scholarly journals Origin of Superluminal radio jets in GRS 1915+105 and the role of Plateau state

2007 ◽  
Author(s):  
J S Yadav
Keyword(s):  
Radio Jets ◽  
Plateau State

The stability of confined radio jets - The role of reflection modes

1985 ◽  
Vol 291 ◽  
pp. 655 ◽  
Author(s):  
D. G. Payne ◽  
H. Cohn
Keyword(s):  
Radio Jets ◽  
The Stability

scholarly journals The molecular gas content in a protocluster at z = 17: Star formation and AGN feedback

2019 ◽  
Vol 15 (S352) ◽  
pp. 168-170
Author(s):  
Q. D’Amato ◽  
I. Prandoni ◽  
R. Gilli ◽  
M. Massardi ◽  
E. Liuzzo ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Gas Content ◽  
Molecular Gas ◽  
Star Forming ◽  
Physical Conditions ◽  
Radio Jets ◽  
Multi Wavelength ◽  
Data Coverage

AbstractA large-scale structure has been recently discovered at z = 1.7, around a powerful FRII radio galaxy. Eight Star Forming Galaxies (SFGs) have been discovered within Δ z ≍ 0.0095 and at < 1 Mpc from the FRII, indicating that this is a signpost of a protocluster. Furthermore, a significant X-ray diffuse emission overlapping the Eastern lobe of the FRII has been detected. Protoclusters are the ideal targets to investigate the complex assembly processes leading to the formation of local galaxy clusters. We will exploit new ALMA CO(2-1) observations (PI: R. Gilli) of the entire region around the FRII galaxy to trace the molecular gas content, in order to discover new protocluster members. Coupling these measurements with the multi-wavelength data coverage available for this field, we aim at placing constrains on the physical conditions in which star formation occurs, and ultimately infer the role of the radio jets in triggering it.

scholarly journals Submillimeter polarization and variability of quasar PKS 1830–211

2018 ◽  
Vol 621 ◽  
pp. A18 ◽  
Author(s):  
I. Marti-Vidal ◽  
S. Muller
Keyword(s):  
Active Galactic Nuclei ◽  
Flux Density ◽  
Density Ratio ◽  
Galactic Nuclei ◽  
High Accuracy ◽  
Differential Analysis ◽  
Polarization Signal ◽  
Radio Jets ◽  
Submillimeter Wavelengths

Polarization from active galactic nuclei is interpreted as a signpost of the role of magnetic fields in the launch and collimation of their relativistic radio jets. Here, we report the detection of a clear polarization signal from ALMA observations of the gravitationally lensed quasar PKS 1830−211 at submillimeter wavelengths (Band 9, 650 GHz). Applying a differential-polarimetry technique to the two compact lensed images of the quasar, we estimate a fractional polarization of ∼5% for one lensed image, while the other appears nearly unpolarized, which implies that the polarization activity varies on a timescale of a few weeks. With additional ALMA Band 7 and 8 (between 300–500 GHz) concomitant data, we constrain a Faraday rotation of a few 105 rad m−2. We also observe flux-density variability of ≲10% within one hour in Band 9. This work illustrates that a differential analysis can extract high-accuracy information (flux-density ratio and polarimetry) free of calibration issues from resolved sources in the submillimeter domain.

The role of AGN in galaxy star formation: A case study of a radio galaxy at z = 2.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 224-224
Author(s):  
Allison Man
Keyword(s):  
Star Formation ◽  
Radio Galaxy ◽  
Star Formation History ◽  
Molecular Gas ◽  
Ob Stars ◽  
Massive Galaxies ◽  
Radio Jets ◽  
Formation History

AbstractRadio galaxies are ideal sites to scrutinize AGN feedback physics, as they are massive galaxies with jets that interact with the surrounding ISM. I will present a detailed analysis of the recent star formation history and conditions of a starbursting, massive radio galaxy at z = 2.6, PKS 0529-549. In the 8.5-hour VLT/X-Shooter spectrum, we detect unambiguous signatures of stellar photospheric absorption lines originating from OB-stars. Comparison with model spectra shows that more than one burst took place in its recent past: the most recent one at 4 − 7 Myr, and another aged ⩾20 Myr. ALMA observations of the [CI] atomic carbon emission line indicates that it has a low molecular gas fraction (∼13%) and short depletion time (∼40 Myr). Most intriguing is the modest velocity dispersion (⩽50 km/s) of these photospheric lines and the ALMA [CI] cold gas. We attribute its efficient star formation to compressive gas motions, induced by radio jets and/or interaction. Star formation works in concert with the AGN to remove any residual molecular gas and eventually leads to quenching.

scholarly journals Commissions of inquiry and pathways to accountability in Plateau State, Nigeria

2021 ◽  
Vol 59 (4) ◽  
pp. 439-462
Author(s):  
Marjoke Oosterom ◽  
Dung Pam Sha ◽  
Caitriona Dowd
Keyword(s):  
Civil Society ◽  
State Institutions ◽  
General Consensus ◽  
Commissions Of Inquiry ◽  
Plateau State ◽  
Multilevel Networks

ABSTRACTFor decades, Plateau State in Nigeria's Middle Belt has witnessed repeated ethnoreligious violence. Over this period, both state and federal governments have established formal Commissions of Inquiry (COIs) in response to unrest, tasked with investigating violence, identifying perpetrators, and – ultimately – strengthening accountability. While commissions’ mandates and specific outcomes varied, there is general consensus that inquiries have been largely ineffective at securing justice or establishing accountability for violence. This study seeks to understand the expectations placed on, and role of, COIs in Plateau State as pathways to formal accountability in a context of recurring violence. We argue that COIs are embedded in the complex, multilevel networks and politics of state and non-state institutions. Civil society, in turn, has diverse expectations and demands, and articulates these in fragmented ways. As a result, COIs served primarily as another avenue for interest-based negotiations.

Brightness Suppression of Relativistic Radio Jets of Quasars: The Role of the Lower Electron Energy Cutoff

2004 ◽  
Vol 603 (1) ◽  
pp. L9-L12 ◽  
Author(s):  
Gopal-Krishna ◽  
Peter L. Biermann ◽  
Paul J. Wiita
Keyword(s):  
Electron Energy ◽  
Radio Jets ◽  
Energy Cutoff

scholarly journals The Role of Quasars in Galaxy Formation

2009 ◽  
Vol 5 (S267) ◽  
pp. 17-25 ◽  
Author(s):  
D. Elbaz
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Positive Feedback ◽  
Local Environment ◽  
Active Role ◽  
Molecular Gas ◽  
Massive Galaxies ◽  
Radio Jets ◽  
The Galaxy

AbstractWe discuss evidence that quasars, and more generally radio jets, may have played an active role in the formation stage of galaxies by inducing star formation, i.e., through positive feedback. This mechanism first proposed in the 1970s has been considered as anecdotal until now, contrary to the opposite effect that is generally put forward, i.e., the quenching of star formation in massive galaxies to explain the galaxy bimodality, downsizing, and the universal black hole mass over bulge stellar mass ratio. This suggestion is based on the recent discovery of an ultra-luminous infrared galaxy, i.e., an extreme starburst, that appears to be triggered by a radio jet from the QSO HE 0450-2958 at z = 0.2863, together with the finding in several systems of a positional offset between molecular gas and quasars, which may be explained by the positive feedback effect of radio jets on their local environment.

scholarly journals Feedback and environmental effects in elliptical galaxies

2009 ◽  
Vol 5 (H15) ◽  
pp. 289-290
Author(s):  
Craig L. Sarazin
Keyword(s):  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Energy Output ◽  
Radio Sources ◽  
Early Type ◽  
Gas Stripping ◽  
Interstellar Gas ◽  
X Ray ◽  
Radio Jets

AbstractThe role of the environment of an elliptical galaxy on its hot interstellar gas is discussed. In general, the X-ray halos of early-type galaxies tend to be smaller and fainter in denser environments, with the exception of group-central galaxies. X-ray observations show many examples of nearby galaxies which are undergoing gas stripping. On the other hand, most bright galaxies in clusters do manage to retain small coronae of X-ray emission. Recent theoretical and observational results on the role of feedback from AGN at the centers of elliptical galaxies on their interstellar gas are reviewed. X-ray observations show many examples of X-ray holes in the central regions of brightest-cluster galaxies; in many cases, the X-ray holes are filled with radio lobes. Similar radio bubbles are seen in groups and individual early-type galaxies. “Ghost bubbles” are often seen at larger radii in clusters and galaxies; these bubbles are faint in high radio frequencies, and are believed to be old radio bubbles which have risen buoyantly in the hot gas. Low frequency radio observations show that many of the ghost bubbles have radio emission; in general, these long wavelength observations show that radio sources are much larger and involve greater energies than had been previously thought. The radio bubbles can be used to estimate the total energy output of the radio jets. The total energies deposited by radio jets exceed the losses from the gas due to radiative cooling, indicating that radio sources are energetically capable of heating the cooling core gas and preventing rapid cooling.

Sign in / Sign up

Export Citation Format

Share Document