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We use both simulated and real quasar light curves to explore modeling photometric reverberation-mapping (RM) data as a stochastic process. We do this using modifications to our previously developed RM method based on modeling quasar…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-30 Ying Zu , C. S. Kochanek , Szymon Kozłowski , B. M. Peterson

We provide a quantitative description and statistical interpretation of the optical continuum variability of quasars. The Sloan Digital Sky Survey (SDSS) has obtained repeated imaging in five UV-to-IR photometric bands for 33,881…

We study the Rossby wave instability model of high-frequency quasi-periodic oscillations (QPO) of microquasars. We show ray-traced light curves of QPO within this model and discuss perspectives of distinguishing alternative QPO models with…

High Energy Astrophysical Phenomena · Physics 2013-10-04 F. H. Vincent , P. Varniere , H. Meheut , T. Paumard , G. Torok , M. Wildner

Cyclostationary processes are those signals whose have vary almost periodically in statistics. It can give rise to random data whose statistical characteristics vary periodically with time although these processes not periodic functions of…

General Physics · Physics 2009-11-04 Jiang Dong

Using the archives of the American Association of Variable Stars Observers and our own data, we analyse the long-term variability of several well-studied Luminous Blue Variables (LBVs) aiming on a general picture of stochastic variability…

Solar and Stellar Astrophysics · Physics 2015-05-27 Pavel Abolmasov

Automatic classification methods applied to sky surveys have revolutionized the astronomical target selection process. Most surveys generate a vast amount of time series, or \quotes{lightcurves}, that represent the brightness variability of…

Instrumentation and Methods for Astrophysics · Physics 2018-01-31 Nicolas Castro , Pavlos Protopapas , Karim Pichara

We conduct a systematic search for quasars with periodic variations from the archival photometric data of the Zwicky Transient Facility by cross-matching with the quasar catalogs of the Sloan Digital Sky Survey and V{\'e}ron-Cetty \&…

Astrophysics of Galaxies · Physics 2023-12-25 Yong-Jie Chen , Shuo Zhai , Jun-Rong Liu , Wei-Jian Guo , Yue-Chang Peng , Yan-Rong Li , Yu-Yang SongSheng , Pu Du , Chen Hu , Jian-Min Wang

We present an improved photometric error analysis for the 7,100 CRTS (Catalina Real-Time Transient Survey) optical light curves for quasars from the SDSS (Sloan Digital Sky Survey) Stripe 82 catalogue. The SDSS imaging survey has provided a…

Astrophysics of Galaxies · Physics 2017-12-07 Krzysztof Suberlak , Željko Ivezić , Chelsea L. MacLeod , Matthew Graham , Branimir Sesar

Stars exhibit a bewildering variety of variable behaviors ranging from explosive magnetic flares to stochastically changing accretion to periodic pulsations or rotations. The principal LSST surveys will have cadences too sparse and…

Instrumentation and Methods for Astrophysics · Physics 2019-01-24 Eric D. Feigelson , Frederica Bianco , Sara Bonito

A system's internal dynamics and its interaction with the environment can be determined by tracking how external perturbations affect its transition rates between states. Quantitative measurements of these rates are crucial for optimizing…

The study of quasar light curves poses two problems: inference of the power spectrum and interpolation of an irregularly sampled time series. A baseline approach to these tasks is to interpolate a time series with a Damped Random Walk (DRW)…

Astrophysics of Galaxies · Physics 2022-11-21 Egor Danilov , Aleksandra Ćiprijanović , Brian Nord

Blazars exhibit variable emission on diverse timescales. Some light curves show signs of quasiperiodic oscillations (QPOs), which may encode clues regarding the physical processes behind the emission or point to supermassive binary black…

High Energy Astrophysical Phenomena · Physics 2026-02-24 M. A. Hashad , A. Hammad , Amr A. EL-Zant

As the hunt for an Earth-like exoplanets has intensified in recent years, so has the effort to characterise and model the stellar signals that can hide or mimic small planetary signals. Stellar variability arises from a number of sources,…

Solar and Stellar Astrophysics · Physics 2024-04-19 Niamh K. O'Sullivan , Suzanne Aigrain

We develop a method for separating quasars from other variable point sources using SDSS Stripe 82 light curve data for ~10,000 variable objects. To statistically describe quasar variability, we use a damped random walk model parametrized by…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-28 C. L. MacLeod , K. Brooks , Z. Ivezic , C. S. Kochanek , R. Gibson , A. Meisner , S. Kozlowski , B. Sesar , A. C. Becker , W. de Vries

Stars exhibit a bewildering variety of rapidly variable behaviors ranging from explosive magnetic flares to stochastically changing accretion to periodic pulsations or rotation. The principal Rubin Observatory Legacy Survey of Space and…

Solar and Stellar Astrophysics · Physics 2023-08-02 Eric D. Feigelson , Federica B. Bianco , Rosaria Bonito

Based on the long-term light curves collected from the Catalina Sky Survey (CSS) (from 2005 to 2013) and the All-Sky Automated Survey for Supernovae (ASAS-SN) (from 2014 to 2018), optical quasi-periodic oscillations (QPOs) about 300 days…

High Energy Astrophysical Phenomena · Physics 2022-08-17 Qi Zheng , Xueguang Zhang , Qirong Yuan

In the near future, new surveys promise a significant increase in the number of quasars (QSO) at large redshifts. This will help to constrain the dark energy models using quasars. The Large Synoptic Survey Telescope (LSST) will cover over…

Astrophysics of Galaxies · Physics 2019-10-08 Mary Loli Martínez-Aldama , Swayamtrupta Panda , Bożena Czerny , Michal Zajaček

Stochastic treatments of magnetic resonance spectroscopy and optical spectroscopy require evaluations of functions like <exp(i int_0^t Q(s)ds)>, where t is time, Q(s) is the value of a stochastic process at time s, and the angular brackets…

Chemical Physics · Physics 2015-06-05 Daniel M Packwood , Yoshitaka Tanimura

Recent experimental advances have inspired the development of theoretical tools to describe the non-equilibrium dynamics of quantum systems. Among them an exact representation of quantum spin systems in terms of classical stochastic…

Quantum Physics · Physics 2023-04-19 Gennaro Tucci , Stefano De Nicola , Sascha Wald , Andrea Gambassi

Quasi-periodic oscillation (QPOs) analysis is important for understanding the dynamical behavior of many astrophysical objects during transient events such as gamma-ray bursts, solar flares, magnetar flares, and fast radio bursts. In this…

High Energy Astrophysical Phenomena · Physics 2023-12-07 Kuantay Boshkayev , Talgar Konysbayev , Yergali Kurmanov , Marco Muccino , Hernando Quevedo