Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe X-ray luminous galaxy cluster population at 0.9<z<~1.6 as revealed by the XMM-Newton Distant Cluster Project
168
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present the largest sample of spectroscopically confirmed X-ray luminous high-redshift galaxy clusters to date comprising 22 systems in the range 0.9<z<sim1.6 as part of the XMM-Newton Distant Cluster Project (XDCP). All systems were initially selected as extended X-ray sources over 76.1 deg^2 of non-contiguous deep archival XMM-Newton coverage. We test and calibrate the most promising two-band redshift estimation techniques based on the R-z and z-H colors for efficient distant cluster identifications and find a good redshift accuracy performance of the z-H color out to at least zsim1.5, while the redshift evolution of the R-z color leads to increasingly large uncertainties at z>sim0.9. We present first details of two newly identified clusters, XDCP J0338.5+0029 at z=0.916 and XDCP J0027.2+1714 at z=0.959, and investigate the Xray properties of SpARCS J003550-431224 at z=1.335, which shows evidence for ongoing major merger activity along the line-of-sight. We provide X-ray properties and luminosity-based total mass estimates for the full sample, which has a median system mass of M200simeq2times10^14Modot. In contrast to local clusters, the z>0.9 systems do mostly not harbor central dominant galaxies coincident with the X-ray centroid position, but rather exhibit significant BCG offsets from the X-ray center with a median value of about 50 kpc in projection and a smaller median luminosity gap to the second-ranked galaxy of sim0.3mag. We estimate a fraction of cluster-associated NVSS 1.4GHz radio sources of about 30%, preferentially located within 1 from the X-ray center. The galaxy populations in z>sim1.5 cluster environments show first evidence for drastic changes on the high-mass end of galaxies and signs for a gradual disappearance of a well-defined cluster red-sequence as strong star formation activity is observed in an increasing fraction of massive galaxies down to the densest core regions.
rate research
Read More
Observational constraints on the average radial distribution profile of AGN in distant galaxy clusters can provide important clues on the triggering mechanisms of AGN activity in dense environments and are essential for a completeness evaluation of cluster selection techniques in the X-ray and mm-wavebands. The aim of this work is a statistical study with XMM-Newton of the presence and distribution of X-ray AGN in the large-scale structure environments of 22 X-ray luminous galaxy clusters in the redshift range 0.9 < z lesssim 1.6 compiled by the XMM-Newton Distant Cluster Project (XDCP). To this end, the X-ray point source lists from detections in the soft-band (0.35-2.4 keV) and full-band (0.3-7.5 keV) were stacked in cluster-centric coordinates and compared to average background number counts extracted from three independent control fields in the same observations. A significant full-band (soft-band) excess of sim78 (67) X-ray point sources is found in the cluster fields within an angular distance of 8 (4Mpc) at a statistical confidence level of 4.0 sigma (4.2 sigma), corresponding to an average number of detected excess AGN per cluster environment of 3.5pm0.9 (3.0pm0.7). The data point towards a rising radial profile in the cluster region (r<1Mpc) of predominantly low-luminosity AGN with an average detected excess of about one point source per system, with a tentative preferred occurrence along the main cluster elongation axis. A second statistically significant overdensity of brighter soft-band detected AGN is found at cluster-centric distances of 4-6 (2-3Mpc), corresponding to about three times the average cluster radius R200 of the systems. If confirmed, these results would support the idea of two different physical triggering mechanisms of X-ray AGN activity in dependence of the radially changing large-scale structure environment of the distant clusters.
Investigating X-ray luminous galaxy clusters at z>~1 provides a fundamental constraint on evolutionary studies of the largest virialized structures in the Universe, the baryonic matter in form of the hot ICM, their galaxy populations, and the effects of Dark Energy. The main aim of this work is to establish the observational foundation for the XMM-Newton Distant Cluster Project (XDCP). This new serendipitous survey is focused on the most distant systems at z>1, based on the selection of extended X-ray sources, their identification as clusters via two-band imaging, and their final spectroscopic confirmation. Almost 1000 extended sources were selected as cluster candidates from the analysis of 80 deg^2 of deep XMM-Newton archival data, of which 75% could be readily identified as systems at z<~0.6. For the remaining 250 distant cluster candidates a new strategy for their confirmation and redshift estimates was adopted, based on Z- and H-band photometry and the observed Z-H red-sequence color of early-type cluster galaxies. From observations of 25% of the sample, more than 20 X-ray clusters were discovered at a photometric redshift of z>~0.9. The new Z-H method has allowed a cluster sample study over an unprecedented redshift baseline of 0.2<~z<~1.5. From a comparison of the observed color evolution of the red-sequence with model predictions, the formation epoch of early-type galaxies could be constrained as z_f=4.2+-1.1, confirming their well-established old age. The preliminary investigation of the H-band luminosity evolution of 63 BCGs provides for the first time direct observational indications that the most massive cluster galaxies have doubled their stellar mass since z~1.5. The finding that BCGs were assembled in the last 9Gyr is now in qualitative agreement with the latest simulations.
Observations of relaxed, massive and distant clusters can provide important tests of standard cosmological models e.g. using the gas mass fraction. We study the very luminous, high redshift ($z=0.902$) galaxy cluster ClJ120958.9+495352 using XMM-Newton data and measure the temperature profile and cooling time to investigate the dynamical status with respect to the presence of a cool core as well as global cluster properties. We use HST weak lensing data to estimate its total mass and determine the gas mass fraction. We perform a spectral analysis using an XMM-Newton observation of 15ks cleaned exposure time. As the treatment of the background is crucial, we use two different approaches to account for the background emission to verify our results. We account for point-spread-function effects and deproject our results to estimate the gas mass fraction of the cluster. We measure weak lensing galaxy shapes from mosaic HST imaging and select background galaxies photometrically in combination with imaging data from the William Herschel Telescope. The X-ray luminosity of ClJ120958.9+495352 in the 0.1-2.4keV band estimated from our XMM-Newton data is $L_X = (13.4_{-1.0}^{+1.2})times10^{44}$erg/s and thus it is one of the most X-ray luminous clusters known at similarly high redshift. We find clear indications for the presence of a cool core from the temperature profile and the central cooling time, which is very rare at such high redshifts. Based on the weak lensing analysis we estimate a cluster mass of $M_mathrm{500}/10^{14}M_odot=4.4^{+2.2}_{-2.0}(mathrm{stat.})pm0.6(mathrm{sys.})$ and a gas mass fraction of $f_mathrm{gas,2500} = 0.11_{-0.03}^{+0.06}$ in good agreement with previous findings for high redshift and local clusters.
We present results from a 577 ks XMM-Newton observation of SPT-CL J0459-4947, the most distant cluster detected in the South Pole Telescope 2500 square degree (SPT-SZ) survey, and currently the most distant cluster discovered through its Sunyaev-Zeldovich effect. The data confirm the clusters high redshift, $z=1.71 pm 0.02$, in agreement with earlier, less precise optical/IR photometric estimates. From the gas density profile, we estimate a characteristic mass of $M_{500}=(1.8 pm 0.2) times 10^{14}M_{Sun}$; cluster emission is detected above the background to a radius of $sim 2.2 r_{500}$, or approximately the virial radius. The intracluster gas is characterized by an emission-weighted average temperature of $7.2 pm 0.3$ keV and metallicity with respect to Solar of $0.37 pm 0.08$. For the first time at such high redshift, this deep data set provides a measurement of metallicity outside the cluster center; at radii $r > 0.3 r_{500}$, we find it to be $0.33 pm 0.17$, in good agreement with precise measurements at similar radii in the most nearby clusters, supporting an early enrichment scenario in which the bulk of the cluster gas is enriched to a universal metallicity prior to cluster formation, with little to no evolution thereafter. The leverage provided by the high redshift of this cluster tightens by a factor of 2 constraints on evolving metallicity models, when combined with previous measurements at lower redshifts.
We report on the discovery of a very distant galaxy cluster serendipitously detected in the archive of the XMM-Newton mission, within the scope of the XMM-Newton Distant Cluster Project (XDCP). XMMUJ0044.0-2033 was detected at a high significance level (5sigma) as a compact, but significantly extended source in the X-ray data, with a soft-band flux f(r<40)=(1.5+-0.3)x10^(-14) erg/s/cm2. Optical/NIR follow-up observations confirmed the presence of an overdensity of red galaxies matching the X-ray emission. The cluster was spectroscopically confirmed to be at z=1.579 using ground-based VLT/FORS2 spectroscopy. The analysis of the I-H colour-magnitude diagram shows a sequence of red galaxies with a colour range [3.7 < I-H < 4.6] within 1 from the cluster X-ray emission peak. However, the three spectroscopic members (all with complex morphology) have significantly bluer colours relative to the observed red-sequence. In addition, two of the three cluster members have [OII] emission, indicative of on-going star formation. Using the spectroscopic redshift we estimated the X-ray bolometric luminosity, Lbol = 5.8x10^44 erg/s, implying a massive galaxy cluster. This places XMMU J0044.0-2033 at the forefront of massive distant clusters, closing the gap between lower redshift systems and recently discovered proto- and low-mass clusters at z >1.6.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
