scholarly journals Possible Relations between Brightest Central Galaxies and Their Host Galaxies Clusters and Groups

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
R. M. Samir ◽  
A. A. Shaker
Keyword(s):  
Velocity Dispersion ◽  
Absolute Magnitude ◽  
Effective Radius ◽  
Sloan Digital Sky Survey ◽  
The Other ◽  
Host Galaxies ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Sky Survey ◽  
Environmental Relations

Abstract The r-band of the Sloan Digital Sky Survey (SDSS) for 17,924 brightest cluster galaxies (BCGs) in clusters and groups within 0.02 ⩽ z ⩽ 0.20 are used to study possible environmental relations affecting the nature of these galaxies. We find a correlation between BCGs physical properties (the effective radius (Re ), absolute magnitude and central velocity dispersion (σ 0)) and their host groups and clusters velocity dispersion (σcl ). This type of relations suggests that the most massive groups or clusters host larger central galaxies. On the other hand, the σ 0/σcl ratio as a function of σcl is consistent with [10].

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 AGN Activity in Brigtest Cluster Galaxies (BCGs)

2019 ◽  
pp. 153-158
Author(s):  
S. Fisek ◽  
S. Alis ◽  
E. K. Ülgen ◽  
F. K. Yelkenci
Keyword(s):  
Galaxy Cluster ◽  
Sloan Digital Sky Survey ◽  
Cluster Galaxies ◽  
Massive Galaxies ◽  
Brightest Cluster Galaxies ◽  
Sky Survey ◽  
Activity Types ◽  
Hα Emission ◽  
Deep Fields ◽  
The Universe

The aim of our study is to classify the Brightest Cluster Galaxies (BCG), which are the brightest and most massive galaxies in the universe and to determine fraction of BCGs showing AGN activity. Within the scope of the study, we combine BCGs from galaxy cluster catalogs which presented by Hao et al. (2010) and Wen et al. (2009) constructed from the SDSS (Sloan Digital Sky Survey) data and BCGs identified from CFHTLS (Canada-France-Hawaii Telescope Legacy Survey) Deep fields (Alis, 2009). Our combined sample contains 42490 BCGs. We determine activity types of BCGs by means of BPT diagrams and WISE color-color diagrams. 140 BCGs show AGN activity out of 42490. In addition, we calculated star formation rates (SFR) by using Hα emission lines for 5569 BCGs with suitable spectral data and investigated the correlation between SFR and redshift.

Intrinsic Characteristics of Quasars Redshifts

2014 ◽  
Vol 4 (3) ◽  
pp. 655-661
Author(s):  
Waleed Elsanhoury
Keyword(s):  
Absolute Magnitude ◽  
Sloan Digital Sky Survey ◽  
Strong Correlations ◽  
Sky Survey

Using Sloan Digital Sky Survey SDSS catalog, some intrinsic characteristics of Quasars (10,000 points) are developed of these are the strong correlations between redshifts and other parameters, e.g. combined magnitude, luminosity, and absolute magnitude .Moreover ,the Karlsson peak of our sample is also computed.

scholarly journals Searching for Mg ii absorbers in and around galaxy clusters

2021 ◽  
Vol 503 (3) ◽  
pp. 4309-4319
Author(s):  
Jong Chul Lee ◽  
Ho Seong Hwang ◽  
Hyunmi Song
Keyword(s):  
Galaxy Clusters ◽  
Detection Rate ◽  
Massive Star ◽  
Sloan Digital Sky Survey ◽  
Number Density ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Quasar Spectra ◽  
Sky Survey ◽  
The Galaxy

ABSTRACT To study environmental effects on the circumgalactic medium (CGM), we use the samples of redMaPPer galaxy clusters, background quasars, and cluster galaxies from the Sloan Digital Sky Survey (SDSS). With ∼82 000 quasar spectra, we detect 197 Mg ii absorbers in and around the clusters. The detection rate per quasar is 2.7 ± 0.7 times higher inside the clusters than outside the clusters, indicating that Mg ii absorbers are relatively abundant in clusters. However, when considering the galaxy number density, the absorber-to-galaxy ratio is rather low inside the clusters. If we assume that Mg ii absorbers are mainly contributed by the CGM of massive star-forming galaxies, a typical halo size of cluster galaxies is smaller than that of field galaxies by 30 ± 10 per cent. This finding supports that galaxy haloes can be truncated by interaction with the host cluster.

scholarly journals The optically selected 1.4-GHz quasar luminosity function below 1 mJy

2020 ◽  
Vol 492 (4) ◽  
pp. 5297-5312 ◽  
Author(s):  
Eliab Malefahlo ◽  
Mario G Santos ◽  
Matt J Jarvis ◽  
Sarah V White ◽  
Jonathan T L Zwart
Keyword(s):  
Luminosity Function ◽  
Significant Contribution ◽  
Detection Threshold ◽  
Simulated Data ◽  
Sloan Digital Sky Survey ◽  
Radio Luminosity ◽  
Host Galaxies ◽  
Star Forming ◽  
Sky Survey ◽  
Radio Luminosity Function

ABSTRACT We present the radio luminosity function (RLF) of optically selected quasars below 1 mJy, constructed by applying a Bayesian-fitting stacking technique to objects well below the nominal radio flux density limit. We test the technique using simulated data, confirming that we can reconstruct the RLF over three orders of magnitude below the typical 5σ detection threshold. We apply our method to 1.4-GHz flux densities from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey, extracted at the positions of optical quasars from the Sloan Digital Sky Survey over seven redshift bins up to z = 2.15, and measure the RLF down to two orders of magnitude below the FIRST detection threshold. In the lowest redshift bin (0.2 < z < 0.45), we find that our measured RLF agrees well with deeper data from the literature. The RLF for the radio-loud quasars flattens below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 25.5$ and becomes steeper again below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 24.8$, where radio-quiet quasars start to emerge. The radio luminosity where radio-quiet quasars emerge coincides with the luminosity where star-forming galaxies are expected to start dominating the radio source counts. This implies that there could be a significant contribution from star formation in the host galaxies, but additional data are required to investigate this further. The higher redshift bins show a similar behaviour to the lowest z bin, implying that the same physical process may be responsible.

scholarly journals Extreme ionised outflows are more common when the radio emission is compact in AGN host galaxies

2019 ◽  
Vol 631 ◽  
pp. A132 ◽  
Author(s):  
S. J. Molyneux ◽  
C. M. Harrison ◽  
M. E. Jarvis
Keyword(s):  
Radio Emission ◽  
Emission Line ◽  
Sloan Digital Sky Survey ◽  
Line Profiles ◽  
Host Galaxies ◽  
Gas Kinematics ◽  
Radio Jets ◽  
Sky Survey ◽  
Compact Sources

Using a sample of 2922 z <  0.2, spectroscopically identified active galactic nuclei (AGN), we explore the relationship between radio size and the prevalence of extreme ionised outflows, as traced using broad [O III] emission-line profiles in spectra obtained by the Sloan Digital Sky Survey (SDSS). To classify radio sources as compact or extended, we combined a machine-learning technique for morphological classification with size measurements from two-dimensional Gaussian models to data from all-sky radio surveys. We find that the two populations have statistically different [O III] emission-line profiles; the compact sources tend to have the most extreme gas kinematics. When the radio emission is confined within 3″ (i.e. within the spectroscopic fibre or ≲5 kpc at the median redshift), the chance of observing broad [O III] emission-line components, which are indicative of very high velocity outflows and have a full width at half-maximum > 1000 km s−1, is twice as high. This difference is greatest for the highest radio luminosity bin of log[L1.4 GHz/W Hz−1] = 23.5−24.5 where the AGN dominate the radio emission; specifically, > 1000 km s−1 components are almost four times as likely to occur when the radio emission is compact in this subsample. Our follow-up ≈0.3″–1″ resolution radio observations for a subset of targets in this luminosity range reveal that radio jets and lobes are prevalent, and suggest that compact jets might be responsible for the stronger outflows in the wider sample. Our results are limited by the available relatively shallow all-sky radio surveys, but forthcoming surveys will provide a more complete picture of the connection between radio emission and outflows. Overall, our results add to the growing body of evidence that ionised outflows and compact radio emission in highly accreting “radiative” AGN are closely connected, possibly as a result of young or weak radio jets.

scholarly journals A spectroscopic survey of Abell 1703: is it a rare relaxed cluster hosting a radio halo or a usual merging system?

2020 ◽  
Vol 492 (2) ◽  
pp. 2405-2417 ◽  
Author(s):  
W Boschin ◽  
M Girardi ◽  
F Gastaldello
Keyword(s):  
Gravitational Lensing ◽  
Statistical Tests ◽  
Galaxy Cluster ◽  
Theoretical Models ◽  
Sloan Digital Sky Survey ◽  
Cluster Galaxies ◽  
Radio Halo ◽  
Sky Survey ◽  
Galaxies Kinematics ◽  
First Moment

ABSTRACT We present the study of the internal dynamics of the intriguing galaxy cluster Abell 1703, a system hosting a probable giant radio halo whose dynamical status is still controversial. Our analysis is based on unpublished spectroscopic data acquired at the Italian Telescopio Nazionale Galileo and data publicly available in the literature. We also use photometric data from the Sloan Digital Sky Survey. We select 147 cluster members and compute the cluster redshift 〈z〉 ∼ 0.277 and the global line-of-sight velocity dispersion σv ∼ 1300 km s−1. We infer that Abell 1703 is a massive cluster: M200 ∼ 1–2 × 1015 M⊙. The results of our study disagree with the picture of an unimodal, relaxed cluster as suggested by previous studies based on the gravitational lensing analysis and support the view of a perturbed dynamics proposed by recent works based on Chandra X-ray data. The first strong evidence of a dynamically disturbed cluster comes from the peculiarity of the BCG velocity with respect to the first moment of the velocity distribution of member galaxies. Moreover, several statistical tests employed to study the cluster galaxies kinematics find significant evidence of substructure, being Abell 1703 composed by at least two or three subclumps probably caught after the core–core passage. In this observational scenario, the suspected existence of a radio halo in the centre of this cluster is not surprising and well agrees with the theoretical models describing diffuse radio sources in clusters.

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