Most galaxies comparable to or larger than the mass of the Milky Way host hot, X-ray emitting atmospheres, and many such galaxies are radio sources. Hot atmospheres and radio jets and lobes are the ...ingredients of radio-mechanical active galactic nucleus (AGN) feedback. While a consensus has emerged that such feedback suppresses cooling of hot cluster atmospheres, less attention has been paid to massive galaxies where similar mechanisms are at play. Observation indicates that the atmospheres of elliptical and S0 galaxies were accreted externally during the process of galaxy assembly and augmented significantly by stellar mass loss. Their atmospheres have entropy and cooling time profiles that are remarkably similar to those of central cluster galaxies. About half display filamentary or disky nebulae of cool and cold gas, much of which has likely cooled from the hot atmospheres. We review the observational and theoretical perspectives on thermal instabilities in galactic atmospheres and the evidence that AGN heating is able to roughly balance the atmospheric cooling. Such heating and cooling may be regulating star formation in all massive spheroids at late times.
Abstract
Suzaku measurements of a homogeneous metal distribution of Z ∼ 0.3 Solar in the outskirts of the nearby Perseus cluster suggest that chemical elements were deposited and mixed into the ...intergalactic medium before clusters formed, likely over 10 billion years ago. A key prediction of this early enrichment scenario is that the intracluster medium in all massive clusters should be uniformly enriched to a similar level. Here, we confirm this prediction by determining the iron abundances in the outskirts (r > 0.25r
200) of a sample of 10 other nearby galaxy clusters observed with Suzaku for which robust measurements based on the Fe-K lines can be made. Across our sample, the iron abundances are consistent with a constant value, Z
Fe = 0.316 ± 0.012 Solar (χ2 = 28.85 for 25 degrees of freedom). This is remarkably similar to the measurements for the Perseus cluster of Z
Fe = 0.314 ± 0.012 Solar, using the Solar abundance scale of Asplund et al.
Psoriasis as a chronic inflammatory disease often requires effective long-term treatment; a comprehensive systematic evaluation of efficacy and safety of systemic long-term treatments in patients ...with moderate-to-severe psoriasis is lacking. Twenty-five randomized clinical trials were included. Results were pooled and quality of evidence was assessed using GRADE (Grading of Recommendations Assessment, Development and Evaluation). With respect to PASI 75 (psoriasis area and severity index), pooled risk ratios for infliximab (13.07, 95% confidence interval (CI): 8.60–19.87), secukinumab (11.97, 95% CI: 8.83–16.23), ustekinumab (11.39, 95% CI: 8.94–14.51), adalimumab (8.92, 95% CI: 6.33–12.57), etanercept (8.39, 95% CI: 6.74–10.45), and apremilast (5.83, 95% CI: 2.58–13.17) show superiority of biologics and apremilast in long-term therapy compared with placebo. With respect to the addressed safety parameters, no differences were seen between adalimumab, etanercept, or infliximab versus placebo. No placebo-controlled data on conventional treatments was identified. Head-to-head studies showed superior efficacy of secukinumab and infliximab versus etanercept and of infliximab versus methotrexate. A clear ranking is limited by the lack of long-term head-to-head trials. From the available evidence, infliximab, secukinumab, and ustekinumab are the most efficacious long-term treatments. Data on conventionals are insufficient. Further head-to-head comparisons and studies on safety and patient-related outcomes are needed to draw more reliable conclusions.
Abstract
We present results from Suzaku Key Project observations of the Virgo Cluster, the nearest galaxy cluster to us, mapping its X-ray properties along four long ‘arms’ extending beyond the ...virial radius. The entropy profiles along all four azimuths increase with radius, then level out beyond ∼0.5r200, while the average pressure at large radii exceeds Planck Sunyaev–Zel'dovich measurements. These results can be explained by enhanced gas density fluctuations (clumping) in the cluster's outskirts. Using a standard Navarro, Frenk and White model, we estimate a virial mass, radius and concentration parameter of M200 = 1.05 ± 0.02 × 1014 M⊙, r200 = 974.1 ± 5.7 kpc and c = 8.8 ± 0.2, respectively. The inferred cumulative baryon fraction exceeds the cosmic mean at r ∼ r200 along the major axis, suggesting enhanced gas clumping possibly sourced by a candidate large-scale structure filament along the north–south direction. The Suzaku data reveal a large-scale sloshing pattern, with two new cold fronts detected at radii of 233 and 280 kpc along the western and southern arms, respectively. Two high-temperature regions are also identified 1 Mpc towards the south and 605 kpc towards the west of M87, likely representing shocks associated with the ongoing cluster growth. Although systematic uncertainties in measuring the metallicity for low-temperature plasma remain, the data at large radii appear consistent with a uniform metal distribution on scales of ∼90 × 180 kpc and larger, providing additional support for the early chemical enrichment scenario driven by galactic winds at redshifts of 2–3.
We propose a novel method to constrain turbulence and bulk motions in massive galaxies, galaxy groups, and clusters, exploring both simulations and observations. As emerged in the recent picture of ...top-down multiphase condensation, hot gaseous halos are tightly linked to all other phases in terms of cospatiality and thermodynamics. While hot halos (∼107 K) are perturbed by subsonic turbulence, warm (∼104 K) ionized and neutral filaments condense out of the turbulent eddies. The peaks condense into cold molecular clouds (<100 K) raining in the core via chaotic cold accretion (CCA). We show that all phases are tightly linked in terms of the ensemble (wide-aperture) velocity dispersion along the line of sight. The correlation arises in complementary long-term AGN feedback simulations and high-resolution CCA runs, and is corroborated by the combined Hitomi and new Integral Field Unit measurements in the Perseus cluster. The ensemble multiphase gas distributions (from the UV to the radio band) are characterized by substantial spectral line broadening ( v,los 100-200 ) with a mild line shift. On the other hand, pencil-beam detections (as H i absorption against the AGN backlight) sample the small-scale clouds displaying smaller broadening and significant line shifts of up to several 100 (for those falling toward the AGN), with increased scatter due to the turbulence intermittency. We present new ensemble v,los of the warm H +N ii gas in 72 observed cluster/group cores: the constraints are consistent with the simulations and can be used as robust proxies for the turbulent velocities, in particular for the challenging hot plasma (otherwise requiring extremely long X-ray exposures). Finally, we show that the physically motivated criterion C tcool/teddy 1 best traces the condensation extent region and the presence of multiphase gas in observed clusters and groups. The ensemble method can be applied to many available spectroscopic data sets and can substantially advance our understanding of multiphase halos in light of the next-generation multiwavelength missions.
Abstract
The microphysical properties, such as effective viscosity and conductivity, of the weakly magnetized intergalactic plasma are not yet well known. We investigate the constraints that can be ...placed by an azimuthally resolved study of the cold front in Abell 3667 using ∼500 ks archival Chandra data. We find that the radius of the interface fluctuates with position angle and the morphology of the interface is strikingly similar to recent numerical simulations of inviscid gas-stripping. We find multiple edges in the surface brightness profiles across the cold front as well as azimuthal variations, which are consistent with the presence of Kelvin–Helmholtz instabilities (KHIs) developing along the cold front. They indicate that the characteristic length-scale of KHI rolls is around 20–80 kpc. This is the first observational indication of developing KHIs along a merger cold front in a galaxy cluster. Based on the KHI scenario, we estimated the upper limit of the intracluster medium effective viscosity. The estimated value of μ ≲ 200 g cm−1 s−1 is at most 5 per cent of the isotropic Spitzer-like viscosity. The observed apparent mixing towards the outer edges away from the tip of the front provides an additional evidence for suppressed viscosity.
Four decades ago, the firm detection of an Fe-K emission feature in the X-ray spectrum of the Perseus cluster revealed the presence of iron in its hot intracluster medium (ICM). With more advanced ...missions successfully launched over the last 20 years, this discovery has been extended to many other metals and to the hot atmospheres of many other galaxy clusters, groups, and giant elliptical galaxies, as evidence that the elemental bricks of life—synthesized by stars and supernovae—are also found at the largest scales of the Universe. Because the ICM, emitting in X-rays, is in collisional ionisation equilibrium, its elemental abundances can in principle be accurately measured. These abundance measurements, in turn, are valuable to constrain the physics and environmental conditions of the Type Ia and core-collapse supernovae that exploded and enriched the ICM over the entire cluster volume. On the other hand, the spatial distribution of metals across the ICM constitutes a remarkable signature of the chemical history and evolution of clusters, groups, and ellipticals. Here, we summarise the most significant achievements in measuring elemental abundances in the ICM, from the very first attempts up to the era of
XMM-Newton
,
Chandra
, and
Suzaku
and the unprecedented results obtained by
Hitomi
. We also discuss the current systematic limitations of these measurements and how the future missions
XRISM
and
Athena
will further improve our current knowledge of the ICM enrichment.
ABSTRACT We present a study of relations between the masses of the central supermassive black holes (SMBHs) and the atmospheric gas temperatures and luminosities measured within a range of radii ...between Re and 5Re, for a sample of 47 early-type galaxies observed by the Chandra X-ray Observatory. We report the discovery of a tight correlation between the atmospheric temperatures of the brightest cluster/group galaxies (BCGs) and their central SMBH masses. Furthermore, our hydrostatic analysis reveals an approximately linear correlation between the total masses of BCGs (Mtot) and their central SMBH masses (MBH). State-of-the-art cosmological simulations show that the SMBH mass could be determined by the binding energy of the halo through radiative feedback during the rapid black hole growth by accretion, while for the most massive galaxies mergers are the chief channel of growth. In the scenario of a simultaneous growth of central SMBHs and their host galaxies through mergers, the observed linear correlation could be a natural consequence of the central limit theorem.
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