scholarly journals Star Formation in Low Radio Luminosity Active Galactic Nuclei from the Sloan Digital Sky Survey

2007 ◽  
Vol 134 (2) ◽  
pp. 457-465 ◽  
Author(s):  
W. H. de Vries ◽  
J. A. Hodge ◽  
R. H. Becker ◽  
R. L. White ◽  
D. J. Helfand
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Radio Luminosity ◽  
Sky Survey

scholarly journals Fundamental differences in the radio properties of red and blue quasars: insight from the LOFAR Two-metre Sky Survey (LoTSS)

2020 ◽  
Vol 494 (3) ◽  
pp. 3061-3079 ◽  
Author(s):  
D J Rosario ◽  
V A Fawcett ◽  
L Klindt ◽  
D M Alexander ◽  
L K Morabito ◽  
...  
Keyword(s):  
Star Formation ◽  
Control Sample ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Stellar Objects ◽  
Radio Detection ◽  
Sky Survey ◽  
Quasi Stellar Objects ◽  
First Time

ABSTRACT Red quasi-stellar objects (QSOs) are a subset of the luminous end of the cosmic population of active galactic nuclei (AGNs), most of which are reddened by intervening dust along the line of sight towards their central engines. In recent work from our team, we developed a systematic technique to select red QSOs from the Sloan Digital Sky Survey, and demonstrated that they have distinctive radio properties using the Faint Images of the Radio Sky at Twenty centimetres radio survey. Here we expand our study using low-frequency radio data from the LOFAR Two-metre Sky Survey (LoTSS). With the improvement in depth that LoTSS offers, we confirm key results: Compared to a control sample of normal ‘blue’ QSOs matched in redshift and accretion power, red QSOs have a higher radio detection rate and a higher incidence of compact radio morphologies. For the first time, we also demonstrate that these differences arise primarily in sources of intermediate radio loudness: Radio-intermediate red QSOs are × 3 more common than typical QSOs, but the excess diminishes among the most radio-loud systems and the most radio-quiet systems in our study. We develop Monte Carlo simulations to explore whether differences in star formation could explain these results, and conclude that, while star formation is an important source of low-frequency emission among radio-quiet QSOs, a population of AGN-driven compact radio sources is the most likely cause for the distinct low-frequency radio properties of red QSOs. Our study substantiates the conclusion that fundamental differences must exist between the red and normal blue QSO populations.

scholarly journals The Clustering of Active Galactic Nuclei in the Sloan Digital Sky Survey

2004 ◽  
Vol 610 (2) ◽  
pp. L85-L88 ◽  
Author(s):  
David A. Wake ◽  
Christopher J. Miller ◽  
Tiziana Di Matteo ◽  
Robert C. Nichol ◽  
Adrian Pope ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Sky Survey

scholarly journals The impact of disturbed galaxy clusters on the kinematics of active galactic nuclei

2020 ◽  
Vol 499 (3) ◽  
pp. 3792-3805
Author(s):  
Lawrence E Bilton ◽  
Kevin A Pimbblet ◽  
Yjan A Gordon
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Velocity Dispersion ◽  
Signal To Noise Ratio ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Cluster Galaxies ◽  
Sky Survey ◽  
The Impact

ABSTRACT We produce a kinematic analysis of AGN-hosting cluster galaxies from a sample of 33 galaxy clusters selected using the X-ray Clusters Database (BAX) and populated with galaxies from the Sloan Digital Sky Survey Data Release 8. The 33 galaxy clusters are delimited by their relative intensity of member galaxy substructuring as a proxy to core merging to derive two smaller sub-samples of 8 dynamically active (merging) and 25 dynamically relaxed (non-merging) states. The AGN were selected for each cluster sub-sample by employing the WHAN diagram to the strict criteria of log10([N ii]/Hα) ≥ −0.32 and EWHα ≥ 6 Å, providing pools of 70 mergings and 225 non-merging AGN sub-populations. By co-adding the clusters to their respective dynamical states to improve the signal-to-noise ratio of our AGN sub-populations we find that merging galaxy clusters on average host kinematically active AGN between 0–1.5r200 as r200 → 0, where their velocity dispersion profile (VDP) presents a significant deviation from the non-AGN sub-population VDP by ≳3σ. This result is indicative that the AGN-hosting cluster galaxies have recently coalesced on to a common potential. Further analysis of the composite distributions illustrates non-merging AGN-hosting sub-populations have, on average, already been accreted and predominantly lie within backsplash regions of the projected phase-space. This suggests merging cluster dynamical states hold relatively younger AGN sub-populations kinematically compared with those found in non-merging cluster dynamical states.

scholarly journals The X-ray view of merger-induced active galactic nuclei activity at low redshift

2020 ◽  
Vol 499 (2) ◽  
pp. 2380-2389 ◽  
Author(s):  
Nathan J Secrest ◽  
Sara L Ellison ◽  
Shobita Satyapal ◽  
Laura Blecha
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Galaxy Mergers ◽  
Significant Evidence ◽  
X Ray ◽  
The Past ◽  
Sky Survey ◽  
Theoretical Predictions

ABSTRACT Galaxy mergers are predicted to trigger accretion on to the central supermassive black holes, with the highest rates occurring during final coalescence. Previously, we have shown elevated rates of both optical and mid-IR selected active galactic nuclei (AGNs) in post-mergers, but to date the prevalence of X-ray AGNs has not been examined in the same systematic way. We present XMM–Newton data of 43 post-merger galaxies selected from the Sloan Digital Sky Survey along with 430 non-interacting control galaxies matched in stellar mass, redshift, and environment in order to test for an excess of hard X-ray (2–10 keV) emission in post-mergers attributable to triggered AGNs. We find two X-ray detections in the post-mergers ($4.7^{+9.3}_{-3.8}{{\ \rm per\ cent}}$) and nine in the controls ($2.1^{+1.5}_{-1.0}{{\ \rm per\ cent}}$), an excess of $2.22^{+4.44}_{-2.22}$, where the confidence intervals are 90 per cent. While, we therefore do not find statistically significant evidence for an X-ray AGN excess in post-mergers (p = 0.26), we find a factor of ∼17 excess of mid-IR AGNs in our sample, consistent with the past work and inconsistent with the observed X-ray excess (p = 2.7 × 10−4). Dominant, luminous AGNs are therefore more frequent in post-mergers, and the lack of a comparable excess of 2–10 keV X-ray AGNs suggests that AGNs in post-mergers are more likely to be heavily obscured. Our results are consistent with the post-merger stage being characterized by enhanced AGN fueling, heavy AGN obscuration, and more intrinsically luminous AGN, in line with theoretical predictions.

scholarly journals A SEARCH FOR BINARY ACTIVE GALACTIC NUCLEI: DOUBLE-PEAKED [O III] AGNs IN THE SLOAN DIGITAL SKY SURVEY

2010 ◽  
Vol 716 (1) ◽  
pp. 866-877 ◽  
Author(s):  
K. L. Smith ◽  
G. A. Shields ◽  
E. W. Bonning ◽  
C. C. McMullen ◽  
D. J. Rosario ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Sky Survey

scholarly journals Evidence for obscured broad [O iii] components in Type-2 AGN

2021 ◽  
Vol 502 (2) ◽  
pp. 2508-2512
Author(s):  
Xue-Guang Zhang
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Unified Model ◽  
Sloan Digital Sky Survey ◽  
The Core ◽  
Large Samples ◽  
Sky Survey ◽  
Narrow Emission

ABSTRACT In the manuscript, we report evidence on broad [O iii] components apparently obscured in Type-2 active galactic nuclei (AGN) under the framework of the unified model, after checking properties of broad [O iii] emissions in large samples of Type-1 and Type-2 AGN in Sloan Digital Sky Survey DR12. We can well confirm the statistically lower flux ratios of the broad to the core [O iii] components in Type-2 AGN than in Type-1 AGN, which can be naturally explained by stronger obscured broad [O iii] components by central dust torus in Type-2 AGN, unless the unified model for AGN was not appropriate to the narrow emission lines. The results provide further evidence to support broad [O iii] components coming from emission regions nearer to central BHs, and also indicate the core [O iii] component as the better indicator for central activities in Type-2 AGN, due to few effects of obscuration on the core [O iii] component. Considering the broad [O iii] components as signs of central outflows, the results provide evidence for strong central outflows being preferentially obscured in Type-2 AGN. Furthermore, the obscured broad [O iii] component can be applied to explain the different flux ratios of [O iii]λ5007Å/H β between Type-1 and Type-2 AGN in the BPT diagram.

scholarly journals Spectral properties of AGN with very weak [O III] lines

2011 ◽  
pp. 17-24 ◽  
Author(s):  
J. Kovacevic
Keyword(s):  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Galactic Nuclei ◽  
High Density ◽  
Sloan Digital Sky Survey ◽  
Physical Reason ◽  
Narrow Component ◽  
Sky Survey

The spectral properties of a sample of 58 Active Galactic Nuclei (AGN) spectra, in which emission [O III] ??4959, 5007 ? lines are weak or totally absent, are analyzed. In order to investigate the physical reason for the [O III] emission suppression, the spectral properties of the weak [O III] spectra sample are compared with the same properties of a sample of 269 spectra with the strong [O III] lines. The spectra are obtained from Sloan Digital Sky Survey (SDSS) Database. It is found that the objects with the weak or absent [O III] ??4959, 5007 ? lines generally have the high continuum luminosities (log(?L5100) > 45), that they are very rare at smaller redshifts (z < 0.3) and that they usually have strong starburst influence. From the sample with weak or absent [O III] lines, two boundary subgroups may be distinguished: the subgroup with a strong H? narrow component and subgroup with a very weak or negligible H? narrow component. The physical causes for the [O III] lines suppressing are probably different in these two subgroups: the [O III] lines are absent in objects with strong narrow H? probably because of strong starburst (SB) activity, which produces high density of the gas, while in the objects with the negligible narrow H?, the reason for [O III] and narrow H? suppression may be a low covering factor.

scholarly journals Detailed Analysis of Balmer Lines in a Sloan Digital Sky Survey Sample of 90 Broad‐Line Active Galactic Nuclei

2007 ◽  
Vol 671 (1) ◽  
pp. 104-117 ◽  
Author(s):  
G. La Mura ◽  
L. Č. Popović ◽  
S. Ciroi ◽  
P. Rafanelli ◽  
D. Ilić
Keyword(s):  
Active Galactic Nuclei ◽  
Detailed Analysis ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Broad Line ◽  
Sky Survey ◽  
Balmer Lines ◽  
Survey Sample
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