Optical spectroscopy of radio jets in 3C 31, 3C 75, 3C 83.1B, and 3C 465

1986 ◽  
Vol 64 (4) ◽  
pp. 369-372 ◽  
Author(s):  
Christopher P. O'Dea ◽  
Frazer N. Owen ◽  
William C. Keel
Keyword(s):  
Optical Spectroscopy ◽  
External Medium ◽  
Line Emission ◽  
Radio Sources ◽  
Ionized Gas ◽  
Radio Jets ◽  
Upper Limits ◽  
The Galaxy ◽  
Lower Limits ◽  
Total Velocity

We present preliminary results of optical spectroscopy of four radio galaxies with jets (3C 75, 3C 465, 3C 31, and 3C 83. 1B (NGC 1265)). We examined selected regions in and around the radio jets for evidence of the interaction of the jets with their external medium (e.g., entrainment or bending through collision with clouds). We searched for the emission lines expected from ionized gas at a temperature of T ~ 104 K (e.g., Hα and [NII]) as well as those expected at higher temperatures (T ~ 106 K, Fe X (λ6374) and Fe XIV (λ5303)).We found no extranuclear emission in the regions searched in 3C 75, 3C 465, and 3C 83.1B. Assuming values for the pressure in the environment of the radio sources, we found the upper limits to the line emission correspond to model-dependent lower limits to the temperature in the range T ≥ 1.5–3 × 106 K and upper limits to the electron density in the range ne ≤ 5 × 10−2−5 × 10−3 cm−3.In 3C 31, we detected extended Hα and [NII] emission that is peaked on the nucleus and exhibits a velocity gradient. The [NII] emission has a total velocity width of ~800 km∙s−1. It is not yet clear whether any of this emission is associated with the jet (e.g., entrained gas) or whether it is associated with a known dust lane in the galaxy NGC 383.

scholarly journals A Search for Recombination Line Emission from the Galactic Equator at 408 MHz

1976 ◽  
Vol 29 (5) ◽  
pp. 419 ◽  
Author(s):  
MJ Batty
Keyword(s):  
Surface Brightness ◽  
Thermal Emission ◽  
Line Emission ◽  
Hii Regions ◽  
Line Of Sight ◽  
Recombination Line ◽  
Upper Limits ◽  
Low Surface Brightness ◽  
Lower Limits ◽  
Galactic Longitude

A search for H 2520( recombination line emission was made by scanning the galactic equator region using the Molonglo radio telescope. Upper limits were established over the range of galactic longitude accessible to the instrument. For the region III ;S 40�, estimates of the background thermal continuum brightness temperature were used to derive lower limits of ~ 2000 K for the electron temperature of the gas along the line of sight. Lower limits for the electron density obtained by considering probable non-LTE effects suggest that the thermal emission over this range is due to low surface brightness HII regions. The observed H 2520( upper limit averaged over the range 270� ;S I ;S 320� just admits the line intensity calculated by Shaver (1975) for the cold cloud component of the general interstellar medium.

scholarly journals Classification of Supernova Remnants and HII Regions from their Recombination Line Emission

1972 ◽  
Vol 25 (5) ◽  
pp. 539 ◽  
Author(s):  
JR Dickel ◽  
DK Milne
Keyword(s):  
Electron Temperature ◽  
Supernova Remnants ◽  
Line Emission ◽  
Hii Regions ◽  
Radio Sources ◽  
Recombination Line ◽  
Line Frequency ◽  
Upper Limits ◽  
Galactic Radio

H109a, recombination line observations are used in an attempt to classify 46 galactic radio sources as either supernova remnants or HII regions. Long integrations at the H109a line frequency on two well-known supernova remnants (IC 443 and 3C 391) provide improved upper limits on the line emission from these objects. From these results the electron temperature in IC 443 is estimated to be in excess of 1�6 � 104 K.

scholarly journals NIR Line Observations of Starburst Galaxies

1999 ◽  
Vol 186 ◽  
pp. 286-286
Author(s):  
H. Sugai ◽  
M.A. Malkan ◽  
M.J. Ward ◽  
R.I. Davies ◽  
I.S. McLean
Keyword(s):  
Line Emission ◽  
Starburst Galaxies ◽  
Emission Lines ◽  
Ionized Gas ◽  
The Galaxy ◽  
Component C ◽  
Band Spectra ◽  
Marginal Detection ◽  
The Continuum ◽  
K Band

We have obtained images of the H2and Brγ emission lines in the galaxy interacting system NGC 3690 + IC 694. We have also obtained simultaneous H- and K-band spectra for three of its 2μm continuum peaks. The most detectable line emission is concentrated at the continuum peaks. Therefore, the emission lines as well as stellar absorption lines can be used as tracers of the activity in the nuclei themselves. From the strong Brγ and marginal detection of Br10 at the nucleus of IC 694, we derive a large extinction for the fully ionized gas in this nucleus. If we adopt this extinction also for the [Fe II]1.64μm emission, the extinction-corrected [Fe II]1.64μm/Brγ ratio will lie at the higher end of starburst galaxies, and is typical for AGNs or AGN/starburst composites. This might imply that many SNRs are involved in the starburst at this nucleus, unless it includes an AGN. All of our results for Component C, including very little CO absorption in the K band, a largeEW(Brγ), a small H2/Brγ ratio, the effective temperature (Teff≃ 40,000K) derived from HeI 1.70μm/Br10 and HeI 2.06μm/Brγ, are consistent with a very young starburst.

scholarly journals Constraining magnetic fields in the circumgalactic medium

2020 ◽  
Vol 496 (3) ◽  
pp. 3142-3151 ◽  
Author(s):  
Ting-Wen Lan 藍鼎文 ◽  
J Xavier Prochaska
Keyword(s):  
Magnetic Fields ◽  
Column Density ◽  
High Redshift ◽  
Line Of Sight ◽  
Radio Sources ◽  
Number Density ◽  
Ionized Gas ◽  
Upper Limits ◽  
Circumgalactic Medium ◽  
Magnetohydrodynamic Simulations

ABSTRACT We study the properties of magnetic fields in the circumgalactic medium (CGM) of z < 1 galaxies by correlating Faraday rotation measures (RMs) of ∼1000 high-redshift radio sources with the foreground galaxy number density estimated from the DESI Legacy Imaging Surveys. This method enables us to extract signals of RMs contributed by intervening gas around multiple galaxies. Our results show that there is no detectable correlation between the distribution of RMs and the number of foreground galaxies, contrary to several previous results. Utilizing the non-detection signals, we estimate 3σ upper limits to the RMs from the CGM of $\sim \!20 \rm \ rad\, m^{-2}$ within 50 kpc and $\sim \!10 \rm \ rad \, m^{-2}$ at separations of 100 kpc. By adopting a column density distribution of ionized gas obtained from absorption-line measurements, we further estimate the strengths of coherent magnetic fields parallel to the line of sight of $\lt \rm 2 \ \mu G$ in the CGM. We show that the estimated upper limits of RMs and magnetic field strengths are sufficient to constrain outputs of recent galaxy magnetohydrodynamic simulations. Finally, we discuss possible causes for the inconsistency between our results and previous works.

scholarly journals High Velocity Ionized Gas near IRS 16

1989 ◽  
Vol 136 ◽  
pp. 525-526
Author(s):  
T. R. Geballe ◽  
J. B. Lugten
Keyword(s):  
High Velocity ◽  
Spectral Properties ◽  
Radial Flow ◽  
Line Emission ◽  
Compact Object ◽  
Characteristic Dimension ◽  
Ionized Gas ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Important Means

An important means of studying the unusual activity within the central ~0.15 parsec of the galaxy is to obtain detailed information on the high velocity ionized gas there. This gas was first reported by Hall, Kleinmann, and Scoville (1982), who observed the He I line at 2.06 μm. Subsequent observations of this line and the Br ∝ and Br γ lines of H I (4.05 μm and 2.17 μm, respectively) by Geballe et al. (1984, 1987) have defined the coarse spatial and spectral properties more accurately. Briefly, the broad (i.e., |v| > 400 km/s) line emission, as observed at velocity resolutions as high as 400 km/s and angular resolutions as high as 2.5″ (1) extends approximately to +/– 700 km/s (e.g., see Fig. 1), (2) is spatially resolved, with a characteristic dimension of 3″, (3) is centered approximately on IRS 16C, and (4) appears to be due neither to rotational motion nor to a simple radial flow from or onto a single compact object. These properties are difficult to understand in terms of simple models, and point out the necessity for further measurements at higher spectral and spatial resolutions.

scholarly journals Cold and Warm Gas Outflows in Radio AGN

2009 ◽  
Vol 5 (S267) ◽  
pp. 429-437
Author(s):  
Raffaella Morganti ◽  
Joanna Holt ◽  
Clive Tadhunter ◽  
Tom Oosterloo
Keyword(s):  
Galaxy Evolution ◽  
Radio Sources ◽  
Ionized Gas ◽  
Feedback Effects ◽  
Nuclear Activity ◽  
Neutral Gas ◽  
Short Summary ◽  
The Galaxy ◽  
Mass Outflow ◽  
The Impact

AbstractThe study of the conditions and the kinematics of the gas in the central region of AGN provides important information on the relevance of feedback effects connected to the nuclear activity. Quantifying these effects is key for constraining galaxy evolution models. Here we present a short summary of our recent efforts to study the occurrence and the impact of gas outflows in radio-loud AGN that are in their first phase of their evolution. Clear evidence for AGN-induced outflows has been found for the majority of these young radio sources. The outflows are detected both in (warm) ionized as well in (cold) atomic neutral gas, and they are likely to be driven (at least in most of the cases) by the interaction between the expanding jet and the medium. The mass outflow rates of the cold gas (Hi) appear to be systematically higher than those of the ionized gas. The former reach up to ~50 M⊙ yr−1 and are in the same range as “mild” starburst-driven superwinds in ULIRGs, whilst the latter are currently estimated to be a few solar masses per year. However, the kinetic powers associated with these gaseous outflows are a relatively small fraction (a few × 10−4) of the Eddington luminosity of the galaxy. Thus, they do not appear to match the requirements of the galaxy evolution feedback models.

scholarly journals Distant Radio Galaxies: the Strong Link between the Radio and Optical Emission

1996 ◽  
Vol 175 ◽  
pp. 583-584
Author(s):  
Huub Röttgering
Keyword(s):  
Radio Source ◽  
Line Emission ◽  
Optical Emission ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Strong Link ◽  
The Galaxy ◽  
Optical Continuum

Recent observations of distant radio galaxies show that there is a strong link between the radio source and the optical continuum and Lyα line emission from the galaxy. This link is discussed in terms of differences in age, orientation and environment between the radio sources.

scholarly journals Rotating Gas and the Shapes of Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 25-26
Author(s):  
L. S. Sparke
Keyword(s):  
Seyfert Galaxies ◽  
External Pressure ◽  
Opening Angle ◽  
Radio Sources ◽  
Extragalactic Radio Source ◽  
Radio Structure ◽  
Radio Jets ◽  
Extended Radio ◽  
The Galaxy ◽  
Scale Properties

The power for a strong extragalactic radio source comes from deep within the nucleus, but the extended radio structure is clearly related to the larger-scale properties of the galaxy in which it lives. Very large sources are found in elliptical rather than spiral galaxies, and big galaxies have stronger radio sources than small ones. The narrow jets mapped in weaker radio galaxies do not expand with a constant opening angle, but become better focussed along their length, suggesting that they are confined by an external pressure. This paper discusses how the rotation of a radio galaxy affects the distribution of gas within it, and consequently the radio structure in elliptical and Seyfert galaxies. A model is proposed which leads to a specific prediction, relating the width of radio jets to the rotation speed of the galaxy in which they lie.

scholarly journals Ionized and Neutral Gas in the Central 10 PC of the Galaxy

1994 ◽  
Vol 140 ◽  
pp. 156-160
Author(s):  
K. Y. Lo ◽  
R. Plante ◽  
J. Lacy ◽  
M. Wright ◽  
N. Killeen
Keyword(s):  
Line Emission ◽  
Gas Velocity ◽  
Ionized Gas ◽  
Neutral Gas ◽  
The Galaxy ◽  
Sgr A ◽  
The Relationship

AbstractObservations of the 12.8 μm [NeII] line emission, the OH absorption against Sgr A and the HCN emission were compared to determine the relationship between the ionized and neutral gas in the central 10 pc of the Galaxy. The distribution of the neutral gas is too asymmetric to be a ring or disk. Along the western arc, the ionized gas velocity is very different from that of the neutral gas, suggesting it may not be the ionized inner edge of the circum-nuclear neutral gas.

scholarly journals Large Bent Jets in the Inner Region of CSS

1996 ◽  
Vol 175 ◽  
pp. 71-72
Author(s):  
F. Mantovani ◽  
W. Junor ◽  
M. Bondi ◽  
L. Padrielli ◽  
W. Cotton ◽  
...  
Keyword(s):  
Velocity Structure ◽  
Radio Sources ◽  
Ambient Media ◽  
The Core ◽  
Gaseous Environment ◽  
Radio Jets ◽  
Large Size ◽  
Superluminal Motion ◽  
Inner Region ◽  
Quasars And Radio Galaxies

Recently we focussed our attention on a sample of Compact Steep-spectrum Sources (CSSs) selected because of the large bent radio jets seen in the inner region of emission. The largest distortions are often seen in sources dominated by jets, and there are suggestions that this might to some extent be due to projection effects. However, superluminal motion is rare in CSSs. The only case we know of so far is 3C147 (Alef at al. 1990) with a mildly superluminal speed of ≃ 1.3v/c. Moreover, the core fractional luminosity in CSSs is ≃ 3% and ≤ 0.4% for quasars and radio galaxies respectively. Similar values are found for large size radio sources i.e. both boosting and orientations in the sky are similar for the two classes of objects. An alternative possibility is that these bent-jet sources might also be brightened by interactions with the ambient media. There are clear indications that intrinsic distortions due to interactions with a dense inhomogeneous gaseous environment play an important role. Observational support comes from the large RMs found in CSSs (Taylor et al. 1992; Mantovani et al. 1994; Junor et al. these proc.) and often associated with strong depolarization (Garrington & Akujor, t.p.). The CSSs also have very luminous Narrow Line Regions emission, with exceptional velocity structure (Gelderman, t.p.).

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