Possible AGN Shock Heating in the Cool Core Galaxy Cluster Abell 478

We present a detailed X-ray study of the intracluster medium (ICM) of the nearby, cool-core galaxy cluster Abell 478, with Chandra and XMM observations. Using a wavelet smoothing hardness analysis, we derive detailed temperature maps of A478, revealing a surprising amount of temperature structure. The broad band Chandra spectral fits yield temperatures which are significantly hotter than those from XMM, but the Fe ionization temperature shows good agreement. We show that the temperature discrepancy is slightly reduced when comparing spectra from regions selected to enclose nearly isothermal gas. However, by simulating multi-temperature spectra and fitting them with a single temperature model, we find no significant difference between Chandra and XMM, indicating that non-isothermality cannot fully explain the discrepancy. We have discovered 4 hot spots located between 30--50 kpc from the cluster center, where the gas temperature is roughly a factor of 2 higher than in the surrounding material. We estimate the combined excess thermal energy present in these hot spots to be (3+/-1)x10^59 erg. The location of and amount of excess energy present in the hot spots are suggestive of a common origin within the cluster core, which hosts an active galactic nucleus. This cluster also possesses a pair of X-ray cavities coincident with weak radio lobes, as reported in a previous analysis, with an associated energy <10% of the thermal excess in the hot spots. The presence of these hot spots could indicate strong-shock heating of the ICM from the central radio source -- one of the first such detections in a cool core cluster. We also probe the mass distribution in the core and find it to be characterized by a logarithmic slope of -0.35+/-0.22, which is significantly flatter than an NFW cusp of -1. (abridged)Comment: 15 pages, 15 figures; extra section on simulating effect of multiphase gas, plus some restructuring of discussion section. Accepted by ApJ; corrected typo in equation

A statistical analysis of the Two Dimensional XMM-Newton Group Survey: The impact of feedback on group properties

(abridged) We present a statistical analysis of 28 nearby galaxy groups from the Two-Dimensional XMM-Newton Group Survey (2dXGS). We focus on entropy and the role of feedback, dividing the sample into cool core (CC) and non cool core (NCC) systems, the first time the latter have been studied in detail in the group regime. The coolest groups have steeper entropy profiles than the warmest systems, and NCC groups have higher central entropy and exhibit more scatter than their CC counterparts. We compare the entropy distribution of the gas in each system to the expected theoretical distribution ignoring non-gravitational processes. In all cases, the observed maximum entropy far exceeds that expected theoretically, and simple models for modifications of the theoretical entropy distribution perform poorly. Applying initial pre-heating, followed by radiative cooling, generally fails to match the low entropy behaviour, and only performs well when the difference between the maximum entropy of the observed and theoretical distributions is small. Successful feedback models need to work differentially to increase the entropy range in the gas, and we suggest two basic possibilities. We analyse the effects of feedback on the entropy distribution, finding systems with a high measure of `feedback impact' to reach higher entropy than their low feedback counterparts and also to show significantly lower central metallicities. If low entropy, metal-rich gas has been boosted to large entropy in the high feedback systems, it must now reside outside 0.5r_500, to remain undetected. We find similar levels of enrichment in both high and low feedback systems, and argue that the lack of extra metals in the highest feedback systems points to an AGN origin for the bulk of the feedback, probably acting within precursor structures.Comment: 24 pages, 21 figures; accepted for publication in MNRA

Abundance profiles and cool cores in galaxy groups

Using data from the Two Dimensional XMM-Newton Group Survey (2dXGS), we have examined the abundance profile properties of both cool core (CC) and non cool core (NCC) galaxy groups. The ten NCC systems in our sample represent a population which to date has been poorly studied in the group regime. Fitting the abundance profiles as a linear function of log radius, we find steep abundance gradients in cool core (CC) systems, with a slope of -0.54+/-0.07. In contrast, non cool core (NCC) groups have profiles consistent with uniform metallicity. Many CC groups show a central abundance dip or plateau, and we find evidence for anticorrelation between the core abundance gradient and the 1.4 GHz radio power of the brightest group galaxy (BGG) in CC systems. This may indicate the effect of AGN-driven mixing within the central ~0.1r_500. It is not possible to discern whether such behaviour is present in the NCC groups, due to the small and diverse sample with the requisite radio data. The lack of strong abundance gradients in NCC groups, coupled with their lack of cool core, and evidence for enhanced substructure, leads us to favour merging as the mechanism for disrupting cool cores, although we cannot rule out disruption by a major AGN outburst. Given the implied timescales, the disruptive event must have occurred within the past few Gyrs in most NCC groups.Comment: 15 pages, 12 figures, accepted for publication in MNRA

LoCuSS: A comparison of cluster mass measurements from XMM-Newton and subaru - Testing deviation from hydrostatic equilibrium and non-thermal pressure support

We compare X-ray hydrostatic and weak-lensing mass estimates for a sample of 12 clusters that have been observed with both XMM-Newton and Subaru. At an over-density of \u394 = 500, we obtain 1 - M X/M WL = 0.01 \ub1 0.07 for the whole sample. We also divided the sample into undisturbed and disturbed sub-samples based on quantitative X-ray morphologies using asymmetry and fluctuation parameters, obtaining 1 - M X/M WL = 0.09 \ub1 0.06 and -0.06 \ub1 0.12 for the undisturbed and disturbed clusters, respectively. In addition to non-thermal pressure support, there may be a competing effect associated with adiabatic compression and/or shock heating which leads to overestimate of X-ray hydrostatic masses for disturbed clusters, for example, in the famous merging cluster A1914. Despite the modest statistical significance of the mass discrepancy, on average, in the undisturbed clusters, we detect a clear trend of improving agreement between M X and M WL as a function of increasing over-density, M^X/M^WL=(0.908 \ub1 0.004)+(0.187 \ub1 0.010) cdot log_{10} (\u394 /500). We also examine the gas mass fractions, f gas = M gas/M WL, finding that they are an increasing function of cluster radius, with no dependence on dynamical state, in agreement with predictions from numerical simulations. Overall, our results demonstrate that XMM-Newton and Subaru are a powerful combination for calibrating systematic uncertainties in cluster mass measurements

X-ray Substructure Studies of Four Galaxy Clusters using XMM-Newton Data

Mahdavi et al. find that the degree of agreement between weak lensing and X-ray mass measurements is a function of cluster radius. Numerical simulations also point out that X-ray mass proxies do not work equally well at all radii. The origin of the effect is thought to be associated with cluster mergers. Recent work presenting the cluster maps showed an ability of X-ray maps to reveal and study cluster mergers in detail. Here we present a first attempt to use the study of substructure in assessing the systematics of the hydrostatic mass measurements using two-dimensional (2-D) X-ray diagnostics. The temperature map is uniquely able to identify the substructure in an almost relaxed cluster which would be unnoticed in the ICM electron number density and pressure maps. We describe the radial fluctuations in the 2-D maps by a cumulative/differential scatter profile relative to the mean profile within/at a given radius. The amplitude indicates ~10 fluctuations in the temperature, electron number density and entropy maps, and ~15 fluctuations in the pressure map. The amplitude of and the discontinuity in the scatter complement 2-D substructure diagnostics, e.g. indicating the most disturbed radial range. There is a tantalizing link between the substructure identified using the scatter of the entropy and pressure fluctuations and the hydrostatic mass bias relative to the expected mass based on the M-Yx and M-Mgas relations particularly at r500. XMM-Newton observations with ~120,000 source photons from the cluster are sufficient to apply our substructure diagnostics via the spectrally measured 2-D temperature, electron number density, entropy and pressure maps.Comment: 44 pages, 16 figures, 3 tables, including some language editing from ApJ, published in Ap

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Conférence de M. Alexis Sanderson

Sanderson Alexis. Conférence de M. Alexis Sanderson. In: École pratique des hautes études, Section des sciences religieuses. Annuaire. Tome 100, 1991-1992. 1991. pp. 141-144

The Śaiva Religion among the Khmers (Part I)

Alexis Sanderson The Śaiva Religion among the Khmers (Part I) Of Śaivism, Puficarātrika Vaisnavism and Mahāyāna Buddhism, the three Indie religions that flourished among the ruling and priestly elites of the Khmers up to the 14th century, Śaivism was predominant. We see this in the saivization of the land through the creation of a large number of local Śiva bearing the names of Indian prototypes—a phenomenon not seen in the other two traditions, in the role of the Śiva Bhadrešvara of Vat Phu as a national deity and protector of the monarch, in evidence of the institutionalization of Śaivism as the religion of the state, and in traces of Śaiva inroads into Khmer Vaisnavism and Buddhism. Indian Śaivism was not static or homogeneous and Khmer Śaivism reflects some at least of this diversity and development over time. We see Paśupata Śaivas of the Atimārga in the inscriptions of the seventh century and when the epigraphic record returns from the late ninth to the fourteenth we find that they have given way to Śaivas of the Mantramārga practising the Saiddhāntika and Varna ritual systems. The evidence among the Khmers for all of these traditions, and also for that of the lay Śivadharma, will be considered in the sequel of this study. But the differences between the Atimārga and the Mantramārga bear on technicalities within the practice of the initiates who officiated at the Khmers' many Śaiva sites. It had no perceptible effect on the public aspects of the religion as embodied in the iconographie range of Śiva forms and ancillary deities in Śiva's temples. That iconographie program, which concerns the laity rather than fellow-initiates, has no place in either the Atimàxga or the Mantramârga. It has its own history, which neither system did much to modify. The richness of the Khmer iconic and epigraphical evidence is in this as in other respects highly instructive not only for the student of the nature of Indie culture beyond India but also for those seeking to clarify the history of religion in India itself.Alexis Sanderson La religion çivaïte chez les Khmers (1re partie) Des trois religions d'origine indienne - çivaïsme, vishnouisme pāncarātrika et bouddhisme mahāyāna - qui ont prospéré au sein des élites dirigeantes et sacerdotales des Khmers jusqu'au XIVe siècle, le çivaïsme fut prédominant. En attestent la « çivaïsation » du territoire opérée par la création d'un grand nombre de Śiva locaux portant les noms de prototypes indiens - un phénomène que l'on n'observe pas dans les deux autres traditions-, le rôle du Śiva Bhadreśvara de Vat Phu comme divinité nationale et protecteur du monarque, les marques de l'institutionnalisation du çivaïsme comme religion d'État ainsi que les traces des incursions çivaïtes dans le vishnouisme et le bouddhisme khmers. Le çivaïsme indien n'était ni statique, ni homogène, et le çivaïsme khmer reflète au moins partiellement cette diversité et cette évolution. Des inscriptions du VIIe siècle attestent la présence de çivaïtes pāçupata de l'Atimārga, et nous constatons, quand les témoignages épigraphiques réapparaissent, du IXe au XIVe siècle, qu'ils ont cédé la place à des çivaïtes du Mantramārga suivant les systèmes rituels Saiddhāntika et Varna. Les témoignages de la présence chez les Khmers de toutes ces traditions, ainsi que de celle du Śivadharma des laïcs, seront examinés dans la seconde partie de cette étude. Mais les différences entre l'Atimārga et le Mantramārga portent sur des détails techniques de la pratique des initiés officiant dans les nombreux sites çivaïtes des Khmers. Elles n'ont laissé aucune trace dans les aspects publics de la religion que donne à voir la gamme iconographique des formes de Śiva et des divinités secondaires dans les temples çivaïtes. Ce programme iconographique, qui concerne les laïcs plutôt que la communauté des initiés, n'avait de place ni dans l'Atimārga ni dans le Mantramārga. Il a sa propre histoire, qu'aucun des deux systèmes ne chercha à modifier. La richesse des témoignages iconographiques et épigraphiques khmers est, en ce domaine comme en d'autres, très instructive non seulement pour qui étudie les cultures d'origine indienne hors de l'Inde, mais aussi pour qui cherche à élucider l'histoire des religions en Inde même.Sanderson Alexis. The Śaiva Religion among the Khmers (Part I). In: Bulletin de l'Ecole française d'Extrême-Orient. Tome 90-91, 2003. pp. 349-462

The Khecarīvidyā of Ādinātha : a critical edition and annotated translation

This thesis contains a critical edition and annotated translation of the Khecarīvidyā of Ādinātha, an early haṭhayogic text which describes the physical practice of khecarīmudrā. 31 witnesses have been collated to establish the critical edition. The notes to the translation adduce parallels in other works and draw on Ballāla's Bṛhatkhecarīprakāśa commentary and ethnographic data to explain the text. The first introductory chapter examines the relationships between the different sources used to establish the critical edition. An analysis of the development of the text concludes that its compiler(s) took a chapter describing the vidyā (mantra) of the deity Khecarī from a larger text to form the framework for the verses describing the physical practice. At this stage the text preserved the Kaula orientation of the original work and included verses in praise of madirā, alcohol. By the time that the text achieved its greatest fame as an authority on the haṭhayogic practice of khecarīmudrā most of its Kaula features had been expunged so as not to offend orthodox practitioners of haṭhayoga and a short fourth chapter on magical herbs had been added. The second introductory chapter concerns the physical practice. It starts by examining textual evidence in the Pali canon and Sanskrit works for practices similar to the haṭhayogic khecarīmudrā before the time of composition of the Khecarīvidyā and then discusses the non-physical khecarīmudrās described in tantric works. There follows a discussion of how these different features combined in the khecarīmudrā of the Khecarīvidyā. Then a survey of descriptions of khecarīmudrā in other haṭhayogic works shows how the haṭhayogic corpus encompasses various differnt approaches to yogic practice. After an examination of the practice of khecarīmudrā in India today the chapter concludes by showing the haṭhayogic khecarīmudrā has generally been the preserve of unorthodox ascetics. In the third introductory chapter are described the 27 manuscripts used to establish the critical edition, the citations and borrowings of the text in other works, and the ethnographic sources. The appendices include a full collation of all the witnesses of the Khecarīvidyā, critical editions of chapters from the Matsyendrasaṃhitā and Haṭharatnāvalī helpful in understanding the Khecarīvidyā, and a list of all the works cited in the Bṛhatkhecarīprakāśa.EThOS - Electronic Theses Online ServiceGBUnited Kingdo