Are X-ray clusters cooled by heat conduction to the surrounding intergalactic medium?

Loeb, Abraham

doi:10.1016/s1384-1076(02)00140-9

Cited by 31 publications

(42 citation statements)

References 37 publications

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“…The other sources of non-thermal pressure support in outskirts of the cluster (turbulence, magnetic field, and cosmic rays) would reduce the thermal SZ effect relative to the expectation, if these effects are not taken into account in modeling the intracluster medium. Heat conduction may also play some role in suppressing the gas pressure (Loeb 2002(Loeb , 2007.…”

Section: Discussionmentioning

confidence: 99%

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SEVEN-YEARWILKINSON MICROWAVE ANISOTROPY PROBE(WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION

Komatsu¹,

Smith²,

Dunkley³

et al. 2011

ApJS

7,534

471

6,400

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The combination of seven-year data from WMAP and improved astrophysical data rigorously tests the standard cosmological model and places new constraints on its basic parameters and extensions. By combining the WMAP data with the latest distance measurements from the baryon acoustic oscillations (BAO) in the distribution of galaxies and the Hubble constant (H 0 ) measurement, we determine the parameters of the simplest six-parameter ΛCDM model. The power-law index of the primordial power spectrum is n s = 0.968 ± 0.012 (68% CL) for this data combination, a measurement that excludes the Harrison-Zel'dovich-Peebles spectrum by 99.5% CL. The other parameters, including those beyond the minimal set, are also consistent with, and improved from, the five-year results. We find no convincing deviations from the minimal model. The seven-year temperature power spectrum gives a better determination of the third acoustic peak, which results in a better determination of the redshift of the matter-radiation equality epoch. Notable examples of improved parameters are the total mass of neutrinos, m ν < 0.58 eV (95% CL), and the effective number of neutrino species, N eff = 4.34 +0.86 −0.88 (68% CL), which benefit from better determinations of the third peak and H 0 . The limit on a constant dark energy equation of state parameter from WMAP+BAO+H 0 , without high-redshift Type Ia supernovae, is w = −1.10 ± 0.14 (68% CL). We detect the effect of primordial helium on the temperature power spectrum and provide a new test of big bang nucleosynthesis by measuring Y p = 0.326 ± 0.075 (68% CL). We detect, and show on the map for the first time, the tangential and radial polarization patterns around hot and cold spots of temperature fluctuations, an important test of physical processes at z = 1090 and the dominance of adiabatic scalar fluctuations. The seven-year polarization data have significantly improved: we now detect the temperature-E-mode polarization cross power spectrum at 21σ , compared with 13σ from the five-year data. With the seven-year temperature-B-mode cross power spectrum, the limit on a rotation of the polarization plane due to potential parity-violating effects has improved by 38% to Δα = −1.• 1 ± 1.• 4(statistical) ± 1.• 5(systematic) (68% CL). We report significant detections of the Sunyaev-Zel'dovich (SZ) effect at the locations of known clusters of galaxies. The measured SZ signal agrees well with the expected signal from the X-ray data on a cluster-by-cluster basis. However, it is a factor of 0.5-0.7 times the predictions from "universal profile" of Arnaud et al., analytical models, and hydrodynamical simulations. We find, for the first time in the SZ effect, a significant difference between the cooling-flow and non-cooling-flow clusters (or relaxed and non-relaxed clusters), which can explain some of the discrepancy. This lower amplitude is consistent with the lower-than-theoretically expected SZ power spectrum recently measured by the South Pole Telescope Collaboration.

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Section: Discussionmentioning

confidence: 99%

“…Following Section 3.6 of Komatsu et al (2009a), we focus on two physically motivated models for non-adiabatic fluctuations: axion type (Seckel & Turner 1985;Linde 1985Linde , 1991Turner & Wilczek 1991) and curvaton type (Linde & Mukhanov 1997;Moroi & Takahashi 2001, 2002Bartolo & Liddle 2002).…”

Section: Non-adiabaticity: Implications For Axionsmentioning

confidence: 99%

SEVEN-YEARWILKINSON MICROWAVE ANISOTROPY PROBE(WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION

Komatsu¹,

Smith²,

Dunkley³

et al. 2011

ApJS

7,534

471

6,400

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“…In real clusters with conductive heating, the energy for the cooling ultimately comes from gravity, and so the gas in the cluster must slowly settle in the gravitational potential. This effect would be accentuated by conduction to the outside, as discussed by Loeb (2002). We do not include gravitational settling in our model.…”

Section: The Modelmentioning

confidence: 99%

Models of Galaxy Clusters with Thermal Conduction

Zakamska

Narayan

2003

ApJ

214

305

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We present a simple model of hot gas in galaxy clusters, assuming hydrostatic equilibrium and energy balance between radiative cooling and thermal conduction. For five clusters, A1795, A1835, A2199, A2390, and RX J1347.5À1145, the model gives a good description of the observed radial profiles of electron density and temperature, provided that we take the thermal conductivity to be about 30% of the Spitzer conductivity. Since the required is consistent with the recent theoretical estimate of Narayan & Medvedev for a turbulent magnetized plasma, we consider a conduction-based equilibrium model to be viable for these clusters. We further show that the hot gas is thermally stable because of the presence of conduction. For five other clusters, A2052, A2597, Hydra A, Ser 159-03, and 3C 295, the model requires unphysically large values of to fit the data. These clusters must have some additional source of heat, possibly an active galactic nucleus, since all the clusters have strong radio galaxies at their centers. We suggest that thermal conduction, although not dominant in these clusters, may nevertheless play a significant role by preventing the gas from becoming thermally unstable.

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“…Significant evaporation would modify the baryon fraction in clusters and weaken the case for it having a universal value that can be used for cosmological distance determination [7,9,10,11,32]. The evaporation would also heat the gas in voids [13] and potentially change the Lyα absorption signature of voids in quasar spectra at low redshifts [14]. The fractional helium abundance in clusters should also increase as only hydrogen evaporates.…”

Section: Introductionmentioning

confidence: 99%

Thermal evaporation of gas from x-ray clusters

Loeb

2007

J. Cosmol. Astropart. Phys.

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A fraction of the thermal protons in the outer envelope of an X-ray cluster have velocities that exceed the local escape speed from the cluster gravitational potential. The Coulomb mean-freepath of these protons is larger than the virial radius of the cluster at temperatures 2.5keV. The resulting leakage of suprathermal particles generates a collisionless shock in neighboring voids and fills them with heat and magnetic fields. The momentum flux of suprathermal particles cannot be confined by magnetic tension at the typical field strength in the periphery of cluster halos (≪ µG). Over a Hubble time, thermal evaporation could drain up to a tenth of the cluster gas at its virial temperature. The evaporated fraction could increase dramatically if additional heat is deposited into the gas by cluster mergers, active galactic nuclei or supernovae. Thermal evaporation is not included in existing cosmological simulations since they are based on the fluid approximation. Measurements of the baryon mass fraction in the outer envelopes of hot clusters (through their Sunyaev-Zel'dovich effect or X-ray emission) can be used to empirically constrain their evaporation rate.

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Are X-ray clusters cooled by heat conduction to the surrounding intergalactic medium?

Cited by 31 publications

References 37 publications

SEVEN-YEARWILKINSON MICROWAVE ANISOTROPY PROBE(WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION

SEVEN-YEARWILKINSON MICROWAVE ANISOTROPY PROBE(WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION

Models of Galaxy Clusters with Thermal Conduction

Thermal evaporation of gas from x-ray clusters

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