Clusters are quite prominent in X-ray surveys and along with AGN are the brightest X-ray emitting extragalactic objects.

In November, 2007 preliminary results were announced showing direction of origination of the 27 highest energy events were strongly correlated with the locations of active galactic nuclei, where bare protons are believed to be accelerated by strong magnetic fields associated with the large black holes at the AGN centers to energies of 10 < sup > 20 </ sup > eV and higher.

2010 ) have now cataloged several hundred X-ray sources in the direction of the SMC, the of which perhaps half are considered likely HMXBs, and the remainder a mix of foreground stars, and background AGN.

AGN are the most luminous persistent sources of electromagnetic radiation in the universe, and as such can be used as a means of discovering distant objects ; their evolution as a function of cosmic time also provides constraints on models of the cosmos.

It is debatable whether all such systems are true AGN ( powered by accretion on to a supermassive black hole ).

If they are, they constitute the lowest-luminosity class of radio-quiet AGN.

Their other AGN properties are heterogeneous.

The centres of Seyfert galaxies form a subclass of active galactic nuclei ( AGN ), and are thought to contain supermassive black holes with masses between 10 < sup > 7 </ sup > and 10 < sup > 8 </ sup > solar masses.

The narrow lines are believed to originate from the outer part of the AGN where velocities are lower, while the broad lines originate closer to the black hole.

The vast majority of these quasars are not correlated in any way with nearby AGN.

He has further hypothesized that the higher redshift objects are ejected from the lower redshift objects-which are usually active galactic nuclei ( AGN )- and that the large observed redshifts of these " ejected " objects is dominated by a non-cosmological ( intrinsic ) component.

Blazars are members of a larger group of active galaxies that host active galactic nuclei ( AGN ).

Blazars are AGN with a relativistic jet that is pointing in the general direction of the Earth.

Blazars, like all AGN, are thought to be ultimately powered by material falling onto a supermassive black hole at the center of the host galaxy.

AGN which have jets oriented close to the line of sight with Earth can appear extremely different from other AGN even if they are intrinsically identical.

From the point of AGN classification, BL Lacs are a blazar subtype.

A relativistic jet coming out of the center of an AGN is moving along AB with a velocity v. We are observing the jet from the point O.

The AGN could merely be closely associated with the actual sources, for example in galaxies or other astrophysical objects that are clumped with matter on large scales within 100 Mpc.

Some of the supermassive black holes in AGN are known to be rotating, as in the Seyfert galaxy MCG 6-30-15 with time-variability in their inner accretion disks.

" Note that quasars are a class of active galactic nuclei, or AGN.

An active galactic nucleus ( AGN ) is a compact region at the centre of a galaxy that has a much higher than normal luminosity over at least some portion, and possibly all, of the electromagnetic spectrum.

Accreting compact objects and relativistic jets are invoked to explain the following observed phenomena: x-ray binaries, gamma-ray bursts, and, on a much larger scale, active galactic nuclei ( AGN ).

( Quasars are also associated with an accreting compact object, but are thought to be merely a particular variety of AGN.

; Doppler factor: a mathematical expression which measures the strength ( or weakness ) of relativistic effects in AGN, including beaming, based on the jet speed and its angle to the line of sight with Earth

; jet: a relativistic jet of plasma emanating from the polar direction of an AGN

The radiation from AGN is believed to be a result of accretion of mass by the supermassive black hole at the centre of the host galaxy.

For a long time it has been argued that AGN must be powered by accretion onto massive black holes ( with masses between 10 < sup > 6 </ sup > and 10 < sup > 10 </ sup > times that of the Sun ).

In the standard model of AGN, cold material close to the central black hole forms an accretion disc.

Radiatively inefficient AGN would be expected to lack many of the characteristic features of standard AGN with an accretion disc.

They may be the best current candidates for AGN with radiatively inefficient accretion.

Perpendicular to the accretion disk, a pair of relativistic jets carries a highly energetic plasma away from the AGN.

Jets can also contribute to this component of the AGN emission.

A further consequence is that a population of intrinsically identical AGN scattered in space with random jet orientations will look like a very inhomogeneous population on Earth.

The scientific field that OTELO will allow tackling is very wide, and encompasses evolutionary studies of Ly alpha emitters, QSO, AGN, star-forming populations ( specifically the faint end luminosity ), Emissión line ellipticals ( detectable depending upon its evolution ), chemical evolution of the Universe between z = 0. 24 and z = 1. 5, mass / luminosity relation vs. morphological type and redshift ( up to z = 1. 5 ), Tully-Fisher relation up to z = 1. 5 and derivation of cosmological parameters.

However, they radiate in all wavebands from the radio through to the gamma-ray via the synchrotron and inverse-Compton process, and so AGN with jets have a second potential source of any observed continuum radiation.

Additional data collection is important for further investigating possible AGN sources for these highest energy particles.

In November 2007, it was announced that the observatory had found a correlation between the 27 highest energy events and nearby active galactic nuclei ( AGN ).

The blue light from the jet emerging from the bright Active galactic nucleus | AGN core, towards the lower right, is due to synchrotron radiation.

It is not known for sure that the UV radiation is produced purely by star-formation and some astronomers believe ULIRGs to be powered ( at least in part ) by active galactic nuclei ( AGN ).

Several types of astrophysical objects emit, fluoresce, or reflect X-rays, from galaxy clusters, through black holes in active galactic nuclei ( AGN ) to galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf ( cataclysmic variable stars and super soft X-ray sources ), neutron star or black hole ( X-ray binaries ).

Recent results from the Pierre Auger Observatory show that ultra-high-energy cosmic ray arrival directions appear to be correlated with extragalactic supermassive black holes at the center of nearby galaxies called active galactic nuclei ( AGN ).

The environment around the Active galactic nucleus | AGN where the special relativity | relativistic plasma ( physics ) | plasma is collimated into jets which escape along the pole of the supermassive black hole