominant approach in recommender systems, primarily due to its ability to extract self-supervised signals from…

Information Retrieval · Computer Science 2025-04-15 Yu Zhang , Yiwen Zhang , Yi Zhang , Lei Sang , Yun Yang

Point cloud classification plays an important role in a wide range of airborne light detection and ranging (LiDAR) applications, such as topographic mapping, forest monitoring, power line detection, and road detection. However, due to the…

Computer Vision and Pattern Recognition · Computer Science 2020-04-21 Congcong Wen , Lina Yang , Ling Peng , Xiang Li , Tianhe Chi

Discriminant Correlation Filters (DCF) based methods now become a kind of dominant approach to online object tracking. The features used in these methods, however, are either based on hand-crafted features like HoGs, or convolutional…

Computer Vision and Pattern Recognition · Computer Science 2017-04-14 Qiang Wang , Jin Gao , Junliang Xing , Mengdan Zhang , Weiming Hu

We construct the rest-frame 2--10 keV intrinsic X-ray luminosity function of Active Galactic Nuclei (AGNs) from a combination of X-ray surveys from the all-sky Swift BAT survey to the Chandra Deep Field-South. We use ~3200 AGNs in our…

We present detection and analysis of faint X-ray sources in the Chandra deep field south (CDFS) using the 4 Msec Chandra observation and adopting a new detection algorithm, based on a targeted search at the position of known high-z…

We present the accretion disk size estimates for a sample of 19 active galactic nuclei (AGN) using the optical $g$, $r$, and $i$ band light curves obtained from the Zwicky Transient Facility (ZTF) survey. All the AGN have reliable…

Astrophysics of Galaxies · Physics 2022-01-14 Vivek Kumar Jha , Ravi Joshi , Hum Chand , Xue-Bing Wu , Luis C. Ho , Shantanu Rastogi , Qinchun Ma

We conduct an analysis of over 60,000 dwarf galaxies (7<=log(M_*/M_\odot)<=10) in search of photometric variability indicative of active galactic nuclei (AGNs). Using data from the Young Supernova Experiment (YSE), a time domain survey on…

Motivated by upcoming photometric and spectroscopic surveys (Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), Manuakea Spectroscopic Explorer), we design the statistical proxies to measure the cadence effects on active…

Measuring time lags between time-series or lighcurves at different wavelengths from a variable or transient source in astronomy is an essential probe of physical mechanisms causing multiwavelength variability. Time-lags are typically…

Instrumentation and Methods for Astrophysics · Physics 2021-06-17 Nachiketa Chakraborty , Peter Jan van Leeuwen

The study of morphology in galaxies offers a convenient and quantitative method to measure the shapes and characteristics of galaxy light distribution that reflect the evolutionary history. For AGN-host dwarf galaxies, however, there is a…

Astrophysics of Galaxies · Physics 2025-06-09 Jie Tian , Yinghe Zhao , Xiejin Li , Jinming Bai

Rotational modulation of stellar light curves due to dark spots encloses information on spot properties and, thus, on magnetic activity. In particular, the decay of the autocorrelation function (ACF) of light curves is presumed to be linked…

Solar and Stellar Astrophysics · Physics 2021-08-20 A. R. G. Santos , S. Mathur , R. A. García , M. S. Cunha , P. P. Avelino

We test the consistency of active galactic nuclei (AGN) optical flux variability with the $\textit{damped random walk}$ (DRW) model. Our sample consists of 20 multi-quarter $\textit{Kepler}$ AGN light curves including both Type 1 and 2…

Astrophysics of Galaxies · Physics 2015-07-03 Vishal P. Kasliwal , Michael S. Vogeley , Gordon T. Richards

Discriminative correlation filters (DCF) and siamese networks have achieved promising performance on visual tracking tasks thanks to their superior computational efficiency and reliable similarity metric learning, respectively. However, how…

Computer Vision and Pattern Recognition · Computer Science 2021-03-22 Xizhe Xue , Ying Li , Xiaoyue Yin , Qiang Shen

We present a weak lensing analysis of the X-ray luminous cluster CL 0152-1357 at z~0.84 using HST/ACS observations. The unparalleled resolution and sensitivity of ACS enable us to measure weakly distorted, faint background galaxies to the…

We present a new method of discovering galaxy-scale, strongly-lensed QSO systems from unresolved light curves using the autocorrelation function. The method is tested on five rungs of simulated light curves from the Time Delay Challenge 1…

Instrumentation and Methods for Astrophysics · Physics 2021-03-10 Yiping Shu , Vasily Belokurov , N. Wyn Evans

In this paper, a novel and robust algorithm is proposed for adaptive beamforming based on the idea of reconstructing the autocorrelation sequence (ACS) of a random process from a set of measured data. This is obtained from the first column…

Information Theory · Computer Science 2021-06-25 Saeed Mohammadzadeh , Vitor H. Nascimento , Rodrigo C. de Lamare , Osman Kukrer