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Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have been found in a few individual AGN…

Astrophysics of Galaxies · Physics 2025-07-08 Zhen-Bo Su , Zhen-Yi Cai , Hengxiao Guo , Mouyuan Sun , Jun-Xian Wang

Graph convolutional networks (GCNs) have recently enabled a popular class of algorithms for collaborative filtering (CF). Nevertheless, the theoretical underpinnings of their empirical successes remain elusive. In this paper, we endeavor to…

Information Retrieval · Computer Science 2021-08-18 Yifei Shen , Yongji Wu , Yao Zhang , Caihua Shan , Jun Zhang , Khaled B. Letaief , Dongsheng Li

Correlation filters are special classifiers designed for shift-invariant object recognition, which are robust to pattern distortions. The recent literature shows that combining a set of sub-filters trained based on a single or a small group…

Computer Vision and Pattern Recognition · Computer Science 2018-02-14 Baochang Zhang , Shangzhen Luan , Chen Chen , Jungong Han , Wei Wang , Alessandro Perina , Ling Shao

The damped random walk (DRW) process is one of the most commonly used and simplest stochastic models to describe variability of active galactic nuclei (AGN). An AGN light curve can be converted to just two DRW model parameters - the signal…

Astrophysics of Galaxies · Physics 2021-09-10 Szymon Kozłowski

We perform a systematic survey of active galactic nucleus (AGN) continuum lags using $\sim$3 day cadence $gri$-band light curves from the Zwicky Transient Facility. We select a sample of 94 type 1 AGN at $z<0.8$ with significant and…

Astrophysics of Galaxies · Physics 2022-11-30 Hengxiao Guo , Aaron J. Barth , Shu Wang

Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power…

Astrophysics of Galaxies · Physics 2016-05-04 Szymon Kozlowski

A new method for measuring the shear induced by gravitational light deflection is proposed. It is based on analyzing the anisotropy induced in the auto-correlation function (ACF) of the extragalactic background light which is produced by…

Astrophysics · Physics 2007-05-23 L. Van Waerbeke , Y. Mellier , P. Schneider , B. Fort , G. Mathez

Tilt-corrected imaging methods in four-dimensional scanning transmission electron microscopy (4D-STEM) have recently emerged as a new class of direct ptychography methods that are especially useful at low dose. The operation of tilt…

Optics · Physics 2025-10-03 Desheng Ma , David A Muller , Steven E Zeltmann

Modern X-ray telescopes have detected hundreds of thousands of X-ray sources in the universe. However, current methods to classify these sources using the X-ray data themselves suffer problems - detailed X-ray spectroscopy of individual…

High Energy Astrophysical Phenomena · Physics 2023-04-04 Pavan R. Hebbar , Craig O. Heinke

For measurement of the AGN luminosity function and its evolution, X-ray selection samples all types of AGN and provides reduced obscuration bias in comparison with UV-excess or optical surveys. The apparent decline in optically-selected…

Vast amounts of astronomical photometric data are generated from various projects, requiring significant effort to identify variable stars and other object classes. In light of this, a general, widely applicable classification framework…

Instrumentation and Methods for Astrophysics · Physics 2024-09-23 Kaiming Cui , D. J. Armstrong , Fabo Feng

Extended dark matter (DM) substructures may play the role of microlenses in the Milky Way and in extragalactic gravitational lens systems (GLSs). We compare microlensing effects caused by point masses (Schwarzschild lenses) and extended…

Astrophysics of Galaxies · Physics 2022-09-07 E. Fedorova , V. M. Sliusar , V. I. Zhdanov , A. N. Alexandrov , A. Del Popolo , J. Surdej

Accurate modelling of redshift-space distortions (RSD) is challenging in the non-linear regime for two-point statistics e.g. the two-point correlation function (2PCF). We take a different perspective to split the galaxy density field…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-14 Enrique Paillas , Yan-Chuan Cai , Nelson Padilla , Ariel Sánchez

Discriminative Correlation Filters (DCF) have demonstrated excellent performance for visual object tracking. The key to their success is the ability to efficiently exploit available negative data by including all shifted versions of a…

Computer Vision and Pattern Recognition · Computer Science 2016-09-21 Martin Danelljan , Andreas Robinson , Fahad Shahbaz Khan , Michael Felsberg

The Zwicky Transient Facility (ZTF) has been observing the entire northern sky since the start of 2018 down to a magnitude of 20.5 ($5 \sigma$ for 30s exposure) in $g$, $r$, and $i$ filters. Over the course of two years, ZTF has obtained…

The current data acquisition rate of astronomical transient surveys and the promise for significantly higher rates during in the next decade necessitate the development of novel approaches to analyze astronomical data sets and promptly…

Instrumentation and Methods for Astrophysics · Physics 2022-01-28 Robert Strausbaugh , Antonino Cucchiara , Michael Dow , Sara Webb , Jielai Zhang , Simon Goode , Jeff Cooke

We present a measure of the hard (2-8 keV) X-ray luminosity function (XLF) of Active Galactic Nuclei up to z~5. At high redshifts, the wide area coverage of the Chandra Multiwavength Project is crucial to detect rare and luminous (Lx >…

We present a detailed comparison between the 2-10 keV hard X-ray and infrared (IR) luminosity function (LF) of active galactic nuclei (AGN). The composite X-ray to IR spectral energy distributions (SEDs) of AGN used for connecting the hard…

Astrophysics of Galaxies · Physics 2014-08-29 Yunkun Han , Benzhong Dai , Bo Wang , Fenghui Zhang , Zhanwen Han

We present a revised analysis of the photometric reverberation mapping campaign of the narrow-line Seyfert 1 galaxy PKS 0558-504 carried out with the Swift Observatory during 2008--2010. Previously, Gliozzi et al.\ found using the Discrete…

Recently, discriminatively learned correlation filters (DCF) has drawn much attention in visual object tracking community. The success of DCF is potentially attributed to the fact that a large amount of samples are utilized to train the…

Computer Vision and Pattern Recognition · Computer Science 2016-11-16 Kai Chen , Wenbing Tao