scholarly journals POWERFUL RELATIVISTIC JETS IN SPIRAL GALAXIES

2012 ◽  
Vol 08 ◽  
pp. 172-177 ◽  
Author(s):  
LUIGI FOSCHINI
Keyword(s):  
Active Galactic Nuclei ◽  
Spiral Galaxies ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
High Energy ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Accretion Rates ◽  
Γ Rays ◽  
Eddington Limit

The discovery of high-energy (E > 100 MeV) γ rays from Narrow-Line Seyfert 1 Galaxies (γ-NLS1s) has confirmed the presence of powerful relativistic jets in this class of active galactic nuclei (AGN). Although the jet emission is similar to that of blazars and radio galaxies, γ-NLS1s have some striking differences: relatively small masses (106-8 M⊙), high accretion rates (0.1-1 times the Eddington limit) and are generally hosted by spiral galaxies. It is now possible to study a rather unexplored range of mass and accretion rates of AGN with relativistic jets. Specifically, in this work I present some results obtained by comparing a sample of blazars and γ-NLS1s with another sample of Galactic binaries with relativistic jets (stellar mass black holes and neutron stars).

scholarly journals Relativistic jets in Narrow-Line Seyfert 1

2010 ◽  
Vol 6 (S275) ◽  
pp. 176-177
Author(s):  
L. Foschini ◽  
E. Angelakis ◽  
G. Bonnoli ◽  
G. Calderone ◽  
M. Colpi ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Preliminary Results ◽  
New Class ◽  
Γ Ray ◽  
First Time

AbstractNarrow-Line Seyfert 1 (NLS1) class of active galactic nuclei (AGNs) is generally radio-quiet, but a small percent of them are radio-loud. The recent discovery by Fermi/LAT of high-energy γ-ray emission from 4 NLS1s proved the existence of relativistic jets in these systems. It is therefore important to study this new class of γ-ray emitting AGNs. Here we report preliminary results about the observations of the July 2010 γ-ray outburst of PMN J0948+0022, when the source flux exceeded for the first time 10−6 ph cm−2 s−1 (E > 100 MeV).

scholarly journals Jetted Narrow-Line Seyfert 1 Galaxies & Co.: Where Do We Stand?

Universe ◽  
2020 ◽  
Vol 6 (9) ◽  
pp. 136
Author(s):  
Luigi Foschini
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
Small Mass ◽  
High Energy ◽  
Narrow Line ◽  
Large Area ◽  
Central Engine ◽  
Great Performance ◽  
Energy Gamma

The discovery in 2008 of high-energy gamma-rays from Narrow-Line Seyfert 1 Galaxies (NLS1s) made it clear that there were active galactic nuclei (AGN) other than blazars and radio galaxies that can eject powerful relativistic jets. In addition to NLS1s, the great performance of the Fermi Large Area Telescope made it possible to discover MeV-GeV photons emitted from more classes of AGN, like Seyferts, Compact Steep Spectrum Gigahertz Peaked Sources (CSS/GPS), and disk-hosted radio galaxies. Although observations indicate a variety of objects, their physical characteristics point to a central engine powered by a relatively small-mass black hole (but, obviously, there are interpretations against this view). This essay critically reviews the literature published on these topics during the last eight years and analyzes the perspectives for the forthcoming years.

scholarly journals Multi-wavelength observations of the narrow-line Seyfert 1 galaxy RX J2314.9+2243

2014 ◽  
Vol 10 (S312) ◽  
pp. 61-62
Author(s):  
S. Komossa ◽  
I. Myserlis ◽  
L. Fuhrmann ◽  
D. Xu ◽  
D. Grupe ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Extreme Case ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Uv Spectrum ◽  
New Radio ◽  
Multi Wavelength ◽  
Low Mass ◽  
Black Hole Masses

AbstractNarrow-line Seyfert 1 (NLS1) galaxies are a sub-class of active galactic nuclei (AGN) with relatively low-mass black holes, accreting near the Eddington rate. A small fraction of them is radio-loud and harbors relativistic jets. As a class, these provide us with new insights into the cause(s) of radio-loudness, the blazar phenomenon at low black hole masses, and the operation of radio-mode feedback. The NLS1 galaxy RXJ2314.9+2243 is remarkable for its multi-wavelength properties. We present new radio observations taken at Effelsberg, and a summary of the recent results from our multi-wavelength study. RXJ2314.9+2243 is radio-loud, luminous in the infrared, has a flat X-ray spectrum and peculiar UV spectrum, and hosts an exceptionally broad and blueshifted [OIII]λ5007 emission line, indicating the presence of a strong outflow. RXJ2314.9+2243 likely represents an extreme case of AGN induced feedback in the local universe.

scholarly journals Similarity and diversity of black holes - view from the Very High Energies

2016 ◽  
Vol 12 (S324) ◽  
pp. 11-18
Author(s):  
Elina Lindfors
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Mass Scale ◽  
Relativistic Jets ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

AbstractActive galactic nuclei, hosting supermassive black holes and launching relativistic jets, are the most numerous objects on the gamma-ray sky. At the other end of the mass scale, phenomena related to stellar mass black holes, in particular gamma-ray bursts and microquasars, are also seen on the gamma-ray sky. While all of them are thought to launch relativistic jets, the diversity even within each of these classes is enormous. In this review, I will discuss recent very high energy gamma-ray results that underline both the similarity of the black hole systems, as well as their diversity.

Very High Energy γ-rays from AGN

2002 ◽  
Vol 19 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Tadashi Kifune
Keyword(s):  
Electromagnetic Radiation ◽  
Active Galactic Nuclei ◽  
Energy Band ◽  
Galactic Nuclei ◽  
High Energy ◽  
Current Status ◽  
Very High Energy ◽  
Γ Rays ◽  
Γ Ray ◽  
Very High

AbstractEvidence of TeV γ-ray emission has been found for only a handful of active galactic nuclei, with detailed investigations limited to the blazars Mrk 421 and Mrk 501. TeV γ-ray astronomy, as the highest energy band, provides important information that is hard to obtain from longer wavelength electromagnetic radiation. The current status of TeV γ-ray studies of active galactic nuclei is summarized and our understanding of the high energy phenomena taking place in active galactic nuclei is outlined, with the prospects for future TeV γ-ray observations also considered.

A FRAMEWORK FOR INTERPRETING OBSERVED PHENOMENA ASSOCIATED WITH RELATIVISTIC OUTFLOWS IN AGN

2008 ◽  
Vol 17 (09) ◽  
pp. 1521-1530 ◽  
Author(s):  
D. C. GABUZDA
Keyword(s):  
Active Galactic Nuclei ◽  
Circular Polarization ◽  
Faraday Rotation ◽  
Surrounding Medium ◽  
Galactic Nuclei ◽  
High Energy ◽  
Electromagnetic Current ◽  
Relativistic Jets ◽  
Relativistic Shocks ◽  
Abundant Evidence

A growing number of jets in active galactic nuclei (AGN) show clear signs of helical magnetic (B) fields: Faraday-rotation gradients across the VLBI jets, extended regions of jet with orthogonal B fields, transverse polarization and total-intensity structures characteristic of helical fields, interknot polarization implying underlying orthogonal B fields, and a predominance of orthogonal B fields in the VLBI cores. In addition, a link has now been found between the circular polarization detected in AGN cores and the presence of helical jet B fields within these cores. This now abundant evidence compels us to take very seriously the idea that many, possibly all, AGN jets have helical B fields. As a whole, the recent observational results considered here suggest that we must look at AGN jets as fundamentally electromagnetic, current-carrying structures if we wish to fully understand their nature. This provides an overall framework for interpreting various observed phenomena associated with the relativistic jets of AGN, including high-energy phenomena. Superposed on the structure of the underlying helical B field may be the effects of relativistic shocks and interaction with the surrounding medium in some cases; these may dominate observed phenomena locally, while it is the "intrinsic" helical B field of the jet itself that determines the global observed characteristics of the jet.

Very high energy γ rays from close active galactic nuclei Mkn 421, Mkn 501, and NGC 1275

2007 ◽  
Vol 71 (7) ◽  
pp. 906-909 ◽  
Author(s):  
V. G. Sinitsina ◽  
T. P. Arsov ◽  
S. S. Borisov ◽  
S. I. Nikol’sky ◽  
F. I. Musin ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Very High Energy ◽  
Γ Rays ◽  
Ngc 1275 ◽  
Very High

scholarly journals The Origin and Evolution of Giant Radio Galaxies

2022 ◽  
Vol 8 ◽  
Author(s):  
David Garofalo
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Spiral Galaxies ◽  
Radio Galaxy ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
High Excitation ◽  
Origin And Evolution ◽  
Black Hole Spin ◽  
Upper Limit

Giant radio galaxies are arguably the least understood of jetted active galactic nuclei (AGN). We propose that radio galaxies are the product of large mergers that do not involve radio galaxies or radio quasars, such as in merging spiral galaxies, while giant radio galaxies emerge from a merger involving a parent that in the not-too-distant past harbored a radio galaxy. Predictions following from this are an upper limit to the number fraction of giant radio galaxies to radio galaxies, lower average redshift for giant radio galaxies, a higher incidence of high excitation for giant radio galaxies compared with radio galaxies, and lower average prograde black hole spin values for giant radio galaxies compared to radio galaxies and to bright radio quiet quasars.

Sign in / Sign up

Export Citation Format

Share Document