scholarly journals Radio Properties of GPS and CSS Sources: Galaxies versus Quasars

2003 ◽  
Vol 20 (1) ◽  
pp. 118-122 ◽  
Author(s):  
Carlo Stanghellini
Keyword(s):  
Radio Source ◽  
Radio Sources ◽  
Spectrum Radio ◽  
The Common ◽  
The Difference

AbstractOn the basis of the different radio properties (especially different radio morphologies) between GPS galaxies and GPS quasars, I suggest that GPS galaxies are a more homogeneous class mainly consisting of compact symmetric objects, while the majority of GPS quasars are an intrinsically different type of radio source, similar to the common flat spectrum radio sources. For CSS radio sources the difference between galaxies and quasars is less evident. This is interpreted as a bias correlated with size: samples of smaller objects are more likely to be contaminated by unrelated objects. This is consistent also with the high percentage of blazar/quasar objects present in a sample of the even smaller HFP radio sources.

scholarly journals The Milliarcsecond Core of 3C147 at 6 cm

1984 ◽  
Vol 110 ◽  
pp. 29-30 ◽  
Author(s):  
E. Preuss ◽  
W. Alef ◽  
N. Whyborn ◽  
P.N. Wilkinson ◽  
K.I. Kellermann
Keyword(s):  
Radio Source ◽  
Radio Sources ◽  
Radio Structure ◽  
Extragalactic Radio Sources ◽  
North East ◽  
The North ◽  
Vlbi Observations ◽  
Spectrum Radio ◽  
The One

3C147 is a compact (≲1″), steep spectrum radio source identified with a quasar at z = 0.545 (0″.001 = 7.4 pc; c/Ho = 6000 Mpc and qo = 0.5). The radio structure shown by VLBI observations at 18 cm (Readhead & Wilkinson, 1980; Simon et al., this volume), at 50 cm (Wilkinson et al., 1977), and at 90 cm (Simon et al., 1980 and 1983) shows a bright ‘core’ (60 pc at one end of a ‘jet’ ~0″.2 (1.5 kpc) in length oriented in p.a. ~ −130°. In this sense 3C147 is typical of the one-sided ‘core-jet’ structures commonly found in the centres of other extragalactic radio sources. However, MERLIN observations at 6 cm (Wilkinson, this vol.) and VLA observations at 2 cm (Crane & Kellermann, unpubl.; Readhead et al., 1980) show a larger elongated feature extending ~0″.5 (3.7 kpc) to the North East of the bright core in p.a. ~25° or on the opposite side to the 0″.2 jet.

scholarly journals Jet–Cloud Interactions in Compact Steep Spectrum Radio Sources

2003 ◽  
Vol 20 (1) ◽  
pp. 88-93 ◽  
Author(s):  
C. P. O'Dea ◽  
W. H. de Vries ◽  
A. M. Koekemoer ◽  
S. A. Baum ◽  
D. J. Axon ◽  
...  
Keyword(s):  
Emission Line ◽  
Radio Source ◽  
Bow Shock ◽  
Radio Sources ◽  
Line Profiles ◽  
Multiple Components ◽  
Spectrum Radio ◽  
Velocity Variations

AbstractWe have obtained HST/STIS long slit spectroscopy of the aligned emission line nebulae in three compact steep spectrum (CSS) radio sources — 3C 67, 3C 277.1, and 3C 303.1. We find systematic offsets (˜300–500 kms) of the emission line velocities on one or both sides of the radio sources. We also see evidence for broad lines (FWHM ˜500 kms) and complex emission line profiles. In 3C 303.1 the data are consistent with multiple components and possibly split lines. The amplitude of the velocity variations is not so large as to exclude gravitationally-induced motions. However, the complex kinematics, the lack of a signature of Keplerian rotation, and the association of the velocity variations with the radio lobes are consistent with the observed ˜300–500 kms velocities being driven by the expansion of the radio source. Acceleration of the clouds by the bow shock is plausible given the estimated densities in the clouds and the velocities observed in the much smaller compact symmetric objects and with expansion velocities estimated from spectral ageing. This conclusion is unchanged if we consider the scenario in which the cloud acceleration is dominated by the post bow shock flow.

scholarly journals Radio-optical Identification of Very-Steep Spectrum Radio Sources from the UTR-2 Catalogue

2002 ◽  
Vol 199 ◽  
pp. 217-218 ◽  
Author(s):  
H. Andernach ◽  
O.V. Verkhodanov ◽  
N.V. Verkhodanova
Keyword(s):  
Radio Source ◽  
High Redshift ◽  
Radio Galaxies ◽  
Image Databases ◽  
Radio Continuum ◽  
Radio Sources ◽  
Optical Identification ◽  
X Ray ◽  
Spectrum Radio

We used radio source catalogues accessible from the CATS database to establish radio continuum spectra for decametric radio sources in the UTR-2 catalogue. In an attempt to find further candidates for high-redshift radio galaxies, we searched the FIRST and NVSS surveys for counterparts of a sample of UTR sources with ultra-steep radio spectra (USS, α ≤ −1.2, S ∼ vα). We derived accurate positions and sizes for 23 of these USS sources. The search for optical counterparts from the APM (object) and DSS (image) databases, as well as infrared and X—ray identifications of these UTR sources are in progress.

scholarly journals Probing multi-phase outflows and AGN feedback in compact radio galaxies: the case of PKS B1934-63

2018 ◽  
Vol 617 ◽  
pp. A139 ◽  
Author(s):  
F. Santoro ◽  
M. Rose ◽  
R. Morganti ◽  
C. Tadhunter ◽  
T. A. Oosterloo ◽  
...  
Keyword(s):  
Radio Source ◽  
Radio Sources ◽  
Ionized Gas ◽  
Near Ir ◽  
Spectrum Radio ◽  
Radial Extent ◽  
Outflow Rate ◽  
Mass Outflow ◽  
Low Efficiency ◽  
Multi Phase

Young radio AGN are pivotal for our understanding of many of the still-debated aspects of AGN feedback. In this paper we present a study of the interstellar medium (ISM) in the compact, peaked-spectrum radio galaxy PKS B1934-63 using X-shooter observations. Most of the warm ionized gas resides within a circum-nuclear disk with a radius of about 200 pc that is likely to constitute the gas reservoir from which the central black hole feeds. On the other hand, we find a biconical outflow of warm ionized gas with an estimated radius of 59 ± 12 pc. This matches the radial extent of the radio source and suggests that the outflow is jet driven. Thanks to the superior wavelength coverage of the data, we can estimate the density of the warm ionized gas using the trans-auroral line technique, and we find that the outflowing gas has remarkably high density, up to log ne (cm−3) ≃ 5.5. The estimated mass outflow rate is low (Ṁ = 10−3 −10−1 M⊙ yr−1), and the AGN feedback operates at relatively low efficiency (Ė/Lbol ∼ 10−4−10−3%). In addition, optical and near-IR line ratios show that the expansion of the radio source drives fast shocks (with velocities vs ≳ 500 km s−1) that ionize and accelerate the outflowing gas. At odds with the properties of other compact, peaked-spectrum radio sources hosting warm ionized gas outflows, we do not find signs of kinematically disturbed or outflowing gas in phases colder than the warm ionized gas. We argue that this is due to the young age of our source and thus to the recent nature of the AGN-ISM interaction, and suggest that cold gas forms within the outflowing material and the shock-ionized outflowing gas of PKS B1934-63 did not have enough time to cool down and accumulate in a colder phase. This scenario is also supported by the multi-phase outflows of other compact and young radio sources in the literature.

scholarly journals Compact Steep Spectrum Radio Sources

2002 ◽  
Vol 199 ◽  
pp. 209-210
Author(s):  
S. Jeyakumar ◽  
D. J. Saikia
Keyword(s):  
Radio Source ◽  
Radio Sources ◽  
Spectrum Radio

We suggest that most compact radio sources are young objects advancing outwards through a dense environment which is asymmetric on opposite sides of the nucleus. This gas might be intimately related to the supply of fuel for the young radio source.

scholarly journals A VLBI Study of GHz-Peaked-Spectrum Radio Sources

1996 ◽  
Vol 175 ◽  
pp. 67-68 ◽  
Author(s):  
C. Stanghellini ◽  
C.P. O'DEA ◽  
S.A. Baum ◽  
D. Dallacasa ◽  
R. Fanti ◽  
...  
Keyword(s):  
Radio Source ◽  
Radio Sources ◽  
Narrow Line ◽  
Radio Observations ◽  
Turbulent Environment ◽  
Line Region ◽  
Spectrum Radio ◽  
Narrow Line Region ◽  
Simple Convex

The GHz-Peaked-Spectrum (GPS) radio sources are powerful (Lradio ≈ 1045 erg sec–1) and compact (10–100 mas, 10–1000 parsecs) sources characterized by a simple convex spectrum which peaks near 1 GHz (O'Dea et al. 1991 and references therein).Optical and radio observations lead to the conclusion that GPS sources are formed when the radio source is confined to the narrow line region (or an even smaller scale) by a dense and clumpy medium. This could lead to 2 different evolutionary scenarios: as first suggested by Phillips and Mutel (1982) GPS radio sources could be classical double radio sources at the very first stage of their life, or alternatively they will never become as large as the classical doubles since the dense and turbulent environment is able to confine and trap the radio emitting region on the scale of the NLR (Baum et al. 1990).

scholarly journals Variability Observations of a Complete Sample of Flat-Spectrum Radio Sources: Preliminary Results

2001 ◽  
Vol 182 ◽  
pp. 93-96
Author(s):  
A.G. Gorshkov ◽  
V.K. Konnikova ◽  
M.G. Mingaliev
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Time Scale ◽  
Radio Sources ◽  
Complete Sample ◽  
Limited Sample ◽  
Preliminary Results ◽  
Spectrum Radio ◽  
Intrinsic Mechanism ◽  
Short Time

AbstractThis report presents preliminary results of daily observations, over 60 and 100 days, of a complete, flux-limited sample of radio sources with flat spectra. The existence of flicker up to 21.7 GHz was confirmed, for sources with flat spectra, on a time-scale of 4 days. A model explaining the flux density variations of the unique radio source 0524+034, on long and short time-scales, by an intrinsic mechanism is proposed.

scholarly journals Searching for signs of jet-driven negative feedback in the nearby radio galaxy UGC 05771

2019 ◽  
Vol 489 (4) ◽  
pp. 4944-4961 ◽  
Author(s):  
Henry R M Zovaro ◽  
Nicole P H Nesvadba ◽  
Robert Sharp ◽  
Geoffrey V Bicknell ◽  
Brent Groves ◽  
...  
Keyword(s):  
Star Formation ◽  
Radio Source ◽  
Large Fraction ◽  
Host Galaxy ◽  
Radio Sources ◽  
Host Galaxies ◽  
Ionized Gas ◽  
Spectrum Radio ◽  
Hydrodynamical Simulations ◽  
Jet Plasma

ABSTRACT Hydrodynamical simulations predict that the jets of young radio sources can inhibit star formation in their host galaxies by injecting heat and turbulence into the interstellar medium (ISM). To investigate jet–ISM interactions in a galaxy with a young radio source, we have carried out a multiwavelength study of the z = 0.025 Compact Steep Spectrum radio source hosted by the early-type galaxy UGC 05771. Using Keck/OSIRIS observations, we detected H2 1–0 S(1) and [Fe ii] emission at radii of 100s of parsecs, which traces shocked molecular and ionized gas being accelerated outwards by the jets to low velocities, creating a ‘stalling wind’. At kpc radii, we detected shocked ionized gas using observations from the CALIFA survey, covering an area much larger than the pc-scale radio source. We found that existing interferometric radio observations fail to recover a large fraction of the source’s total flux, indicating the likely existence of jet plasma on kpc scales, which is consistent with the extent of shocked gas in the host galaxy. To investigate the star formation efficiency in UGC 05771, we obtained IRAM CO observations to analyse the molecular gas properties. We found that UGC 05771 sits below the Kennicutt–Schmidt relation, although we were unable to definitively conclude if direct interactions from the jets are inhibiting star formation. This result shows that jets may be important in regulating star formation in the host galaxies of compact radio sources.

Ḥadith ‘Āishah fī Man’i al-Nisā’ Min al-Masājid; Niqāsh ‘Ulamā’ Bangladesh Ḥaulahu

2020 ◽  
Vol 9 (1) ◽  
pp. 97-115
Author(s):  
Syed Mahmudul Hasan
Keyword(s):  
Analytical Method ◽  
Inductive Method ◽  
The Common ◽  
The Difference ◽  
Common Situation

The Narration of Aisyah (May Allah be pleased with her), is the main focus of the controversy among Bangladeshi scholars on the issue of women's prayer in the mosque. The reason for the dispute is that a group of them issued the ruling based on the phenomenon of the text, and the others explained the ruling of Hadith according to the common situation in the society. If the circumstances change, the ruling will change along with it, because the originality of the issue is permissible, that is proven from other texts. This research adopts an inductive method to survey the Prophetic hadiths that talk about the prayer of women in the Mosque in terms of permissibility and prohibition and analytical method to analyze the difference in opinion of Bangladeshi scholars related to this issue. The research finds that the ruling of Shari’ah is a process that is continuous and permanent. But in necessity and emergency, it has the notion of flexibility and explanation. In the issue of women’s presence in the mosque, they should be allowed if they abide by the suggestions of Prophet (s) and should not if they don’t. So, Prohibition is not from the prophet (s), but it is from their obedience to the ruling.

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