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.

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.

scholarly journals A Morphological Classification of Clusters of Galaxies from Einstein Images

1982 ◽  
Vol 97 ◽  
pp. 97-106 ◽  
Author(s):  
C. Jones ◽  
W. Forman
Keyword(s):  
Line Emission ◽  
Stellar Systems ◽  
Single Individual ◽  
Clusters Of Galaxies ◽  
Morphological Classification ◽  
Iron Line ◽  
Emission Process ◽  
X Ray ◽  
Extended Sources

The earliest Uhuru observations showed that cluster X-ray sources were not associated with single individual galaxies but were extended sources (Gursky et al. 1971, Kellogg et al. 1972, and Forman et al. 1972). The detection of iron line emission from X-ray spectroscopic observations (Mitchell et al. 1976 and Serlemitsos et al. 1977) showed both that the dominant X-ray emission process was thermal bremsstrahlung and that the gas had been processed through stellar systems before being injected into the intracluster medium.

scholarly journals UHURU Results on Extragalactic X-Ray Sources

1973 ◽  
Vol 55 ◽  
pp. 171-183 ◽  
Author(s):  
Edwin M. Kellogg
Keyword(s):  
High Latitude ◽  
Luminosity Function ◽  
Optical Data ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
Total Contribution ◽  
X Ray ◽  
Normal Galaxies ◽  
X Ray Background ◽  
Individual Galaxies

Data from the UHURU satellite have provided a list of more than forty high latitude sources (|b| > 20°). X-rays have been detected from among the nearest normal galaxies, giant radio galaxies, Seyferts, QSOs and clusters of galaxies. The cluster sources appear to be extended by several hundred kiloparsecs as well as being very luminous. These cluster sources have systematic differences in their X-ray spectra from individual galaxies.About twenty sources are not reliably identified so far. A few of these are located near undistinguished 3C or MSH radio sources. The rest are either located near distant clusters or undistinguished bright galaxies, or are too far south, so that we have not sufficient optical data to allow a thorough search for possible association with clusters or unusual individual galaxies.The luminosity function for weak, high latitude X-ray sources is determined, and the contribution of sources just below the UHURU threshold of detectability to observed fluctuations in the diffuse X-ray background is evaluated. The total contribution of all observed types of extragalactic sources to the X-ray background is estimated.

scholarly journals ASCA Observations of Distant Clusters of Galaxies

1998 ◽  
Vol 188 ◽  
pp. 65-68
Author(s):  
Takeshi Go Tsuru
Keyword(s):  
Luminosity Function ◽  
Red Shift ◽  
Clusters Of Galaxies ◽  
X Ray

Investigation of evolution of X-ray properties of clusters of galaxies is a key study of cosmology. The most important result in this field before ROSAT and ASCA observatories is the detection of the negative evolution of the X-ray luminosity function at red-shift lower than 0.6 (Gioia et al., 1990). Following it, many groups have been investigating evolution of X-ray luminosity function from various surveys with ROSAT observatory (eg. Collins et al., 1997). Many of them indicate no negative evolution at the red-shift lower than 0.7, which is against the Einstein result.

scholarly journals X-ray selected clusters of galaxies

1988 ◽  
Vol 130 ◽  
pp. 542-542
Author(s):  
Isabella M. Gioia ◽  
T. Maccacaro ◽  
S. L. Morris ◽  
R. E. Schild ◽  
J. T. Stocke ◽  
...  
Keyword(s):  
Energy Band ◽  
Luminosity Function ◽  
High Redshift ◽  
Cosmic Time ◽  
Entire Population ◽  
Clusters Of Galaxies ◽  
Limited Sample ◽  
X Ray ◽  
Identification Process ◽  
Cluster Evolution

Studies of the evolution of X-ray emission from clusters of galaxies have so far used optically discovered distant clusters then observed at X-ray wavelengths. A different approach to the study of cluster evolution is to use clusters selected directly by their X-ray emission since X-ray selection is extremely successful at discovering high redshift clusters (up to z = 0.5). The Extension of the Medium Sensitivity Survey (Gioia, Maccacaro and Wolter, 1987), a flux limited sample of serendipitous X-ray sources discovered with the Einstein IPC, has been used to select 68 optically identified clusters and 66 possible candidates (using X-ray isointensity maps and optical POSS and ESO prints). Their X-ray fluxes are in the range 10−13 – 10−12 ergs cm−2 s−1 in the 0.3–3.5 keV energy band. Few misidentifications are expected, thus the results presented here have to be considered as preliminary. This sample can be used to study the X-ray logN-logS, the cluster luminosity function and its possible evolution with cosmic time, and also to compare the properties of X-ray selected clusters with those of samples selected by other techniques. Since the identification process is still in progress, and has not proceeded completely at random, the subset of identified sources is not representative of the entire population. With this caveat in mind we have constructed the redshift and X-ray luminosity distributions for the clusters for which we have spectroscopic observations. 68% of the clusters are at z > 0.1, 34% at z > 0.2, and 12% at z > 0.3. Their X-ray luminosities range from about 3 × 1042 to 1045 ergs s−1. At present the lack of a redshift determination for many of the cluster candidates in our sample prevents us from studying the cluster luminosity function. W e can however derive their logN(>S)-logS relation.

scholarly journals An X-ray view of Sagittarius C

2016 ◽  
Vol 11 (S322) ◽  
pp. 208-209 ◽  
Author(s):  
D. Chuard ◽  
R. Terrier ◽  
A. Goldwurm ◽  
M. Clavel ◽  
S. Soldi ◽  
...  
Keyword(s):  
Molecular Complex ◽  
Line Emission ◽  
Iron Line ◽  
X Ray ◽  
The Past ◽  
Over Time

AbstractOver the past 15 years, the molecular complex Sgr C has been repeatedly observed with both XMM-Newton and Chandra. These observations reveal new features indicating that the region might be more complex than previously thought. We find that its strong iron line emission at 6.4 keV varies significantly over time, which supports the X-ray reflection scenario.

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 The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A5 ◽  
Author(s):  
C. Adami ◽  
P. Giles ◽  
E. Koulouridis ◽  
F. Pacaud ◽  
C. A. Caretta ◽  
...  
Keyword(s):  
Present Article ◽  
Present State ◽  
Luminosity Function ◽  
Selection Function ◽  
Clusters Of Galaxies ◽  
Temperature Relation ◽  
X Ray ◽  
Cluster Sample ◽  
Medium Mass

Context. In the currently debated context of using clusters of galaxies as cosmological probes, the need for well-defined cluster samples is critical. Aims. The XXL Survey has been specifically designed to provide a well characterised sample of some 500 X-ray detected clusters suitable for cosmological studies. The main goal of present article is to make public and describe the properties of the cluster catalogue in its present state, as well as of associated catalogues of more specific objects such as super-clusters and fossil groups. Methods. Following from the publication of the hundred brightest XXL clusters, we now release a sample containing 365 clusters in total, down to a flux of a few 10−15 erg s−1 cm−2 in the [0.5–2] keV band and in a 1′ aperture. This release contains the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. In this paper, we give the details of the follow-up observations and explain the procedure adopted to validate the cluster spectroscopic redshifts. Considering the whole XXL cluster sample, we have provided two types of selection, both complete in a particular sense: one based on flux-morphology criteria, and an alternative based on the [0.5–2] keV flux within 1 arcmin of the cluster centre. We have also provided X-ray temperature measurements for 80% of the clusters having a flux larger than 9 × 10−15 erg s−1 cm−2. Results. Our cluster sample extends from z ~ 0 to z ~ 1.2, with one cluster at z ~ 2. Clusters were identified through a mean number of six spectroscopically confirmed cluster members. The largest number of confirmed spectroscopic members in a cluster is 41. Our updated luminosity function and luminosity–temperature relation are compatible with our previous determinations based on the 100 brightest clusters, but show smaller uncertainties. We also present an enlarged list of super-clusters and a sample of 18 possible fossil groups. Conclusions. This intermediate publication is the last before the final release of the complete XXL cluster catalogue when the ongoing C2 cluster spectroscopic follow-up is complete. It provides a unique inventory of medium-mass clusters over a 50 deg2 area out to z ~ 1.

scholarly journals Hot Gas in Clusters of Galaxies

1980 ◽  
Vol 5 ◽  
pp. 387-396
Author(s):  
J. L. Culhane
Keyword(s):  
Surface Brightness ◽  
Luminosity Function ◽  
Clusters Of Galaxies ◽  
X Rays ◽  
Will Emit ◽  
X Ray ◽  
Hot Gas ◽  
Sky Survey ◽  
To Come ◽  
Einstein Observatory

The discovery of extended X-ray sources associated with clusters of galaxies which resulted from the Uhuru X-ray sky survey was one of the most important observations to come from that programme. Following Uhuru, the Ariel V and HEAO-1 sky surveys have found many more cluster X-ray sources and the recently launched Einstein observatory has begun to increase further the number of identifications. However there is in any case evidence from the X-ray cluster luminosity function that all rich clusters of galaxies will emit X-rays at some level.Preliminary results from the Einstein observatory (Murray, 1979) suggest that the extended X-ray emission from centrally condensed (cD) clusters is itself centrally condensed and spherically symmetrical in appearance. However irregular clusters have non-uniform X-ray surface brightness distributions. In addition there are some galaxies in clusters of irregular morphology that have associated X-ray halos.

scholarly journals X-Ray Binaries in M51 I: Catalog and Statistics

2021 ◽  
Vol 922 (2) ◽  
pp. 178
Author(s):  
Jared R. Rice ◽  
Blagoy Rangelov ◽  
Andrea Prestwich ◽  
Rupali Chandar ◽  
Luis Bichon ◽  
...  
Keyword(s):  
Optical Properties ◽  
Data Analysis ◽  
Luminosity Function ◽  
Binary Systems ◽  
Hubble Space Telescope ◽  
Archival Data ◽  
Optical Counterpart ◽  
Space Telescope ◽  
X Ray ◽  
X Ray Binaries

Abstract We used archival data from the Chandra X-ray Observatory (Chandra) and the Hubble Space Telescope, to identify 334 candidate X-ray binary systems and their potential optical counterparts in the interacting galaxy pair NGC 5194/5195 (M51). We present the catalog and data analysis of X-ray and optical properties for those sources, from the deep 892 ks Chandra observations, along with the magnitudes of candidate optical sources as measured in the 8.16 ks Hubble Space Telescope observations. The X-ray luminosity function of the X-ray sources above a few times 1036 erg s−1 follows a power law N ( > L X , b ) ∝ L X , b 1 − α with α = 1.65 ± 0.03. Approximately 80% of sources are variable over a 30 day window. Nearly half of the X-ray sources (173/334) have an optical counterpart within 0.″5.

Sign in / Sign up

Export Citation Format

Share Document