scholarly journals Constraining the past X-ray luminosity of AGN in clusters of galaxies: The role of resonant scattering

2002 ◽  
Vol 393 (3) ◽  
pp. 793-807 ◽  
Author(s):  
S. Yu. Sazonov ◽  
R. A. Sunyaev ◽  
C. K. Cramphorn
Keyword(s):  
Resonant Scattering ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
The Past

scholarly journals The Role of Wide Field X-ray Surveys in Astronomy

2012 ◽  
Vol 10 (H16) ◽  
pp. 669-670
Author(s):  
Richard D. Saxton
Keyword(s):  
High Variability ◽  
Wide Field ◽  
Clusters Of Galaxies ◽  
Tidal Disruption ◽  
X Ray ◽  
Sky Survey ◽  
History Of ◽  
X Ray Background ◽  
Rare Classes

AbstractWe review the history of X-ray sky surveys from the early experiments to the catalogues of 105 sources produced by ROSAT, Chandra and XMM-Newton. At bright fluxes the X-ray sky is shared between stars, accreting binaries and extragalactic sources while deeper surveys are dominated by AGN and clusters of galaxies. The X-ray background, found by the earliest missions, has been largely resolved into discrete sources at soft (0.3-2 keV) energies but at higher energies an important fraction still escapes detection. The possible identification of the missing flux with Compton-thick AGN has been probed in recent years by Swift and Integral.Variability seen in objects observed at different epochs has proved to be an excellent discriminator for rare classes of objects. The comparison of ROSAT All Sky Survey (RASS) and ROSAT pointed observations identified several Novae and high variability AGN as well as initiating the observational study of Tidal Disruption events. More recently the XMM-Newton slew survey, in conjunction with archival RASS data, has detected further examples of flaring objects which have been followed-up in near-real time at other wavelengths.

scholarly journals Theoretical Implications of Diffuse Non-Thermal Emission from Clusters of Galaxies

2002 ◽  
Vol 199 ◽  
pp. 141-148
Author(s):  
T.A. Enßlin
Keyword(s):  
Thermal Emission ◽  
Extreme Ultraviolet ◽  
Short Review ◽  
Radio Galaxies ◽  
High Energy ◽  
Clusters Of Galaxies ◽  
Thermal Electron ◽  
Electron Population ◽  
X Ray

A short review on theoretical implications of non-thermal emission (radio, extreme ultraviolet, high energy X-ray) from the intra-cluster medium is given. The origin of cluster radio halos and cluster radio relics is discussed within the framework of a network of processes producing a non-thermal electron population. Emphasis is given to the role of old, remnant, presently invisible relativistic plasma released by former radio galaxies.

scholarly journals The Sunyaev-Zeldovich effect from clusters of galaxies

2020 ◽  
Vol 228 ◽  
pp. 00020
Author(s):  
Etienne Pointecouteau
Keyword(s):  
Structure Formation ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
The Past ◽  
Formation And Evolution ◽  
Massive Halos

In this paper, we recall the basics of the the Sunyaev-Zeldovich effect from groups and clusters of galaxies. We review the transformational results from SZ surveys in the past decade, that have led to the detection of new clusters of galaxies from the local to the very distant Universe. The SZ effect has become a very efficient way to investigate the astrophysics of the hot intra-cluster gas, very competitive and complementary to X-ray observations. It renewed the use of massive halos as a cosmological probe or to study the physics of structure formation and evolution. We discuss the present strong synergies between the SZ and X-ray observations.

scholarly journals Space Distribution of X-Ray Clusters of Galaxies

1988 ◽  
Vol 130 ◽  
pp. 541-541
Author(s):  
A. Cavaliere ◽  
S. Colafrancesco
Keyword(s):  
Generation X ◽  
Luminosity Function ◽  
Past History ◽  
Space Distribution ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Groups Of Galaxies ◽  
The Past ◽  
History Of ◽  
Chemical Events

The Intra-Cluster Plasma constitutes an archive of the past history of all clusters and of many groups of galaxies: statistical observations of their X-ray emission will set significant constraints on the dynamical, thermal and chemical events in these cosmic structures. Data on the local X-ray luminosity function N(L, z ≃ 0) were provided by the 1st generation X-ray surveys. HEAO II provided an integral of N(L, z) out to z ≃ 0.4, the counts from a subsample of the MSS (Gioia et al. 1984, Ap.J. 283, 495): these counts result very flat, cf. Fig. 2.

Stellar populations and ages of ultra-hard X-ray AGN in the BASS survey

2019 ◽  
Vol 15 (S356) ◽  
pp. 370-370
Author(s):  
Mirjana Pović
Keyword(s):  
Galaxy Evolution ◽  
Selection Criteria ◽  
Stellar Populations ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
The Past ◽  
Open Questions ◽  
Stellar Ages

AbstractConnection between star formation and AGN activity has been studied widely over the past years, which shown to be very important for understanding better the role of AGN in galaxy evolution. In this context, what are the stellar ages and average stellar populations of AGN host galaxies, and if there are any differences depending on AGN type, are still open questions that brought many inconsistencies, very often due to different selection criteria used. The AGN sample detected in the ultra-hard X-rays (14–195 keV) by the Swift BAT telescope is not affected by obscuration nor is it contaminated by stellar emission, and presents some of the most unbiased samples. In this talk we will present the results obtained on AGN stellar populations and ages through spectral fittings by using the Swift-BAT AGN Spectroscopic Survey (BASS) which gives us an unique opportunity to understand better the connection between AGN and their host galaxies.

scholarly journals Dark Matter in Clusters of Galaxies

1995 ◽  
Vol 164 ◽  
pp. 227-235
Author(s):  
Claude R. Canizares
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Clusters Of Galaxies ◽  
Rapid Progress ◽  
X Ray ◽  
Mass Distributions ◽  
The Past ◽  
Accurate Picture ◽  
Made In

An appropriate subtitle for this talk might be “Newton meets Einstein.” For many decades, the prime tool for studying the amount and distribution of matter in galaxy clusters was decidedly Newtonian, involving at first the measurements of the dynamics of the galaxies themselves and, for the past 15 years or so, the imputed dynamics of the hot, X-ray emitting intra-cluster gas. Einstein enters more recently with the introduction of gravitational lensing as a tool for studying cluster mass distributions. Rapid progress is being made in each of these areas, and there are now attempts to bring them together to give a consistent and more accurate picture of clusters.

scholarly journals X-Ray Observations of Clusters of Galaxies

1978 ◽  
Vol 79 ◽  
pp. 165-177 ◽  
Author(s):  
J. L. Culhane
Keyword(s):  
Optical Properties ◽  
Present Status ◽  
Luminosity Function ◽  
Cluster Structure ◽  
Current Situation ◽  
Clusters Of Galaxies ◽  
Iron Line ◽  
X Ray ◽  
The Past

X-ray astronomy has, in the past year, seen the publication of the second Ariel (2A) and fourth Uhuru (4U) catalogues of X-ray sources. A number of new X-ray cluster identifications and the confirmation of several others has resulted. in this review I will briefly summarise the situation regarding identifications and, for the 2A clusters, discuss the luminosity function and the possible relationships between a number of cluster X-ray and optical properties. Superclusters have been tentatively proposed as a class of X-ray sources and I will comment briefly on recent observations of these objects. Cluster structure has been studied by the Copernicus and SAS-3 spacecraft and by a number of rocket observations with imaging X-ray telescopes undertaken by the Harvard Centre for Astrophysics. I will review the current situation regarding structural measurements. Finally I will discuss the present status of Iron line observations at 6.7 keV in cluster spectra and the estimates of Fe abundance that result from these data.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

On Future Directions in Pathology

1982 ◽  
Vol 40 ◽  
pp. 274-277
Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Pathology ◽  
Future Directions ◽  
Diagnostic Pathology ◽  
The Past ◽  
Transmission Electron ◽  
Organ Systems ◽  
The Many

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.

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