scholarly journals SPIDERS: overview of the X-ray galaxy cluster follow-up and the final spectroscopic data release

2020 ◽  
Vol 497 (3) ◽  
pp. 3976-3992 ◽  
Author(s):  
N Clerc ◽  
C C Kirkpatrick ◽  
A Finoguenov ◽  
R Capasso ◽  
J Comparat ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Sample Selection ◽  
Galaxy Cluster ◽  
Sloan Digital Sky Survey ◽  
Observable Universe ◽  
Data Set ◽  
X Ray ◽  
Data Release ◽  
The Galaxy

ABSTRACT SPIDERS (The SPectroscopic IDentification of eROSITA Sources) is a large spectroscopic programme for X-ray selected galaxy clusters as part of the Sloan Digital Sky Survey-IV (SDSS-IV). We describe the final data set in the context of SDSS Data Release 16 (DR16): the survey overall characteristics, final targeting strategies, achieved completeness, and spectral quality, with special emphasis on its use as a galaxy cluster sample for cosmology applications. SPIDERS now consists of about 27 000 new optical spectra of galaxies selected within 4000 photometric red sequences, each associated with an X-ray source. The excellent spectrograph efficiency and a robust analysis pipeline yield a spectroscopic redshift measurement success rate exceeding 98 per cent, with a median velocity accuracy of 20 km s−1 (at z = 0.2). Using the catalogue of 2740 X-ray galaxy clusters confirmed with DR16 spectroscopy, we reveal the 3D map of the galaxy cluster distribution in the observable Universe up to z ∼ 0.6. We highlight the homogeneity of the member galaxy spectra among distinct regions of the galaxy cluster phase space. Aided by accurate spectroscopic redshifts and by a model of the sample selection effects, we compute the galaxy cluster X-ray luminosity function and we present its lack of evolution up to z = 0.6. Finally we discuss the prospects of forthcoming large multiplexed spectroscopic programmes dedicated to follow up the next generation of all-sky X-ray source catalogues.

scholarly journals Anisotropy of the galaxy cluster X-ray luminosity–temperature relation

2018 ◽  
Vol 611 ◽  
pp. A50 ◽  
Author(s):  
Konstantinos Migkas ◽  
Thomas H. Reiprich
Keyword(s):  
Galaxy Clusters ◽  
Statistical Significance ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
Luminosity Distance ◽  
Temperature Relation ◽  
X Ray ◽  
Two Samples ◽  
The Galaxy ◽  
Group A

We introduce a new test to study the cosmological principle with galaxy clusters. Galaxy clusters exhibit a tight correlation between the luminosity and temperature of the X-ray-emitting intracluster medium. While the luminosity measurement depends on cosmological parameters through the luminosity distance, the temperature determination is cosmology-independent. We exploit this property to test the isotropy of the luminosity distance over the full extragalactic sky, through the normalization a of the LX–T scaling relation and the cosmological parameters Ωm and H0. To this end, we use two almost independent galaxy cluster samples: the ASCA Cluster Catalog (ACC) and the XMM Cluster Survey (XCS-DR1). Interestingly enough, these two samples appear to have the same pattern for a with respect to the Galactic longitude. More specifically, we identify one sky region within l ~ (−15°, 90°) (Group A) that shares very different best-fit values for the normalization of the LX–T relation for both ACC and XCS-DR1 samples. We use the Bootstrap and Jackknife methods to assess the statistical significance of these results. We find the deviation of Group A, compared to the rest of the sky in terms of a, to be ~2.7σ for ACC and ~3.1σ for XCS-DR1. This tension is not significantly relieved after excluding possible outliers and is not attributed to different redshift (z), temperature (T), or distributions of observable uncertainties. Moreover, a redshift conversion to the cosmic microwave background (CMB) frame does not have an important impact on our results. Using also the HIFLUGCS sample, we show that a possible excess of cool-core clusters in this region, is not able to explain the obtained deviations. Furthermore, we tested for a dependence of the results on supercluster environment, where the fraction of disturbed clusters might be enhanced, possibly affecting the LX–T relation. We indeed find a trend in the XCS-DR1 sample for supercluster members to be underluminous compared to field clusters. However, the fraction of supercluster members is similar in the different sky regions, so this cannot explain the observed differences, either. Constraining Ωm and H0 via the redshift evolution of LX–T and the luminosity distance via the flux–luminosity conversion, we obtain approximately the same deviation amplitudes as for a. It is interesting that the general observed behavior of Ωm for the sky regions that coincide with the CMB dipole is similar to what was found with other cosmological probes such as supernovae Ia. The reason for this behavior remains to be identified.

scholarly journals Redshift measurement through star formation

2019 ◽  
Vol 629 ◽  
pp. A7
Author(s):  
Mikkel O. Lindholmer ◽  
Kevin A. Pimbblet
Keyword(s):  
Star Formation ◽  
Galaxy Clusters ◽  
Main Sequence ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Star Forming ◽  
Sky Survey ◽  
The Galaxy ◽  
Galaxy Population

In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass – the so called galaxy main sequence – to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR–M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz = ±0.017 ⋅ (z + 1) and is only accurate up to z ≈ 0.2.

scholarly journals The probability distribution of 3D shapes of galaxy clusters from 2D X-ray images

2021 ◽  
Vol 503 (2) ◽  
pp. 2791-2803
Author(s):  
Swapnil Shankar ◽  
Rishi Khatri
Keyword(s):  
Probability Distribution ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Data Sets ◽  
X Rays ◽  
Data Set ◽  
X Ray ◽  
Individual Object ◽  
3D Shape ◽  
3D Shapes

ABSTRACT We present a new method to determine the probability distribution of the 3D shapes of galaxy clusters from the 2D images using stereology. In contrast to the conventional approach of combining different data sets (such as X-rays, Sunyaev–Zeldovich effect, and lensing) to fit a 3D model of a galaxy cluster for each cluster, our method requires only a single data set, such as X-ray observations or Sunyaev–Zeldovich effect observations, consisting of sufficiently large number of clusters. Instead of reconstructing the 3D shape of an individual object, we recover the probability distribution function (PDF) of the 3D shapes of the observed galaxy clusters. The shape PDF is the relevant statistical quantity, which can be compared with the theory and used to test the cosmological models. We apply this method to publicly available Chandra X-ray data of 89 well-resolved galaxy clusters. Assuming ellipsoidal shapes, we find that our sample of galaxy clusters is a mixture of prolate and oblate shapes, with a preference for oblateness with the most probable ratio of principle axes 1.4 : 1.3 : 1. The ellipsoidal assumption is not essential to our approach and our method is directly applicable to non-ellipsoidal shapes. Our method is insensitive to the radial density and temperature profiles of the cluster. Our method is sensitive to the changes in shape of the X-ray emitting gas from inner to outer regions and we find evidence for variation in the 3D shape of the X-ray emitting gas with distance from the centre.

scholarly journals X-ray and Radio Observations of the Radio Relic Galaxy Clusters 1RXS J0603.3+4214 and RXC J1053.7+5453

Galaxies ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 2 ◽  
Author(s):  
Motokazu Takizawa
Keyword(s):  
Mach Number ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Shock Acceleration ◽  
Temperature Structure ◽  
Radio Observations ◽  
Diffusive Shock Acceleration ◽  
X Ray ◽  
Acceleration Model ◽  
The Galaxy

We study two galaxy clusters with radio relics, 1RXS J0603.3+4214 and RXC J1053.7+5453, through X-ray and radio observations. Radio relics are diffuse non-thermal radio sources found in outskirts of galaxy clusters. Because of their shape and location, they are thought to be related to cluster merger shocks. The galaxy cluster 1RXS J0603.3+4214 has a well-known linear-shape “toothbrush” radio relic. We investigate the temperature structure across the relic to constrain the Mach number of the associated shock. The results are compared with radio spectral results, which suggest that a simple diffusive shock acceleration model does not hold for this relic. The RXC J1053.7+5453 harbors a standard arc-like relic. We also get the Mach number from the temperature profile. In addition, we found an edge-like structure in the X-ray image between the X-ray peak and relic. We investigate the density and temperature profiles across the edge and found that the structure is likely relevant to not a shock but a contact discontinuity.

scholarly journals Diffuse galaxy cluster emission at 168 MHz within the Murchison Widefield Array Epoch of Reionization 0-h field

2021 ◽  
Vol 38 ◽  
Author(s):  
S. W. Duchesne ◽  
M. Johnston-Hollitt ◽  
A. R. Offringa ◽  
G. W. Pratt ◽  
Q. Zheng ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Scaling Relations ◽  
Cluster Emission ◽  
X Ray ◽  
Diffuse Sources ◽  
Radio Halo ◽  
The Galaxy ◽  
Murchison Widefield Array

Abstract We detect and characterise extended, diffuse radio emission from galaxy clusters at 168 MHz within the Epoch of Reionization 0-h field: a $45^{\circ} \times 45^{\circ}$ region of the southern sky centred on R. A. ${}= 0^{\circ}$ , decl. ${}=-27^{\circ}$ . We detect 29 sources of interest; a newly detected halo in Abell 0141; a newly detected relic in Abell 2751; 4 new halo candidates and a further 4 new relic candidates; and a new phoenix candidate in Abell 2556. Additionally, we find nine clusters with unclassifiable, diffuse steep-spectrum emission as well as a candidate double relic system associated with RXC J2351.0-1934. We present measured source properties such as their integrated flux densities, spectral indices ( $\alpha$ , where $S_\nu \propto \nu^\alpha$ ), and sizes where possible. We find several of the diffuse sources to have ultra-steep spectra including the halo in Abell 0141, if confirmed, showing $\alpha \leq -2.1 \pm 0.1$ with the present data making it one of the steepest-spectrum haloes known. Finally, we compare our sample of haloes with previously detected haloes and revisit established scaling relations of the radio halo power ( $P_{1.4}$ ) with the cluster X-ray luminosity ( $L_{\textrm{X}}$ ) and mass ( $M_{500}$ ). We find that the newly detected haloes and candidate haloes are consistent with the $P_{1.4}$ – $L_{\textrm{X}}$ and $P_{1.4}$ – $M_{500}$ relations and see an increase in scatter in the previously found relations with increasing sample size likely caused by inhomogeneous determination of $P_{1.4}$ across the full halo sample. We show that the MWA is capable of detecting haloes and relics within most of the galaxy clusters within the Planck catalogue of Sunyaev–Zel’dovich sources depending on exact halo or relic properties.

scholarly journals The Deepest Chandra View of RBS 797: Evidence for Two Pairs of Equidistant X-ray Cavities

2021 ◽  
Vol 923 (2) ◽  
pp. L25
Author(s):  
F. Ubertosi ◽  
M. Gitti ◽  
F. Brighenti ◽  
G. Brunetti ◽  
M. McDonald ◽  
...  
Keyword(s):  
Radial Distance ◽  
Galaxy Cluster ◽  
Age Difference ◽  
X Ray ◽  
The North ◽  
The Galaxy ◽  
Centrally Symmetric ◽  
First Results ◽  
East West

Abstract We present the first results of a deep Chandra observation of the galaxy cluster RBS 797 whose previous X-ray studies revealed two pronounced X-ray cavities in the east–west (E–W) direction. Follow-up VLA radio observations of the central active galactic nucleus (AGN) uncovered different jet and lobe orientations, with radio lobes filling the E–W cavities and perpendicular jets showing emission in the north–south (N–S) direction over the same scale (≈30 kpc). With the new ∼427 ks total exposure, we report the detection of two additional, symmetric X-ray cavities in the N–S direction at nearly the same radial distance as the E–W ones. The newly discovered N–S cavities are associated with the radio emission detected at 1.4 and 4.8 GHz in archival VLA data, making RBS 797 the first galaxy cluster found to have four equidistant, centrally symmetric, radio-filled cavities. We derive the dynamical and radiative ages of the four cavities from X-ray and radio data, respectively, finding that the two outbursts are approximately coeval, with an age difference of ⪅10 Myr between the E–W and N–S cavities. We discuss two scenarios for the origin of the two perpendicular, equidistant cavity systems: either the presence of a binary AGN that is excavating coeval pairs of cavities in perpendicular directions or a fast (<10 Myr) jet reorientation event that produced subsequent, misaligned outbursts.

scholarly journals CODEX clusters

2020 ◽  
Vol 638 ◽  
pp. A114 ◽  
Author(s):  
A. Finoguenov ◽  
E. Rykoff ◽  
N. Clerc ◽  
M. Costanzi ◽  
S. Hagstotz ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Sample Selection ◽  
Sloan Digital Sky Survey ◽  
Selection Function ◽  
Large Area ◽  
X Ray ◽  
Galaxy Groups ◽  
Sky Survey ◽  
Area X

Context. Large area catalogs of galaxy clusters constructed from ROSAT All-Sky Survey provide the basis for our knowledge of the population of clusters thanks to long-term multiwavelength efforts to follow up observations of these clusters. Aims. The advent of large area photometric surveys superseding previous, in-depth all-sky data allows us to revisit the construction of X-ray cluster catalogs, extending the study to lower cluster masses and higher redshifts and providing modeling of the selection function. Methods. We performed a wavelet detection of X-ray sources and made extensive simulations of the detection of clusters in the RASS data. We assigned an optical richness to each of the 24 788 detected X-ray sources in the 10 382 square degrees of the Baryon Oscillation Spectroscopic Survey area using red sequence cluster finder redMaPPer version 5.2 run on Sloan Digital Sky Survey photometry. We named this survey COnstrain Dark Energy with X-ray (CODEX) clusters. Results. We show that there is no obvious separation of sources on galaxy clusters and active galactic nuclei (AGN) based on the distribution of systems on their richness. This is a combination of an increasing number of galaxy groups and their selection via the identification of X-ray sources either by chance or by groups hosting an AGN. To clean the sample, we use a cut on the optical richness at the level corresponding to the 10% completeness of the survey and include it in the modeling of the cluster selection function. We present the X-ray catalog extending to a redshift of 0.6. Conclusions. The CODEX suvey is the first large area X-ray selected catalog of northern clusters reaching fluxes of 10−13 ergs s−1 cm−2. We provide modeling of the sample selection and discuss the redshift evolution of the high end of the X-ray luminosity function (XLF). Our results on z <  0.3 XLF agree with previous studies, while we provide new constraints on the 0.3 <  z <  0.6 XLF. We find a lack of strong redshift evolution of the XLF, provide exact modeling of the effect of low number statistics and AGN contamination, and present the resulting constraints on the flat ΛCDM.

scholarly journals Exploring the multiphase medium in MKW 08: from the central active galaxy up to cluster scales

2019 ◽  
Vol 629 ◽  
pp. A82
Author(s):  
A. Tümer ◽  
F. Tombesi ◽  
H. Bourdin ◽  
E. N. Ercan ◽  
M. Gaspari ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galactic Center ◽  
Galaxy Cluster ◽  
Pressure Profile ◽  
Nearby Galaxy ◽  
Cluster Galaxy ◽  
X Ray ◽  
The Galaxy ◽  
Central Regions ◽  
Photon Index

Context. The study of the brightest cluster galaxy (BCG) coronae embedded in noncool core (NCC) galaxy clusters is crucial to understand the BCG’s role in galaxy cluster evolution as well as the activation of the self-regulated cooling and heating mechanism in the central regions of galaxy clusters. Aims. We explore the X-ray properties of the intracluster medium (ICM) of the NCC galaxy cluster MKW 08 and the BCG corona, along with their interface region. With recent and deep archival Chandra observations, we study the BCG corona in detail, and with archival XMM-Newton observations, we investigate the implications of the central active galactic nuclei (AGN) on the BCG. Methods. We carry out imaging and spectral analyses of MKW 08 with archival XMM-Newton and Chandra X-ray observations. Results. Our spectral analysis suggests the presence of a central AGN by a power-law with a photon index of Γ ≃ 1.8 at the core of its BCG. Although the ICM does not exhibit a cluster scale cool core, the BCG manifests itself as a mini cool core characterized by a cooling time as short as 64 Myr at r = 3 kpc centered at the galaxy. The isothermality of the BCG corona seems to favor mechanical feedback from the central AGN as the major source of gas heating. The gas pressure profile of this mini cool core suggests that the BCG coronal gas reaches pressure equilibrium with the hotter and less dense ICM inside an interface of nearly constant pressure, delimited by radii 4 ≤ r ≤ 10 kpc at the galactic center. As revealed by the presence of a metal enriched tail (Z ≃ 0.5–0.9 Z⊙) extending up to 40 kpc, the BCG corona seems to be experiencing ram-pressure stripping by the surrounding ICM and/or interacting with a nearby galaxy, IC 1042.

scholarly journals Multiwavelength classification of X-ray selected galaxy cluster candidates using convolutional neural networks

2020 ◽  
Vol 496 (4) ◽  
pp. 4141-4153
Author(s):  
Matej Kosiba ◽  
Maggie Lieu ◽  
Bruno Altieri ◽  
Nicolas Clerc ◽  
Lorenzo Faccioli ◽  
...  
Keyword(s):  
Neural Networks ◽  
Galaxy Clusters ◽  
Convolutional Neural Networks ◽  
Galaxy Cluster ◽  
Optical Data ◽  
Data Set ◽  
Extended Source ◽  
X Ray ◽  
Extended Sources

ABSTRACT Galaxy clusters appear as extended sources in XMM–Newton images, but not all extended sources are clusters. So, their proper classification requires visual inspection with optical images, which is a slow process with biases that are almost impossible to model. We tackle this problem with a novel approach, using convolutional neural networks (CNNs), a state-of-the-art image classification tool, for automatic classification of galaxy cluster candidates. We train the networks on combined XMM–Newton X-ray observations with their optical counterparts from the all-sky Digitized Sky Survey. Our data set originates from the XMM CLuster Archive Super Survey (X-CLASS) survey sample of galaxy cluster candidates, selected by a specially developed pipeline, the XAmin, tailored for extended source detection and characterization. Our data set contains 1707 galaxy cluster candidates classified by experts. Additionally, we create an official Zooniverse citizen science project, The Hunt for Galaxy Clusters, to probe whether citizen volunteers could help in a challenging task of galaxy cluster visual confirmation. The project contained 1600 galaxy cluster candidates in total of which 404 overlap with the expert’s sample. The networks were trained on expert and Zooniverse data separately. The CNN test sample contains 85 spectroscopically confirmed clusters and 85 non-clusters that appear in both data sets. Our custom network achieved the best performance in the binary classification of clusters and non-clusters, acquiring accuracy of 90 per cent, averaged after 10 runs. The results of using CNNs on combined X-ray and optical data for galaxy cluster candidate classification are encouraging, and there is a lot of potential for future usage and improvements.

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

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