79 research outputs found

    A New X-ray Selected Sample of Very Extended Galaxy Groups from the ROSAT All-Sky Survey

    Full text link
    Some indications for tension have long been identified between cosmological constraints obtained from galaxy clusters and primary CMB measurements. Typically, assuming the matter density and fluctuations, as parameterized with Omega_m and sigma_8, estimated from CMB measurements, many more clusters are expected than those actually observed. One possible explanation could be that certain types of galaxy groups or clusters were missed in samples constructed in previous surveys, resulting in a higher incompleteness than estimated. We aim to determine if a hypothetical class of very extended, low surface brightness, galaxy groups or clusters have been missed in previous X-ray cluster surveys based on the ROSAT All-Sky Survey (RASS). We applied a dedicated source detection algorithm sensitive also to more unusual group or cluster surface brightness distributions. We found many known but also a number of new group candidates, which are not included in any previous X-ray / SZ cluster catalogs. In this paper, we present a pilot sample of 13 very extended groups discovered in the RASS at positions where no X-ray source has been detected previously and with clear optical counterparts. The X-ray fluxes of at least 5 of these are above the nominal flux-limits of previous RASS cluster catalogs. They have low mass (10131014M10^{13} - 10^{14} M_{\odot}; i.e., galaxy groups), are at low redshift (z<0.08), and exhibit flatter surface brightness distributions than usual. We demonstrate that galaxy groups were missed in previous RASS surveys, possibly due to the flat surface brightness distributions of this potential new population. Analysis of the full sample will show if this might have a significant effect on previous cosmological parameter constraints based on RASS cluster surveys. (This is a shortened version of the abstract - full text in the article)Comment: 18 pages, 7 figures, accepted by A&

    High-redshift galaxy groups as seen by Athena/WFI

    Full text link
    The first massive galaxy groups in the Universe are predicted to have formed at redshifts well beyond two. Baryonic physics, like stellar and active galactic nuclei (AGN) feedback in this very active epoch, are expected to have left a strong imprint on the thermo-dynamic properties of these early galaxy groups. Therefore, observations of these groups are key to constrain the relative importance of these physical processes. However, current instruments are not sensitive enough to detect them easily and characterize their hot gas content. In this work, we quantify the observing power of the Advanced Telescope for High ENergy Astrophysics (Athena), the future large X-ray observatory of the European Space Agency (ESA), for discovering and characterizing early galaxy groups at high redshifts. We used the SImulation of X-ray TElescopes (SIXTE) simulator to mimic Athena observations, and a custom-made wavelet-based algorithm to detect galaxy groups and clusters in the redshift range 0.5z40.5 \le z \le 4. We performed extensive X-ray spectral fitting in order to characterize their gas temperature and X-ray luminosity. We also investigate how well Athena will constrain different feedback mechanisms. In the deep Wide Field Imager (WFI) survey expected to be carried out during part of Athena's first four years (the nominal mission lifetime) more than 10,000 galaxy groups and clusters at z0.5z\ge 0.5 will be discovered. We find that Athena can detect 20\sim20 high-redshift galaxy groups with masses of M500M_{500}\geq 5×10135\times 10^{13} MM_{\odot} and z2z\geq2, and almost half of them will have a gas temperature determined to a precision of ΔT/T25%\Delta T/T \le 25\%. We demonstrate that high-redshift galaxy groups can be detected very efficiently as extended sources by Athena and that a key parameter determining the total number of such newly discovered sources is the area on the sky surveyed by Athena.Comment: 24 pages, 18 figures, accepted for publication in A&

    MXene Supported Cobalt Layered Double Hydroxide Nanocrystals: Facile Synthesis Route for a Synergistic Oxygen Evolution Reaction Electrocatalyst

    Get PDF
    International audienceThe development of reliable electrolyzers is closely related to the development of a cost-effective highly active and stable electrocatalysts for the oxygen evolution reaction (OER). Herein, a simple method is used to synthesize a non-noble metal-based electrocatalyst for OER by synergistically coupling a catalytically active cobalt layered double hydroxide (Co-LDH) with a highly electrically conducting 2D transition metal carbide, Ti3C2Tx MXene. The synergy between these two bidimensional materials (Co-LDH and Ti3C2Tx), evidenced by coupling electron energy loss spectroscopy and density functional theory simulations, results in superior electrocatalytic properties and makes possible having an excellent and stable oxygen evolution electrocatalyst. Moreover, the oxidative-sensitive MXene structure is preserved during the synthesis of the composite and the formation of a well recovering Co-LDH phase avoids the irreversible oxidation of MXene at high potential values, which may affect its conductivity. With an overpotential of approximate to 330 mV at a current density of 10 mA cm(-2) the catalyst exhibits a higher catalytic activity toward OER than commercial IrO2 catalysts

    The eROSITA view of the Abell 3391/95 field: The Northern Clump. The largest infalling structure in the longest known gas filament observed with eROSITA, XMM-Newton, and Chandra

    Full text link
    SRG/eROSITA PV observations revealed the A3391/95 cluster system and the Northern Clump (MCXC J0621.7-5242 galaxy cluster) are aligning along a cosmic filament in soft X-rays, similarly to what has been seen in simulations before. We aim to understand the dynamical state of the Northern Clump as it enters the atmosphere (3×R2003\times R_{200}) of A3391. We analyzed joint eROSITA, XMM-Newton, and Chandra observations to probe the morphological, thermal, and chemical properties of the Northern Clump from its center out to a radius of 988 kpc (R200R_{200}). We utilized the ASKAP/EMU radio data, DECam optical image, and Planck y-map to study the influence of the WAT radio source on the Northern Clump central ICM. From the Magneticum simulation, we identified an analog of the A3391/95 system along with an infalling group resembling the Northern Clump. The Northern Clump is a WCC cluster centered on a WAT radio galaxy. The gas temperature over 0.20.5R5000.2-0.5R_{500} is kBT500=1.99±0.04k_BT_{500}=1.99\pm0.04 keV. We employed the MTM-T scaling relation and obtained a mass estimate of M500=(7.68±0.43)×1013MM_{500}=(7.68\pm0.43)\times10^{13}M_{\odot} and R500=(636±12)R_{500}=(636\pm12) kpc. Its atmosphere has a boxy shape and deviates from spherical symmetry. We identify a southern surface brightness edge, likely caused by subsonic motion relative to the filament gas. At  ⁣R500\sim\! R_{500}, the southern atmosphere appears to be 42% hotter than its northern atmosphere. We detect a downstream tail pointing toward the north with a projected length of 318\sim318 kpc, plausibly the result of ram pressure stripping. The analog group in the Magneticum simulation is experiencing changes in its gas properties and a shift between the position of the halo center and that of the bound gas, while approaching the main cluster pair.Comment: 24 pages, 17 figures (main text), 6 figures (appendix). Submitted to A&A for the Special Issue: The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission. For more information, see https://astro.uni-bonn.de/~averonica/NorthernClump/eROSITA_A3391_Northern_Clump_AIfA.htm

    Differentiation of high-latitude and polar marine faunas in a greenhouse world

    Get PDF
    Aim The aim was to investigate those factors that influenced the differentiation of high-latitude and polar marine faunas on both ecological and evolutionary time-scales. Can a focus on a greenhouse world provide some important clues? Location World-wide, but with particular emphasis on the evolution of Antarctic marine faunas. Time period Early Cenozoic era and present day. Major taxa studied Mollusca, especially Neogastropoda. Methods The Early Cenozoic global radiation of one of the largest extant marine clades, Neogastropoda, was examined, and detailed comparisons were made between two tropical localities and Antarctica. High- to low-latitude faunal differentiation was assessed using Sørensen's dissimilarity index, and component species in each of the three faunas were assigned to 29 families and family groups. Relative diversity distributions were fitted to these three faunas and two modern ones to assess the contrast in evenness between high- and low-latitude assemblages. Results By the Middle Eocene, a distinct high-latitude neogastropod fauna had evolved in Antarctica. In addition, the distribution of species within families in this fauna is statistically significantly less even than that in the tropics. Indeed, there is no detectable difference in the scale of this separation from that seen today. Exactly as in the modern fauna, Middle Eocene Antarctic neogastropods are dominated by a small number of trophic generalist groups. Main conclusions As the hyperdiverse Neogastropoda clade radiated globally through the Early Cenozoic, it differentiated into distinct high- and low-latitude components. The fact that it did so in a greenhouse world strongly suggests that something else besides temperature was involved in this process. The predominance of generalist feeding types in the Antarctic fossil faunas is linked to the phenomenon of a seasonally pulsed food supply, exactly as it is today. Seasonality in primary productivity may act as a fundamental control on the evolution of large-scale biodiversity pattern

    Meta-analysis of ciltacabtagene autoleucel versus physician’s choice therapy for the treatment of patients with relapsed or refractory multiple myeloma

    Get PDF
    [Objective]: In the absence of head-to-head trials, indirect treatment comparisons (ITCs) between ciltacabtagene autoleucel (cilta-cel; in CARTITUDE-1) and treatments used in real-world clinical practice (physician’s choice of treatment [PCT]), were previously conducted. We conducted multiple meta-analyses using available ITC data to consolidate the effectiveness of cilta-cel versus PCT for patients with triple-class exposed relapsed or refractory multiple myeloma (RRMM). [Methods]: Five ITCs were assessed for similarity to ensure robust comparisons using meta-analysis. Effectiveness outcomes were overall survival (OS), progression-free survival (PFS), time to next treatment (TTNT), and overall response rate (ORR). A robust variance estimator was used to account for the use of CARTITUDE-1 in each pairwise ITC. Analyses were conducted in both treated and enrolled populations of CARTITUDE-1. [Results]: Four ITCs were combined for evaluation of OS. Results were statistically significantly in favor of cilta-cel versus PCT in treated patients (hazard ratio [HR]: 0.24, 95% confidence interval [CI]: 0.22–0.26). Three ITCs were combined for evaluation of PFS and TTNT. Cilta-cel reduced the risk of progression and receiving a subsequent treatment by 80% (HR: 0.20 [95% CI: 0.06, 0.70]) and 83% (HR: 0.17 [95% CI: 0.12, 0.26]), respectively. Three ITCs were combined for evaluation of ORR. Cilta-cel increased the odds of achieving an overall response by 86-times versus PCT in treated patients. Findings were consistent in the enrolled populations and across sensitivity analyses. [Conclusions]: Evaluating multiple indirect comparisons, cilta-cel demonstrated a significantly superior advantage over PCT, highlighting its effectiveness as a therapy in patients with triple-class exposed RRMM.The CARTITUDE-1 study and these analyses were funded by Janssen Research & Development, LLC, and Legend Biotech, Inc. Medical writing support was provided by EVERSANA and funded by Janssen Global Services, LLC

    Meta-analysis of ciltacabtagene autoleucel versus physician’s choice therapy for the treatment of patients with relapsed or refractory multiple myeloma [Dataset]

    Get PDF
    Figure A.1: Selection of Comparator Arms for ITC Analyses Figure A.2: Results of sensitivity analyses with OIs removed for OS at all (A) and first (B) index dates Figure A.3: Results of sensitivity analyses with LocoMMotion removed for OS at all (A) and first (B) index dates, and PF at first index dates (C) Table A.1: Characteristics of Data Sources for PCT arms in ITCs Table A.2: Published ITC Results and Augmented Results Included in Meta-analyses (All Index Dates) Table A.3: Published ITC Results and Augmented Results Included in Meta-analyses (First Index Dates) Table A.4: Baseline Covariates After Adjustment (mITT Populations; All Index Dates) Table A.5: Baseline Covariates After Adjustment (mITT Populations; First Index Dates) Table A.6: Outcome Definitions in ITC Analyses[Objective]: In the absence of head-to-head trials, indirect treatment comparisons (ITCs) between ciltacabtagene autoleucel (cilta-cel; in CARTITUDE-1) and treatments used in real-world clinical practice (physician’s choice of treatment [PCT]), were previously conducted. We conducted multiple meta-analyses using available ITC data to consolidate the effectiveness of cilta-cel versus PCT for patients with triple-class exposed relapsed or refractory multiple myeloma (RRMM). [Methods]: Five ITCs were assessed for similarity to ensure robust comparisons using meta-analysis. Effectiveness outcomes were overall survival (OS), progression-free survival (PFS), time to next treatment (TTNT), and overall response rate (ORR). A robust variance estimator was used to account for the use of CARTITUDE-1 in each pairwise ITC. Analyses were conducted in both treated and enrolled populations of CARTITUDE-1. [Results]: Four ITCs were combined for evaluation of OS. Results were statistically significantly in favor of cilta-cel versus PCT in treated patients (hazard ratio [HR]: 0.24, 95% confidence interval [CI]: 0.22–0.26). Three ITCs were combined for evaluation of PFS and TTNT. Cilta-cel reduced the risk of progression and receiving a subsequent treatment by 80% (HR: 0.20 [95% CI: 0.06, 0.70]) and 83% (HR: 0.17 [95% CI: 0.12, 0.26]), respectively. Three ITCs were combined for evaluation of ORR. Cilta-cel increased the odds of achieving an overall response by 86-times versus PCT in treated patients. Findings were consistent in the enrolled populations and across sensitivity analyses. [Conclusions]: Evaluating multiple indirect comparisons, cilta-cel demonstrated a significantly superior advantage over PCT, highlighting its effectiveness as a therapy in patients with triple-class exposed RRMM.Peer reviewe

    The XXL survey: first results and future

    Get PDF
    The XXL survey currently covers two 25 sq. deg. patches with XMM observations of ~10ks. We summarise the scientific results associated with the first release of the XXL data set, that occurred mid 2016. We review several arguments for increasing the survey depth to 40 ks during the next decade of XMM operations. X-ray (z1 cluster density. It will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions
    corecore