Photoionization models and the low-excitation line emission region of active galaxy nuclei

1981 ◽  
Vol 74 (1) ◽  
pp. 71-82
Author(s):  
R. B. Gruenwald
Keyword(s):  
Line Emission ◽  
Active Galaxy ◽  
Emission Region ◽  
Excitation Line

scholarly journals The MURALES survey

2020 ◽  
Vol 645 ◽  
pp. A12
Author(s):  
B. Balmaverde ◽  
A. Capetti ◽  
A. Marconi ◽  
G. Venturi ◽  
M. Chiaberge ◽  
...  
Keyword(s):  
Emission Line ◽  
Large Scale ◽  
Line Emission ◽  
Emission Region ◽  
Gas Velocity ◽  
Ionized Gas ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Integral Field Spectrograph ◽  
Integral Field

We present the final observations of a complete sample of 37 radio galaxies from the Third Cambridge Catalogue (3C) with redshift < 0.3 and declination < 20° obtained with the VLT/MUSE optical integral field spectrograph. These data were obtained as part of the MUse RAdio Loud Emission line Snapshot (MURALES) survey with the main goal of exploring the AGN feedback process in the most powerful radio sources. We present the data analysis and, for each source, the resulting emission line images and the 2D gas velocity field. Thanks to the unprecedented depth these observations reveal emission line regions (ELRs) extending several tens of kiloparsec in most objects. The gas velocity shows ordered rotation in 25 galaxies, but in several sources it is highly complex. We find that the 3C sources show a connection between radio morphology and emission line properties. In the ten FR I sources the line emission region is generally compact, only a few kpc in size; only in one case does it exceed the size of the host. Conversely, all but two of the FR II galaxies show large-scale structures of ionized gas. The median extent is 16 kpc with the maximum reaching a size of ∼80 kpc. There are no apparent differences in extent or strength between the ELR properties of the FR II sources of high and low gas excitation. We confirm that the previous optical identification of 3C 258 is incorrect: this radio source is likely associated with a quasi-stellar object at z ∼ 1.54.

Detection of Far-Ultraviolet High-Excitation Line Emission and Lyman- beta Absorption in the Gravitational Lens Q0957+561

1993 ◽  
Vol 417 ◽  
pp. L57 ◽  
Author(s):  
A. G. Michalitsianos ◽  
J. Nichols-Bohlin ◽  
F. C. Bruhweiler ◽  
D. Kazanas ◽  
Y. Kondo ◽  
...  
Keyword(s):  
Line Emission ◽  
Gravitational Lens ◽  
High Excitation ◽  
Excitation Line ◽  
Far Ultraviolet

scholarly journals The Line Emission Region in III Zw 2: Kinematics and Variability

2003 ◽  
Vol 599 (1) ◽  
pp. 185-192 ◽  
Author(s):  
L. Č. Popović ◽  
E. G. Mediavilla ◽  
E. Bon ◽  
N. Stanić ◽  
A. Kubičela
Keyword(s):  
Line Emission ◽  
Emission Region

scholarly journals Radio spectral index distribution of SDSS-FIRST sources across optical diagnostic diagrams

2019 ◽  
Vol 630 ◽  
pp. A83 ◽  
Author(s):  
Michal Zajaček ◽  
Gerold Busch ◽  
Mónica Valencia-S. ◽  
Andreas Eckart ◽  
Silke Britzen ◽  
...  
Keyword(s):  
Black Holes ◽  
Emission Line ◽  
Spectral Index ◽  
Line Emission ◽  
Optical Emission ◽  
Supermassive Black Holes ◽  
Emission Region ◽  
Optical Diagnostic ◽  
Liner Galaxies ◽  
Ionization Ratio

Context. The empirical relations between supermassive black holes and their host spheroids point towards the crucial role of galactic nuclei in affecting the properties of their hosts. A detailed understanding of how the activity of a galactic nucleus regulates the growth of its host is still missing. Aims. To understand the activity and the types of accretion of supermassive black holes in different hosts, it is essential to study the radio-optical properties of a large sample of extragalactic sources. In particular, we aim to study the radio spectral index trends across the optical emission line diagnostic diagrams to search for potential (anti)correlations. Methods. To this goal, we combined flux densities from the radio FIRST survey at 1.4 GHz (with the flux density range 10 mJy ≤ F1.4 ≤ 100 mJy) for 396 SDSS sources at intermediate redshift (0.04 ≤ z ≤ 0.4) with the Effelsberg radiotelescope measurements at 4.85 GHz and 10.45 GHz. The information about the optical emission-line ratios is obtained from the SDSS-DR7 catalogue. Results. Using the Effelsberg data, we were able to infer the two-point radio spectral index distributions for star-forming galaxies, composite galaxies (with a combined contribution to the line emission from the star formation and AGN activity), Seyferts, and low ionization narrow emission region (LINER) galaxies. Conclusions. While studying the distribution of steep, flat, and inverted sources across optical diagnostic diagrams, we found three distinct classes of radio emitters for our sample: (i) sources with a steep radio index, high ionization ratio, and high radio loudness, (ii) sources with a flat radio index, lower ionization ratio, and intermediate radio loudness, (iii) sources with an inverted radio index, low ionization ratio, and low radio loudness. The classes (i), (ii), and (iii) cluster mainly along the transition from Seyfert to LINER sources in the optical diagnostic (Baldwin, Phillips & Telervich; BPT) diagram. We interpret these groups as a result of the recurrent nuclear-jet activity.

scholarly journals Effects of Eccentric Orbit of BF Cygni on IUE and Optical Spectra

1988 ◽  
Vol 103 ◽  
pp. 299-300
Author(s):  
J. Mikolajewska ◽  
M. Mikolajewski
Keyword(s):  
Emission Measure ◽  
Line Emission ◽  
Optical Spectra ◽  
Emission Lines ◽  
Recent Analysis ◽  
Emission Region ◽  
Galactic Rotation ◽  
Resonance Emission ◽  
High Ionization ◽  
Cosmic Abundance

A recent analysis of all available photometric data has resulted in a new ephemeris for BF Cyg: MIN=JD 2415058 + 756.8E. Simultaneously, optical spectra collected in 1979–1986 showed periodic changes of all emission lines (Mikolajewska 1987; Mikolajewska & lijima 1987). It is interesting that the forbidden lines of [OIII] varied in antiphase to the permitted emission lines and optical brightness.IUE spectra taken in 1979–1981 showed a strong hot continuum and high ionization resonance emission lines of NV, SilV CIV, intercombination lines of NIV], NIII], SiIII], CIII] and OIII] as well as Hell emission. The observed λ2200Å interstellar absorption band suggests E(B-V)≃0.3. Taking into account the interstellar reddening distribution in the vicinity of BF Cyg (Lucke 1978; Mikolajewska & Mikolajewski 1980), the observed extinction implies a distance d≲1.5kpc. This distance is in good agreement with the observed low value of the systemic radial velocity (∼15 km/s, Fig.1) of BF Cyg and the standard galactic rotation law. The standard extinction curve with E(B-V)=0.3 (Seaton 1979) was used for reddening correction of the spectra. The UV continuum of BF Cyg can be interpreted as a combination of a hot subdwarf (Teff≃60000K, L≃2500L⊙ for d=1.5kpc) and hydrogen bf+ff emission (Te≃10000K). The emission measure of the nebular (bf+ff) continuum varied from ∼4×1059cm−3 at maximum to ∼1059cm−3 at minimum. Assuming cosmic abundance of Si/C the observed SiIII]/CIII] line ratio implies ne≃2×l010cm−3 at the photometric maximum and ne≃3×109cm−3 at the minimum. We assume that these values are representative of the region where the bulk of the HI Balmer and intercombination line emission is produced. The ratio of NV(1240)/NIV(1720) gives Te(NV)≃11500K close to the value derived for the Balmer emission region from the UV continuum fit.

Broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495

Nature ◽  
2009 ◽  
Vol 459 (7246) ◽  
pp. 540-542 ◽  
Author(s):  
A. C. Fabian ◽  
A. Zoghbi ◽  
R. R. Ross ◽  
P. Uttley ◽  
L. C. Gallo ◽  
...  
Keyword(s):  
Line Emission ◽  
Active Galaxy ◽  
Broad Line

scholarly journals Molecular Line Emission from the Young Planetary Nebula NGC 7027

2003 ◽  
Vol 209 ◽  
pp. 272-272
Author(s):  
Tatsuhiko I. Hasegawa ◽  
Sun Kwok
Keyword(s):  
Planetary Nebula ◽  
Small Volume ◽  
Line Emission ◽  
Peak Level ◽  
Ionization Front ◽  
Emission Region ◽  
Molecular Line ◽  
Ngc 7027 ◽  
Line Widths ◽  
Co Emission

NGC 7027 has been observed in eleven molecular species (in seventeen transitions) in the 200 and 300 GHz bands with the James Clarke Maxwell Telescope (Hasegawa & Kwok 2001). The results include a first detection of C2H in this source. The observed spectra of HCO+, H13CO+, HCN, CN, C2H, and CO+ show line widths larger than that of bulk CO emission but coincident with the full width at detection limit of weak wings in CO spectra. The sizes of the HCO+, HCN, and CN emitting regions are 13″ in diameter at half-peak level, significantly smaller than that (60″) of the CO emitting region. The emission of all the observed molecules other than CO and 13CO must originate from a very small volume compared with the entire CO envelope of NGC 7027. Since the central 10″ region is an ionized region, the molecular emission region (except CO) must be geometrically thin (ΔR = 1″ – 2″) and must be close to the ionization front.

scholarly journals SPECTROSCOPY OF THE ORION MOLECULAR CLOUD CORE

1981 ◽  
Vol 96 ◽  
pp. 187-205 ◽  
Author(s):  
N. Z. Scoville
Keyword(s):  
Molecular Cloud ◽  
Thermal Structure ◽  
Line Emission ◽  
Outer Radius ◽  
Emission Region ◽  
Vibrationally Excited ◽  
Hii Region ◽  
Brightness Temperatures ◽  
Neutral Gas ◽  
Expansion Time

Recent infrared and radio spectroscopic data pertaining to the Orion BN-KL infrared cluster are reviewed. A new, high resolution CO map shows that the thermal structure over the central 10′(1.5 pc) in the Orion molecular cloud is dominated by energy sources in the infrared cluster and M42. Peak CO brightness temperatures of 90 K occur on KL and near the bar at the southern edge of M42.Within the central 45″ of the infrared cluster, both radio and IR data reveal a highly energetic environment. Millimeter lines of several molecules (e.g. CO, HCN, and SiO) show emission over a full velocity range of 100 km s−1. These supersonic flows can be modeled as a differentially expanding envelope containing a total of ~5 M⊙ of gas within an outer radius of r ≃ 1.3 × 1017 cm. Over the same area emission is seen from vibrationally excited molecular hydrogen at an excitation temperature of 2000 K. The high velocity mm-line emission and the NIR H2 lines are clearly related since they exhibit similar spatial extents and line widths. Comparison of the total cooling rate for all the H2 lines with the estimated kinetic energy and expansion time for the mm-emission region indicates that the H2 emission probably arises from shock fronts where the expanding envelope impinges on the outer cloud.Near IR spectroscopy also probes ionized and neutral gas closely associated with BN. Br α and Br γ emission is detected from an ultracompact HII region of mass MHII ≲ 10−4 M⊙. Full widths for the HII lines are ~400 km s−1. CO bandhead emission detected in BN at λ ≃ 2.3 μm is probably collisionally pumped in a high excitation zone (nH+H2 > 1010 cm−3 and TK ≃ 3000 K) at only a few AU from the star. The velocity of both the HII and CO emission is VLSR ≃ + 20 km s−1; thus BN appears to be redshifted by 11 km s−1 with respect to OMC-1.

scholarly journals Inhomogeneous winds: the nature of emission-line profile variations in Wolf-Rayet spectra

1999 ◽  
Vol 193 ◽  
pp. 250-251
Author(s):  
Sébastien Lépine ◽  
Anthony F.J. Moffat
Keyword(s):  
Line Profile ◽  
Radial Direction ◽  
Fractal Structure ◽  
Line Emission ◽  
Emission Lines ◽  
Emission Region ◽  
Dynamical Structure ◽  
Wind Model ◽  
Large Fluctuations ◽  
Emission Line Profile

We present the results of simulations which show that stochastic line-profile variations (LPVS) of Wolf-Rayet emission lines can be reproduced with an inhomogeneous wind model, in which line-emission arises from a large number of discrete wind emission elements (DWEES). A comparison between simulations and LPVS from 9 WR stars provides useful information about the nature of the inhomogeneous and dynamical structure of the wind. Although the detailed spatial/fractal structure of the inhomogeneous wind is poorly constrained by analysis of LPVS, simulations suggest the wind to be highly fragmented, being composed of at least 104 DWEES in the line-emission region. Analysis of lpv patterns reaveal DWEES to be associated with large fluctuations in the velocity field. These fluctuations are locally anisotropic; the velocity dispersions of DWEES. are systematically larger in the radial direction (≈vr ≍ 200 km s−1) than in the transverse direction (σvθ ≈ 50 kms−1). lpv patterns also yield estimates of the wind acceleration, which can be used to test hypotheses about the wind velocity-law.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

Sign in / Sign up

Export Citation Format

Share Document