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200 papers

We adopt a Bayesian X-ray spectral approach to investigate the accretion properties of unobscured ($20<\log(N_{\rm H}/{\rm cm}^{-2}<22$) and obscured ($22< \log(N_{\rm H}/{\rm cm}^{-2}<24$) active galactic nuclei (AGN) to shed light on the…

Active Galactic Nuclei (AGN) are highly energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, which present unique observational signatures covering the full electromagnetic spectrum (and more) over…

High Energy Astrophysical Phenomena · Physics 2023-04-05 Stefano Bianchi , Vincenzo Mainieri , Paolo Padovani

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze…

Instrumentation and Methods for Astrophysics · Physics 2026-04-01 Krzysztof Findeisen , Ann Marie Cody , Lynne Hillenbrand

We examine all possible stationary, optically thick, geometrically thin accretion disc models relevant for active galactic nuclei (AGN) and identify the physical regimes in which they are stable against the thermal-viscous hydrogen…

Astrophysics · Physics 2015-06-24 L. Burderi , A. R. King , E. Szuszkiewicz

The spectral shape of the prompt emissions of gamma-ray bursts (GRBs) is typically expressed by the Band function: smooth joining of two power-law functions for high-energy and low-energy regions. To reveal the origin of the Band function,…

High Energy Astrophysical Phenomena · Physics 2015-10-21 Katsuaki Asano , Toshio Terasawa

Multivariate dynamic time series models are widely encountered in practical studies, e.g., modelling policy transmission mechanism and measuring connectedness between economic agents. To better capture the dynamics, this paper proposes a…

Econometrics · Economics 2020-10-06 Yayi Yan , Jiti Gao , Bin Peng

This paper develops a stochastic and unifying framework to examine variability in car-following (CF) dynamics of commercial automated vehicles (AVs) and its direct relation to traffic-level dynamics. The asymmetric behavior (AB) model by…

Applications · Statistics 2024-01-02 Xinzhi Zhong , Yang Zhou , Soyoung Ahn , Danjue Chen

Current mm-interferometers can provide a complete view of the distribution and kinematics of molecular gas in the circumnuclear disks of nearby galaxies. High-resolution CO maps are paramount in order to track down the feeding of active…

Astrophysics · Physics 2008-11-26 S. Garcia-Burillo , F. Combes , A. Usero , J. Gracia-Carpio

Phenotypical variability in the absence of genetic variation often reflects complex energetic landscapes associated with underlying gene regulatory networks (GRNs). In this view, different phenotypes are associated with alternative states…

Molecular Networks · Quantitative Biology 2018-06-27 M. Ali Al-Radhawi , Domitilla Del Vecchio , Eduardo D. Sontag

Many real-world datasets, such as healthcare, climate, and economics, are often collected as irregular time series, which poses challenges for accurate modeling. In this paper, we propose the Amortized Control of continuous State Space…

Machine Learning · Statistics 2025-03-03 Byoungwoo Park , Hyungi Lee , Juho Lee

The variability of the X-ray spectra of active galactic nuclei (AGN) usually includes a change of the spectral slope. This has been investigated for a small sample of local AGNs by Sobolewska and Papadakis, who found that slope variations…

Astrophysics of Galaxies · Physics 2016-03-23 Roberto Serafinelli , Fausto Vagnetti , Riccardo Middei

The high luminosity displayed by an active galactic nucleus (AGN) requires that gas be transported to the centre of the galaxy by some mechanism. Bar-driven processes are often pointed out in this context and a number of studies have…

Astrophysics of Galaxies · Physics 2022-05-11 Luiz A. Silva-Lima , Lucimara P. Martins , Paula R. T. Coelho , Dimitri A. Gadotti

The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) program monitors 849 active galactic nuclei (AGN) both spectroscopically and photometrically. The photometric observations used in this work span over four years and provide an…

We use the Athena hydrodynamics code to model propagating two-dimensional relativistic jets as approximations to the growth of radio-loud active galactic nuclei for various input jet velocities and jet-to-ambient matter density ratios.…

High Energy Astrophysical Phenomena · Physics 2016-03-23 Maxwell Pollack , David Pauls , Paul J. Wiita

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

We study dissipative transport of spontaneously emitting atoms in a 1D standing-wave laser field in the regimes where the underlying deterministic Hamiltonian dynamics is regular and chaotic. A Monte Carlo stochastic wavefunction method is…

Atomic Physics · Physics 2012-01-04 V. Yu. Argonov , S. V. Prants

The broad emission lines (BELs) in active galactic nuclei (AGN) respond to ionizing continuum variations. The time and velocity dependence of their response depends on the structure of the broad-line region: its geometry, kinematics and…

Astrophysics of Galaxies · Physics 2017-07-26 S. W. Mangham , C. Knigge , J. H. Matthews , K. S. Long , S. A. Sim , N. Higginbottom

In this paper we give a brief review of the astrophysics of active galactic nuclei (AGN). After a general introduction motivating the study of AGNs, we discuss our present understanding of the inner workings of the central engines, most…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-18 Henric Krawczynski , Ezequiel Treister

We present soft X-ray variability time-scales for 65 active galactic nuclei (AGNs) derived from ROSAT/PSPC pointing data. For these 65 objects with obvious exponential increasing or decreasing patterns in their light curves, we use the…

Astrophysics · Physics 2009-11-07 W. Bian , Y. Zhao

Off-nucleus active galactic nuclei (AGN) can be signposts of inspiraling supermassive black holes (SMBHs) on galactic scales, or accreting SMBHs recoiling after the coalescence of a SMBH binary or slingshot from three-body interactions.…

Astrophysics of Galaxies · Physics 2021-08-17 Yue Shen , Hsiang-Chih Hwang , Nadia Zakamska , Xin Liu