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We use a set of 45 simulated clusters with a wide mass range ($8\times 10^{13} < M_{500}~[$M$_{\odot}]~< 2\times 10^{15}$) to investigate the effect of varying hydrodynamics flavours on cluster mass estimates. The cluster zooms were simulated using the same cosmological models as the BAHAMAS and C-EAGLE projects, leading to differences in both the hydrodynamic solvers and the subgrid physics but still producing clusters which broadly match observations. At the same mass resolution as BAHAMAS, for the most massive clusters ($M_{500} > 10^{15}$ M$_{\odot}$), we find changes in the SPH method produce the greatest differences in the final halo, while the subgrid models dominate at lower mass. By calculating the mass of all of the clusters using different permutations of the pressure, temperature and density profiles, created with either the true simulated data or mock spectroscopic data, we find that the spectroscopic temperature causes a bias in the hydrostatic mass estimates which increases with the mass of the cluster, regardless of the SPH flavour used. For the most massive clusters, the estimated mass of the cluster using spectroscopic density and temperature profiles is found to be as low as 50 per cent of the true mass compared to $\sim$ 90 per cent for low mass clusters. When including a correction for non-thermal pressure, the spectroscopic hydrostatic mass estimates are less biased on average and the mass dependence of the bias is reduced, although the scatter in the measurements does increase., 21 pages, 14 figures. Accepted for publication by MNRAS

Modeling collisionless magnetic reconnection rate is an outstanding challenge in basic plasma physics research. While the seemingly universal rate of an order $\mathcal{O}(0.1)$ is often reported in the low-$\beta$ regime, it is not clear how reconnection rate scales with a higher plasma $\beta$. Due to the complexity of the pressure tensor, the available reconnection rate model is limited to the low plasma-$\beta$ regime, where the thermal pressure is arguably negligible. However, the thermal pressure effect becomes important when $\beta \gtrsim \mathcal{O}(1)$. Using first-principle kinetic simulations, we show that both the reconnection rate and outflow speed drop as $\beta$ gets larger. A simple analytical framework is derived to take account of the self-generated pressure anisotropy and pressure gradient in the force-balance around the diffusion region, explaining the varying trend of key quantities and reconnection rates in these simulations with different $\beta$. The predicted scaling of the normalized reconnection rate is $\simeq \mathcal{O}(0.1/\sqrt{\beta_{i0}})$ in the high $\beta$ limit, where $\beta_{i0}$ is the ion $\beta$ of the inflow plasma., Comment: 19 pages, 7 figures, accepted for publication in ApJ

Galaxy clusters are the endpoints of structure formation and are continuously growing through the merging and accretion of smaller structures. Numerical simulations predict that a fraction of their energy content is not yet thermalized, mainly in the form of kinetic motions (turbulence, bulk motions). Measuring the level of non-thermal pressure support is necessary to understand the processes leading to the virialization of the gas within the potential well of the main halo and to calibrate the biases in hydrostatic mass estimates. We present high-quality measurements of hydrostatic masses and intracluster gas fraction out to the virial radius for a sample of 12 nearby clusters with available XMM-Newton and Planck data. We compare our hydrostatic gas fractions with the expected universal gas fraction to constrain the level of non-thermal pressure support. We find that hydrostatic masses require little correction and infer a median non-thermal pressure fraction of $\sim6\%$ and $\sim10\%$ at $R_{500}$ and $R_{200}$, respectively. Our values are lower than the expectations of hydrodynamical simulations, possibly implying a faster thermalization of the gas. If instead we use the mass calibration adopted by the Planck team, we find that the gas fraction of massive local systems implies a mass bias $1-b=0.85\pm0.05$ for SZ-derived masses, with some evidence for a mass-dependent bias. Conversely, the high bias required to match Planck CMB and cluster count cosmology is excluded by the data at high significance, unless the most massive halos are missing a substantial fraction of their baryons., Comment: 11 pages, 7 figures, A&A in press. This is one of three companion papers (including Ghirardini et al. and Ettori et al.) on the X-COP sample. X-COP data products are available for download on https://www.astro.unige.ch/xcop

We explore the relation between the star formation rate surface density ($\Sigma$SFR) and the interstellar gas pressure for nearby compact starburst galaxies. The sample consists of 17 green peas and 19 Lyman break analogs. Green peas are nearby analogs of Ly$\alpha$ emitters at high redshift and Lyman break analogs are nearby analogs of Lyman break galaxies at high redshift. We measure the sizes for green peas using Hubble Space Telescope Cosmic Origins Spectrograph (COS) NUV images with a spatial resolution of $\sim$ 0.05$^{''}$. We estimate the gas thermal pressure in HII regions by $P = N_{total}Tk{_B} \simeq 2n_{e}Tk{_B}$. The electron density is derived using the [SII] doublet at 6716,6731 \AA, and the temperature is calculated from the [OIII] lines. The correlation is characterized by $\Sigma$ SFR = 2.40$\times$10$^{-3\,}$M$_{\odot\,}$yr$^{-1\,}$kpc$^{-2}$$\left(\frac{P/k_{B}}{10^{4}cm^{-3}K}\right)^{1.33}$. Green peas and Lyman break analogs have high $\Sigma$SFR up to 1.2 M$_{\odot\,}$yr$^{-1\,}$kpc$^{-2}$ and high thermal pressure in HII region up to P/k$_B$ $\sim$10$^{7.2}{\rm\, K\, cm}^{-3}$. These values are at the highest end of the range seen in nearby starburst galaxies. The high gas pressure and the correlation, are in agreement with those found in star-forming galaxies at z $\sim$ 2.5. These extreme pressures are shown to be responsible for driving galactic winds in nearby starbursts. These outflows may be a crucial in enabling Lyman-$\alpha$ and Lyman-continuum to escape., Comment: 16 pages, 6 figures, 1 table; Accepted for publication in ApJ

Clumping and turbulence are expected to affect the matter accreted onto the outskirts of galaxy clusters. To determine their impact on the thermodynamic properties of Abell 2142 we perform an analysis of the X-ray temperature data from XMM-Newton via our SuperModel, a state-of-the-art tool for investigating the astrophysics of the intracluster medium already tested on many individual clusters (since Cavaliere et al. 2009). Using the gas density profile corrected for clumpiness derived by Tchernin et al. (2016), we find evidence for the presence of a nonthermal pressure component required to sustain gravity in the cluster outskirts of Abell 2142, that amounts to about 30% of the total pressure at the virial radius. The presence of the nonthermal component implies the gas fraction to be consistent with the universal value at the virial radius and the electron thermal pressure profile to be in good agreement with that inferred from the SZ data. Our results indicate that the presence of gas clumping and of a nonthermal pressure component are both necessary to recover the observed physical properties in the cluster outskirts. Moreover, we stress that an alternative method often exploited in the literature (included Abell 2142) to determine the temperature profile k_BT = P_e/n_e basing on a combination of the Sunyaev-Zel'dovich (SZ) pressure P_e and of the X-ray electron density n_e does not allow to highlight the presence of nonthermal pressure support in the cluster outskirts., Comment: 8 pages, 4 figures, Accepted by MNRAS

Dynamic and thermal processes regulate the structure of the multi-phase interstellar medium (ISM), and ultimately establish how galaxies evolve through star formation. Thus, to constrain ISM models and better understand the interplay of these processes, it is of great interest to measure the thermal pressure ($P_{\rm th}$) of the diffuse, neutral gas. By combining [C II] 158 $\mu$m, HI, and CO data from 31 galaxies selected from the Herschel KINGFISH sample, we have measured thermal pressures in 534 predominantly atomic regions with typical sizes of $\sim$1 kiloparsec. We find a distribution of thermal pressures in the $P_{\rm th}/k\sim10^3-10^5$ K cm$^{-3}$ range. For a sub-sample of regions with conditions similar to those of the diffuse, neutral gas in the Galactic plane, we find thermal pressures that follow a log-normal distribution with a median value of $P_{\rm th}/k\approx3600$ K cm$^{-3}$. These results are consistent with thermal pressure measurements using other observational methods. We find that $P_{\rm th}$ increases with radiation field strength and star formation activity, as expected from the close link between the heating of the gas and the star formation rate. Our thermal pressure measurements fall in the regime where a two-phase ISM with cold and warm neutral medium could exist in pressure equilibrium. Finally, we find that the midplane thermal pressure of the diffuse gas is about $\sim30$% of the vertical weight of the overlying ISM, consistent with results from hydrodynamical simulations of self-regulated star formation in galactic disks., Comment: Accepted for publication in ApJ on Dec. 20th, 2016; 17 pages; 7 figures and 1 table

Non-thermal pressure in the intracluster gas has been found ubiquitously in numerical simulations, and observed indirectly. In this paper we develop an analytical model for intracluster non-thermal pressure in the virial region of relaxed clusters. We write down and solve a first-order differential equation describing the evolution of non-thermal velocity dispersion. This equation is based on insights gained from observations, numerical simulations, and theory of turbulence. The non-thermal energy is sourced, in a self-similar fashion, by the mass growth of clusters via mergers and accretion, and dissipates with a time-scale determined by the turnover time of the largest turbulence eddies. Our model predicts a radial profile of non-thermal pressure for relaxed clusters. The non-thermal fraction increases with radius, redshift, and cluster mass, in agreement with numerical simulations. The radial dependence is due to a rapid increase of the dissipation time-scale with radii, and the mass and redshift dependence comes from the mass growth history. Combing our model for the non-thermal fraction with the Komatsu-Seljak model for the total pressure, we obtain thermal pressure profiles, and compute the hydrostatic mass bias. We find typically 10% bias for the hydrostatic mass enclosed within $r_{500}$., Comment: 12 pages, 9 figures, published in MNRAS. Discussions and references added. A factor of 2 corrected in t_dyn (Fig. 2), definition of t_d (Eq. 3) changed accordingly

UV absorption studies with FUSE have observed H2 molecular gas in translucent and diffuse clouds. Observations of the 158 micron [C II] fine structure line with Herschel also trace the same H2 molecular gas in emission. We present [C II] observations along 27 lines of sight (LOSs) towards target stars of which 25 have FUSE H2 UV absorption. We detect [C II] emission features in all but one target LOS. For three Target LOSs, which are close to the Galactic plane, we also present position-velocity maps of [C II] emission observed by HIFI in on-the-fly spectral line mapping. We use the velocity resolved [C II] spectra towards the target LOSs observed by FUSE to identify C II] velocity components associated with the H2 clouds. We analyze the observed velocity integrated [C II] spectral line intensities in terms of the densities and thermal pressures in the H2 gas using the H2 column densities and temperatures measured by the UV absorption data. We present the H2 gas densities and thermal pressures for 26 target LOSs and from the [C II] intensities derive a mean thermal pressure in the range 6100 to 7700 K cm^-3 in diffuse H2 clouds. We discuss the thermal pressures and densities towards 14 targets, comparing them to results obtained using the UV absorption data for two other tracers CI and CO., Comment: 16 pages; 13 figures

While clusters of galaxies are regarded as one of the most important cosmological probes, the conventional spherical modeling of the intracluster medium (ICM) and the dark matter (DM), and the assumption of strict hydrostatic equilibrium (i.e., the equilibrium gas pressure is provided entirely by thermal pressure) are very approximate at best. Extending our previous works, we developed further a method to reconstruct for the first time the full three-dimensional structure (triaxial shape and principal axis orientation) of both DM and intracluster (IC) gas, and the level of non-thermal pressure of the IC gas. We outline an application of our method to the galaxy cluster Abell 383, taken as part of the CLASH multi-cycle treasury program, presenting results of a joint analysis of X-ray and strong lensing measurements. We find that the intermediate-major and minor-major axis ratios of the DM are 0.71+/-0.10 and 0.55+/-0.06, respectively, and the major axis of the DM halo is inclined with respect to the line of sight of 21.1+/-10.1 deg. The level of non-thermal pressure has been evaluated to be about 10% of the total energy budget. We discuss the implications of our method for the viability of the CDM scenario, focusing on the concentration parameter C and the inner slope of the DM gamma, since the cuspiness of dark-matter density profiles in the central regions is one of the critical tests of the cold dark matter (CDM) paradigm for structure formation: we measure gamma=1.02+/-0.06 on scales down to 25 Kpc, and C=4.76+/-0.51, values which are close to the predictions of the standard model, and providing further evidences that support the CDM scenario. Our method allows us to recover the three-dimensional physical properties of clusters in a bias-free way, overcoming the limitations of the standard spherical modelling and enhancing the use of clusters as more precise cosmological probes.

We directly probed the phonon density of states (DOS) of hexagonal close-packed iron (e-Fe) with high statistical quality between pressures of 30 GPa and 151 GPa using nuclear resonant inelastic X-ray scattering and insitu synchrotron X-ray diffraction experiments at 300 K. From each measured phonon DOS, we determined the vibrational free energy (F_(vib)) and mean-square displacement of atoms, 〈u^2〉. The volume dependence of F_(vib) is directly related to the vibrational thermal pressure, which we combine with previously reported theoretical values for the electronic and anharmonic thermal pressures to find the total thermal pressure (P_(th)). In addition, we obtained the shape of e-Fe’s melting curve from the volume dependence of our 〈u^2〉, and anchored it with an experimentally determined melting point to obtain the high-pressure melting behavior of e-Fe. Considering thermal pressure and anharmonic effects, we found e-Fe’s melting temperature at the pressure of Earth’s core–mantle boundary (P = 135 GPa) to be 3500 ± 100 K. Extrapolating our melting curve to the pressure of the inner-core boundary (ICB, P = 330 GPa), where Earth’s solid inner-core and liquid outer-core are in contact, we determined a melting temperature for e-Fe of 5600 ± 200 K. Finally, combining this temperature constraint with our P_(th), we determined the density of e-Fe under ICB conditions to be 13.50 ± 0.03 g/cm^3, which is 5.5 ± 0.2% higher than the seismically inferred density at the ICB.

Non-thermal pressure in galaxy clusters leads to underestimation of the mass of galaxy clusters based on hydrostatic equilibrium with thermal gas pressure. This occurs even for dynamically relaxed clusters that are used for calibrating the mass-observable scaling relations. We show that the analytical model for non-thermal pressure developed in Shi & Komatsu 2014 can correct for this so-called 'hydrostatic mass bias', if most of the non-thermal pressure comes from bulk and turbulent motions of gas in the intracluster medium. Our correction works for the sample average irrespective of the mass estimation method, or the dynamical state of the clusters. This makes it possible to correct for the bias in the hydrostatic mass estimates from X-ray surface brightness and the Sunyaev-Zel'dovich observations that will be available for clusters in a wide range of redshifts and dynamical states., 9 pages, 8 figures, published in MNRAS

Galaxy evolution depends strongly on the physics of the interstellar medium (ISM). Motivated by the need to incorporate the properties of the ISM in cosmological simulations we construct a simple method to include the contribution of non-thermal components in the calculation of pressure of interstellar gas. In our method we treat three non-thermal components - turbulence, magnetic fields and cosmic rays - and effectively parametrize their amplitude. We assume that the three components settle into a quasi-steady-state that is governed by the star formation rate, and calibrate their magnitude and density dependence by the observed Radio-FIR correlation, relating synchrotron radiation to star formation rates of galaxies. We implement our model in single cell numerical simulation of a parcel of gas with constant pressure boundary conditions and demonstrate its effect and potential. Then, the non-thermal pressure model is incorporated into RAMSES and hydrodynamic simulations of isolated galaxies with and without the non-thermal pressure model are presented and studied. Specifically, we demonstrate that the inclusion of realistic non-thermal pressure reduces the star formation rate by an order of magnitude and increases the gas depletion time by as much. We conclude that the non-thermal pressure can prolong the star formation epoch and achieve consistency with observations without invoking artificially strong stellar feedback., Comment: 18 pages, 14 figures, accepted to MNRAS. Updated to match final version

In order to represent the pressure dependent thermodynamic functions for phase diagram calculations, the thermal volume model extends the Swenson concept of thermal pressure which is independent of volume and varies linearly with temperature. The expressions for the thermodynamic potentials: enthalpy, Gibbs energy and their derivatives such as molar volume, thermal expansion and heat capacity are then deduced for non-magnetic solids. The phases considered are simple oxides and silicates of the Earth's lower mantle under high pressure and high temperature. As a practical application, the thermodynamic functions of periclase are calculated and compared with available experimental data. A good agreement is achieved.

We show that the X-ray emission observed towards the center of our Milky Way Galaxy is consistent with a strong (2.1 M ⊙ /yr) outflow powered by both cosmic-ray pressure and thermal-gas pressure. In addition, the inferred launch parameters of such an outflow seem consistent with conditions inferred in the central Milky Way and other galaxies (although it is not clear if a significant vertical magnetic field exists in the center of the Galaxy). We also show that in galaxies with cosmic-ray pressure, gas pressure, and a vertical magnetic field component, cosmic-ray pressure can yield outflows over a wider range of conditions.

Turbulent gas motion inside galaxy clusters provides a non-negligible non-thermal pressure support to the intracluster gas. If not corrected, it leads to a systematic bias in the estimation of cluster masses from X-ray and Sunyaev-Zel'dovich (SZ) observations assuming hydrostatic equilibrium, and affects interpretation of measurements of the SZ power spectrum and observations of cluster outskirts from ongoing and upcoming large cluster surveys. Recently, Shi & Komatsu developed an analytical model for predicting the radius, mass, and redshift dependence of the non-thermal pressure contributed by the kinetic random motions of intracluster gas sourced by the cluster mass growth. In this paper, we compare the predictions of this analytical model to a state-of-the-art cosmological hydrodynamics simulation. As different mass growth histories result in different non-thermal pressure, we perform the comparison on 65 simulated galaxy clusters on a cluster-by-cluster basis. We find an excellent agreement between the modelled and simulated non-thermal pressure profiles. Our results open up the possibility of using the analytical model to correct the systematic bias in the mass estimation of galaxy clusters. We also discuss tests of the physical picture underlying the evolution of intracluster non-thermal gas motions, as well as a way to further improve the analytical modeling, which may help achieve a unified understanding of non-thermal phenomena in galaxy clusters., 10 pages, 13 figures, accepted to MNRAS

Cosmological constraints from X-ray and microwave observations of galaxy clusters are subjected to systematic uncertainties. Non-thermal pressure support due to internal gas motions in galaxy clusters is one of the major sources of astrophysical uncertainties. Using a mass-limited sample of galaxy clusters from a high-resolution hydrodynamical cosmological simulation, we characterize the non-thermal pressure fraction profile and study its dependence on redshift, mass, and mass accretion rate. We find that the non-thermal pressure fraction profile is universal across redshift when galaxy cluster radii are defined with respect to the mean matter density of the universe instead of the commonly used critical density. We also find that the non-thermal pressure is predominantly radial, and the gas velocity anisotropy profile exhibits strong universality when galaxy cluster radii are defined with respect to the mean matter density of the universe. However, we find that the non-thermal pressure fraction is strongly dependent on the mass accretion rate of the galaxy cluster. We provide fitting formulae for the universal non-thermal pressure fraction and velocity anisotropy profiles of gas in galaxy clusters, which should be useful in modeling astrophysical uncertainties pertinent to using galaxy clusters as cosmological probes., 9 pages, 6 figures; Accepted by ApJ

While the pressureless dust assumption has been widely adopted in the standard model of cosmology, a quantitative estimate of the actual contribution of thermal pressure of the baryonic matter and the hot/cold dark matter to the dynamical evolution of the Universe has not yet been made in literature. In this paper we provide a simple scenario of how the solution, e.g. the age of the Universe, is affected by the inclusion of the thermal pressure of the baryon and dark matter particles.

I present and discuss a unified scheme for jet launching that is based on stochastic dissipation of the accretion disk kinetic energy, mainly via shock waves. In this scheme, termed thermally-launched jet model, the kinetic energy of the accreted mass is transferred to internal energy, e.g., heat or magnetic energy. The internal energy accelerates a small fraction of the accreted mass to high speeds and form jets. For example, thermal energy forms a pressure gradient that accelerates the gas. A second acceleration stage is possible wherein the primary outflow stretches magnetic field lines. The field lines then reconnect and accelerate small amount of mass to very high speeds. This double-stage acceleration process might form highly relativistic jets from black holes and neutron stars. The model predicts that detail analysis of accreting brown dwarfs that launch jets will show the mass accretion rate to be larger than 10^{-9}-10^{-8} Mo/year, which is higher than present claims in the literature., To appear in the proceedings of Star-disk interaction in young stars, Grenoble 2007, ed. J. Bouvier

We found equilibrium conditions for a self-gravitating toroidal vortex by taking into account thermal pressure. These conditions are shown to significantly differ from those for a disk and a sphere. The evolution of a thin vortex turns it into a compact vortex that loses mechanical stability for low masses at a polytropic index $\gamma < 4/3$ but retains stability for sufficiently high masses and densities determined by the velocity circulation in the vortex., Comment: 11 pages, 4 figures

We have used the Deep Survey telescope of EUVE to investigate shadows in the diffuse EUV/Soft X-Ray background cast by clouds in the interstellar medium. We confirm the existence of a shadow previously reported, and provide evidence for two new shadows. We used IRAS data to identify the clouds producing these shadows and to determine their optical depth to EUV radiation. The EUV-absorbing clouds are optically thick in the EUV, and all EUV emission detected in the direction of these shadows must be produced from material in front of the clouds. We obtained new optical data to determine the distance to these clouds. We use a new differential cloud technique to obtain the pressure of the interstellar medium. These results do not depend on any zero level calibration of the data. Our results provide evidence that the pressure of the hot interstellar gas is the same in three different directions in the local interstellar medium, and is at least 8 times higher than derived for the local cloud surrounding our Sun. This provides new evidence for large thermal pressure imbalances in the local ISM, and directly contradicts the basic assumption of thermal pressure equilibrium used in almost all present models of the interstellar medium., 13 pages, 13 figures

The merger of two neutron stars leaves behind a rapidly spinning hypermassive object whose survival is believed to depend on the maximum mass supported by the nuclear equation of state, angular momentum redistribution by (magneto-)rotational instabilities, and spindown by gravitational waves. The high temperatures (~5-40 MeV) prevailing in the merger remnant may provide thermal pressure support that could increase its maximum mass and, thus, its life on a neutrino-cooling timescale. We investigate the role of thermal pressure support in hypermassive merger remnants by computing sequences of spherically-symmetric and axisymmetric uniformly and differentially rotating equilibrium solutions to the general-relativistic stellar structure equations. Using a set of finite-temperature nuclear equations of state, we find that hot maximum-mass critically spinning configurations generally do not support larger baryonic masses than their cold counterparts. However, subcritically spinning configurations with mean density of less than a few times nuclear saturation density yield a significantly thermally enhanced mass. Even without decreasing the maximum mass, cooling and other forms of energy loss can drive the remnant to an unstable state. We infer secular instability by identifying approximate energy turning points in equilibrium sequences of constant baryonic mass parametrized by maximum density. Energy loss carries the remnant along the direction of decreasing gravitational mass and higher density until instability triggers collapse. Since configurations with more thermal pressure support are less compact and thus begin their evolution at a lower maximum density, they remain stable for longer periods after merger., 20 pages, 12 figures. Accepted for publication in ApJ

This is a review paper concerning the thermal pressure, PTH, of solids and the conditions under which it is independent of volume. When PTH is independent of V, the general equation of state (EoS) reduces from P(V,T)=P 1 (V,0)+P TH (V,T) to P(V,T)=P 1 (V,0)+P TH V 0 ,T , and thus is separated into two independent mathematical functions. P1(V,0) is the isothermal EoS. Four tests of thermoelastic data are shown to determine the T and V range in which PTH is independent of volume. Eighteen solids are examined. Most of these are minerals, but two metals, three alkali metals and three noble gases are also included. The focus is on three lower mantle minerals, MgSiO3, MgO, and CaSiO3. For these three minerals (∂PTH/∂V)T vanishes at conditions of the lower mantle, but PTH is a function of V at ambient conditions. However, for most solids, (∂PTH/∂V)T becomes zero at high temperature. The behavior of (∂PTH/∂V)T is apparently not correlated with such properties as crystal class, chemical composition, bonding type, and anharmonicity. The vanishing of (∂PTH/∂V)T is strictly a high temperature property of solids.

Statistical analysis of magnetic helicity spectra in the solar wind at 1 au is carried out. A large database of the solar wind intervals assembled from Wind spacecraft magnetic and plasma data is used. The effect of the electron thermal pressure on the wavenumber position of the helicity signature, i.e., the peak of the spectrum, is studied. The position shows a statistically significant dependence on both the electron and proton pressures. However, the strongest dependence is seen when the two pressures are summed. These findings confirm that the generation of the magnetic helicity is associated with an increasing compressibility of the turbulent fluctuations at smaller kinetic scales. It is argued that instrumental artifacts do not contribute to the helicity signature.

We present a spherically symmetric model for the origin and evolution of the temperature profiles in the hot plasma filling galaxy groups and clusters. We find that the gas in clusters is generically not isothermal, and that the temperature declines with radius at large distances from the cluster center (outside the core- and scale radii). This temperature profile is determined by the accretion history of the halo, and is not quantitatively well-described by a polytropic model. We explain quantitatively how the large-scale temperature gradient persists in spite of thermal conduction and convection. These results are a consequence of the cosmological assembly of clusters and cannot be reproduced with non-cosmological simulations of isolated halos. We show that the variation in halo assembly histories produces a ~10% scatter in temperature at fixed mass. On top of this scatter, conduction decreases the temperature of the gas near the scale radius in massive clusters, which may bias hydrostatic mass estimates inferred from x-ray and SZ observations. As an example application of our model profiles, we use mixing-length theory to estimate the turbulent pressure support created by the magnetothermal instability (MTI): in agreement with our earlier MHD simulations, we find that the convection produced by the MTI can provide ~5% non-thermal pressure support near r_500. The magnitude of this turbulent pressure support is likely to be non-monotonic in halo mass, peaking in ~10^14.5 M_sun halos., accepted for publication in MNRAS

We compare the gravitational potential profiles of the elliptical galaxies NGC 4486 (M87) and NGC 1399 (the central galaxy in the Fornax cluster) derived from X-ray and optical data. This comparison suggests that the combined contribution of cosmic rays, magnetic fields and micro-turbulence to the pressure is ~10% of the gas thermal pressure in the cores of NGC 1399 and M87, although the uncertainties in our model assumptions (e.g., spherical symmetry) are sufficiently large that the contribution could be consistent with zero. In the absence of any other form of non-thermal pressure support, these upper bounds translate into upper limits on the magnetic field of ~10-20 muG at a distance of 1'-2' from the centers of NGC1399 and M87. We show that these results are consistent with the current paradigm of cool cluster cores, based on the assumption that AGN activity regulates the thermal state of the gas by injecting energy into the intra-cluster medium. The limit of ~10-20% on the energy density in the form of relativistic protons applies not only to the current state of the gas, but essentially to the entire history of the intra-cluster medium, provided that cosmic ray protons evolve adiabatically and that their spatial diffusion is suppressed., Comment: Accepted for MNRAS. 19 pages; 14 figures; expanded version in response to comments from the referee

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 Δ = 500, we obtain 1 − MX/MWL = 0.01 ± 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 − MX/MWL = 0.09 ± 0.06 and −0.06 ± 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 MX and MWL as a function of increasing overdensity, MX/MWL = (0.908 ± 0.004) + (0.187 ± 0.010) · log10(Δ/500). We also examine the gas mass fractions, fgas = Mgas/MWL, 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., We acknowledge support from KICP in Chicago for hospitality, and thank our LoCuSS collaborators, especially Masahiro Takada and Keiichi Umetsu, for helpful comments on the manuscript. Y.Y.Z. thanks Massimo Meneghetti and Gabriel Pratt for useful discussion. Y.Y.Z. acknowledges support by the DFG through Emmy Noether Research Grant RE 1462/ 2, through Schwerpunkt Program 1177, and through project B6 “Gravitational Lensing and X-ray Emission by Non-Linear Structures” of Transregional Collaborative Research Centre TRR 33 The Dark Universe, and support by the German BMBF through the Verbundforschung under grant 50 OR 0601. This work is supported by a Grant-in-Aid for the COE Program “Exploring New Science by Bridging Particle-Matter Hierarchy” and G-COE Program “Weaving Science Web beyond Particle-Matter Hierarchy” in Tohoku University, funded by theMinistry of Education, Science, Sports and Culture of Japan. This work is, in part, supported by a Grant-in-Aid for Science Research in a Priority Area “Probing the Dark Energy through an Extremely Wide and Deep Survey with Subaru Telescope” (18072001) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. N.O. is, in part, supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (20740099). A.F. acknowledges support from BMBF/DLR under grant 50 OR 0207 and MPG, and was partially supported by a NASA grant NNX08AX46G to UMBC. G.P.S. acknowledges support from the Royal Society and STFC. D.P.M. acknowledges support provided by NASA through Hubble Fellowship grant HF-51259.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.

We numerically study the thermal pressure distribution in a gas with thermal properties similar to those of the cold neutral interstellar gas by analyzing three-dimensional hydrodynamic models in boxes with sides of 100 pc with turbulent compressible forcing at 50 pc and different Mach numbers. We find that at high pressures and for large Mach numbers, both the volume-weighted and the density-weighted distributions can be appropriately described by a log-normal distribution, whereas for small Mach numbers they are better described by a power law. Thermal pressure distributions resulting from similar simulations but with self-gravity differ only for low Mach numbers; in this case, they develop a high pressure tail.

The utility of large Sunyaev Zel'dovich (SZ) surveys for determining cosmological parameters from cluster abundances is limited by the theoretical uncertainties in the integrated SZ-flux-to-mass relation, Y-M. We explore how non-thermal pressure and the anisotropic shape of the gas distribution of the intracluster medium (ICM) impacts Y-M scaling using a suite of SPH simulations of the cosmic web. We contrast results for models with different treatments of entropy injection and transport, varying radiative cooling, star formation and accompanying supernova feedback, cosmic rays, and energetic feedback from active galactic nuclei (AGN). We find that the gas kinetic-to-thermal pressure ratio from internal bulk motions depends on the cluster mass, and increases in the outer-cluster due to enhanced substructure, as does the asphericity of the ICM gas. With only a ~5-10% correction to projected (observable) ellipticities, we can infer the 3D ellipticities. Our simulated Y-M-slope roughly follows the self-similar prediction, except for a steepening due to a deficit of gas in lower mass clusters at low redshift in our AGN-feedback simulations. AGN feedback enhances slightly the overall Y-M-scatter, from ~11% to ~13%, a reflection of accretion history variations due to cluster merging. If we split the cluster system into lower, middle and upper bands of both P_kin/P_th and long-to-short axis ratio, we find a ~10% effect on Y-M. Identifying observable second parameters related to internal bulk flows and anisotropy for cluster-selection to minimize Y-M scatter in a "fundamental plane" would allow tighter cosmological parameter constraints., Comment: To be submitted to ApJ, 22 pages, 22 figures

The central mass distribution of clusters of galaxies can be inferred from gravitationally lensed arcs with known redshifts. For the Abell cluster 2218, this method yields a core mass which is larger by a factor of $2.5 \pm 0.5$ than the value deduced from X-ray observations, under the assumptions that the gas is supported by thermal pressure and that the cluster is spherical. We show that a non-thermal pressure support is the most plausible explanation for this discrepancy. Such a pressure can be naturally provided by strong turbulence and equipartition magnetic fields ($\sim 50��$G) that are tangled on small spatial scales (, 12 pages, Postcript file

(Abridged) The main purpose of this paper is to consider the contribution of all three non-thermal components to total mass measurements of galaxy clusters: cosmic rays, turbulence and magnetic pressures. To estimate the thermal pressure we used public XMM-\textit{Newton} archival data of 5 Abell clusters. To describe the magnetic pressure, we assume a radial distribution for the magnetic field, $B(r) \propto \rho_{g}^{\alpha}$, to seek generality we assume $\alpha$ within the range of 0.5 to 0.9, as indicated by observations and numerical simulations. For the turbulent component, we assumed an isotropic pressure, $P_{\rm turb} = {1/3}\rho_{\rm g}(\sigma_{r}^{2}+\sigma_{t}^{2})$. We also consider the contribution of cosmic ray pressure, $P_{cr}\propto r^{-0.5}$. It follows that a consistent description for the non-thermal component could yield variation in mass estimates that vary from 10% up to $\sim$30%. We verified that in the inner parts of cool-core clusters the cosmic ray component is comparable to the magnetic pressure, while in non cool-core cluster the cosmic ray component is dominant. For cool-core clusters the magnetic pressure is the dominant component, contributing with more than 50% of total mass variation due to non-thermal pressure components. However, for non cool-core clusters, the major influence comes from the cosmic ray pressure that accounts with more than 80% of total mass variation due to non-thermal pressure effects. For our sample, the maximum influence of the turbulent component to total mass variation can be almost 20%. We show that this analysis can be regarded as a starting point for a more detailed and refined exploration of the influence of non-thermal pressure in the intra-cluster medium (ICM)., Comment: 14 pages, 4 figures, accepted for publication in A&A

Ground temperature, pressure and wind speed monthly averages in the area of the Italian Station at Terra Nova Bay, Antarctica, were analyzed for the period 1987–1991 by means of a network of nine AWS (automatic weather stations). Spatial configurations of temperature show a well-defined, relatively warm island in the area of Terra Nova Bay, between Drygalsky and Campbell ice tongues, throughout the year. A second warm island is present to the north along the coast, between Aviator and Mariner ice tongues, for most of the year. From February to March a rapid drop in temperature is observed at all stations. A strong thermal gradient develops during February, March, April and October, November, December, between the coastal region and inner highlands. The baric configuration follows the elevation of the area. Annual average pressure and temperature as functions of stations altitude show linear trends. Severe katabatic wind episodes are recorded at all stations, with wind speed exceeding 25 m s–1 and direction following the orographic features of the inner areas. Co-occurrences of these episodes were observed for stations located along stream lines of cold air drainage. The autocorrelation function of maximum wind speed time series shows wind persistence of 2–3 days and wind periodicity of about one week.

The density and temperature profiles of a planet's interior are calculated using a set of differential equations defining the major thermal and mechanical variables of a planet. One of these equations, the equation of state (EOS), is perhaps unique, because the density and volume effects are separated into two independent functions. The temperature-dependent part of the EOS is found from high-temperature properties measured on minerals at one atmosphere. The volume-dependent part of the EOS requires parameters determined by high-pressure experiments at room temperature. The density profile of the earth found from this relatively simple model matches the density profile determined from seismic models quite well. The temperature profile of the earth determined by this model agrees well with recently published temperature profiles. Temperature and density profiles of Mercury, Mars, and the Moon are found using assumed physical properties of the planets' outer mantles and using an assumed thickness of the planets' lithospheres.

We present a modelization of the non-thermal pressure, $P_{NT}$, and we apply it to the X-ray (and Sunayev-Zel'dovich) derived radial profiles of the X-COP galaxy clusters. We relate the amount of non-thermal pressure support to the hydrostatic bias, $b$, and speculate on how we can interpret this $P_{NT}$ in terms of the expected levels of turbulent velocity and magnetic fields. Current upper limits on the turbulent velocity in the intracluster plasma are used to build a distribution $\mathcal{N}(, Comment: 6 pages, 3 figures. Accepted for publication in A&A Letters

We use the MACSIS hydrodynamical simulations to estimate the extent of gas clumping in the intracluster medium of massive galaxy clusters and how it affects the hydrostatic mass bias. By comparing the clumping to the azimuthal scatter in the emission measure, an observational proxy, we find that they both increase with radius and are larger in higher-mass and dynamically perturbed systems. Similar trends are also seen for the azimuthal temperature scatter and non-thermal pressure fraction, both of which correlate with density fluctuations, with these values also increasing with redshift. However, in agreement with recent work, we find only a weak correlation between the clumping, or its proxies, and the hydrostatic mass bias. To reduce the effect of clumping in the projected profiles, we compute the azimuthal median following recent observational studies, and find this reduces the scatter in the bias. We also attempt to correct the cluster masses by using a non-thermal pressure term and find over-corrected mass estimates ($1-b=0.86$ to $1-b=1.15$) from 3D gas profiles but improved mass estimates ($1-b=0.75$ to $1-b=0.85$) from projected gas profiles, with the caveat of systematically increased scatter. We conclude that the cluster-averaged mass bias is minimised from applying a non-thermal pressure correction ($1-b=0.85$) with more modest reductions from selecting clusters that have low clumping ($1-b=0.79$) or are dynamically relaxed ($1-b=0.80$). However, the latter selection is most effective at minimising the scatter for individual objects. Such results can be tested with next generation X-ray missions equipped with high-resolution spectrometers such as Athena., Comment: 13 pages, 10 figures, accepted by MNRAS

We analyze the physical properties of gas in the circumgalactic medium (CGM) of 132 Milky Way (MW)-like central galaxies at $z=0$ from the cosmological magneto-hydrodynamical simulation TNG50, part of the IllustrisTNG project. The properties and abundance of CGM gas across the sample are diverse, and the fractional budgets of different phases (cold, warm, and hot), as well as neutral HI mass and metal mass, vary considerably. Over our stellar mass range of $10^{10.5} < M_\star / \rm{M}_\odot < 10^{10.9}$, radial profiles of gas physical properties from $0.15 < R\rm{ / R_{\rm 200c}} < 1.0$ reveal great CGM structural complexity, with significant variations both at fixed distance around individual galaxies, and across different galaxies. CGM gas is multi-phase: the distributions of density, temperature and entropy are all multimodal, while metallicity and thermal pressure distributions are unimodal; all are broad. We present predictions for magnetic fields in MW-like halos: a median field strength of $|B|\sim\,1μ$G in the inner halo decreases rapidly at larger distance, while magnetic pressure dominates over thermal pressure only within $\sim0.2 \times \rm{R_{200c}}$. Virial temperature gas at $\sim 10^6\,$K coexists with a sub-dominant cool, $< 10^5\,$K component in approximate pressure equilibrium. Finally, the physical properties of the CGM are tightly connected to the galactic star formation rate, in turn dependent on feedback from supermassive black holes (SMBHs). In TNG50, we find that energy from SMBH-driven kinetic winds generates high-velocity outflows ($\gtrsim 500-2000$ km/s), heats gas to super-virial temperatures ($> 10^{6.5-7}$ K), and regulates the net balance of inflows versus outflows in otherwise quasi-static gaseous halos., Minor typos fixed. Additional visuals at www.tng-project.org/ramesh22!

The circumgalactic medium (CGM) is often assumed to exist in or near hydrostatic equilibrium with the regulation of accretion and the effects of feedback treated as perturbations to a stable balance between gravity and thermal pressure. We investigate global hydrostatic equilibrium in the CGM using four highly-resolved $L^*$ galaxies from the Figuring Out Gas & Galaxies In Enzo (FOGGIE) project. The FOGGIE simulations were specifically targeted at fine spatial and mass resolution in the CGM ($\Delta x \lesssim 1$ kpc $h^{-1}$ and $M \simeq 200M_\odot$). We develop a new analysis framework that calculates the forces provided by thermal pressure gradients, turbulent pressure gradients, ram pressure gradients of large-scale radial bulk flows, centrifugal rotation, and gravity acting on the gas in the CGM. Thermal and turbulent pressure gradients vary strongly on scales of $\lesssim5$ kpc throughout the CGM. Thermal pressure gradients provide the main supporting force only beyond $\sim 0.25R_{200}$, or $\sim50$ kpc at $z=0$. Within $\sim0.25R_{200}$, turbulent pressure gradients and rotational support provide stronger forces than thermal pressure. More generally, we find that global equilibrium models are neither appropriate nor predictive for the small scales probed by absorption line observations of the CGM. Local conditions generally cannot be derived by assuming a global equilibrium, but an emergent global equilibrium balancing radially inward and outward forces is obtained when averaging over the non-equilibrium local conditions on large scales in space and time. Approximate hydrostatic equilibrium holds only at large distances from galaxies even when averaging out small-scale variations., Comment: 36 pages, 24 figures. Accepted to ApJ. See https://foggie.science/cgm_forces.html for animated Figures 6 and 7

The degree of turbulent pressure support by residual gas motions in galaxy clusters is not well known. Mass modelling of combined X-ray and Sunyaev Zel'dovich observations provides an estimate of turbulent pressure support in the outer regions of several galaxy clusters. Here, we test two different filtering techniques to disentangle bulk from turbulent motions in non-radiative high-resolution cosmological simulations of galaxy clusters using the cosmological hydro code ENZO. We find that the radial behavior of the ratio of non-thermal pressure to total gas pressure as a function of cluster-centric distance can be described by a simple polynomial function. The typical non-thermal pressure support in the centre of clusters is $\sim$5%, increasing to $\sim$15% in the outskirts, in line with the pressure excess found in recent X-ray observations. While the complex dynamics of the ICM makes it impossible to reconstruct a simple correlation between turbulent motions and hydrostatic bias, we find that a relation between them can be established using the median properties of a sample of objects. Moreover, we estimate the contribution of radial accelerations to the non-thermal pressure support and conclude that it decreases moving outwards from 40% (in the core) to 15% (in the cluster's outskirts). Adding this contribution to one provided by turbulence, we show that it might account for the entire observed hydrostatic bias in the innermost regions of the clusters, and for less than 80% of it at $r > 0.8 r_{200, m}$., 20 pages; 21 figures; Substantial Revision; MNRAS in press

A chain of events accompanying the occurrence of a substorm in the Earth’s ionosphere and magnetosphere is considered. Features of geomagnetic pulsations and mechanisms of their generation are indicated. Measurements of magnetic field fluctuations from fluxgate magnetometers, as well as the data on temperature, velocity, and concentration of electrons, and different types of ions from the PEACE and CIS-CODIF experiments of the Cluster-2 space mission, have been analyzed. It was found that a significant increase in temperature, velocity fluctuations, and concentration is observed during the initiation of a substorm that was accompanied by dipolarization (sharp change in the magnetic field configuration from the elongated tail-like force lines to a more dipole structure). A time delay in the heating of protons and oxygen ions, as well as in the concentration variations, was detected. The comparison of wave characteristics for different pressures was carried out using wavelet analysis. The magnetic field pressure, as well as dynamic and thermal pressure for different types of particles, was considered. Pc5 and strong Pc4 pulsations, as well as direct and inverse cascades, were observed in the fluctuations of the magnetic field pressure and thermal pressure of electrons and protons. The results point to a significant role of kinetic effects in the complex chain of processes in the Earth’s magnetosphere during the explosive phase of a substorm.

We present the properties of magnetic fields (B-fields) in two clumps (clump 1 and clump 2), located at the waist of the bipolar H II region Sh2-201, based on JCMT SCUBA-2/POL-2 observations of 850 $\mu$m polarized dust emission. We find that B-fields in the direction of the clumps are bent and compressed, showing bow-like morphologies, which we attribute to the feedback effect of the H II region on the surface of the clumps. Using the modified Davis-Chandrasekhar-Fermi method we estimate B-fields strengths of 266 $\mu$G and 65 $\mu$G for clump 1 and clump 2, respectively. From virial analyses and critical mass ratio estimates, we argue that clump 1 is gravitationally bound and could be undergoing collapse, whereas clump 2 is unbound and stable. We hypothesize that the interplay between thermal pressure imparted by the H II region, B-field morphologies, and the various internal pressures of the clumps (such as magnetic, turbulent, and gas thermal pressure), has the following consequences: (a) formation of clumps at the waist of the H II region; (b) progressive compression and enhancement of the B-fields in the clumps; (c) stronger B-fields will shield the clumps from erosion by the H II region and cause pressure equilibrium between the clumps and the H II region, thereby allowing expanding I-fronts to blow away from the filament ridge, forming bipolar H II regions; and (d) stronger B-fields and turbulence will be able to stabilize the clumps. A study of a larger sample of bipolar H II regions would help to determine whether our hypotheses are widely applicable., Comment: 25 pages, 10 figures, and 4 tables. Accepted for publication in ApJ

We constrain the cosmic ray (CR) population in the circumgalactic medium (CGM) of Milky Way by comparing the observations of absorption lines of OVIII ion with predictions from analytical models of CGM : precipitation (PP) and isothermal (IT) model. For a CGM in hydrostatic equilibrium, the introduction of CR suppresses thermal pressure, and affects the OVIII ion abundance. We explore the allowances given to the ratio of CR pressure to thermal pressure ($\rm{P}_{\rm{CR}}/\rm{P}_{\rm{th}}=\eta$), with varying boundary conditions, CGM mass content, photoionization by extragalactic ultraviolet background and temperature fluctuations. We find that the allowed maximum values of $\eta$ are : $\eta\lesssim10$ in the PP model and $\eta\lesssim6$ in the IT model. We also explore the spatial variation of $\eta$ : rising ($\eta=Ax$) or declining ($\eta=A/x$) with radius, where A is the normalization of the profiles. In particular, the models with declining ratio of CR to thermal pressure fare better than those with rising ratio with suitable temperature fluctuation (larger $\sigma_{\rm ln T}$ for PP and lower for IT). The declining profiles allow $A\lesssim8$ and $A\lesssim10$ in the case of IT and PP models, respectively, thereby accommodating a large value of $\eta \,(\simeq 200)$ in the central region, but not in the outer regions. These limits, combined with the limits derived from $\gamma$-ray and radio background, can be useful for building models of Milky Way CGM including CR population. However, the larger amount of CR can be packed in cold phase which may be one way to circumvent these constraints., Comment: 11 pages, 5 figures, 1 table Accepted for publication in ApJ on Apr 22, 2022

Context. Water photodissociation in the 114–143 nm UV range forms excited OH which emits at mid-infrared (MIR) wavelengths via highly excited rotational lines. These lines have only been detected with Spitzer in proto-planetary disks and shocks. Previous studies have shown that they are a unique diagnostic for water photodissociation. Thanks to its high sensitivity and angular resolution, the James Webb Space Telescope (JWST) could be able to detect them in other environments such as interstellar photodissociation regions (PDRs). Aims. Our goal is to predict OH MIR lines for a large range of thermal pressures and UV fields in PDRs. Methods. We use the Meudon PDR Code to compute the thermal and chemical structure of PDRs. In order to predict the emerging spectrum of OH, we amended the code to include prompt emission induced by H2O photodissociation between 114 and 143 nm. We performed a detailed study of the influence of thermal pressure (Pth/k = nHTK) and UV field strength on the integrated intensities and their detectability with the JWST. Results. OH MIR emission is predicted to originate very close to the H0/H2 transition and is directly proportional to the column density of water photodissociated in that layer. Because gas-phase neutral-neutral reactions forming water require relatively high temperatures (TK ≳ 300 K), the resulting OH MIR lines are primarily correlated with the temperature at this position, and are therefore brighter in regions with high pressure. This implies that these lines are predicted to be only detectable in strongly irradiated PDRs (G0incident > 103) with high thermal pressure (Pth/k ≳ 5x107 K cm–3). In the latter case, OH MIR lines are less dependent on the strength of the incident UV field. The detection of such lines in PDRs such as the Orion bar – which should be possible – is also investigated and we show that the line-to-continuum ratio could be a major limitation for detection because of instrumental limitations. Conclusions. OH MIR lines observable by JWST are a promising diagnostic for dense and strongly irradiated PDRs and proplyds. Their intensities are directly proportional to the amount of water photodissociated and they are therefore an indirect but sensitive probe of the gas temperature at the H0/H2 transition.

We combine the Santa-Cruz Semi-Analytic Model (SAM) for galaxy formation and evolution with the circumgalactic medium (CGM) model presented in Faerman et al. (2020) to explore the CGM properties of $L^{*}$ galaxies. We use the SAM to generate a sample of galaxies with halo masses similar to the Milky Way (MW) halo, $M_{\rm vir} \approx 10^{12}~{\rm M_{sun}}$, and find that the CGM mass and mean metallicity in the sample are correlated. We use the CGM masses and metallicities of the SAM galaxies as inputs for the FSM20 model, and vary the amount of non-thermal support. The density profiles in our models can be approximated by power-law functions with slopes in the range of $0.75 < a_n < 1.25$, with higher non-thermal pressure resulting in flatter distributions. We explore how the gas pressure, dispersion measure, OVI-OVIII column densities, and cooling rates behave with the gas distribution and total mass. We show that for CGM masses below $\sim 3 \times 10^{10}~{\rm M_{sun}}$, photoionization has a significant effect on the column densities of OVI and OVIII. The combination of different MW CGM observations favors models with similar fractions in thermal pressure, magnetic fields/cosmic rays, and turbulent support, and with $M_{\rm gas} \sim 3-10 \times 10^{10}~{\rm M_{sun}}$. The MW OVI column requires $t_{\rm cool}/t_{\rm dyn} \sim 4$, independent of the gas distribution. The AGN jet-driven heating rates in the SAM are enough to offset the CGM cooling, although exact balance is not required in star-forming galaxies. We provide predictions for the columns densities of additional metal ions - NV, NeVIII, and MgX., Submitted to ApJ. 19 pages, 15 figures (+ appendix)

Observations of the ICM in the outskirts of the Virgo cluster with Suzaku have found the gas mass fraction in the northern direction to be significantly above the expected level, indicating that there may be a very high level of gas clumping on small scales in this direction. Here, we explore the XMM-Newton data in the outskirts of Virgo, dividing it into a Voronoi tessellation to separate the bulk ICM component from the clumped ICM component. As the nearest galaxy cluster, Virgo's large angular extent allows the spatial scale of the tessellation to be much smaller than has been achieved using the same technique on intermediate redshift clusters, allowing us to probe gas clumping on the scales down to 5$\times$5 kpc. We find that the level of gas clumping in the outskirts to the north is relatively mild, ($\sqrt{C} < 1.1$), suggesting that our point-source detection procedure may have excluded a significant fraction of clumps. While correcting for clumping brings the gas mass fraction at $r_{200}$ into agreement with the universal gas mass fraction, the values outside $r_{200}$ remain significantly above it. This may suggest that non-thermal pressure support in the outskirts to the north is significant, and we find that a non-thermal pressure support at the level of 20 per cent of the total pressure outside $r_{200}$ can explain the high gas mass fraction to the north, which is in agreement with the range expected from simulations., 10 pages, 12 figures, 1 table. Accepted for publication in MNRAS

A certain appeal to the alpha model for turbulence and related viscosity in accretion disks was that one scales the Reynolds stresses simply on the thermal pressure, assuming that turbulence driven by a certain mechanism will attain a characteristic Mach number in its velocity fluctuations. Besides the notion that there are different mechanism driving turbulence and angular momentum transport in a disk, we also find that within a single instability mechanism, here the Vertical Shear Instability, stresses do not linearly scale with thermal pressure. Here we demonstrate in numerical simulations the effect of the gas temperature gradient and the thermal relaxation time on the average stresses generated in the non-linear stage of the instability. We find that the stresses scale with the square of the exponent of the radial temperature profile at least for a range of $d \log T /d \log R = [-0.5, -1]$, beyond which the pressure scale height varies too much over the simulation domain, to provide clear results. Stresses are also dependent on thermal relaxation times, provided they are longer than $10^{-3}$ orbital periods. The strong dependence of viscous transport of angular momentum on the local conditions in the disk (especially temperature, temperature gradient, and surface density/optical depth) challenges the ideas of viscosity leading to smooth density distributions, opening a route for structure (ring) formation and time variable mass accretion., Comment: 9 pages, 14 figures, accepted for publication in MNRAS

We present the detection of excited fine-structure energy levels of singly-ionized silicon and neutral carbon associated with the proximate damped Lyman-$\alpha$ system at $z_{\rm abs}=2.811$ towards \qso. This absorber has an apparent relative velocity that is inconsistent with the Hubble flow indicating motion along the line-of-sight towards the quasar, i.e., $z_{\rm abs}>z_{\rm em}$. We measure the metallicity of the system to be ${\rm [Zn/H]}=-0.68\pm 0.02$. Using the relative populations of the fine-structure levels of SiII and CI, as well as the populations of H$_2$ rotational levels, we constrain the physical conditions of the gas. We derive hydrogen number densities of $n_{\rm H}=190^{+70}_{-50}$ cm$^{-3}$ and $260^{+30}_{-20}$ cm$^{-3}$ in two velocity components where both CI and H$_2$ are detected. Taking into account the kinetic temperature in each component, $\sim 150$K, we infer high values of thermal pressure in the cold neutral medium probed by the observations. The strengths of the UV field in Draine's unit are $I_{\rm UV} = 10^{+5}_{-3}$ and $14^{+3}_{-3}$ in each of these two components, respectively. Such enhanced UV fluxes and thermal pressure compared to intervening DLAs are likely due to the proximity of the quasar. The typical size of the absorber is $\sim 10^4$ a.u. Assuming the UV flux is dominated by the quasar, we constrain the distance between the quasar and the absorber to be $\sim 150-200$ kpc. This favours a scenario where the absorption occurs in a companion galaxy located in the group where the quasar-host galaxy resides. This is in line with studies in emission that revealed the presence of several galaxies around the quasar., Comment: 11 pages, 5 figures, accepted for publication in MNRAS

Pressure balance plays a central role in models of the interstellar medium (ISM), but whether and how pressure balance is realized in a realistic multiphase ISM is not yet well understood. We address this question using a set of FIRE-2 cosmological zoom-in simulations of Milky Way-mass disk galaxies, in which a multiphase ISM is self-consistently shaped by gravity, cooling, and stellar feedback. We analyze how gravity determines the vertical pressure profile as well as how the total ISM pressure is partitioned between different phases and components (thermal, dispersion/turbulence, and bulk flows). We show that, on average and consistent with previous more idealized simulations, the total ISM pressure balances the weight of the overlying gas. Deviations from vertical pressure balance increase with increasing galactocentric radius and with decreasing averaging scale. The different phases are in rough total pressure equilibrium with one another, but with large deviations from thermal pressure equilibrium owing to kinetic support in the cold and warm phases, which dominate the total pressure near the midplane. Bulk flows (e.g., inflows and fountains) are important at a few disk scale heights, while thermal pressure from hot gas dominates at larger heights. Overall, the total midplane pressure is well-predicted by the weight of the disk gas, and we show that it also scales linearly with the star formation rate surface density (Sigma_SFR). These results support the notion that the Kennicutt-Schmidt relation arises because Sigma_SFR and the gas surface density (Sigma_g) are connected via the ISM midplane pressure., 22 pages, 16 figures, accepted in MNRAS

X-ray and microwave cluster scaling relations are immensely valuable for cosmological analysis. However, their power is limited by astrophysical systematics that bias mass estimates and introduce additional scatter. Turbulence injected into the intracluster medium via mass assembly contributes substantially to cluster non-thermal pressure support, a significant source of such uncertainties. We use an analytical model to compute the assembly-driven non-thermal pressure profiles of haloes based on Monte Carlo-generated accretion histories. We introduce a fitting function for the average non-thermal pressure fraction profile, which exhibits minimal dependence on redshift at fixed peak height. Using the model, we predict deviations from self-similarity and the intrinsic scatter in the Sunyaev--Zel'dovich effect observable-mass scaling relation ($Y_\mathrm{SZ}-M$) due solely to inter-cluster variation in mass accretion histories. We study the dependence of $Y_\mathrm{SZ}-M$ on aperture radius, cosmology, redshift, and mass limit. The model predicts $5-9\%$ scatter in $Y_\mathrm{SZ}-M$ at $z=0$, increasing as the aperture used to compute $Y_\mathrm{SZ}$ increases from $R_\mathrm{500c}$ to $5R_\mathrm{500c}$. The predicted scatter lies slightly below that of studies based on non-radiative hydro-simulations, illustrating that assembly history variance is likely responsible for a substantial fraction of scatter in $Y_\mathrm{SZ}-M$. This should be regarded as a lower bound, which will likely increase with the use of an updated gas density model that incorporates a more realistic response to halo assembly. As redshift increases, $Y_\mathrm{SZ}-M$ deviates more from self-similarity and scatter increases. We show that the $Y_\mathrm{SZ}-M$ residuals correlate strongly with the recent halo mass accretion rate, potentially providing an opportunity to infer the latter., Comment: 19 pages, 10 figures, accepted to MNRAS

Several earlier studies have attempted to estimate some of the thermodynamic properties of Coronal Mass Ejections (CMEs) either very close to the Sun or at 1 AU. In the present study, we attempt to extrapolate the internal thermodynamic properties of 2010 April 3 flux rope CME from near the Sun to 1 AU. For this purpose, we use the flux rope internal state (FRIS) model which is constrained by the kinematics of the CME. The kinematics of the CME is estimated using the \textit{STEREO}/COR and HI observations in combination with drag based model (DBM) of CME propagation. Using the FRIS model, we focus on estimating the polytropic index of the CME plasma, heating/cooling rate, entropy changing rate, Lorentz force and thermal pressure force acting inside the CME. Our study finds that the polytropic index of the selected CME ranges between 1.7 to 1.9. This implies that the CME is in the heat-releasing state (i.e., entropy loss) throughout its journey from the Sun to Earth. The hindering role of Lorentz force and contributing role of thermal pressure force in governing the expansion of the CME is also identified. On comparing the estimated properties of the CME flux rope from the FRIS model with the in situ observations of the CME taken at 1 AU, we find relevant discrepancies between the results predicted by the model and the observations. We outline the approximations made in our study of probing the internal state of the CME during its heliospheric evolution and discuss the possible causes of the observed discrepancies.

We propose a novel method to constrain the Milky Way (MW) mass $M_{\rm vir}$ with its corona temperature observations. For a given corona density profile, one can derive its temperature distribution assuming a generalized equilibrium model with non-thermal pressure support. While the derived temperature profile decreases substantially with radius, the X-ray-emission-weighted average temperature, which depends most sensitively on $M_{\rm vir}$, is quite uniform toward different sight lines, consistent with X-ray observations. For an Navarro-Frenk-White (NFW) total matter distribution, the corona density profile should be cored, and we constrain $M_{\rm vir}=(1.19$ - $2.95) \times 10^{12} M_{\rm sun}$. For a total matter distribution contributed by an NFW dark matter profile and central baryons, the corona density profile should be cuspy and $M_{\rm vir,dm}=(1.34$ - $5.44) \times 10^{12} M_{\rm sun}$. Non-thermal pressure support leads to even higher values of $M_{\rm vir}$, while a lower MW mass may be possible if the corona is accelerating outward. This method is independent of the total corona mass, its metallicity, and temperature at very large radii., Comment: Significantly revised version, accepted for publication in ApJ Letters. Discussions largely expanded. 7 pages, 4 figures

As cosmic structures form, matter density fluctuations collapse gravitationally and baryonic matter is shock-heated and thermalized. We therefore expect a connection between the mean gravitational potential energy density of collapsed halos, $\Omega_{W}^{\rm halo}$, and the mean thermal energy density of baryons, $\Omega_{\rm th}$. These quantities can be obtained using two fundamentally different estimates: we compute $\Omega_{W}^{\rm halo}$ using the theoretical framework of the halo model which is driven by dark matter statistics, and measure $\Omega_{\rm th}$ using the Sunyaev-Zeldovich (SZ) effect which probes the mean thermal pressure of baryons. First, we derive that, at the present time, about 90% of $\Omega_{W}^{\rm halo}$ originates from massive halos with $M>10^{13}\,M_\odot$. Then, using our measurements of the SZ background, we find that $\Omega_{\rm th}$ accounts for about 80% of the kinetic energy of the baryons available for pressure in halos at $z\lesssim 0.5$. This constrains the amount of non-thermal pressure, e.g., due to bulk and turbulent gas motion sourced by mass accretion, to be about $\Omega_{\rm non-th}\simeq 0.4\times 10^{-8}$ at $z=0$., Comment: 11 pages + references, 4 figures, 2 tables. (v2) Expanded discussion on the modelling uncertainty. (v3) Fixed a minor typo in Eq.(22). Accepted for publication in the Astrophysical Journal. Julia codes to reproduce the figures and tables are available in https://github.com/komatsu5147/OmegaGrav.jl