500 citations · 4.8k across the 143 of their papers we have counts for
8 papers · 1 filter
Short time-scale X-ray spectral variability in the Seyfert 1 galaxy NGC 3783
D. Costanzo, M. Dadina, C. Vignali +9
We report on the X-ray time resolved spectral analysis of XMM-Newton observations of NGC 3783. The main goal is to detect transient features in the Fe K line complex, in order to s…
Changing-look event in NGC 3516: continuum or obscuration variability?
Missagh Mehdipour, Gerard A. Kriss, Laura W. Brenneman +6
The Seyfert-1 galaxy NGC 3516 has undergone major spectral changes in recent years. In 2017 we obtained Chandra, NuSTAR, and Swift observations during its new low-flux state. Using…
The Paschen Jump as a Diagnostic of the Diffuse Nebular Continuum Emission in Active Galactic Nuclei
Hengxiao Guo, Aaron J. Barth, Kirk T. Korista +17
Photoionization modeling of active galactic nuclei (AGN) predicts that diffuse continuum (DC) emission from the broad-line region makes a substantial contribution to the total cont…
Transient obscuration event captured in NGC~3227 II. Warm absorbers and obscuration events in archival XMM-Newton and NuSTAR observations
Yijun Wang, Jelle Kaastra, Missagh Mehdipour +18
The relation between warm absorber (WA) outflows of AGN and nuclear obscuration activities caused by optically-thick clouds (obscurers) crossing the line of sight is unclear. NGC 3…
New radiative loss curve from updates to collisional excitation in the low-density, optically thin plasmas in SPEX
L. Štofanová, J. Kaastra, M. Mehdipour +1
Understanding and modelling astrophysical plasmas on atomic levels while taking into account various assumptions (for example, collisional ionisation equilibrium or photoionisation…
Transient obscuration event captured in NGC 3227. I. Continuum model for the broadband spectral energy distribution
M. Mehdipour, G. A. Kriss, J. S. Kaastra +21
From Swift monitoring of a sample of active galactic nuclei (AGN) we found a transient X-ray obscuration event in Seyfert-1 galaxy NGC 3227, and thus triggered our joint XMM-Newton…