Analysis of the X-ray spectrum of the hot bubble of BD+30°3639

AbstractWe developed a model for wind-blown bubbles with temperature and density profiles based on self-similar solutions including thermal conduction. We constructed also heat-conduction bubbles with chemical discontinuities. The X-ray emission is computed using the well-documented CHIANTI code (v6.0.1). These bubble models are used to (re)analyse the high-resolution X-ray spectrum of the hot bubble of BD+30°3639, and they appeared to be much superior to constant temperature approaches.We found for the X-ray emission of BD+30°3639 that temperature-sensitive and abundance-sensitive line ratios computed on the basis of heat-conducting wind-blown bubbles and with abundances as found in the stellar photosphere/wind can only be reconciled with the observations if the hot bubble of BD+30°3639 is chemically stratified, i.e. if it contains also a small mass fraction (≃ 3 %) of hydrogen-rich matter immediately behind the conduction front. Neon appears to be strongly enriched, with a mass fraction of at least about 0.06.

Download Full-text

Hot bubbles of planetary nebulae with hydrogen-deficient winds

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832683 ◽

2018 ◽

Vol 620 ◽

pp. A98 ◽

Cited By ~ 3

Author(s):

R. Heller ◽

R. Jacob ◽

D. Schönberner ◽

M. Steffen

Keyword(s):

Chemical Composition ◽

High Resolution ◽

Thermal Conduction ◽

Thermal Structure ◽

Neutral Hydrogen ◽

Planetary Nebulae ◽

Chemical Compositions ◽

Heat Conducting ◽

X Ray ◽

Similar Solutions

Context. The first high-resolution X-ray spectroscopy of a planetary nebula, BD +30° 3639, opened the possibility to study plasma conditions and chemical compositions of X-ray emitting “hot” bubbles of planetary nebulae in much greater detail than before. Aims. We investigate (i) how diagnostic line ratios are influenced by the bubble’s thermal structure and chemical profile, (ii) whether the chemical composition inside the bubble of BD +30° 3639 is consistent with the hydrogen-poor composition of the stellar photosphere and wind, and (iii) whether hydrogen-rich nebular matter has already been added to the bubble of BD +30° 3639 by evaporation. Methods. We applied an analytical, one-dimensional (1D) model for wind-blown bubbles with temperature and density profiles based on self-similar solutions including thermal conduction. We also constructed heat-conduction bubbles with a chemical stratification. The X-ray emission was computed using the well-documented CHIANTI code. These bubble models are used to re-analyse the high-resolution X-ray spectrum from the hot bubble of BD +30° 3639. Results. We found that our 1D heat-conducting bubble models reproduce the observed line ratios much better than plasmas with single electron temperatures. In particular, all the temperature- and abundance-sensitive line ratios are consistent with BD +30° 3639 X-ray observations for (i) an intervening column density of neutral hydrogen, NH = 0.20-0.10+0.05 × 1022cm−2, (ii) a characteristic bubble X-ray temperature of TX = 1.8 ± 0.1 MK together with (iii) a very high neon mass fraction of about 0.05, virtually as high as that of oxygen. For lower values of NH, we cannot exclude the possibility that the hot bubble of BD +30° 3639 contains a small amount of “evaporated” (or mixed) hydrogen-rich nebular matter. Given the possible range of NH, the fraction of evaporated hydrogen-rich matter cannot exceed 3% of the bubble mass. Conclusions. The diffuse X-ray emission from BD +30° 3639 can be well explained by models of wind-blown bubbles with thermal conduction and a chemical composition equal to that of the hydrogen-poor and carbon-, oxygen-, and neon-rich stellar surface.

Download Full-text

From universal profiles to universal scaling laws in X-ray galaxy clusters

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038586 ◽

2020 ◽

Vol 644 ◽

pp. A111

Author(s):

S. Ettori ◽

L. Lovisari ◽

M. Sereno

Keyword(s):

Galaxy Clusters ◽

Mass Fraction ◽

Cold Dark Matter ◽

Scaling Laws ◽

Dark Matter Halo ◽

X Rays ◽

X Ray ◽

Radial Profiles ◽

Self Similar ◽

Physical Quantities

As the end products of the hierarchical process of cosmic structure formation, galaxy clusters present some predictable properties, like those mostly driven by gravity, and some others more affected by astrophysical dissipative processes that can be recovered from observations and that show remarkable universal behaviour once rescaled by halo mass and redshift. However, a consistent picture that links these universal radial profiles and the integrated values of the thermodynamical quantities of the intracluster medium, also quantifying the deviations from the standard self-similar gravity-driven scenario, has to be demonstrated. In this work we use a semi-analytic model based on a universal pressure profile in hydrostatic equilibrium within a cold dark matter halo with a defined relation between mass and concentration to reconstruct the scaling laws between the X-ray properties of galaxy clusters. We also quantify any deviation from the self-similar predictions in terms of temperature dependence of a few physical quantities such as the gas mass fraction, the relation between spectroscopic temperature and its global value, and, if present, the hydrostatic mass bias. This model allows us to reconstruct both the observed profiles and the scaling laws between integrated quantities. We use the Planck Early Sunyaev-Zeldovich sample, a Planck-selected sample of objects homogeneously analysed in X-rays, to calibrate the predicted scaling laws between gas mass, temperature, luminosity, and total mass. Our universal model reproduces well the observed thermodynamic properties and provides a way to interpret the observed deviations from the standard self-similar behaviour, also allowing us to define a framework to modify accordingly the characteristic physical quantities that renormalise the observed profiles. By combining these results with the constraints on the observed YSZ − T relation we show how we can quantify the level of gas clumping affecting the studied sample, estimate the clumping-free gas mass fraction, and suggest the average level of hydrostatic bias present.

Download Full-text

X-ray emission from hot gas in galaxy groups and clusters in simba

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2394 ◽

2020 ◽

Vol 498 (3) ◽

pp. 3061-3076

Author(s):

Dylan Robson ◽

Romeel Davé

Keyword(s):

Galaxy Formation ◽

Self Similarity ◽

Dominant Form ◽

Density Profiles ◽

X Ray ◽

Star Forming ◽

Galaxy Groups ◽

The Core ◽

Self Similar ◽

Electron Density Profiles

ABSTRACT We examine X-ray scaling relations for massive haloes ($M_{500}\gt 10^{12.3}\, \mathrm{M}_\odot$) in the simba galaxy formation simulation. The X-ray luminosity, LX versus M500 has power-law slopes ${\approx }\frac{5}{3}$ and ${\approx }\frac{8}{3}$ above and below $10^{13.5} \, \mathrm{M}_{\odot }$, deviating from the self-similarity increasingly to low masses. TX − M500 is self-similar above this mass, and slightly shallower below it. Comparing simba to observed TX scalings, we find that LX, LX-weighted [Fe/H], and entropies at 0.1R200 (S0.1) and R500 (S500) all match reasonably well. S500 − TX is consistent with self-similar expectations, but S0.1 − TX is shallower at lower TX, suggesting the dominant form of heating moves from gravitational shocks in the outskirts to non-gravitational feedback in the cores of smaller groups. simba matches observations of LX versus central galaxy stellar mass M*, predicting the additional trend that star-forming galaxies have higher LX(M*). Electron density profiles for $M_{500}\gt 10^{14}\, \mathrm{M}_\odot$ haloes show a ∼0.1R200 core, but the core is larger at lower masses. TX are reasonably matched to observations, but entropy profiles are too flat versus observations for intermediate-mass haloes, with Score ≈ 200–400 keV cm2. simba’s [Fe/H] profile matches observations in the core but overenriches larger radii. We demonstrate that Simba’s bipolar jet AGN feedback is most responsible for increasingly evacuating lower-mass haloes, but the profile comparisons suggest this may be too drastic in the inner regions.

Download Full-text

Oblique waves in steady supersonic flows of Bethe–Zel’dovich–Thompson fluids

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.633 ◽

2018 ◽

Vol 855 ◽

pp. 445-468 ◽

Cited By ~ 2

Author(s):

Davide Vimercati ◽

Alfred Kluwick ◽

Alberto Guardone

Keyword(s):

Classical Case ◽

Dynamic Regime ◽

Oblique Shock ◽

Heat Conducting ◽

Shock Adiabats ◽

Initial State ◽

Gas Dynamic ◽

Classical Gas ◽

Self Similar ◽

Similar Solutions

Steady self-similar solutions to the supersonic flow of Bethe–Zel’dovich–Thompson fluids past compressive and rarefactive ramps are derived. Inviscid, non-heat-conducting, non-reacting and single-phase vapour flow is assumed. For convex isentropes and shock adiabats in the pressure–specific volume plane (classical gas dynamic regime), the well-known oblique shock and centred Prandtl–Meyer fan occur at a compressive and rarefactive ramp, respectively. For non-convex isentropes and shock adiabats (non-classical gas dynamic regime), four additional wave configurations may possibly occur; these are composite waves in which a Prandtl–Meyer fan is adjacent up to two oblique shock waves. The steady two-dimensional counterparts of the wave curves defined for the one-dimensional Riemann problem are constructed. In the present context, such curves consist of all the possible states connected to a given initial state (namely, the uniform state upstream of the ramp/wedge) by means of a steady self-similar solution. In addition to the classical case, as many as six non-classical wave-curve configurations are singled out. Moreover, the necessary conditions leading to each type of wave curves are analysed and a map of the upstream states leading to each configuration is determined.

Download Full-text