English
Related papers

Related papers: Evidence for coronal temperature variation in Seyf…

200 papers

We present a coherent multi-band modelling of the CO Spectral Energy Distribution of the local Seyfert Galaxy NGC7130 to assess the impact of the AGN activity on the molecular gas. We take advantage of all the available data from X-ray to…

Astrophysics of Galaxies · Physics 2017-07-26 F. Pozzi , L. Vallini , C. Vignali , M. Talia , C. Gruppioni , M. Mingozzi , M. Massardi , P. Andreani

We present a detailed analysis of the X-ray and molecular gas emission in the nearby galaxy NGC 34, to constrain the properties of molecular gas, and assess whether, and to what extent, the radiation produced by the accretion onto the…

Astrophysics of Galaxies · Physics 2017-12-27 M. Mingozzi , L. Vallini , F. Pozzi , C. Vignali , A. Mignano , C. Gruppioni , M. Talia , A. Cimatti , G. Cresci , M. Massardi

We show that coronal magnetic dissipation in thin active sheets that sandwich standard thin accretion disks in active galactic nuclei may account for canonical electron temperatures of a few $\times 10^9$K if protons acquire most of the…

Astrophysics · Physics 2016-01-13 T. Di Matteo , E. G. Blackman , A. C. Fabian

We discuss ROSAT, ASCA, {\it Beppo}SAX and optical observations of the young active star Gl 355. During the ROSAT observation a strong flare was detected with a peak flux more than an order of magnitude larger than the quiescent level.…

We present analyses of observations of epsilon Eridani (K2 V) made with the Low Energy Transmission Grating Spectrometer on Chandra and the Extreme Ultraviolet Explorer, supplemented by observations made with the Space Telescope Imaging…

Astrophysics · Physics 2009-11-13 J. -U. Ness , C. Jordan

Recent detection of very-high-energy neutrino emission from Seyfert type active galactic nuclei (AGN) provides a new insight into the physics of the AGN central engines. We notice that if high-energy protons responsible for neutrino…

High Energy Astrophysical Phenomena · Physics 2025-07-01 A. Neronov , O. Kalashev , D. V. Semikoz , D. Savchenko , M. Poleshchuk

One of the outstanding problems in all of space science is uncovering how the solar corona is heated to temperatures greater than 1 MK. Though studied for decades, one of the major difficulties in solving this problem has been unraveling…

Solar and Stellar Astrophysics · Physics 2015-06-15 Nicholeen M. Viall , James A. Klimchuk

Compact radio AGN are thought to be young radio active galactic nuclei (AGN) at the early stage of AGN evolution, thus are ideal laboratory to study the high-energy emission throughout the evolution of radio AGN. In this work, we report for…

High Energy Astrophysical Phenomena · Physics 2024-01-11 Mai Liao , Junxian Wang , Jialai Kang , Xiaofeng Li , Minhua Zhou

We present the first intensive study of the variability of the near-infrared coronal lines in an active galactic nucleus (AGN). We use data from a one-year long spectroscopic monitoring campaign with roughly weekly cadence on NGC 5548 to…

Astrophysics of Galaxies · Physics 2022-09-14 Daniel Kynoch , Hermine Landt , Maryam Dehghanian , Martin J. Ward , Gary J. Ferland

VLT and NTT spectra are used to examine the nuclear and extended coronal line emission in a sample of well-known Seyfert 1 and 2 galaxies. The excellent spatial resolution obtained with VLT allowed us to map [SiVI] 1.963 $\mu$m and [SiVII]…

Astrophysics · Physics 2009-11-10 A. Rodriguez-Ardila , A. Prieto , S. M. Viegas

Much evidence suggests that the solar corona is heated impulsively, meaning that nanoflares may be ubiquitous in quiet and active regions (ARs). Hard X-ray (HXR) observations with unprecedented sensitivity $>$3~keV are now enabled by…

We present the second extensive study of the coronal line variability in an active galaxy. Our data set for the well-studied Seyfert galaxy NGC 5548 consists of five epochs of quasi-simultaneous optical and near-infrared spectroscopy…

Astrophysics of Galaxies · Physics 2015-10-28 Hermine Landt , Martin J. Ward , Katrien C. Steenbrugge , Gary J. Ferland

The near-infrared spectra of Active Galactic Nuclei (AGN) present emission lines of different atomic and molecular species. The mechanisms involved in the origin of these emission lines in AGN are still not fully understood. We use J and K…

The presence of an obscuring torus at pc-scale distances from the central black hole is the main ingredient for the Unified Model of Active Galactic Nuclei (AGN), as obscured sources are thought to be seen through this structure. However,…

We describe a complete volume limited sample of nearby active galaxies selected by their 14-195keV luminosity, and outline its rationale for studying the mechanisms regulating gas inflow and outflow. We describe also a complementary sample…

MCG-5-23-16 was targeted in early 2015 with a half mega-seconds observing campaign using NuSTAR. Here we present the spectral analysis of these datasets along with an earlier observation and study the relativistic reflection and the primary…

Changing-look active galactic nuclei (CLAGNs) are known to change their spectral type between 1 and 2 (changing-state) or change their absorption between Compton-thick and Compton-thin (changing-obscuration) on timescales of years or less.…

High Energy Astrophysical Phenomena · Physics 2025-01-17 Bing Lyu , Zhen Yan , Xue-bing Wu , Qingwen Wu , Wenfei Yu , Hao Liu

The aim of this paper is to study the variability of the warm absorber "clouds of ionised gas within AGN", for the Seyfert 1 galaxies Arakelian 564. The X-ray spectra for four XMM-Newton observations of this object are analysed in EPIC and…

High Energy Astrophysical Phenomena · Physics 2019-09-04 B. Korany , M. I. Nouh

The X-ray spectrum of the late-type M-dwarf binary AT Mic (dM4.5e+dM4.5e) is observed in the wavelength range 1 - 40 Angstrom by means of rgs and epic-mos on board XMM-Newton. During the exposure a flare occured. We have performed a…

Astrophysics · Physics 2009-11-10 A. J. J. Raassen , R. Mewe , M. Audard , M. Guedel

Near-infrared and optical spectroscopy of the nuclear and extended emission region of the Seyfert2 galaxy Mrk1210 is presented. This galaxy is outstanding because it displays signatures of recent circumnuclear star formation and a…

Astrophysics · Physics 2015-06-24 X. Mazzalay , A. Rodriguez-Ardila