scholarly journals Star Formation and Active Galactic Nuclei in the Core of the Shapley Supercluster: A Very Large Array Survey of A3556, A3558, SC 1327-312, SC 1329-313, and A3562

2005 ◽  
Vol 130 (6) ◽  
pp. 2541-2558 ◽  
Author(s):  
Neal A. Miller
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array ◽  
The Core

AGN Feedback and its Importance to Galaxy Evolution in the Era of the ngVLA

2018 ◽  
Vol 14 (A30) ◽  
pp. 78-81
Author(s):  
Kristina Nyland
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galaxy Evolution ◽  
Angular Resolution ◽  
Galactic Nuclei ◽  
Gas Content ◽  
Large Array ◽  
Very Large Array ◽  
Frequency Coverage ◽  
Evolutionary Role

AbstractEnergetic feedback by Active Galactic Nuclei (AGN) plays an important evolutionary role in the regulation of star formation (SF) on galactic scales. However, the effects of this feedback as a function of redshift and galaxy properties such as mass, environment and cold gas content remain poorly understood. The broad frequency coverage (1 to 116 GHz), high collecting area (about ten times higher than the Karl G. Jansky Very Large Array), and superb angular resolution (maximum baselines of at least a few hundred km) of the proposed next-generation Very Large Array (ngVLA) are uniquely poised to revolutionize our understanding of AGN and their role in galaxy evolution.

Multiwavelength analysis of OH Megamaser galaxies: The case of IRAS11506-3851

2020 ◽  
Vol 15 (S359) ◽  
pp. 347-349
Author(s):  
Carpes P. Hekatelyne ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Active Galactic Nuclei ◽  
Hubble Space Telescope ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array ◽  
Star Forming ◽  
Star Forming Regions ◽  
Field Unit ◽  
Mixed Transition ◽  
Integral Field

AbstractWe present Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Hubble Space Telescope (HST) and Very Large Array (VLA) observations of the inner kpc of the OH Megamaser galaxy IRAS 11506-3851. In this work we discuss the kinematics and excitation of the gas as well as its radio emission. The HST images reveal an isolated spiral galaxy and the combination with the GMOS-IFU flux distributions allowed us to identify a partial ring of star-forming regions surrounding the nucleus with a radius of ≍500 pc. The emission-line ratios and excitation map reveal that the region inside the ring present mixed/transition excitation between those of Starbursts and Active Galactic Nuclei (AGN), while regions along the ring are excited by Starbursts. We suggest that we are probing a buried or fading AGN that could be both exciting the gas and originating an outflow.

scholarly journals THE ORIGIN OF DOUBLE-PEAKED NARROW LINES IN ACTIVE GALACTIC NUCLEI. I. VERY LARGE ARRAY DETECTIONS OF DUAL AGNs AND AGN OUTFLOWS

2015 ◽  
Vol 813 (2) ◽  
pp. 103 ◽  
Author(s):  
F. Müller-Sánchez ◽  
J. M. Comerford ◽  
R. Nevin ◽  
R. S. Barrows ◽  
M. C. Cooper ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array

scholarly journals Looking for the Elusive: Mining the VLA Archives for Radio Transients

2006 ◽  
Vol 5 (2) ◽  
Author(s):  
Destry Saul ◽  
Geoffrey Bower
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array ◽  
Massive Black Holes ◽  
Stellar Collapse ◽  
Upper Limit ◽  
Radio Transients

Detecting extragalactic radio transients will provide valuable information on several astronomical phenomena. Orphan gamma-ray burst afterglows (OGRBAs) and radio supernovae detection will be important for the theories of stellar collapse while the detection of tidal flares and variable active galactic nuclei (AGN) will provide details on massive black holes and galactic centers. In this paper we present the results of a survey we conducted using archived observations from the Very Large Array (VLA). We did not detect any transients in this set of data and from this we computed an upper limit on the rate of radio transients above 400 μJansky at 0.23 transients per square degree per year. This rules out one of several theories on the rates of OGRBAs.

scholarly journals RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY

2015 ◽  
Vol 799 (1) ◽  
pp. 72 ◽  
Author(s):  
Hai Fu ◽  
A. D. Myers ◽  
S. G. Djorgovski ◽  
Lin Yan ◽  
J. M. Wrobel ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Large Array ◽  
Very Large Array

scholarly journals Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

2020 ◽  
Vol 636 ◽  
pp. A64
Author(s):  
M. Berton ◽  
E. Järvelä ◽  
L. Crepaldi ◽  
A. Lähteenmäki ◽  
M. Tornikoski ◽  
...  
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
High Frequency ◽  
Galactic Nuclei ◽  
Large Array ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Ionized Gas ◽  
Very Large Array ◽  
Relativistic Jet

Narrow-line Seyfert 1 (NLS1) galaxies are peculiar active galactic nuclei. Most of them do not show strong radio emission, but seven radio-quiet (or radio-silent) NLS1s have recently been detected flaring multiple times at 37 GHz by the Metsähovi Radio Telescope, indicating relativistic jets in these peculiar sources. We observed them with the Karl G. Jansky Very Large Array (JVLA) in A configuration at 1.6, 5.2, and 9.0 GHz. Our results show that these sources are either extremely faint or not detected in the JVLA bands. At these frequencies, the radio emission from their relativistic jet must be absorbed, either through synchrotron self-absorption as it occurs in gigahertz-peaked sources, or more likely, through free-free absorption by a screen of ionized gas associated with starburst activity or shocks. Our findings cast new shadows on the radio-loudness criterion, which seems to be increasingly frequently a misleading parameter. New high-frequency and high-resolution radio observations are essential to test our hypotheses.

scholarly journals Constraining photoionization models with a reprojected optical diagnostic diagram

2020 ◽  
Vol 499 (4) ◽  
pp. 5749-5764 ◽  
Author(s):  
Xihan Ji ◽  
Renbin Yan
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Theoretical Models ◽  
Line Ratio ◽  
Star Forming ◽  
Optical Diagnostic ◽  
Diagnostic Diagram ◽  
Upper Limits ◽  
Nitrogen Abundance

ABSTRACT Optical diagnostic diagrams are powerful tools to separate different ionizing sources in galaxies. However, the model-constraining power of the most widely used diagrams is very limited and challenging to visualize. In addition, there have always been classification inconsistencies between diagrams based on different line ratios, and ambiguities between regions purely ionized by active galactic nuclei (AGNs) and composite regions. We present a simple reprojection of the 3D line ratio space composed of [N ii]λ6583/H α, [S ii]λλ6716, 6731/H α, and [O iii]λ5007/H β, which reveals its model-constraining power and removes the ambiguity for the true composite objects. It highlights the discrepancy between many theoretical models and the data loci. With this reprojection, we can put strong constraints on the photoionization models and the secondary nitrogen abundance prescription. We find that a single nitrogen prescription cannot fit both the star-forming locus and AGN locus simultaneously, with the latter requiring higher N/O ratios. The true composite regions stand separately from both models. We can compute the fractional AGN contributions for the composite regions, and define demarcations with specific upper limits on contamination from AGN or star formation. When the discrepancy about nitrogen prescriptions gets resolved in the future, it would also be possible to make robust metallicity measurements for composite regions and AGNs.

scholarly journals Intensity ratios for XDR/PDR identification

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
C.-E. Green ◽  
M. R. Cunningham ◽  
J. A. Green ◽  
J. R. Dawson ◽  
P. A. Jones ◽  
...  
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Active Galactic Nuclei ◽  
Intensity Ratio ◽  
Galactic Nuclei ◽  
Relative Influence ◽  
Calculation Methods ◽  
X Ray ◽  
Ratio Calculation ◽  
Intensity Ratios

AbstractThe intensity ratios of HCO+/HCN and HNC/HCN (1-0) reveal the relative influence of star formation and active galactic nuclei (AGN) or black holes on the circum-nuclear gas of a galaxy, allowing the identification of X-ray dominated regions (XDRs) and Photon-dominated regions (PDRs). It is not always clear in the literature how this intensity ratio calculation has been, or should be performed. This paper discusses ratio calculation methods for interferometric data.

scholarly journals STAR FORMATION RATES FROM [C II] 158 μm AND MID-INFRARED EMISSION LINES FOR STARBURSTS AND ACTIVE GALACTIC NUCLEI

2014 ◽  
Vol 790 (1) ◽  
pp. 15 ◽  
Author(s):  
L. Sargsyan ◽  
A. Samsonyan ◽  
V. Lebouteiller ◽  
D. Weedman ◽  
D. Barry ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Infrared Emission ◽  
Emission Lines ◽  
Mid Infrared
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