A Brief History of AGN

  title={A Brief History of AGN},
  author={Gregory Alan Shields},
Astronomers knew early in the twentieth century that some galaxies have emission-line nuclei. However, even the systematic study by Seyfert (1943) was not enough to launch active galactic nuclei (AGN) as a major topic of astronomy. The advances in radio astronomy in the 1950s revealed a new universe of energetic phenomena, and inevitably led to the discovery of quasars. These discoveries demanded the attention of observers and theorists, and AGN have been a subject of intense effort ever since… 

Evolution of cold gas in active galaxies.

Atomic hydrogen, hereafter referred to as HI, plays a crucial role in the evolution of galaxies and their central super-massive black-holes, fueling the formation of stars and feeding of active

Active Galactic Nuclei Influence the Genesis of Galaxies

Most or all spiral and elliptical galaxies were formed by quasars with supermassive black holes. The genesis of such galaxies occurred when the universe was young, approximately 5 billion years ago.

A Physical Model for the UV/Optical Power Spectra of AGN

The UV/optical variability of active galactic nuclei (AGN) has long been thought to be driven by the X-ray illumination of the accretion disk. However, recent multiwavelength campaigns of nearby

Active Galactic Nuclei and Pulsars

With the discovery of radio emission of extraterrestrial origin, it had opened a new and broader window in the electromagnetic spectrum to observe the sky. Two of the common sources of radio

The 3CR Chandra Snapshot Survey: Extragalactic Radio Sources with Redshifts between 1 and 1.5

The aim of this paper is to present an analysis of newly acquired X-ray observations of 16 extragalactic radio sources listed in the Third Cambridge Revised (3CR) catalog and not previously observed

Low-rate accretion onto isolated stellar-mass black holes

Magnetic field behaviour in a spherically-symmetric accretion flow for parameters typical of single black holes in the Galaxy is discussed. It is shown that in the majority of the Galaxy volume,

Antigravity—Its Manifestations and Origin

Dark energy has been introduced in order to explain the observed acceleration of the expansion of our Universe. It seems to be distributed almost uniformly and it has an essential influence on the

Russell Lecture: Dark Star Formation and Cooling Instability

Optically thin cooling gas at most temperatures above 30 K will make condensations by pressure, pushing material into cool, dense regions. This works without gravity. Cooling condensations will

High energy emission of jet sources

In this thesis I have conducted different multiwavelength campaigns on blazars triggered through AO proposals of the INTEGRAL mission and ToOs of other missions. Ground based observation facilities

Gravitational lensing signature of matter distribution around Schwarzschild black hole

In this work, we focus on the situation where a significant amount of matter could be located close to the event horizon of the central black hole and how it affects the gravitational lensing signal.



Modern cosmology in retrospect

Preface Part I. The General Framework: 1. Cosmology, a peculiar science B. Bertoti 2. The early years J. D. North Part II. Riddles of and Clues to Cosmology: 3. Olbers' paradox in recent times E.


Abstract : Contents include: Gravitational collapse; Properties of massive objects; Relativistic astrophysics; Massive stars, relativistic polytropes, and gravitational radiation; Massive stars in

Active Galactic Nuclei a

Our current knowledge of active galactic nuclei is reviewed. The importance of observational data taken over a wide range of frequencies, from radio and infrared through optical and ultraviolet to

Astrophysics of Gaseous Nebulae and Active Galactic Nuclei

Preface Preface to First Edition General Introduction Photoionization Equilibrium Thermal Equilibrium Calculation of Emitted Spectrum Comparison of Theory with Observations Internal Dynamics of


The luminosity-volume test for a complete sample of quasi-stellar objects which consists of all those brighter than prescribed limiting radio and optical flux densities is investigated. The best

on absorption lines and chemical evolution; Ulrich, Maraschi, and Urry (1997) on variability; and Hewett and Foltz (1994) on quasar surveys

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