相关论文: CLASS: Coronal Line Activity Spectroscopic Survey

We present a spectroscopic study of the incidence of AGN nuclear activity in two samples of isolated galaxies (Karachentseva, V.E. & Varela, J.). Our results show that the incidence of non-thermal nuclear activity is about 43% and 31% for…

The majority of low-ionization nuclear emission-line regions (LINERs) harbor supermassive black holes with very low accretion rates. However, the accretion flows do not produce enough ionizing photons to power the emission lines emitted on…

The physical conditions near the optical continuum peak (``hot spot'') in the inner narrow line region (NLR) of the Seyfert 2 galaxy, NGC 1068. Spectra were taken with HST/STIS through the 0.1X52 arcsec slit, covering the full STIS 1200 to…

We analyze the high-resolution XRISM/Resolve spectrum of the Fe K$\alpha$ emission line of the nearest active galactic nucleus, in Centaurus A. The line features two narrow and resolved peaks of Fe K$\alpha_1$, and Fe K$\alpha_2$ with a…

Central supermassive black holes of active galactic nuclei host hot plasma with a temperature of $10^9$ K, namely coronae. Like the Sun, black hole coronae are theoretically believed to be heated by their magnetic activity, which have never…

Dwarf galaxies are characterised by a very low luminosity and low mass. Because of significant accretion and ejection activity of massive black holes, some dwarf galaxies also host low-luminosity active galactic nuclei (AGNs). In a few…

X-ray observations of several active galactic nuclei show prominent iron K-shell fluorescence lines that are sculpted due to special and general relativistic effects. These observations are important because they probe the space-time…

The total solar eclipse of August 21st, 2017 was observed with a Digital Single Lens Reflex (DSLR) camera equipped with a linear polarizing filter. A method was developed to combine images acquired with 15 different exposure times (from…

In this paper we assess the relationship of the population of Active Galactic Nuclei (AGN) selected by hard X-rays to the traditional population of AGN with strong optical emission lines. First, we study the emission-line properties of a…

(abbreviated): This paper presents the results of a high resolution radio imaging survey of all known (96) low-luminosity active galactic nuclei (LLAGNs) at D<19Mpc. We find that almost half of all LINERs and low-luminosity Seyferts have…

We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral data, to explore the potential of narrow band EUV imaging data for diagnosing the presence of hot (T >~5MK) coronal plasma in active regions. We analyze observations…

The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…

This paper is the second in a series in which we present intermediate-resolution spectra for a complete sample of 14 compact radio sources, taken with the aim of investigating the impact of the nuclear activity on the cirumnuclear…

We have compiled a large sample of low-redshift active galactic nuclei (AGN) identified via their emission line characteristics from the spectroscopic data of the Sloan Digital Sky Survey. Since emission lines are often contaminated by…

Using archival Chandra observations of 19 LINERs we explore the X-ray properties of their inner kiloparsec to determine the origin of their nuclear X-ray emission, to investigate the presence of an AGN, and to identify the power source of…

We report the discovery using Spitzers high resolution spectrograph of 7 Active Galactic Nuclei (AGN) in a sample of 32 late-type galaxies that show no definitive signatures of AGN in their optical spectra. Our observations suggest that the…

Hard X-ray emission in radio-quiet active galactic nuclei (AGNs) is believed to be produced via inverse Compton scattering by hot and compact coronae near the super massive black hole. However the origin and physical properties of the…

We present X-ray and multiwavelength studies of a sample of eight high-luminosity active galactic nuclei (AGNs) with disc-like H\beta emission-line profiles selected from the Sloan Digital Sky Survey Data Release 7. These sources have…

Extreme coronal-line emitter (ECLE) SDSSJ095209.56+214313.3, known by its strong, fading, high ionization lines, has been a long standing candidate for a tidal disruption event, however a supernova origin has not yet been ruled out. Here we…

We introduce a novel galaxy classification methodology based on the visible spectra of a sample of over 68,000 nearby ($z\leq 0.1$) Sloan Digital Sky Survey lenticular (S0) galaxies. Unlike traditional diagnostic diagrams, which rely on a…